Creosote  (1994)

Creosote comes from the Greek kréas, “flesh”, and sö’zö, “save”, “preserve”. Creosote products are mixed from the medium fractions obtained in the distillation of tar, to meet specifications of such physical parameters as density, water content and distillation fractions. These are often defined in various standards, geared to the various functional requirements traditionally maintained by the users.

Creosote can be made from both wood and coal tar. Wood tar is mostly used as such, and so output of wood tar creosote is very small. This type of creosote has a low boiling point and consists mainly of phenol, cresol and guaiacol.

Wood creosote is used for pharmaceutical purposes and for incense manufacturing, which as been going on for many years in Sweden.

Coal tar is above all a by-product from the coking plants of steel mills. Tars are also formed in such processes as production of town gas and domestic coke. Their chemical composition varies because different processes are used, e.g. with very different processing temperatures. This of course makes a difference to the substances included in the different distillates. Creosote is made from the distillates which have boiling points in excess of 200ºC. The distillation is discontinued at about 360ºC. The end point ends on the specifications of viscosity and softness of the residue, the coal tar pitch. The fractions distilled below 200ºC contain, for example, benzenes, toluene, xylene and phenol and are used as chemical raw materials or fuels.

The medium distillates are known, according to distillation interval, as naphthalene oils, middle oils, creosote oils, wash oils, anthracene oils and heavy oils, for example, and above all contain the substances which have boiling points within the distillation interval. Different manufacturers extract different numbers and widths of fractions, according to type of facility and customer requirements. Unfortunately, not only is roughly the same function called by a variety of names, but one and the same name can represent different fractions extracted in different distillation intervals, depending on trademark. One thing they all have in common, though, is that in the distillation interval they all mostly contain boiling hydrocarbons of aromatic type including 1% or so of every substance. Small amounts of all the other substances in the tar can also be found in every fraction. 

Naphthalene oils are distilled between 200ºC and 250ºC (the boiling point of naphthalene is 217ºC) and they can contain up to 60-65% naphthalene. This reaction can be used for extracting naphthalene. In addition to methyl naphthalenes they also contain indene and biphenyl, heterocyclic compounds like quinoline and lighter tar bases and tar acids like pyridine and phenol. About 50 different substances have been identified in this fraction.

Middle oils, creosote oils and wash oils are distilled at between 250ºC and 300ºC and contain various combinations of 2 aromatic rings and single alkyl groups, e.g. acenaphthene, dibenzophurane and methyl fluorenes.

The heavier distillates are called anthracene oil and/or heavy oil, the distillation interval is about 300-350ºC and, as the name implies, they can be used for anthracene extraction. These mostly include more or less conjugated systems of 3 and 4 aromatic rings, which, for example, in addition to anthracene, also include fluoranthene, pyrene, crysene and systems of hetero-atoms like carbazol. Conjugated 4-ring systems and heavier molecules mostly remain in the residue, pitch. The temperature at which the distillation is discontinued has a great influence on the chemical composition of the next lighter fraction.

The products known as creosote are mixed, then, from these fractions. Sometimes residual products from other processes in the plant, e.g. residual oils from the extraction of naphthalene or phenol, are also used in them. The result is an amber-coloured to black liquid, which is practically insoluble in water.

Creosotes are very widely used for impregnating wood. Another common use is to pyrolyse them to carbon black. A minor proportion is used for admixture to pitch and asphalt, to give them the right consistency for use, e.g. as road surfacing. Tar coal products also make good fuels; creosote has roughly the same boiling point as petroleum fuels like diesel and the lighter fuel oils.

No coal tar creosotes are manufactured in Sweden. Such creosote is imported for use as a wood impregnating agent.

ANTHRACENE

PRODUCT IDENTIFICATION

CAS NO. 120-12-7

EINECS NO. 204-371-1 FORMULA C14H10 MOL WT. 178.23 H.S. CODE 2902.90

TOXICITY

  SYNONYMS Paranaphthalene; Anthracen (German); Anthraxcene; DERIVATION coal tar

CLASSIFICATION

 

GENERAL DESCRIPTION

Anthracene is a tricyclic aromatic hydrocarbonn derived from coal tar; melts at 218°C,boils at 354°C, insoluble in water but is soluble in most organic solvents such as carbon disulfide, alcohols, benzene, chloroform, and hydronaphthalenes. Its molecular structure consists of three benzenelike rings joined side by side (the general formula CnH2n-18) and its oxidation yields anthraquinone, the parent substance of a large class of dyes and pigments.

PHYSICAL AND CHEMICAL PROPERTIES

PHYSICAL STATE White to yellow crystalline flakes with green fluorescence MELTING POINT 216 - 218 C BOILING POINT 340 C SPECIFIC GRAVITY 1.24 SOLUBILITY IN WATER Insoluble

SOLVENT SOLUBILITY

soluble in alcohols, benzene, Hydronaphthalenes, carbon disulfide, chloroform, and other organic solvents AUTOIGNITION

538 C

pH

 

VAPOR DENSITY 6.2 NFPA RATINGS Health: 1 Flammability: 1 Reactivity: 0 FLASH POINT

121 C

STABILITY Stable under ordinary conditions. Light sensitive.

APPLICATIONS

Anthracene is a basic subsance for production of anthraquinone, dyes, pigments, insecticides, wood preservatives and coating materials.

SALES SPECIFICATION

APPEARANCE

yellowish flakes

ASSAY

95.0% min

VOLATILE CONTENT 0.5% max TRANSPORTATION PACKING 25ks in bag. 1mt in bag HAZARD CLASS   UN NO.   OTHER INFORMATION European Hazard Symbols: XI, Risk Phrases: 36/37/38, Safety Phrases: 22/36

GENERAL DESCRIPTION OF PAHs

Polycyclic aromatic hydrocarbons (also called polynuclear hydrocarbons) have two or more single or fused aromatic rings if a pair of carbon atoms is shared between rings in their molecules. In particular, the term 'PAH' refers to the compounds consisting of only carbon and hydrogen atoms while the wider term 'polycyclic aromatic compounds' includes the alkyl-substituted derivatives and functional derivatives such as nitro- and hydroxy-PAH as well as the heterocyclic analogues, which contain one or more hetero atoms in the aromatic structure. PAHs exist in various combinations that manifest various functions such as light sensitivity, heat resistance, conductivity, emittability, corrosion resistance and physiological action. The simplest examples are naphthalene having two benzene rings side by side and biphenyl having two bond-connected benzene rings. PAHs are not found in synthetic products and are non-essential for the growth of living cells. The general characteristics of PAH describe high melting- and boiling-points (they are solid), low vapour pressure, and very low water solubility, decreasing with increasing molecular weight whereas resistance to oxidation, reduction, and vapourization increases. Vapour pressure tends to decrease with increasing molecular weight. PAHs are highly lipophilic and readily soluble in organic solvents. The lower molecular weight PAHs of 2 or 3 ring groups such as naphthalenes, fluorenes, phenanthrenes, and anthracenes have toxicity which tends to decrease with increasing molecular weight. PAHs are not synthesized chemically for industrial purposes but are isolated from concentrated coal-tar products (or from pyrolysis of coal hydrocarbons) followed by subsequent purification through repeated distillation and crystallization. Some PAHs such as naphthalene are also obtained from the concentration of the high boiling residual oil (and asphalt) derived from crude petroleum refinery processing. These PAHs are mostly used as intermediaries

in pharmaceuticals, agricultural products, photographic products, thermosetting plastics, lubricating materials, and other chemical industries. General uses are;

Acenaphthene: Intermediate for naphthalic acids, naphthalic anhydride (intermediate for pigments) and for acenaphthylene (intermediate for resins); Intermediate for dyes, soaps, pigments, pharmaceuticals, insecticide, fungicide, herbicide and plant growth hormones. It is used to manufacture plastics and as an agent for inducing polyploidy.

Acridine: Dye and pharmaceutical manufacturing Anthracene: Its oxidation yields anthraquinone, the parent substance of a

large class of dyes and pigments; .diluent for wood preservatives; scintillant (for detection of high-energy radiation)

Fluoranthene: manufacturing fluorescent and vat dyes, pharmaceuticals and agrochemicals.

Fluorene: basic subsance for production of dyes, pigments, pesticides, thermoset plstic and pharmaceuticals; manufacturing fluorenone (mild oxidizing agent)

Naphthalene: In the production of phthalic anhydride, carbaryl insecticide, beta-naphthol, tanning agents, moth repellent, and surfactants - naphthalene: main use: production of phthalic anhydride (intermediate for polyvinyl chloride plasticizers); also, production of azo dyes, surfactants and dispersants, tanning agents, carbaryl (insecticide), alkylnaphthalene solvents (for carbonless copy paper), and use without processing as a fumigant (moth repellent)

Phenanthrene: manufacturing phenanthrenequinone (intermediate for pesticides); manufacturing diphenic acid (intermediate for resins)

Pyrene: manufacturing perinon pigments Quinoline: solvent for resins & terpines; decarboxylation agent; parent

compound to make drugs, fungicides, biocides, alkaloids, dyes, rubber chemicals and flavoring agents

Precise PAHs, specific refined products are used also in the field of electronics, functional plastics and liquid crystals. Pharmaceutical and agricultural PAHs obtained coal tar are such materials as indole, indolizine, indene, quinoline, quinalidine, isoquinoline and their derivatives. High boiling-point special solvent are such materials as tetoralin, decaline, methyl-naphthalenes. Coumarins and dihydrocoumarins which can be obtained coal tar are PAHs used in perfumery. Thermosensitive paper sensitizer PAHs are such materials as p-benzylbiphenyl and ethylbiphenyl.