Patented Aug. 20, 1940. 2,212,141

UNITED STATES PATENT OFFICE 2,212,141 ESTERS AND THEIR PREPARATION Van Vernon Alderman, Arden, and Merlin Martin Brubaker and William Edward Hanford, Wil mington, Del, assignors to E. I. du Pont de Nemours & Company, Wilmington, Del, a cor poration of Delaware No Drawing. Application April 11, 1939, Seria No. 267,336 4. Clains. (C. 260-455) This invention relates to esters and their prep or other basic catalyst, preferably one soluble aration and more particularly to esters of hy in the reaction mixture, is of advantage. droxythiols. Certain of the simpler reactions involved are This invention has as an object the provision indicated below: 5 of a new process for the preparation of esters of hydroxythiols. A further object comprises cer (a) tain new classes of esters thus produced. Other R1-CH CO-Rs objects will appear hereinafter. Ys+o? -R-CO-O-CER-CEIRS-CO-R These objects are accomplished by the follow R-CH Yoo-R O ing invention wherein an ethylene sulfide is re O acted with an interanhydride of an organic (b) carboxylic acid. R-CE The term “ethylene sulfide' or the term "a- y Ys+Rico-x-Roos CHR-CHRX), alkylene sulfide' designates a compound contain RCE 5 ing the grouping (c) 15 R-H co, y s+yo R--CHR-CHR-8-co-R-co-o), The term “interanhydride' designates a COm R2-CE CO 20 pound derived or to be regarded as derived either wherein R, R are hydrogen or monovalent or 20 by intermolecular abstraction of the elements of ganic radicals preferably hydrocarbon and pref water from the functional groups of two com erably aliphatic, R and R are the monovalent. pounds, at least one of which is a carboxylic acid, residues of an organic monocarboxylic acid, at the other being either a carboxylic acid or a hy least one of which is a monovalent organic radi 25 drohalogen acid, or by intramolecular abstraction cal, R is an Organic radical of valence gy, y being 25 of the elements of water from the carboxyl groups a positive integer and at least one, R8 is a di of a dicarboxylic acid. Thus the interanhydride valent organic radical, and X is a halogen. is to be regarded as derived by abstraction of the The more detailed practice of the invention is elements of Water from two acidic groups, a car illustrated by the following examples, wherein boxyl group furnishing a hydroxyl of the water, parts given are by Weight and temperatures in 30 the remaining proton being the acidic hydrogen, degrees centigrade. There are of course many either of another carboxyl group or a hydrohalo forms of the invention other than these specific gen acid. embodiments. In the process of the present invention an ole fin sulfide exemplified by ethylene Sulfide is re ExAMPLE I acted with an intermolecular anhydride of an Acetate of acetyloayethanthiol organic carboxylic acid with or without the as sistance of an inert solvent for the reactants, To one hundred parts of ethylene sulfide con with or without a catalyst for the reaction, un tained in a reactor equipped with an efficient 40 40 der conditions such that the olefin sulfide re reflux condenser is added a solution of 12.6 parts mains in the reaction mixture. until reacted, of pyridine with 408 parts acetic anhydride. The e.g., in a sealed reaction vessel or under efficient reactor is heated on a steam bath for 18 hours, reflux. The temperature of reaction, while de at the end of which time the contents are dis pendent in part upon other reaction conditions, tilled. Four hundred and forty parts or 82% 45 e.g., the nature of the anhydride and the type of yield of the crude acetate of beta-acetyloxyethan sulfide used, longer or heavier substituted Sulfides thiol, CH3-CO-S-CH2-CH-O-CO-CH3 is in general requiring higher temperatures, may obtained based on the ethylene. Sulfide. The vary although in general temperatures between product purified by redistillation boils at 104-106 50 0° C. and 250°C, are chosen. The use of pyridine C. at 17 mm. A sample of the purified product 50 2 2,212,141 prepared by this procedure gave an index of re carbon radicals. Thus in the case of cyclohexene fraction of sulfide, R and R are hydrogen and R2 and R. together form the tetramethylene radical. The n1.4707 open chain ethylene sulfides are preferred, and of - ExAMPLE II. these, the ethylene Sulfides Containing not more than one substituent, and that hydrocarbon, on Acetate of beta-chloroethanthiol any one ethylene carbon are most useful. To 103 parts of ethylene sulfide contained in a While it has been found advantageous to carry reactor equipped with a mechanical stirrer and a these reactions out in the presence of a small 10 reflux condenser is added 160 parts of acetyl amount of pyridrine at room temperature or at O chloride with stirring. Sufficient external cool 100° C. in order to obtain good yields of the de ing is applied to prevent escape of either the sired products, the process is not limited to the acetyl chloride or the ethylene sulfide. The re particular basic substance or to these tempera action mixture is then transferred to a pressure tures, Or to the time stated. 5 reactor which is closed and maintained at room The reactions may be carried out at any tem 5 temperature for three days. The product is then perature between 0° C. and 250° C. with or with distilled. A 75% yield of the acetate of beta out a catalyst. As such there may be employed chloroethanthiol, Cl-CH-CH2-S-CO-CH3 ... any basic Substance inert to the acid anhydride, boiling at 176-178° C. at atmospheric pressure is i.e., any substance inert to the acid anhydride 20 obtained. A sample of the purified product pre and capable of adding to or combining with the 20 pared by this procedure gave on analysis 23.10% hydrogen proton of an acid. Thus, there may be used any tertiary amine, e. g., pyridine, di sulfur as compared with a calculated value of methylaniline, diethylbenzylamine, trimethyl 23.42% for CHCIOS. The index of refraction. amine, dimethylaminoethanol, tripropylamine, dimethyllaurylamine. The reaction may be conducted either in the was found to be 14950. . presence or absence of neutral Solvents or dilu ents, such as ether, dioxane, benzene, or in gen ExAMPLE III eral, any neutral Organic compound, liquid at the Polymeric reaction product of succinic anhydride temperature used, and capable of dissolving the 30 and ethylene sulfide. Poly hydroacyethanethiol Components of the reaction mixture, in either sealed vessels or in open vessels, providing proper succinate . . . . precautions are taken to avoid loss of the react To 9.67 parts succinic anhydride in a pressure ants. reactor is added 5.80 parts ethylene sulfide and . The products may be used as intermediates in 0.2 part pyridine. The reactor is closed and the preparation of other useful chemicals, e. g., heated at 130° for 10 hours. A homogeneous, vinyl thiolacetate. The products prepared from dark colored, pitch-like, very tacky polymeric olefin sulfides and acid chlorides are particular material is obtained from which no Succinic an ly useful as intermediates in the preparation of hydride is separable. ethers and thioethers of beta-acyloxyethanethiols In the process of this invention any Organic and of many other derivatives because of the carboxylic acid interanhydride, i. e., any organic reactivity of the chlorine atom in the products, compound derivable from or hydrolysable, per e.g., the acetate of beta-chloroethanethiol. mol of interanhydride, to a plurality of acid This invention describes a novel and ready groups, at least one of which is a carboxyl group, method for the preparation of the esters of beta may be employed, including simple and mixed Or substituted ethanethiols. The reactions, under ganic acid anhydrides of monocarboxylic acids, suitable conditions, proceed to give yields of 80% and of polycarboxylic acids as well as the mixed Or better. anhydrides of organic carboxylic acids and hy The above description and examples are in idrohalogen acids, e. g., acetic anhydride, caproic tended to be illustrative only. Any modification anhydride, palmitic anhydride, acetic caproic an of or variation therefrom which conforms to the hydride, acetic propionic anhydride, propionic spirit of the invention is intended to be included anhydride, butyric anhydride, lauric anhydride, within the scope of the claims. benzoic anhydride, naphtholic anhydride, phenyl We claim: acetic anhydride, p-nitrobenzoic anhydride, ace 1. Process of preparing esters which comprises 55 tyl chloride, propionyl chloride, palmityl chlo reacting an alpha-alkylene sulfide with a member ride, butyryl chloride, lauryl chloride, stearyl of the class consisting of halides and anhydrides chloride, crotonyl chloride, benzoyl chloride, of organic carboxylic acids. naphthoyl chloride, the corresponding bromides, 2. Process of preparing esters which comprises iodides and fluorides, phthalic anhydride, naph reacting an alpha-alkylene sulfide with an an 50 thalic anhydride, 3-nitrophthalic anhydride, hydride of an organic carboxylic acid. phthalyl chloride, succinyl chloride, both sym 3. Process of preparing esters which comprises metrical and unsymmetrical, terephthalyl chlo reacting an ethylene sulfide with an anhydride of ride, isophthalyl chloride. - . an organic carboxylic acid. Any ethylene sulfide may be used including 4. Process of preparing esters which comprises 65 ethylene sulfide and the homologs and Substi reacting ethylene sulfide with an anhydride of an tuted derivatives of ethylene sulfide, such as organic carboxylic acid. propylene sulfide, the various butylene sulfides, 5. Process of preparing esters which comprises hexene-3 sulfide, styrene sulfide, cyclohexene sul reacting an ethylene sulfide with an anhydride O fide, etc. These have the generic formula of an organic monocarboxylic acid. 70 6. Process of preparing esters which comprises RRC-CRR reacting ethylene sulfide with an anhydride of an organic monocarboxylic acid. Wherein R, R*, R and R4 are hydrogen or hydro 7. Process of preparing esters which comprises 2,212,141 3 reacting an alpha-alkylene sulfide with a halide 11. A monocarboxylic acid ester of a beta of an organic carboxylic acid. halogen-alkanthiol. 8. Process of preparing esters which comprises 12. A monocarboxylic acid ester of a betaa reacting an alpha-alkylene sulfide with a halide halogen-ethanthiol. of an Organic monocarboxylic acid, 13. A monocarboxylic acid ester of beta 5 9. Process of preparing esters which comprises chloro-ethanthiol. reacting an open chain alpha-alkylene sulfide 14. The acetate of beta-chloroethanthiol. with a halide of an organic monocarboxylic acid. 10. Process of preparing esters which COm WAN WERNON ADERMAN. 0 prises reacting ethylene sulfide with a halide of MERLIN MARTIN BRUBAKER. 10 an organic monocarboxylic acid. WLAM EDWARD HANFORO.