US2468725A - Preparation of long-chain esters of beta-thiodipropionic acid - Google Patents

Description

Patented May 3, 1949' OFFICE PREPARATION OF LONG-CHAIN ESTERS OF BETA-THIODIPROPIONIC ACID William F. Gresham and Myers F. Gribbins, Wu mington, Del., assignors to E. I. du Pont de Nemours & Company, poration of Delaware Wilmington, Del., a cor- No Drawing. Application April 8, 1947, I Serial No. 740,268

Claims. (01. 250-481) This invention relates to a process for the preparation of the higher molecular weight alcohol esters of thiodicarboxylic acids and more particularly to the preparation of such esters of thiodipropionic acid. 4

The 3-substituted mercaptoaliphatic organic acid esters and more particularly the mercaptopropionic acid esters have been found to be especially effective anti-rancidity agents for use in oils, fats, waxes and the like, as is described in the D. K. OLeary and in the Gribbins et al. Patents 2,397,960 and 2,397,976 of April 9, 1946. These esters have likewise been found suitable for use in soap for preventing rancidity as is described in the Gribbins Patent 2,416,052 of February 18, 1947. These uses demand esters of high quality that are not only colorless, for off-color is highly undesirable in soaps, food products and the like, but also odorless, for foreign odors are not tolerated in foods or in the better grades of soap and soap products.

An object of the present inventionis to provide a process for the preparation of esters of 3- substituted mercaptolaliphatic organic, acid esters which are substantially colorless and odorless. A further object is to provide a process for preparing the higher aliphatic alcohol esters of these 3-substituted mercaptopropionic acids and more particularly such esters of 3-substituted mercaptopropionic acid by the alcoholysis of the lower alkyl esters of 3-substituted merpaptopropionic acid, more particularly the methyl ester with higher aliphatic alcohols. Other objects and advantages of the invention will hereinafter appear.

The invention is directed to the preparation of substantially colorless and odorless higher aliphatic alcohol esters of a beta-thioether of an ester of propionic acid having the formula:

ROOCCHzCHzS-X group and more particularly, thosecontaining from 10 to 24 carbon atoms and in which X is:

' 1. A hydrocarbon group such as e. g.: the alkyl groups: methyl, ethyl, propyl, butyl, lauryl, and the aryl groups: phenyl, naphthyl, benzyl; and such groups as cyclohexyl; v

2. An oxygenated-hydrocarbon group such as e. g.: the alcohol groups: hydroxymethyl, hydroxyethyl, and hydroxybutyl; the ether-groups;

2 methoxymethyl, methoxyethyl, and ethoxyethyl; the acid groups and the R esters thereof: carbonymethyl, carboiwethyl, carbo'xypropyl and carboxybutyl; and the aldehyde groups such as aldehydroethyl;

3. A sulfur-hydrocarbon group such as e. g.: mercaptoethyl, mercaptopropyl, mercaptobutyl, mercaptoisobutyl, mercaptohexyl and ethiaethyl.

4. A sulfurand oxygenated-hydrocarbon group such as e. g.: carboxyethiaethyl,

-CH2CH2SCH2CH:COOH carboxyethiaethdithiaethyl,

-cH2cHsscH2cH2scH2cH=coon carboxythiaisobutyl,

-CH 2CH2CH(CH3) SCHzCHzCOOH and carboxyethiapropyl,

is maintained until substantially no more of the lower alcohol, which is formed by the interchange, distills over, the product is then cooled rapidly to 40 to 50 C. and a suflicient amount of water and caustic soda or alkali dissolved in water added to neutralize the acid catalyst used. l Neutralization is carried out as accurately as possible in order not to contaminate the product. After filtering off the precipitated catalyst (a catalyst and neutralizer being selected such that a. precipitate is obtained, such for example, as sulfuric acid and barium hydroxide or phosphoric acid and sodium hydroxide) the filtered ester is subjected to a deodorizing treatment by passing it countercurrent to the flow of steam at a temperature between. and 225 C. and under a vacuum of less than about 40 millimeters, preferably below 20 millimeters.

The example which follows illustrates a preferred embodiment of the invention in which parts are by weight unless otherwise indicated.

Eq:ample.-Stoichiometric amounts of dimethyi thiodipropionate and a mixture of alcohols, prinabsolute'to facilitate cipally l'auryl alcohol obtained in water was added (1% acid based on the ester) sac 99.2... I

by the cartons-' and the-temperature raised as rapidly-as possible to 2009p mately two hours.

-150-l60 C. .(made evident by the evolution of where it was'main'tained ior' approxi- The reaction started at niethanol) andproceeded quite rapidly until about I about 7 5 wasred'uced to about .290;millinije1ters'of mercury pl'ete methanol removaL- when the reaction-{was}.completed ino more distiliate coming oif) the-product was cooled rapidly I to 4,0 to 50 C. and the proper amounts 0! water cormilete.v At this 'point'th 'pre s and sodium hydroxidedissolved inwater added to neutralize 'the phosphoric acid catalyst to NaaHPOe'IHzC). The product was then"cooled to room temperature and filtered.

The above product was. further- 7 subjecting it to acountercurrent steam scrubbing proximately 190 C. (although temperatures be- 1'iormed,?.t I temperature .2. The process of clalm'l in which the product is deodorized by subjecting it to countercurrent v scrubbingwith steam, the scrubbing operation being'conducted at a temperature between 150 C,- to .225": C. and at absolute.

A' process for thepreparation of a substantially odorless: and tasteless stearylalcohol ester g, p e ure below 100 mm. B!

Lot betaathiodipropionic-acid, which comprises hea ing ethy beta thiodipi'opionate with stem] alcohol-inthe presenceloi anxacid catalyst while withdrawingthe methanolas formed, the reaction being conducted at a temperature below process .t or the "preparation or a substana ,tially odorless and tasteless higher. alcohol ester deodorized by":

operation maintained at a. temperature of apliquid stream of the-ester was continuously passed into-the top of areaction vessel and continuously withdrawn from'the bottom, superheated steam passing through the vessel counter-current to the now of ester, the deodorization being conducted at apressure'below 100 mm. and preferably as in this example, between. and mm; Hg absolute pressure. The product obtained in accord with this process was substantially odorless and colorless and wholly acceptable for comestible The other higher aliphatic alcohol esters of the other 3-substituted dicarboxylic acids may similarly prepared to give products thatare both odorless and tasteless" by reacting these-alcohols withthe methylfesters of the acids and subsequently it necessary removing the final traces-of odor'by the countercurrent flow steam distiila- Y vtiorrprocess. v I.

"We claim:

' '1. Av process for the preparation of a substantially odorless and tasteless monohydric alcohol-,

.- of beta-thiodipropionlc acid, the higher alcohol consisting ofa mixture or higher alcohols, pre "dominately lauryl alcohol, obtained by the catalytic hydrogenation of fats and oils underelevatv ed temperaturesl a'nd pressures, which comprises tween and 300. (3..maybeiusedl wherein-a.

heating" methyl beta-thlodipropionate with the aforesaid-higher alcohol-in the presence of an acid catalyst while withdrawing the methanol as formed, the reaction being conducted at a temperature below 250C; '5.2.A- process tor thepreparation of a substan tially odorless and tasteless monohydric alcohol ester of .beta-thiodipropionic acid, the alcohol containing 10in 24 carbon atoms, which. comprises heating a'lower dialkyl ester of beta-thicdipropionic, acid with amonohydric alcohol containing 10 to 24 carbon atoms in the presence of an acid catalyst while withdrawing the lower boiling alcohol formed, the reaction being conducted at a temperature below 250C.

WILLIAMEGRESHAM.

MYERS F; GRIBBINS.

REFERENCES CITED The'following references are of record in the file of this patent:

. UNITED STATES PATENTS Number in thepresenoeoi -e d-Qata s hflewlthdrawing themethan'ol' conducted at a p Certificate of Correction Patent No. 2,468,725.

. May 3, 1949.

WILLIAM F. GRESHAM ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 2, lines 4 and 5, for the Word aldehydroethyl read aldehydoethyl; line 16, for carboxythiaisobutyl read carbozyethiaisobutyl;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 11th day of October, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.