March 14, 1961 A. B. HERRICK ET Al. 2,975,170 PROCESS FOR MANUFACTURING TERPENELESS ESSENTIAL OILS

Filed May 14, 1958 4.0

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SEPARATION OF TERPENES FROM OXYGENATED COMPOUNDS OF ESSENTIAL OIL OF PETITGRAIN (ELUTION WITH ALCOHOL AFTER ABSORPTION BY RUBBER)

Bale-14:? W ATTORNEY

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United States atent 0 " 1

2,975,170 PROCESS FOR MANUFACTURING TERPENELESS

ESSENTIAL OILS

Aaron 'Brown Herrick, Cedar Grove, and James R. Trow bridge, Glen Rock, N.J., assignors to Colgate-Palm

olive Company, New York, N.Y., a corporation of Delaware ~

Filed May 14, 1958, Ser. 'No. 735,213 7 Claims. (Cl. 260-2366)

This invention relates to a process for removing terpene hydrocarbons from essential oils. More particularly the invented process is one in which terpene hydrocarbons are preferentially absorbed from an essential oil by a'

I particulate solid material, terpeneless essential oil being obtained as the desired product. , The essential oils of commerce comprise a distinct

class of organic chemical mixtures found in nature. They include those liquid or near liquid mixtures of odoriferous compounds obtained by pressing, maceration, extraction, en?eurage or distillation of dried, ?owers, berries, fruits, nuts, seeds, rinds, leaves, stems, buds and roots from plants, trees, shrubs, vines and vegetables. These oils are generally pleasantly odoriferous and are of perceptible

' volatility at room temperature. Almost all of the essential oils contain a signi?cant

proportion of terpenes. In the cases of citrus oils, such as lemon, orange, grapefruit, lime and mandarin oils, to name a few, the terpenes constitute a major propor tion of the essential oil. Other oils, such as petitgrain (bigarade, Paraguayan, South American), bergamot, lavender, pirnenta berry, leaf, stem and bud clove oils, bay leaf, Sassafras and geranium, for examples, are com para-tively low in terpene content, having a minor pro portion, generally less than about 30% of such com pounds. ' 1 .

In some perfumery, cosmetic and ?avor applications of essential oils the terpene content performs a useful function and is a desirable constituent of the essential oil employed. However, there is a large number of products and applications in which the terpenes are either harmful or undesirable. , 1 ,

Terpenes are generally of lower solubility in aqueous or alcoholic compositions thanare the oxygenated com- ponents of the essential oils. In ?avors intended for vuse in aqueous mixture, solution oremulsion, the terpenes are often insu?iciently dispersible and usually rise to the top of the product, e.g., a soft drink. or fruit juice, and form an unsightly oily layer, often of unpleasant taste. The oxygenated constituents of the essential oils, which are much more readily- emulsi?ed or otherwise dispersed, do not give rise to this problem. Additionally, these essential oil constituents, such as alcohols, esters, ketones, ,. ,aldehydes, acids and others, contribute to the more de sirable perfume or ?avor note of the oils, and are not as strong, harsh or bitter as the terpenes. The terpenes are not of satisfactory stability for many Perfumery, and

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?avor applications and natural oils containing themtend ' to be oxidized causing the production of unwanted odors > and ?avors. The oxidationiof ,the?terpenes may some times result in products which very'se'riously detract from the value and utility of the essential oils. .

According to the present invention there is provided a process for removing terpenes from essential oils which comp'risescontacting'k an essential oil containing OdOI'lfr. erous compounds and terpenes with a solid absorbent. material of high surface/volume ratio, whichmaterial has a greater a?inity. for'the terpenes than for the odoriferous

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2,975,170 Patented Mar. 14, 1961\ 1C@ 2

compounds, and recovering essential oil from which terpenes have been'removed. ' \ , A'number of commercially important essential oils has

been listed above. The present process is applicable to! removal of terpene hydrocarbons from those oils but is not to be restricted thereto since it ?nds general use in removing terpenes and preparing terpeneless products from a wide variety of terpene-containing essential oils. By the term terpene it is meant those hydrocarbons of empirical formula C1oH16 and C15H24, the mono-terpenes and sesquiterpenes which are considered to be the major insoluble and unsuitable constituents of the essential oils. As examples of these compounds may be mentioned alpha and beta pinenes, myrcene, dipentene, ocimene, terpino lene, d-limonene, gamma-terpinene, phellandrene, thujene, sesquicitronellene, bisabolene, beta-caryophyllene and cadinene. Essential oils usually consist substantially of mixtures of the terpenes and several more oxygenated odoriferous compounds. In the present process the terpenes are removed from the other constituents of the essential oil due to the action of a solid absorbent, The solid material having a greater a?inity for the

terpene hydrocarbons than for the other odoriferous com ponents of the natural essential oils is one which perfer-. entially absorbs the terpenes. The mechanism oflthis absorption is apparently one in which the solid acts as a preferential solvent for the terpene molecules. Such ~ action is evidenced by the pronounced swelling of some absorbents when in contact with terpenes. For the sake of simplicity the term absorption will be employed in this speci?cation to denote the act-ionof the solid employed even though'adsorption may also take place. The solid will be characterized as an absorbent. P j k l

, The solid absorbent material has a high surface/ volume , ratio to promote intimate contact between essential oil' ~ and absorbent and thereby obtain high effectiveness of' the absorbent in separating terpenes from the oxygenated components of the essential oils. , To obtain a high sur- face/volume ratio the absorbent may be in ?ne particles ' or may be of larger size but of porous, perforated or_ ' spongy structure, possessing many intercornmunicating . voids or passageways through which essential oil solu- tion may ?ow and on and through thewalls of which terpenes may be absorbed. Whether the absorbent is in particulate or other useful form it is su?iciently form-'7 retaining to leave interstices adequate for passage of essential oil when the absorbent is packediin a column. Where the absorbent is controllably com- 1 pressible the sizes of interstices can be regulated by the ~ packing force applied, thereby resulting in a versatile column of various regulatable ?ow rates and degrees of absorbency. _ - - f = = '_ ' , -

It has been found that those absorbents which are non; '. a , polar exert a preferential a?inity for terpenes inessen- tial oils. ' Unlike the polar adsorbents, such as alumina, . silica gel, magnesia and so forth, the non-polar absorbents do not tend to react with the oils being processed and ._ '

do not preferentially sorb the oxygenated,odoriferouskv constituents. Among the non-polar absorbents highly; _ Q ' polymeric products,such asi-rubbers and non-polar'mem- - _ ~ ~ bers of the class commonly referred to as plasticsv are ' suitable in the present processes. 7These materials are , characterized as non-polar in this speci?cation although they are sometimes considered as being of low polarity when compared with the highly polar adsorbents'men' tioned above. Azfew examples of suitablejjpolymeri absorbents are processed natural rubber, prefer-ably only; slightly vulcanized, Buna S, neoprene and siliconerubbers Various plastics'may alsov be employed, such; as 7 vinyl chloride, polyvinylidene chloride, apolyethv other lower alkylene polymers, polystyrene, such as Dacron, and so'forthL Usually it'is preferable

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to use the softer, more elastorneric forms of these organic polymers, which often are more absorbent and have a greater a?inity for terpenes, but harder plastics may also be usefully employed providing that they are of sut?cient absorbency. -

Usually the polymeric absorbent is granulated or other wise reduced in size to particles having a maximum di ameter of about 0.1 inch. Generally, the ground ab sorbent should be no smaller than 0.001 inch in diameter. To facilitate regular ?ow without channelling the par ticles should be of about the same size. However, so long as the powdered solid is separable from the liquid media employed and su?ioient contact is obtained with the essential oil being treated sizes outside the range given may ?nd use. Grinding of the elastomeric polymers and the thermoplastic absorbents may be facilitated by lower ing the temperature of the absorbent before size reduc tion, as by chilling with Dry Ice. The particulate absorbent is preferably packed in a

container through which the natural essential oil can be passed. In this packed container the absorbent may be considered to act as if it were a multiplicity of plates in a distilling column, each successive layer of absorbent tending to hold back the ?ow of some of the terpene content of the feed to that layer. Thus, after passing the natural essential oil through a packed tower or column of polymeric non-polar absorbent the terpene has been stripped from the valuable odoriferous oxygenated com ponents of the oil. In many instances the terpene is so strongly 'attracted by the non-polar absorbent that a batch-type separation may be carried out successfully. This typeof process is especially applicable when the essential oil is comparatively low in terpene content. When the non-polar absorbent employed possesses some

adhesive properties particles thereof tend to be loosely held together and are sometimes removable from an absorption column as a unit. Providing that the com pacting of the absorbent is'not. so great as to make it into an impenetrable mass this light cementing action is of advantage because it promotes retention of the packing in position and diminishes settling of the ab sorbent during use. The resiliency of the non-polar pack ing also causes it to resist sifting.

If used as a sponge having interconnecting voids the resilient and elastomeric absorbents can be inserted and removed as a unit and, as previously mentioned, can be easily adjusted in solid/void ratio by regulated compres sion, giving various controllable ?ow rates and degrees of absorption. , Such unitary absorbents can be partially freed of terpenes and solvent after the deterpenation of essential oil, by squeezing, or alternate compression and relaxation of the sponge absorbent in a desorbing solvent. They are easier to handle during regenerative operations and require a minimum of effort to be re-set in the column for use in another absorption. The speed of flow of essentialoil through a column

of absorbent may be increased and the degree of contact with the absorbent may beirnproved by ?rst dissolving or dispersing the oil in a suitablesolvent or other liquid medium. The medium employed is one that is_at_ least comparatively polar in nature and preferably is strongly polar, comparable in polarity to methanol.

the lower aliphatic organic alcohols, e.g., methanol, etha no], isopropanol, although those of up to 6 carbonatoms are useful. The lower ketones, e.g.,' acetone, methyl ethyl ketone, ethyl ketone and the lower etherrs, e.g., ethyl ether, also usually having no more than 6 carbon atoms to the molecule, are useful solvents (in mixture with the lower alcohols. The lower ketones, ethers and other solvents of lower polarity than the lower aliphatic alcohols, such as chlorinatedhydrocarbons, aromatic ethers, lower esters and so forth, when employedalone do, not give satisfactory separations hof'terpenes. and the other constituents of essential oils by the present processes.

Of the sol-V vents which may be used included among the best are,

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4 Often these solvents can be usedif polarity is increased by mixing with lower alcohol or other suitable polar solvent. Addition of a small amount of water to solvents with which it is miscible also satisfactorily increases the polarity thereof and makes them useful in the present processes. Usually the water present in such adjusted solvents will be less than 5% but more may be used if it is miscible with the solvent and does not render insoluble the essential oil components.

Before contacting the solution of natural essential oil with the absorbent it is usually advantageous to wet the absorbent with polar solvent and displace air or other gas from the absorbing surface. The presence of gas bubbles within the absorbent interstices is generally un desirable since it both limits free ?ow of the liquid phase and diminishes the area of contact of absorbent with solution of essential oil. . The choice of solvent is to some extent dependent on

the character of the absorbent material itself, particularly its solubility. It has been found that the comparatively polar solvents usually do not dissolve or plasticize the elastomers or other polymeric absorbents and the various granules do not coalesce or adhere too strongly. On the other hand the relatively non-polar solvents, such as petroleum ether, and other hydrocarbons, either aliphatic or aromatic, tend to dissolve or fuse the usual non-polar absorbents, which action will make the column inoperative for the present processes. The oxygenated polar solvents aid in keeping the

odoriferous essential oil components in solution and un absorbed by the polymeric absorbent. Where some ab sorption has taken place, they assist in removal of these desired aromatic essences, allowing the terpenes to be held back by the absorbent. After the solution of essen tial oil in polar solvent has been brought into contact with a packed column of absorbent, additional solvent may be passed through the container to completely re move the oxygenated components of the oil. By flow of even more solvent the terpenes themselves can he re moved. '

The point of demarkation in the ?ow of desired oxy genated compounds and terpenes may be established by any suitable detection method. The effluent may be separated into 'a multiplicity of cuts which can later be analyzed and re-blended as desired. Alternatively, a chemical or physical test may be applied to the effluent to determine when the ?rst terpenes are removed from the column, at which point the separation of solution of desired essences from terpene solution is made. Prefer ably, the e?luent is passed through a continuous record ing refractometer and the desired oxygenated essences are collected as indicated by the variations in refractive index charted by this instrument. Other instruments, such as infrared and ultraviolet spectrometers; may be adapted to the described processes. In some instances it may also be advantageous to make separations of the

.various oxygenated components, e.g., alcohols from es ' ters and the described techniques lend themselves readily to such applications.

In a preferred embodiment of the invented process the essential oil employed contains a minor proportion of terpene hydrocarbon. Minor amounts of other hydrocar bons may also be present but the essential oil itself prefer ably possesses a major proportion of odoriferous oxy genated constituents. This natural oil is ?rst dissolved in a suf?cient amount of suitable polar solvent, selected because of its compatibility with the absorbent and solutes and its utility in improving the separation of terpenes from the desired components of the essential oil. The comparatively broad range of polarities of alcohols and mixed solvents previously described and their gradations

V of absorption characteristics assure the availability of a

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solvent. particularly adapted to et?ciently separate the essential oil-fractions.v After the absorbent has been se lectd'it may be slulrriedwith'a'polar solvent, usually the

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same as that employed to dissolve theessential oil, and then packed in a column or alternatively it may be wet down after packing. To allow for expansion of elas tomeric absorbents due to the swelling action of absorbed ' terpenes columns are packed loosely enough. to allow good ?ow throughout the process. The solution of oil is > the unwanted terpenes. allowed to pass through the container of absorbent and ' ef?uent is collected. Additional quantities of solvent are added and the ?ow through the column is maintained at a desirable rate. A continuously registering instrument for measuring physical characteristics is employed on the e?luent to ascertain when the desired separations have been effected and the e?iuent is collected accordingly. Afterward, if any terpenes remain on the column their desorption may be speeded by addition of a less polar solvent. ' The oxygenated essential oil constituents may be recovered from the polar solvent by careful dis-tilla tion or evaporation. In some instances they may be used directly as solvent solutions. For example, when ethanol is the solvent there will often be no need to re move it completely from the terpeneless oils useful in perfumery. The following example is given to'illustrate the in

vented process. It is typical of the sharpness of the sep arations obtained by this particular method of reverse phase partition chromatographic puri?cation of natural essential oils and must not be taken as limitative of the invention. All proportions in the example, speci?cation and claims are by weight unless otherwise indicated.

Example A quantity ofgum rubber (Davolbrand) was chilled

with Dry Ice and was ground to an average particle size of about 0.02 inch in diameter, as evidenced by the fact that it passed a 20 mesh U.S. sieve and'was partlyre tained by a 40' mesh U_.S. sieve. This powder was sub jected to a continuous extraction with methanol at 64 C. for a period of about 24 hours, 450 gramsof the extracted rubber powder, from which soluble plasticizers and lower polymers had been removed, were slurried in methanol and packed into a column of desired degree of , compression in a uniform absorbent bed 18 inches long and 2% inches in diameter. 5.1 grams of oil of petit grain (South American, like'Paraguayan). dissolved in 25 ~ milliliters of methanol were applied to the top of ,the column after which additional methanol was added, the entire process being conducted at about room tempera ture. The ?ow rate was regulated at one liter per hour and the e?luent was passed through a continuously recording differential refractometer of sensitivity of 4>

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sorbent alone the desorptive and regenerative processes necessary may have an adverse eifect on the oxygenated odoriferous compounds of the essential oil. The in vented process obviates the di?iculties of such unsatisfac tory techniques. The above invention has been described in conjunction

with an illustrative example and detailed descriptions of the invented process. It will be obvious to one skilled in the art that other variations and modi?cations of the invention can be made and equivalents can be substituted therein without departing from the principles revealed or being outside the purview of the claims or the process of the speci?cation. What is claimed is: 1. A process for removing terpenes from essential oils

which comprises contacting an essential oil containing odoriferous compounds and terpenes with a solid absorb ent material of high surface/volume ratio, which mate rial has a greater a?inity for the terpenes than for the odoriferous compounds, and recovering essential oil from which terpenes have been removed.

2. A process for removing terpenes from essential, oils which comprises contacting an essential oil containing odoriferous compounds and terpenes with a particulate solid absorbent material which has a greater a?inity for the terpenes than for the odoriferous compounds and recovering essential oil from which the terpenes have been removed.

3. A process for removing terpenes from essential oils which comprises contacting an essential oil containing odoriferous oxygenated compounds and terpenes with a comparatively non-polar particulate solid absorbent ma terial which has a greater af?nity for the terpenes than for the oxygenated compounds and contacting the mix ture of absorbent and essential oil with a comparatively polar solvent to remove the terpeneless odoriferous oxy genated compounds.

4. A process for removing terpenes from essential oils containing odoriferous oxygenated compounds which comprises contacting a mass of particulate non-polar polymeric solid absorbent material with a solution of terpene-containing essential oil in a comparatively polar solvent and subsequently contacting the absorbent with polar solvent to remove the odoriferous oxygenated compounds free of terpenes.

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8 5. A processpfor removing terpene hydrocarbons from

essential oils containing ,odoriferous oxygenated com pounds from the group consisting of'organic alcohols,

~ esters and mixtures thereof, which comprises mixing the essential oil with an organic polar solvent, adding the essential oil in such a solvent to a column of particulate non-polar highly polymeric solid absorbent material and ?owing through the column of absorbent containing es sential oil a suitable low molecular weight polar solvent to remove the odoriferous oxygenated compounds free of terpenes.

6. A process for removing undesirable terpene hydro carbons from essential oils containing oxygenated odor iferous compounds from the group consisting of higher organic alcohols, esters and mixtures thereof which com prises dissolving the essential oil in a suitable volatile organic alcohol of 1-3 carbon atoms, adding the solution of essential oil to a packed column of granular non~ polar highly polymeric solid absorbent material, ?ow ing through the column of absorbent containing essential oil a suitable volatile organic alcohol of 1-3 carbon atoms to remove the terpene-free oxygenated odoriferous compounds from the absorbent and then making a low temperature separation of solvent from the odoriferous terpene-free alcohol.

7. A process according to claim 5 in which the essen tial oil contains a minor proportion of terpene hydro carbons, the absorbent is a granulated rubber and meth anol is the solvent for the essential oil.

References Cited in the ?le of this patent UNITED STATES PATENTS

1,786,630 Reid ________________ __ Dec. 30, 1930 2,712,008 Kirchner et a1 _________ __ June 28, 1955

FOREIGN PATENTS 488,359 France _______________ __ May 7, 1917 977,373 France ______________ __ Dec. 17, 1948 619,545 France ______________ __ July 30, 1955

OTHER REFERENCES Plachenov et al.: Chem. Abs., vol. 48, p. 3638 (1954),

abstracting Zuhr. Priklad Khim., vol. 26, pp. 482-494 (1953).

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