5261 5265.output

* GB785668 (A)

Description: GB785668 (A) ? 1957-10-30

Improvements in the separation of acetylene from gas mixtures

Description of GB785668 (A)

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DE1040171 (B) FR1140610 (A) NL102376 (C) DE1040171 (B) FR1140610 (A) NL102376 (C) less Translate this text into Tooltip

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

COMPLETE SPECIFICATION Improvements in the Separation of Acetylene from Casr Mixtures We, BADISCHE ANILIN & SODA-FABRIR AKTIENGESELLSCEAFT, a Joint Stock Company organised under the laws of Germany, of Ludwigshafen/Rhein, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- For the separation of acetylene from gas mixtures, in particular those which have been obtained by thermal or electrical cracking of hydrocarbons with or without oxygen, pro cesses are known according to which the acetylene is washed out from the gas mixture by a solvent. In order to be able to absorb the largest possible amounts of acetylene, this washing is carried out under increased pressure. If the gas is put under pressure, however, difficulties are encountered, chief among which are the following: black deposits will form on the

suction valves of the compressor and affect the functioning of the valves after some time; incrustations of more or less dark colour will form in the cooling devices of the compressor, reduce the cooling effect and even clog the condenser tubes after some time. These incrustations can only be removed by mechanical means. According to our knowledge these incrustations partly consist of polycyclic hydrocarbons, as for example naphthalene, beta-methylnaphthalene, acenaphthene, and acenaphthylene. The said shortcomings can be remedied by subjecting the gas to a pre-wash treatment with a solvent capable of absorbing the said contaminants. Thus, it has heretofore already been proposed to strip the gap of diacetylene with a solvent prior to compression. Wherever solvents have been used for a prewash of a gas, they have had to be stripped from the gas separately in order to be re-used in a cycle. We have now found that the separation of acetylene can be carried out in a simpler nanner while avoiding the said disadvantages md with only one solvent by working in two sllges, a smaller amount of the solvent being used in the first stage at atmospheric pressure or at the pressure at which the gas mixture is formed or slightly above the same, and a larger amount of the same solvent being used in the second stage at a higher pressure than in the first stage. The washing liquids are freed from the absorbed substances in the usual way by releasing the pressure and degas sing, preferably at elevated temperature and sub-atmospheric pressure, and used again for the washing. Since the same solvent is used in both stages, the working up of the laden washing liquids can be carried out together so that the process is simplified considerably. The washing in the two stages is preferably carried out at room temperature. In the first stage atmospheric or only slightly increased pressure, for instance up to 1.5 atmospheres, is used. The pressure is determined by the necessity that the temperature may not fall below the dew point of the said polycyclic hydrocarbons. A pressure inferior to one atmosphere absolute is also applicable, but a pressure below atmospheric pressure will preferably be avoided in practical operation in view of sucking in air and having to compress a mixture of acetylene and oxygen which might cause danger of explosion. If the acetylenecontaining gas has been obtained by a process which operates under pressure, the washing can be carried out at this pressure or a slightly higher pressure. In the second stage the pressure is higher; it may lie for example between about 8 and 30 atmospheres. The lower pressure limit is mainly dependent upan economic considerations, the quantities of solvent to be circulatedGbeing too large when employing

too low a pressure. The upper pressure limit is determined by the necessity for the partial pressure of the acetylene being not higher than that to which acetylene can be compressed without danger of explosion. The pressure limits, as a result, are also determined by the composition of the gas mixture, i.e. by the percentage of acetylenes. The amount of washing liquid which is necessary in the first stage is only a small frac tion of the washing liquid which is used in the main washing in the second stage. As a rule, for the preliminary washing in the first stage, less than 2% of the amount of washing agent used in the second stage is sufficient. The amount of solvent used in the first stage is preferably an amount just sufficient to recover substances harmful to high-pressure operation while absorbing only a small quantity of acetylene and a minor part of the diacetylene present in the gas mixture. Optimum quantities of solvent can be readily determined by simple experimentation. To obviate the said difficulties the said polycyclic hydrocarbons which melt at a temperature lying above that of the cooling water used; need only be washed out to such an extent that the temperature under the prevailing pressure conditions, does not fall below the dew point Solvents suitable in the practice of our invention are such organic solvents with a boiling point higher, for example, than 1500 C. and a high solvent power for acetylene, as are stable thermally and at least partially miscible with water, as for example butyrolactone and N-methylpyrrolidone. The separation of the acetylene from the laden washing liquid is effected in the usual way by releasing the pressure, for example to atmospheric pressure, and also by gassing out with the aid of pure acetylene, for example acetylene obtained from the process, and if desired by further gassing out at elevated temperature and/or at reduced pressure. It is advantageous to use several stages when degassing and to remove first the gases which have a lower solubility coefficient than acetylene. The washing liquid freed from acetylene is returned to the two washing stages. It is preferable to branch off a small portion and to remove therefrom, for example by distillation, the constituents absorbed thereby which are not separable by degassing. The washing liquid thus purified, if desired together with a part of the liquid which has only been degassed, is used for the preliminary washing in the first stage. The washing liquid withdrawn from the first stage, without previous gassing, can also be freed by distillation from the constituents not separable by degassing and returned to the two washing stages either alone or together with degassed washing liquid. The invention will now be described with reference to the accompanying

drawings which illustrate diagrammatically by way of example three embodiments of the process according to this invention. Similar parts are designated by similar letters in each of the drawings. Referring to Figure 1, an acetylene-containing gas mixture is led at atmospheric pressure through a pipe A into a washing tower B into which a solvent for acetylene is charged at the top through a pipe C. The solvent laden with impurities and some acetylene leaves the washing tower B through a pipe R which conducts it toward the degassing tower 0. The preliminary purified gas mixture is led from the tower B through a pipe D to a compressor Z from which it passes into a washing tower E. The bulk of the solvent for the acetylene is supplied to this tower through a pipe F. The laden washing liquid is withdrawn through a pipe H and led into a rectification tower I while being released from pressure through an expansion valve V. In this tower there takes place a separation of the gases dissolved in the washing liquid into pure acetylene which is withdrawn through a pipe M and gases with a smaller solubility coefficient than acetylene which escape through a pipe L and are supplied to the compressor Z. The washing liquid leaves the tower I through a pipe N and, after it has been combined with the washing liquid flowing from the preliminary washing tower B through the pipe R, passes to the degassing tower 0. From this the residual gas escapes through a pipe K and is led into the lower part of the rectification tower I. The constituents which have a higher solubility coefficient than acetylene escape from the degassing tower 0 through a pipe P. The washing liquid freed from acetylene and other readily soluble constituents leaves the degassing tower 0 through a pipe Q and passes through pipes F and C to the washing towers E and B. Figure 2 shows the same process but in which a part of the degassed washing liquid, leaving the degassing tower 0, is branched off, freed in the vessel S from substances having a low vapour pressure which therefore have not been removed by the degassing (these are withdrawn through a pipe U) and supplied through pipes T and C to the first washing stage B. The portion of the washing liquid which has only been degassed and which leaves the degassing tower 0 through the pipe Q, is led to the second washing stage E and partly to the first washing stage B. According to Figure 3, the washing liquid laden in the first washing stage is led through the pipe R, if desired together with a portion of the washing liquid leaving the degassing tower 0, to the treatment plant S and thence, after separation of the constituents not removable by gassing, to the washing stages E and

B together with the washing liquid which has only been degassed from the degassing tower 0. The following examples, given with reference to Figure 2, will further illustrate this invention but the invention is not restricted to these example. Parts are parts by weight unless otherwise specified. EXAMPLE 1. By incomplete combustion of methane a gs mixture is produced having the following avlr- age composition expressed as percentages by volume: Acetylene - - - - 8.15 C3H4-hydrocarbons - - 0.1 Diacetylene - - - - 0.12 Benzene - - - - - 0.03 Ethylene - - - - 0.3 Methane - - - - 4.1 Carbon dioxide - - - 3.5 Oxygen - - - - - 0.1 Carbon monoxide - - 26.0 Hydrogen - - - - 56.7 Nitrogen plus argon - - 0.9 In addition the mixture contains the following contaminants in grams per cubic metre: Phenylacetylene - - - 0.11 Naphthalene - - - 020 Acenaphthene - - - 0.04 Acenaphthylene - - - 0.06 Using a plant system as illustrated in Figure 2 of the accompanying diagrammatic drawing 100 cubic metres of the said gas is passed through line A into the pre-washer B at a pressure of 1.1 atmospheres absolute and a temperature of 19 C., 2 kilograms of butyrolactone being simultaneously fed in through line C. From line D a gas of the following average composition (expressed as percentages by volume) is withdrawn: Acetylene - - - - 8.14 C3H4-hydrocarbons - - 0.1 Diacetylene - - - - 0.11 Benzene - - - - 0.02 Ethylene - - - - 0.3 Methane - - - - 4.1 Carbon dioxide - - - 3.5 Oxygen - - - - - 0.1 Carbon monoxide - - 26.0 Hydrogen - - - - 56.73 Nitrogen plus argon - - 0.9

In addition the gas contains the following substances in grams per cubic metre : - Phenylacetylene - - - 0.09 Naphthalene circa - - 0.02 Acenaphthene - - - < 0.01 Acenaphthylene - - - < 0.01 As a result, about 10% of diacetylene, about 2030 % of benzene and phenylacetylene, about 90% of naphthalene and at least 9()% of acenaphthene and acenaphthylene have been removed. The pre-washed gas is compressed to a pressure of 9 atmospheres absolute in a compressor Z. The compressor and the condensers attached to it remain perfectly dean, apart from a faint film of carbon black, even after operation for weeks, while in the absence of a pre-wash stage deposits of carbon black and naphthalene will form after a few hours in the compressor and especially in the condensers resulting in a decrease in the efficiency of the compressor and the cooling effect of the condensers after a two weeks' operation. These deposits can only be removed by mechanical means The gas mixture compressed to 9 atmospheres absolute then passes to the scrubber E into which 1150 kilograms of butyrolactone are fed overhead through line F at a temperature of 23 C. Through line G 91 cubic metres of a gas having the following average composition in percentages by volume are with drawn: Acetylene - - - - 0.1 Ethylene - - - - 0.3 Methane - - - - 4.5 Carbon dioxide - - - 3.8 Oxygen - - - - - 0.1 Carbon monoxide - - 28.3 Hydrogen - - - - 61.8 Nitrogen plus argon - - 1.1 No polycyclic hydrocarbons and higher acety lenes can be identified. The washing agent laden with acetylene and part of the other constituents contained in the crude gas leaves the tower E through the pipe H and passes into the rectification tower I and thence through the pipe N into the degassing tower O where by heating to 100 C. and reducing the pressure to 0.2 atmosphere the dissolved gases are set free. The liberated gases pass through the pipe K into the lower end of the rectification column I in which they flow in countercurrent to the solvent. A part of the acetylene with the gases expelled from the solution leave the tower I through the pipe L and are supplied to the

suction side of the compressor Z. 7.9 cubic metres of acetylene which contains about 0.1% of C,H4-hydrocarbons less than .1% of carbon dioxide, less than 0.02% of diacetylene and less than 0.01% of benzene, are withdrawn through the pipe M. No polycyclic hydrocarbons can be identified The gas constituents of better solubility than acetylene escape from the degassing tower 0 through the pipe P. In the said gas, in addition to small quantities of acetylene, the following components are detected: Methylacetylene Relatively large proportions of : Diacetylene, Phenylacetylene, Naphthalene, Acenaphthene, and Acenaphthylene. The solvent which has been degassed in the degas sing tower O is for the most part returned to the washer B through the pipe Q while a smaller partial stream is subjected to a distillation in the tower S. The solvent distilled over, after condensation and cooling, is returned through the pipe T to the tower B and if desired supplemented by solvent from the pipe Q. The impurities incapable of distillation in the tower S are withdrawn through the pipe U. EXAMPLE 2. By incomplete combustion of methane a gas mixture of the following average composition in percentages by volume is produced : Acetylene - - - - - 8.65 C3H4-hydrocarbons - - - 0.1 Diacetylene - - - - - 0.17 Benzene - - - - - 0.08 Ethylene - - - - - 0.3 Methane - - - - - 5.2 Carbon dioxide - - - - 3.6 Oxygen - - - - - - 0.12 Carbon monoxide - - - - 24.9 Hydrogen - - - - - 55.8 Nitrogen plus argon - - - 1.1 In addition the mixture contains the following contaminants in grams per cubic metre: Phenylacetylene - - - - 0.21 Naphthalene - - - - - 0.36 Acenaphthene - - - - 0.10 Acenaphthylene - - - - 0.27 Pyrene - - - - - - 0.001 Using a plant system as illustrated in

Figure 2, 100 cubic metres of the said gas are passed through line A to the pre-washer B at a pressure of 1.05 atmospheres absolute and a temperature of 25 C., 4.9 kilograms of Nmerhylpyrrolidone being supplied through line C. The gas withdrawn from line D has the following average composition in percentages by volume: Acetylene - - - - - 8.63 C3H4-hydrocarbons - - 0.1 Diacetylene - - - - - 0.11 Benzene - - - - - - 0.06 Ethylene - - - - - 0.3 Methane - - - - - 5.2 Carbon dioxide - - - - 3.6 Oxygen - - - - - - 0.1 Carbon monoxide - - - - 24.9 Hydrogen - - - - - 55.9 Nitrogen plus argon - - - 1.1 In addition the mixture contains the following contaminants in grams per cubic metre: Phenylacetylene - - - - 0.15 Naphthalene - - - - - 0.03 Acenaphthene - - - - < 0.01 Acenaphthylene - - - - < 0.01 Pyrene - - - - - - not identifiable As a result, about 30% of diacetylene, of benzene and of phenylacetylene and about 90% of naphthalene, of acenaphthene and of acenaphthylene have been removed. The gas mixture is then compressed to 13 atmospheres absolute in the compressor Z. Both the compressor and the condensers attached thereto, apart from a faint film of carbon black, remain perfectly clean even after an operation for weeks. The compressed gas mixture is then scrubbed with 450 kilograms of N-methylpyrrolidone in the scrubber E. The result is substantially the same as that obtained in Example 1, except that 8.4 cubic metres of acetylene with about 0.1% of C,H4-hydrocarbons, less than 0.1% of carbon dioxide, less than 0.01% of diacetylene and less than 0.005 O of benzene are obtained. Specification No. 689,444 claims a process for the removal of acetylene from a gaseous mixture containing the same which consists in treating the mixture with an N-alkyl-1-pyrrolidone the alkyl radical of which is a-saturated hydrocarbon radical not containing more than 3 carbon atoms to absorb the acetylene. What we claim is: -

1. An improved process for the separation of acetylene from a gas mixture containing acetylene and obtained by cracking hydrocarbons which comprises washing said gas mixture in a first stage with an amount of solvent and at a sufficiently low pressure such that only a small quantity of acetylene and diacetylene is absorbed, and washing the gas from the first stage in a second stage with a larger amount of the same solvent and at a higher pressure than in the first stage so as to recover acetylene. 2. A process as claimed in Claim 1 wherein the pressure in the first stage is between about atmospheric to 1.5 atmospheres and the pressure in the second stage is between about 8 to 30 atmospheres. 3. A process as claimed in Claim 1 wherein the pressure in the first stage is of the same range as the pressure under which the acetylene-containing gas mixture has been obtained. 4. A process as claimed in any of Claims 1 to 3 wherein the amount of solvent employed in the first stage is less than 2 .. -' of the amount of solvent employed in the second stage. 5. A process as claimed in any of Claims 1 to 4 wherein the solvent employed is butyrolactone. 6. A process as claimed in any of Claims 1 to 4 wherein the solvent employed is methylpyrrolidone. 7. A process as claimed in any of Claims 1 to 6 wherein the solvent leaving each stage is freed from absorbed substances and reused for the washings. 8. A process as claimed in any of Claims 1 to 6 wherein the solvent leaving the second stage is freed from acetylene and is then combined with solvent from the first stage and the combined solvents are freed from other absorbed substances and reused for the washings. 9. A process as claimed in Claim 8 wherein the combined solvents from each stage are subjected to a degassing, at least part of the degassed solvent returned to the second stage washing, the remaining degassed solvent distilled to remove absorbed constituents not separable by degassing, and the distilled solvent returned to the first stage. 10. A process as claimed in Claim 1 which also comprises rectifying the solvent from the second stage to free pure acetylene, degassing the rectified solvent from the second stage, distilling at least part of the solvent from at least one of the two stages to free absorbed constituents not separable by gassing, and reusing

* GB785669 (A)

Description: GB785669 (A) ? 1957-10-30

Additive for high altitude brush

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PATENT SPECIFICATION 7859,669 Date of Application and filing Complete Specification: March 6, 1956. No 6943/56. Application made in United States of America on March 8, 1955. Complete Specification Published: Oct 30 1957. Index at acceptance:-Class 35, A 2 B 3. International Classification:-HO 2 k. COMPLETE SPECIFICATION Additive for High Altitude Brush We, UNION CARBIDE CORPORATION (formerly Union Carbide and Carbon Corporation), of 30, East 42nd Street, New York, State of New York, United States of America, a Corporation organised under the laws of the State of New York, United States of Amnerica, (Assignee of DIMITER RAMADANOFF), do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to brushes for the supply of electric current, and more particularly concerns long wearing commutator brushes which are suitable for use at conditions encountered at both sea level and at high altitudes. For sea level and high altitude applications, high altitude metal graphite brushes, such as high altitude copper-graphite brushes, have several desirable properties At a given current density and rubbing speed, the coppergraphite brushes generally operate with a lower icontact voltage drop and a lower temperature at a given load than high altitude electrographitic brushes The brush stock has low

electrical resistivity, which is helpful in cutting down power losses But coppergraphite brushes also have some disadvantages. They operate with high coefficient of friction than electrographitic brushes, and are sensitive to commutator or ring eccentricity Sometimes the combination of these two factors may intensify sparking, and even cause under some conditions, the release of small streamers at the trailing edges This may lead to undesirable ring wear Consequently, the conventional copper-graphite brushes are usually limited in their application. The conventional high altitude metal graphite brush containing approximately 25 per cent to 75 per cent copper, 10 per cent to, per cent graphite, 5 per cent to 25 per cent barium fluoride and a small amount of binder material has some unusually good properties as a high altitude brush For instance, a brush having a composition of about 75 per cent copper, 15 per cent graphite and 10 per cent barium fluoride has an electrical resistivity of 0.000008 ohms per cubic inch Its contact voltage drop of 0 35 volts with a current density of 180 amperes per square inch at an altitude of 40,000 feet above sea level is one of the lowest on record Such a brush grade has proven to commutate very well, and due to its barium fluoride content, has resisted dusting at altitudes up to 70,000 feet It is generally known that other alkali earth salts and oxides and those of the rare earth family also impart resistance to dusting under high altitude conditions However, a weakness possessed by this copper graphite brush is representative of the behavior of brushes falling within the above composition range is its short life under some conditions It has an average brush life of only 975 hours per inch at sea level, and, 510 hours per inch under simulated altitude conditions, at 40,000 feet. According to the present invention a coppergraphite electrical contact brush having improved wear resistance comprises a coppergraphite mixture containing 25 per icent to 75 per cent by weight of copper, 10 per cent to per cent gralphite and 5 per cent to 25 per cent by weight of barium fluoride, and an additive of boron nitride or an additive mixture of boron nitride with one or more of the following: lead, silver, or a coumatone indene resin, such additive or additive mixture being present in an amount between 0 5 per cent and 15 0 per cent by weight of the coppergraphite mixture. Table I lists the components of the preferred additive embodying the principles of the invention in percentage by weight of the copper-graphite mixture All percentage figures appearing anywhere in the description relate to percentages by weight. lPrice 3 s 6 d l 2785,669 TABLE I Composition, Per Cent Broad Range Preferred Range 1 Boron Nitride up to 5 % 0 5 % to 1 5 % 2 Silver up to 10 % 4 % to 6 % Boron Nitride up

to 5 % 0 5 % to 1 5 % 3 Lead up to 10 % 4 % to 6 % Boron Nitride up to 5 % 0 5 % to 1 5 % 4 Boron Nitride up to 5 % 0 5 % to 1 5 % Silver up to 10 % 4 % to 6 % Coumarone Indene Resin up to 5 % 2 % to 3 % The invention will be more fully understood from the following detailed description of typical examples of its use for prolonged brush life at sea level or high altitude iconditions. EXAMPLE I. The composition of a copper-graphite mixture containing 75 parts copper, 15 parts graphite, 10 parts barium fluoride and a small amount of binder material was modified by adding to it boron nitride powder in an amount equal to 1 per cent by weight of the mixture The said ingredients were then well mixed and molded at a pressure of 15 tons per square inch to a block of suitable size for making a commutator brush The blozk was then baked at 900 C by suitable heating means for a period sufficient to impart known and inherent brush characteristics. Table II, which follows the examples, sets forth the conditions and results of a number of typical tests wherein the brush was tested at sea level conditions, and at an altitude of 40,000 feet In these tests the brushes were subjected to a current density of 60 amperes per square inch at sea level, and current densities of 120 and 180 amperes per square inch at 40,000 feet altitude. EXAMPLE II. To a mixture having the composition of Example I containing 1 per cent boron nitride, was added 5 per cent metallic silver powyder. The mixture was formed into the shape -cif a commutator brush, and baked in the manner described in Example I to impart to it the requisite brush characteristics Table II sets forth the conditions and results of a number of typical tests. EXAMPLE III. To a mixture having the composition, of Example II containing 1 per cent boron nitride and 5 per cent silver, there was added coumarone indene resin in an amount equal to about 2 5 per cent of the metal-graphite mixture The mixture was then formed and baked in the manner previously described. Table II sets forth the conditions and results of a number of typical tests. The procedure used for testing the brushes in Examples I, II and III at sea level consisted in applying the brush to a machine having an operating speed of 6500 revolutions per minute and a rubbing speed of 5100 feet per minute A brush spring pressure of 7 1 pounds per square inch was used The current flow through the brush was adjusted to 40 amperes or a current density of about 120 amperes per square inch Tests were conducted in room air for a total of 20 hours or more

During that time readings were taken of contact voltage drop, brush temperature, and coefficient of friction At the end of the tests brush length was measured and brush life in hours per inch of wear was calculated All altitude tests were made on rotating copper rings. In similar fashion, a number of other brushes were tested, the compositions, operating conditions and properties being shown in Table 1 I. Additive 785,669 TABLE II Composition Cu C Ba F 2 BN Pb Ag Resin A 75 15 10 B 75 15 10 1 C 75 15 10 1 5 D 75 15 10 1 5 2 5 E 45 45 10 F 45 45 10 1 5 G 45 45 10 1 5 Conventional High Altitude Brush Composition Operating Properties Current Brush Coef of Density Contact Brush Life Friction Altitude Amps Per Drop Temp Hrs Per Against Brush in Feet Sq Ft Volts OC Inch Copper A 0 60 0 27 83 975 0 09 40,000 120-180 0 24-0 38 70-89 510 B 0 60 0 20 91 1470 0 11 40,000 120-180 0 38-0 48 72-102 807 C 0 60 0 13 99 1305 0 12 40,000 120-180 0 42-0 59 79-128 890 D 0 60 0 23 88 2360 0 07 40,000 120-180 0 54-0 76 106-147 930 E 0 120 0 85 143 2960 0 24 40,000 120 0 58 179 620 F 0 120 1 24 126 3616 0 13 40,000 120 1 00 158 2260 G 0 120 1 32 139 5790 0 15 40,000 120 1 12 185 2380 Conventional Brush Composition

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* GB785670 (A)

Description: GB785670 (A) ? 1957-10-30

Improvements in or relating to chemical compounds for use as x-raydiagnostic agentsand to processes for their preparation


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COMPLETE SPECIFICATION Improvements in or relating to Chemical Comlrounds for use as X-Ray Diagnostic Agents' and to processes for their preparation We, SCHERING CORPORATION, of 60, Orange Street, Bloomfield, New Jersey, United States of America, a corporation organized under the laws of the State of New Jersey, United Srates of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a new group of halogenated compounds which have important X-ray contrast properties. More particularly, this invention relates to new 5-acylaminopoly- iodoisophthalic acids, their salts and esters and to methods for preparing same. It is an object of this invention to provide derivatives of isophthalic acid containing a plurality of iodine atoms and possessing a relatively low toxicity as well as a substantial solubility in water in the form of their salts. It is a further object 6f this invention to provide for improved contrast media in X-ray diagnosis and to further provide improved X-ray contrast agents which are relatively stable under normal conditions of storage and use in the presence of body fluids. According to the present invention, it has been found that aliphatic-acylated-5-aminopolyiodoisophthalic acids, specifically, 5acetylamino - 2,4,6 - triiodo-isophthalic acid, possess many valuable properties. The compounds of the invention consist of the acids of the general formula: <img class="EMIRef" id="026598853-00010001" /> wherein R is H or lower acyl and n is 2 or 3, together with their non-toxic salts and esters. By ' lower acyl,' 'lower aliphatic ' and 'lower aLkyl ' in the Idescription and claims we mean groups containing not more than 7 carbon atoms. Some of the compounds of this invention are of value as X-ray contrast agents in uro

graphy when visualization of the kidneys is desired. Furthermore, under the proper tech niques it it possible to obtain visualization of the calyx and ureters. These panticular com pounds which are utilized as urographic agents when injected intravenously in the form of a solution of one of their pharmacologically acceptable salts, Isuch as the sodium salt, the diethanolamine salt, glucamine salts and other nonztoxic salts, are rapidly concentrated in the kidneys and are excreted in the urine. In addi tion, under the proper compression techniques whereby the diffusion rate of the injected compound throughout the blood stream is reduced, visualization of the calyx and ureters is made possible within 5 to 20 minutes after in jection. These aforementioned urographic properties appear to be peculiar to those compounds of the general formula which contain three iodine atoms, a lower acyl group on the amino-nitrogen atom and a free carboxylic acid group preferably in the form of its salt. For example, the formyl, acetyl and propionyl derivatives of the biiodinated acids of the general formula are excellent urograxphic agents, with the acetyl compound exhibiting the most desirable properties. As the number of carbon atoms in the acyl group is increased, there is an observable transitional change in the properties of the compounds. Specifically, the urographic utility decreases and the com pounds become better suited as cholecystographic agents. Esters of the acids of the general formula, especially those compounds containing three iodine atoms, provide for X-ray contrast agents useful in bronchography and hysterosalpingo- graphy. For these diagnostic methods the esters are used preferably in oil solution or sus pension. It is possible, however,- to employ salts of the acids for use in bronchography and hysterosalpiugography provided thickening agents such as methyl- cellulose, gelatin, dex- tran, and other acceptable agents are employed whereby proper concentration of the

radio- paque material is obtained with concomitant reduction in diffusion rate away from the site under examination. Thus it is seen that the compounds of this invention may be administered parenterally, orally or deposited at the site to be visualized. Depending upon the mode of administration, the compounds therefore are useful in urogenital, gynecological and gastrointestinal diagnoses. The compounds of the invention possess a favorable therapeutic ratio in that the dose: toxicity value is very small. It has been found that the intravenous toxicity of many of the compounds of this invention lie between 5 and 10 grams of substance per kilogram of body weight as compared with a maximum of 400 mg. per kilogram as an effective dose. Thus, these compounds can be utilized effectively as about ane-twentieth of the LD/50 dose. With 5-acetylamino - 2,4,6 - triiodo - isophthalic acid, as the preferred compound in the form of a pharmacologically acceptable soluble salt, excellent X-ray visualization is obtainable at a dose which is corn parable to other diagnostic agents in use. At the dose employed, there is a marked absence of side effects including venous spasm which is sometimes noted with iodinated acids of this type. Excretion urography is based upon parenteral administration, usually by intravenous injection, of a contrast agent which is then excreted bv the kidneys in such concentration that the kidneys and urinary tract are clearly outlined in a roentgenogram. As stated heretofore, a urogram may generally be taken within about five to twenty minutes after injection. It is generally known, however, that if normal renal function is impaired, sufficient medium may not concentrate in the kidneys until about one to nveny-four hours after injection. With 5 - acetylamino - 2,4,6 ,triiodo-isophthalic acid in solution as its sodium, or other therapeutically acceptable salt, generally about twenty millilitres of a 50% solution is sufficient for intravenous urography in adults. For children half the adult dose is generally sufficient Obviously the restriction of fluid for several hours prior to examination permits greater urinary concentration of the salt allowing for more clearly defined roentgenograms. It is not intended that the compounds of this invention be limited solely to urographic, cholecystographic and similar media since the properties of these compounds make them useful for many other purposes. As heretofore stated, visualization of the gastrointestipal tract is made possible by the proper administration of some of the compounds of this invention. In such an indication the compounds may for example be administered orally in the form of solutions, suspensions, tablets, capsules and the like. It is not even essential

that soluble salts be employed. Furthermore, the utility of these compounds is not recessarilv restricted to visualization of human organs since they are equally adaptable for X-ray visualization of other structures which cannot be visualized directly. The compounds of this invention may be prepared from 5-amino-isophthalic acid according to the following scheme: <img class="EMIRef" id="026598853-00020001" /> (The preparation of the requisite starting material 5-amino-isophthalic acid and its precursor Snitro-isophrhalic acid has been reported in the literature). In addition to the above scheme, amino-isophthalic acid in glacial acetic acid may be iodinated with iodine monochloride in acetic acid giving rise to a mixture of both monoiodo and diiodo-5-aminoisophthalic acid which are easily separable by fractional recrystallization. It is possible to carry out the reaction in such a manner so as to obtain a preponderance of the diiodo acid over monohalogenated substances. By employing an excess of iodine monochioride in hydrochloric acid it is possible to triiodinate the amino-isophthalic acid although one can stepwise iodinate whereby the intermediate monoor dihalogenated substance is isolated and subjected to further iodination. The jodinated amino acids are acylated with a suitable agent such as a carboxylic acid, carboxylic acid chloride or anhydride preferably in the presence of a trace of a strong mineral acid such as sulphuric acid. Specific examples of acylated agents which are envisaged as coming within the scope of this invention are formic acid, acetic acid, acetyl chloride, acetic anhydride, prop ionic anhydride, butyric anhydride and the like. Thus, although acetic anhydride is preferred because of its relative economy and availability, other lower aliphatic acylating agents may be employed. The salts and esters of these compounds are prepared by the usual methods employed in preparing salts and esters of organic acids. The following examples further illustrate but in no way limit the invention EXAMPLE I. Mono- and di-iodo-5-amino-isophthalic acid To a solution of 26.4 g. of iodine monochloride and 40 ml. glacial acetic acid is added a stirred suspension of 9 g. of 5-amino-iso- phalioacid in 160 ml. of acetic acid over a onehour period. After stirring for an additional hour, 200 ml. of water is added dropwise and the mixture is allowed to stand at room temerature for about 30 minutes. The mixture is heated on a steam bath at about 70" for about 40 minutes and then allowed to stand at room temperature overnight Excess iodine monochioride is destroyed bv the addition of sodium bisulfite solution and the acetic acid is removed by steam

distillation. Upon the addition of concentrated hydrochloric acid to the residue from the steam distillation there is obtained 10 g. of a mixture of iodmated acids melting at 270-2850 (dec.). The crude iodinated acid is recrystallized from 500 ml. of water yielding mono-iodo - 5 - aminoisophthalic acid, m.n. 293 (dec.). Upon the addition of concentrated hvdro- chloric acid to the recrystallization liauor, there is obtained about 5 . of diodo-5-amino- isonhthalic acid as a white microcrystalline solid, m.p. 308309 (dec.). EXAMPLE II. Diiodo-5-amino-isophthalic acid To a suspension of 9 g. of 5-amino-isophthalic acid in 1 liter of water there is added sufficient concentrated hydrochloric acid (about 15 ml.) to effect complete solution, To the solution is then added 26.7 g. of iodine monochioride and the reaction mixture is stirred at room temperature for three days. After removing a small amount of insolubles by filtration, the filtrate is treated with sodium hydrosulfite until the color indicative of excess iodine monochloride disanpears. The solution is then saturated with sodium chloride and extracted thoroughly with ether. The ether solution is dried with anhvdrous sodium sulfate and evaporated to a residue, yielding 14 g. of crude diiodo-5-amino-isophthalic add. The crude acid is purified by recrystallization from water using decolorizing charcoal land reprecinitated from the cooled filtrate by the addition of concentrated hydrochloric acid. EXAMPLE III. 2,4,6-Triiodo-5-amino-isophthalic acid To a solution of 4.5 g. of 5-amino-isophthalic acid in 250 ml. of water and 8.5 ml. of concentrated hydrochloric acid there is added 14 g. of iodine monochloride and the reaction mixture is allowed to stand for two days. After filtration of the insoluble material, the filtrate is treated with sodium hydrosulfite, saturated wtih sodium chloride iand extracted thoroughly with ether. The ether extracts are dried over anhydrous sodium sulfate and evaporated to a residue yielding 7.5 $ of the crude acid of this example, m.p. 270274 . Purification is effected by treating ia hot aqueous solution of the iodinated acid with charcoal and reprecipitating the product from the cold filtrate by the addition of concentrated hydrochloric acid, m.p. 278280 (dec.). EXAMPLE IV. Diiodo-5 -acetylamino-isophthalic acid A suspension of 4.3 g. of diiodo-5-aminb isophthalic acid in 12 ml. of acetic ainhydride is treated with 1-2 drops of concentrated sulfuric

acid and the mixture is refluxed for 30 minutes. After cooling, the mixture is poured into 60 ml. of water, neutralized with .5-1 g. of sodium acetate land evaporated to a residue iwz actt Recrystallization from water and the addition of concentrated hydrochloric acid yields 3 g. of the acetylamino compound of this example, m.p. over 340 EXAMPLE V. 2,4,6 Triiodo-5-acetylamWino isophthalic acid A suspension of 5 g. of 2,4,6-triiodo-5amino-isopht;halic acid in 15 ml. of acetic anhydride in the presence of 1-2 drops of sulphuric acrid is refluxed for 30 minutes. The crude acetylated acid ils obtained according to the procedure in the Preceding example. Purification is effected by solution in dilute ammo- opium hydroxide land treatment with decolorizing charcoal followed by filtration, cooling and reprecipitation with concentrated hydrochloric acid. Recrystallization from water as described in the preceding example yields the lodinated acid of this example, 3 g., m.p. above 340 . EXAMPLE VI. 2,4,6-Triiodo-5-formylamino-ibsophthalic lacid To a mixture of 50 g. of 2,4,6-triiodo-5amino-isophthalic acid and 500 ml. of 8790;% formic acid is added about dx drops of concentrated sulfuric acid and the resultant reaction mixture is heated and 'stirred on a steam bath for two hours. After cooling, the sulfuric acid is neutralized by the addition of a small amount of sodium acetate and the mixture is evaporated to a residue z zoo Upon recrystallization of the residue from water to which has been added concentrated hydrochloric acid, the formyl derivative of this example is obtained. EXAMPLE VII. 2,4,6-Triiodo5-propionylamino4sophthalic acid -A mixture of 25 g. of 2,4,6-triiodo-5-aminoisophthalic acid, 100 ml. of propionic anhydride and 3-4 drops of concentrated sulfuric aciil is stirred and heated at 125 to 1305 for approximately nvo hours. After cooling, 500 ml. of water is added and the resultant mixture is- stirred at room temperature until the excess propionic anhydride is completely hydrolyzed. Upon concentration of the aqueous solution in rra-IEo: there is obtained the crude propionylamino acid of this example which is purified by recrystallization from water as analogously described in Example III. EXAMPLE VIII 2,4,6-Triiodo-5-butyrylamino-isophthalic acid A mixture of 30 g. of 2,4,6-triiodo-5-amin- isophthalic acid, 100 ml. of butyric anhydride and about six drops of concentrated sulfuric acid is stirred and heated at 150 to 160 for about two hours. The excess anhydrIde is destroyed by the addition of 600 ml. of water as

described in the preceding example and the sulfuric acid is neutralized with sodium acetate. Upon evaporation of ithe resultant mixture - in scato, there is obtained a semi-solid residue which is dissolved in warm, dilute ammonium hydroxide. The alkaline solution is treated with decolorizing charcoal and the butyrylamino acid is reprecipitated by the addition of concentrated sulfuric acid and recrystallized - from water as heretofore described. EXAMPLE IX. 2,4,6-Triiodo-5-caproylamino-isophthalic acid A mixture of 55.9 g. of 2,4-,6-triiodo-5- aminoXisophthalic acid, 500 ml. of anhydrous toluene and 20 grams of caproyl chloride is stirred and refluxed for one hour. After cooling, the crude product is removed by filtration and triturated with ether to remove unacylated material. After decanting the ether layer, the remaining solid is recrystallized from aqueous ethanol affording the caproylamino acid of this example. EXAMPLE X. Diethyl 2,4,6-Triiodo-5-acetylamino isophthalate To a mixture of 50 grams of 2,4,6-triiodo5-acetylamino-isophthalic acid and 200 ml. of anhydrous ethanol is added 15 ml. of acetyl chloride. The reaction mixture is allowed to stand at room temperature overnight with occasional shaking whereupon it is diluted with one litre of water and the precipitate so formed is removed by filtration or decantation. The crude ester is dissolved in ether and the ether solution is washed, in turn, with sodium bicarbonate solution and water. After drying the ether solution with anhydrous sodium sulfate, the solvent is removed in eacuo. There is obtained the diethyl ester of this example which is purified by recrystallization from aqueous alcohol. Alternatively, the diethyl ester is prepared by treating a solution of 2,4,6 - triiodo - 5acetylamino-isophthalic acid in absolute ethanol containing a catalytic amount of sodium ethoxide with diethyl sulfate and isolating the ester in a known manner. In addition to the foregoing procedures the diethyl ester of this example is prepared by distilling an ethanol-benzene solution of the amino acid in the presence of 0.5 g. of ptoluene sulfonic acid (or 0.5 ml. of concentraced sulfuric acid) and azeotropically removing the water so formed. EXAMPLE XI. Disbdium sak of 2,4,6-triiedo-5-acetylamino- isophthalic acid A suspension of 5.58 grams of purified 2,4,6-triiodo-5-acetylamino isopfrthalic and (obtained in Example V) in 15 ml. of distilled water is neutralized with 30% aqueous sodium hydroxide until the pH rises

from 7 to 7.5. The alkaline solution is filtered and the filtrate is evaporated in vacua. Upon recrystallization of the residue from alcohol-ether, using decolorizing charcoal, six grams of the sodium salt of this example is obtained as a white crystalline solid. It is generally not necessary to isolate the sodium salt per se~if the appropriate quantities of amino acid, water, and alkali are used to yield a solution containing the desired concentration of sodium salt. EXAMPLE XII. Di-N-methylglucamine salt of 2,4,6-triiodo- 5-acetylatnino isophthalic acid To an intimate mixture of 4.67 grams of 2,4,6-triiodo - 5 - acetylamino-isophthalic acid and 3.03 grams of N-methylglucamine is added 4.0 ml.of distilled water and the mixture is stirred until complete solutionis effected. - - The solution is then diluted to 10 ml. with distilled water affording a 77% W/V solution which is comparable in iodine content to a 50% W/V solution of the sodium salt. Alternatively the di-N-methylglucamine salt is isolated by evaporation of the aqueous solution in vactro. EXAMPLE XIII. Di-diethanolamine salt of 2,4,6-triiodo-5 acetylamino isophthalic acid One mole of 2,4,6-triiodo-5-acetylamino- isophthalic acid and -two moles of diethanolamine are mixed and dissolved in water according to the procedure described in Example XII, giving rise to a similar W/V concentration Isolation of the salt is accomplished by evaporation of its aqueous solution in vacuo.


* GB785671 (A)

Description: GB785671 (A) ? 1957-10-30

Ozone manufacture

Description of GB785671 (A)

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FR1148901 (A) US2876188 (A) FR1148901 (A) US2876188 (A) less Translate this text into Tooltip



PATENT SPECIFICATION A A d, ' Date of Application and filing Complete Specification: March 19, 1956. No 8490/56. Application made in United States of America on March 21, 1955. Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 39 ( 1), I. International Classification:-HO 5 f. COMPLETE SPECIFICATION Ozone Manufacture We, AIR REDUCTION COMPANY, INCORPORATED, a corporation of the State of New York, United States of America, having an office at 60, East 42nd Street, New York 17, New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to the production of ozone from oxygen and more particularly concerns the use of a glow-type electrical discharge in such production. It has long been known that ozone has many potentially important uses, for example as a water purifying agent or as an oxidizer in chemical reactions The fact that ozone has not been more extensively used is due in large part to the unit cost of manufacturing ozone.

A basic factor in this cost is the low electrical power efficiences which are obtained with known ozone manufacturing processes The heat of formation of ozone is -34 4 kg cal. per mole or 04 kw hours per mole, but all known ozonizers have required five to twenty times this amount of energy to produce one mole of ozone In addition to low efficiency, high concentration ozone presents an additional problem in that power costs increase rapidly with slight increases in ozone concentration For instance, it is believed that conventional electrostatic ozonizers operate at an efficiency not exceeding 10 per cent at an ozone concentration of one weight per cent and not exceeding 4 per cent at an ozone concentration of 6 weight per cent, and that electrolytic processes have not exceeded 20 per cent efficiency at a maximum ozone concentration of 18 per cent by weight. It is the primary object of the instant invention to provide an improved method and apparatus for the production of ozone from oxygen. Another object is to provide means for producing liquid ozone from commercially-available oxygen. L Ptice 3 s 6 d l A further object is to produce ozone at a much higher electrical power efficiency than has been previously possible 50 The accomplishment of the above objects and others, along with features and advantages of the invention, will be apparent from the following description and the accompanying drawing in which: 55 Fig 1 is a flow sheet of the preferred form of the process of the invention and Fig 2 shows one form of ozonizer constructed in accordance with the invention and incorporating a U-tube which is immersed in 60 a liquid nitrogen bath. In its broad aspects, the present invention involves continually introducing oxygen at subatmospheric pressure into a glow-type electrical discharge ozonizer, converting oxygen to 65 ozone by such a discharge, and condensing the ozone on very cold ozonizer surfaces very rapidly after the ozone is formed The preferred operating conditions are such as to provide an optimum electron density in relation 70 to the molecular concentration of oxygen flowing through or into the ozonizer, an optimum oxygen density or gaseous mean free path and an optimum temperature In accordance with one form of construction the ozonizer includes 75 a small-diameter U-tube which is immersed in a quantity of liquid nitrogen The U-tube has electrodes at the top of each leg and is constructed to permit the flow of a gas therethrough and to provide for the suitable collec 80 tion of liquid ozone. Referring to the Fig 1 flow sheet, the oxygen supply 13 represents a source of oxygen, such as -commercial oxygen cylinders This supply is connected to an oxygen purification 85 device 15, such as a combustion

tube furnace which is originally packed with 12 gauge, pure copper elements The flow path next includes a trap 17 containing liquid oxygen for the removal of any carbon dioxide and water, 90 resulting from the purification in device 15 A rotameter 19 is connected to trap 17 The ozonizer 21 which converts oxygen to ozone receives oxygen from the rotameter 19 through 35.671 -i J 4 _ jc a valved conduit 23 The outlet of the ozonizer 21 is connected to conduit 25 which extends to a suitable valve 27 which is manipulated to provide communication with the conduit 29 in the normal flow path or with conduit 31 which serves for a purpose to be explained hereinafter Conduit 29 connects to a trap 33 containing liquid nitrogen The remaining two items in the flow path are a vacuum pump 35 and a meter 37 for measuring the effluent gas from the ozonizer A conduit 39 is connected to the outlet of meter 37 and serves to pass the effluent gas from the ozonizer to suitable oxygen recovery means (not shown) or other devices. The flow sheet also shows the means for determining the pressure in the ozonizer 21. This means includes conduit 41 having valve 43, a combustion tube furnace 45 and a pressure measuring device 47 which is connected to the furnace 45 by means of conduit 48. In Fig 2 the details of the ozonizer 21, which includes a U-tube, are shown The conduit 23 (leading from the rotameter 19 shown in Fig 1) is connected to the inlet tubing 51 of the ozonizer This tubing 51 branches at 53 and then joints tvo dip loops 55, 57 which connect to the U-tube 59 at locations just below the electrodes 61, 63 in the tops of each leg 65, 67 of the U-tube The dip loops 55, 57 serve to move the incoming oxygen into a cooling indirect heat exchange with the liquid nitrogen in container 69, which is represented by dashed lines and also serve to prevent electrical short circuit of the ozonizer which would occur if the oxygen inlets were joined to a short uncooled common oxygen source Any suitably insulated container, such as a Dewar flask, can be used for the liquid nitrogen. The electrodes 61, 63 are made from a commercially available, high purity aluminium. The annular space between the side of the electrodes and the interior surfaces of the adjacent portions of the legs 65, 67 is about 0 001 of an inch in width The electrodes are supplied with electricity, by tungsten leads 71, 73, from a neon-sign type of transformer (not shown) which is operated by 110 volt A C. supply Above the electrodes, two bleed-offs 75, 77, which provide for removal of heat from the electrodes, are connected to the upper part of the legs of the U-tube and extend to the conduit 25 leading to the vacuum pump above mentioned An effluent gas conduit 81 extends from the bottom 87 of the U-tube to the conduit 25 and also connected to

the bottom of the U-tube is a drain or exit conduit 83 which empties in a bulb 85 A pressure tap conduit 89 is connected to the U-tube near its junction with the effluent gas conduit 81 and extends to, and makes connection with, conduit 41 shown in Fig 1. The bleed-offs 75, 77 have an inside diameter of 0 5 millimeters The inside diameter of tube 25 is 30 millimeters The inside diameter of the U-tube legs 65, 67 the effluent gas conduit 81, and the tube 83 leading to bulb 85 from the bottom of the U-tube arc, respectively, 9 millimeters, 8 millimeters, and 6 millimeters The inside diameter of the pres 70 sure tap tube 89, which connects with conduit 41 shown in Fig 1, is 5 millimeters The interelectrode distance is about 19 inches. In operation, commercial-grade cylinder oxygen ( 99 6 per cent pure) containing as im 75 purities, principally argon with some nitrogen, from supply 13 is passed through the furnace which is operated at 1450 'F In the furnace, any trace of combustible hydrocarbon contaminants which may be in the oxygen are 80 burned to water and carbon dioxide The small amounts of water and carbon dioxide present in the oxygen are removed in the liquid oxygen trap 17 in which they solidify The purified gaseous oxygen is admitted, at a controlled 85 rate by the valve in conduit 23, to the previously evacuated ozonizer through the calibrated rotameter 19 A glow-type discharged is then initiated in the ozonizer 21 between the electrodes 61, 63 The ozonizer has been previ 90 ously cooled with liquid nitrogen The refrigerant level is maintained at a level one-quarter inch below the bottom level of the electrodes during the entire run Liquid ozone immediately condenses on the walls of the U-tube and 95 drains into the bulb or reservoir 85 The effluent gas, including the 0 4 per cent of other components, from the ozonizer flows through outlet 81 and conduit 25 to the downstream trap device 33 which is comprised of two 100 traps filled with glass wool and refrigerated at a temperature of 1960 C by liquid nitrogen. This effluent then passes through the vacuum pump 35 and the meter means 37 which is a wet gas meter From meter 37 the residual 105 effluent is passed through conduit 39 to recovery means (not shown) or otherwise disposed of. For determining the pressure adjacent the outlet of the ozonizer the gas is passed through 110 pressure tap 89, conduit 41, and valve or stopcock 43 to the combustion tube furnace 45 (shown in Fig 1) which is packed with pure copper wire and is operated at 1200 'F This furnace is installed as a safety device, serving 115 the dual purpose of preventing contamination of the system by the pressure measuring device 47 and of preventing small amounts of ozone from reaching the sensing element of the pressure gauge The pressure gauge which is pre 120 ferred is a commercial item which operates due to the ionization

of gas molecules by a radioactive source and the resulting ion current which is directly proportional to the number of ions collected in a given time The pressure of 125 synthetic rubber (Neoprene) in the sensing element of the pressure gauge necessitated the use of the furnace 45. The furnace 45 is typical of safety measures incorporated in the entire system Extreme pre 130 785,671 through the oxygen is derived from a currentlimiting type of transformer which is operated from an alternating current supply, for example a conventional 60 cycle, 110 volt supply. With the illustrated ozonizer in which the oxygen flows down each leg of the U-tube, it should be noted that the electrical discharge is used to full advantage since the more potent, ozone-producing part of the discharge alternates between electrodes in accordance with the alternating current Electrical measurements were made by a circuit which included a voltage divider and voltmeter for measuring the average secondary volts of a 10,000 volt neon sign transformer which is an un-enclosed core and coil type immersed in mineral oil. Peak voltages were measured by means of an electrostatic voltmeter The secondary current was measured by a milliameter and the secondary watt value was obtained by multiplying secondary current by the average secondary volts and using a power factor equal to unity. Per cent power efficiency was calculated as follows: cautions must be taken to prevent even a trace of combustible hydrocarbons from contaminating the ozone, since such contamination might cause detonation of the ozone. During operation, it is apparent that a very small flow of oxygen will move up past the electrodes 61, 63 and out of the U-tube through bleed offs 75, 77 which are of such construction (diameter and length) as to prevent electrical discharge therethrough between electrodes This small flow of oxygen past the electrodes, thus serves to remove heat It is to be noted that the electrodes are removed from the region where they could affect the ozone draining down the walls of the discharge vessel and that the maximum average distance for an ozone molecule to travel in order to contact a very cold surface is of the order of 4.5 mm A very important related feature is the very low temperature of the U-tube walls which is provided by the liquid nitrogen bath at -196 C This is significant because it serves to cause the removal of the ozone from the reaction and also it prevents decomposition of ozone by electrons It is noteworthy that at the boiling point temperature of liquid air (about 1910 C) the vapor pressure of ozone has been determined to be about 0 015 mm Hg while at the boiling point temperature of liquid nitrogen ( 1960 C), the corresponding vapor pressure is about 0 0035 mm Hg With prevailing

operating pressures, this factor is, of course, even more significant It is considered essential for satisfactory operation that the refrigerant bath be below 193 C and preferably at 1960 C. Since gaseous ozone is usually desired for commercial uses, the collected liquid ozone can be slowly evaporated by lowering, with suitable conventional means, the liquid nitrogen bath after the ozonizer's oxygen and electrical supplied are discontinued In this manner, the liquid ozone is slowly evaporated and escapes in gaseous state via valved conduit 31 for use in chemical reactions or other operations It is also possible to obtain the liquid ozone as such from the ozonizer by means of suitable conduits, valves, couplings, and containers, which can be connected to the ozone drain tube and would be suitably arranged with respect to the nitrogen container The transfer apparatus must be such that explosive impurities, such as hydrocarbons, do not contaminate the ozone With this arrangement, it is possible to continuously remove liquid ozone. The electricity for effecting the discharge Per cent Power Efficiency0.835 x ozone production rate (g/hr) x 100 secondary watts The value of 0 835 watts has been determined as the theoretical energy necessary to form one gram of ozone, based on 100 per cent conversion of electrical energy for supplying the 34 4 K cal per mole for ozone formation. The production rate was calculated by assuming the difference between oxygen in and oxygen out to be ozone The ozone condensed per unit time in other similar tests was measured by the liquid level rise in a calibrated tip or bulb at the bottom of the U-tube and it was established that the measured quantity in the present process was entirely ozone and was equivalent to the difference between the input and output of oxygen, as converted to ozone Gas conversion was calculated in the following manner: 2 in- 2 out x 100 =per cent gas conversion 02 in Data and results, based on the above calculation and obtained during the operation of the disclosed ozonization system shown in Fig. 1 and 2, are presented in the following table: 105 785,671 TABLE I Sec. Run Pri Volts No Volts Average Sec. Volts ESVM Sec I 2 Flow % % Gas (ma) (cc/min) P E Conv. 03 Sec. Pressure Production Volt (mm Hg) (gm/hr) Amps 1 30 2 30 3 30 4 35 37 6 39 5 7 39 5 8 40 9 40 42 11 45 12 45 13 45 14 45 45 16 45 17 45 18 48 19 50 50 21 50 22 50 23 50 24 50 885 829 985 1075 1010 1210 1210 1165 1175 1310 1165 1265 1110 1175 929 1300 1290 1545 1120 1558 1531 1531 1120 1540 1980 1830 2080 2320 2310 2500 2550 2490 2490 2680 2460 2640 2340 2450 2050 2630 2630 3050 2400 3040 3030 3050 2390 3050 2.9 3.3

2.4 3.3 3.8 3.9 3.9 4.1 4.1 4.3 5.9 5.5 6.4 6.1 7.05 5.6 5.3 4.6 7.5 5.3 5.3 5.3 7.3 5.3 23.5 13.8 2.6 48.5 53.5 68.5 68.5 68.5 68.5 83.5 83.5 93.5 73.5 83.5 33.5 2.0 93.5 123 5 83.5 138 5 133 5 133 5 83.5 5 37.4 22.95 7.8 50.5 47.4 52 52.3 53.1 50.4 48.5 48.6 46.9 44.8 46.4 27.1 1.96 48.4 48.9 45.2 49.6 50.2 51.9 43.7 49.7 59.7 64.8 52.8 52.2 50.2 50.4 52.8 49.7 45.8 57.2 50.0 61.7 56.8 75.3 50.6 39.3 63.6 42.1 42.6 45.1 61.2 41.7 0.23 0.125 0.054 395 53 58 67 59 655 49 58 19 058 67 97 535 984 935 88 515 1.18 0.752 0.223 2.15 2.39 2.94 2.96 3.04 2.91 3.28 4.01 3.92 3.81 3.98 2.12 1.171 3.97 4.16 4.55 4.9 4.88 5.06 4.29 4.85 2.56 2.735 2.36 3.55 4.21 4.72 4.72 4.78 7.82 5.64 6.88 6.96 7.1 7.17 6.55 7.28 6.84 7.1 8.4 8.25 8.13 8.13 8.16 8.15 586 302 not measurable 1.4 1.54 2.05 2.04 1.98 2.07 2.71 2.2 2.86 1.74 2.22 514 not measurable 2.83 4.5 38 4.88 4.59 4.47 1.99 4.74 02 Volume Out (liters/hr) 00 mthis form of the apparatus, it is to be noted that the oxygen is introduced at the midpoint between electrodes and then is subjected to electrical discharge as it flows up each leg, rather than down each leg as is illustrated 70 The residual gases are caused to move past the electrodes and out of the U-tube through conduits by means of a vacuum pump With this mode of operation, the residual gases tend to remove heat from the electrodes The level 75 of the liquid nitrogen bath was as previously described, as were all operating conditions and characteristics It is also feasible to make ozone, in accordance with features of the present invention, by using a U-tube in which 80 the oxygen is admitted at the top of one leg and a vacuum pump is connected to the top of the other leg, but efficiences will be somewhat lower. With reference to the ozonizers herein dis 85 closed, it is to be noted that the oxygen flowthrough in the ozonizers prevents the accumulation of gases, such as argon and nitrogen, which will not be condensed under the operating conditions and so interference with the 90 electrical discharge does not occur The residual gases, after ozone formation, are removed by the flow means such as conduit 81. It can be stated that another material which has been found suitable for the electrodes is 95 stainless steel. It is to be noted that it is essential that the oxygen be purified by means such as the copper oxide furnace 15 and that the entire system does not contain any source of oxidiz 100 able materials Thus, there is nothing in the oxygen, admitted to the ozonizer, which will trigger the decomposition of ozone and there is nothing in the system, such as rubber gaskets, which can contaminate the ozone 105 It is also to be noted that the geometry of the U-tube is such that the ozone drains away from the electrodes. In all ozonizers which were satisfactorily tested, it was apparent that for maximum 110 efficiency the ozone must have an adequate

condensing surface and must be refrigerated to at least 1930 C and preferably 1960 C. In most cases, the walls of the U-tube were refrigerated by liquid nitrogen at 1960 C so 115 that the ozone would be condensed rapidly after formation The subatmospheric pressure in the ozonizers is of the order of less than 1 millimeter Hg absolute. The space defined by the electrodes and the 120 condensing surface is referred to as a conversion zone. The term "glow-type discharge," as used herein, means the type of electrical discharge or flow of current in a gas which occurs in 125 a neon sign or a fluorescent lamp Glow discharges take place at low pressures (a few mm of mercury), as is briefly described in the texts, such as Sears' " Principles of Physics " ( 1947). Of course, it is to be appreciated that, due to 130 Other tests were made with the primary volts varying between 52 and 60 volts In general, somewhat higher average secondary currents, oxygen flows, and pressures resulted. Because of the voltage-current relationships of the discharge tube, it is necessary to use the above-mentioned current-limiting type transformer The secondary voltage output of this type of transformer is regulated in an inverse relation to its current capacity If the primary input of such a transformer is set at different voltages as shown in the above table, a series of curves may be plotted from the secondary electrical characteristics at various pressures in the discharge tube By reference to runs numbered 19 to 24 in the above table, it can be seen that the data, or a curve thereof, shows that the power efficiency rises to a maximum as pressure increases and then decreases somewhat with a further increase in pressure The point at which the secondary current is at a minimum at high pressure is called the " break off" point because the discharge cannot be maintained beyond this point It has been determined, as by runs 19 and 24, that the highest electrical efficiencies occur adjacent this " break-off " point It is apparent that this characteristic is a function of electron density, i e, ma/unit number of gas molecules Thus, it was determined that, with below atmospheric pressure which is adjusted in relation to the amount of current to give an electron density of between 6.0 and 8 5 milliamperes per millimeter mercury of pressure, very high electrical efficiencies are obtained Runs numbered 4, 5, 7, 10, 17, and 22 are runs which were made quite adjacent the " break-off " point and it is apparent the quotients of the given secondary milliamperes divided by the given pressures (in mm Hg) for these runs are within the range of 6 0 to 8 5. From the above data, it is also apparent that the best power efficiencies are obtained when between a 40 to 60 per cent gas

conversion occurs. From various tests, it was determined that the inside diameters of the U-tubes must be within the range of 5 to 12 millimeters or, stated differently, the opposed refrigerated wall segments of the conversion zone or chamber must be spaced between 5 and 12 millimeters apart In a flattened U-tube, such as was tested, it is apparent that most of the opposed wall segments would be closely spaced, in the range above mentioned This spacing feature, together with the low temperature provide for the rapid condensation of the ozone. In another design of an ozonizer which worked satisfactorily, the oxygen is fed to the bottom of the U-tube and then divides and flows up each leg of the U-tube The residual gas is removed from the top of each leg by conduits which are connected to the top of the U-tube legs, above the electrodes With 785,671 the conversion of oxygen to ozone, the ozonizers of the present invention differ from the neon sign discharge devices. As above suggested, it is to be understood that the elements of the entire flow path are so selected and constructed that there is substantially no possibility of oxidizable substances entering the system and reacting with the ozone Thus, the part of the system which may contaminate the ozone is maintained absolutely free of hydrocarbon substances which will react with ozone If it is found necessary to provide a seal, inert lubricants are used. It is to be noted that the positive column of the electrical discharge which produces most of the ozone alternates with the alternating current and hence ozone is made in equal amounts in each leg when split-feeding is used. Very important features of the above glowtype discharge process are the use of low temperature refrigeration and the wall spacing whereby it is possible to condense the ozone immediately after it is formed and hence the ozone-to-oxygen decomposition is prevented. From the foregoing, it is apparent that it has been discovered that the maximum electrical efficiency occurs adjacent the "breakoff" point, that is, the point at which the secondary current is at a minimum at relatively high pressure The discharge cannot be maintained beyond this point In the low pressure, low temperature glow-type discharge ozonizer of the invention, the " break-off " feature defines in practical terms the preferred operational condition which is involved in the highly complicated conversion of oxygen to ozone Thus, there are definite advantages in maintaining the quotient of the current in milliamperes divided by the unit number of oxygen molecules as indicated by the measurement of pressure in millimeters of mercury in the range of 6 5 to 8. From the above description, it is also apparent that means have been

provided for effecting the steps of, removing any nonoxygen components, such as argon and nitrogen, from the ozonization zone so that an effect on the electrical discharge will not result due to the concentration of argon, for instance, with the result that commercial-grade, highpurity oxygen as obtained by liquefaction and separation can be used Also means have been provided for cooling the oxygen to be introduced, as shown in the illustrated ozonizer. It is to be understood that this invention is not limited to the specific illustrative embodiment herein disclosed but includes such modifications as fall within the scope of the appended claims.


* GB785672 (A)

Description: GB785672 (A) ? 1957-10-30

Monoazo dyestuffs of the 2-hydroxy-3-naphthoic acid arylamide series




t PATENT SPECIFICATION 785,672 42 Date of Application and filing Complete Specification: March 28, 1956.

g E No 9739156. Application mode in Germany on March 30, 1955. Complete Specification Published: Ocr 30, 1957. Index at acceptance:-Class 2 ( 4), P 1 A 2 B 2 A, P 9 A 4 (B: C). International Classification:-C 09 b. CO 1 PLETE SPECIFICATION Monoazo Dyestuffs of the 2-Hydroxy-3-Naphthoic Acid Arylamide Series SPECIFICATION NO 785,672 The inventor of this invention in the sense of being the actual deviser thereof within the meaning of Section 16 of the Patents Act, 1949, Is Hans Raab, of Friedrich-Bayer-Strasse 10, Leverkasen-Bayerwerk, Germany, of German nationality. THE PATENT OFFICE, 2 oth November, 1957 CO.NH CONH 2 wherein R is an alkyl radical. The new azo dyestuffs are obtainable by coupling a diazotized 3-amino-4-alkoxy-1benzoyl-urea with 1-( 21,31-hvdroxvnaphthoylamnino)-2,4-dimethoxy-5-chlorobenzene The dyestuffs are especially suitable as red pigment dyes for dyeing and printing fibres, lacquers, resins and other materials The dyeings obtained thereby are distinguished by their good fastness to light, an excellent fastness to solvents and high brilliancy of shade. The following Example is given for the purpose of illustrating the invention: EXAMPLE. 15.2 Parts by weight of 3-amino-4-methoxy1-benzoyl-urea are stirred in 200 parts by volume of water and 30 parts by volume of hydrochloric acid ( 195 Be) and then diazotized, after an addition of 30 parts by weight of ice, with 16 7 parts by volume of 30 % sodium nitrite solution The diazo salt solution is filtered with the addition of active carbon. 28.8 Parts by weight of 1-( 21,31-hydroxylPrice 3 S 4 46 DB 00816/1 ( 6)13605 100 11157 R weight of a red pigment dye of good fastness to light and excellent fastness to solvents are 55 obtained. A dyestuff of similar properties is obtained if, instead of 15 2 parts by weight of 3-amino4-methoxy-1-benzoyl-urea, 16 2 parts by weight of 3-amino-4-ethoxy-1-benzoyl-urea are 60 used. The diazo components used in this Example are obtainable by treating a 3-nitro-4-alkoxy1-benzoyl-chloride with urea and reducing the nitro group in the acylated ureas thus obtained 65 The 3-Amino-4-methoxy-1-benzoyl-urea has a melting point of 308 C, and the 3-amino-4ethoxy-1-benzoyl-urea has a melting point of 3200 C.

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