GB573202A - Improved manufacture of ricinoleic esters - Google Patents

Abstract

Ricinoleic esters other than methyl ricinoleate are prepared by reacting a ricinoleic ester of a monohydric alcohol having not more than five carbon atoms in the molecule with a monohydric alcohol having a higher boiling point than that of the combined alcohol. The displaced alcohol is preferably removed by distillation but reaction until equilibrium is attained followed by separation of the products may be effected. The methyl or other ricinoleate used as initial material may be prepared by alcoholysis of castor oil with an alkoxide catalyst as described in Specification 566,324. Other catalysts such as acids, soaps and alkaline-reacting salts, e.g. sodium silicate and trisodium phosphate, may however be used or a catalyst dispensed with. Ethyl and the various propyl, butyl and amyl esters are also specified as initial materials. The displacing alcohol may be n- or iso-propyl, secondary or other butanol, pentanols and higher alcohols such as octanols and wax alcohols, unsaturated alcohols such as allyl, methallyl and crotyl, cyclic alcohols such as cyclohexanols, aralkanols such as benzyl alcohol, heterocyclic alcohols such as tetrahydrofurfuryl, ether alcohols such as ethoxyethanol and ethoxyethoxyethanol, halo-alcohols such as ethylenechlorhydrin and glycerol halohydrins, and nitro-alcohols such as 2-nitro-isobutanol. In reacting octanol with methyl ricinoleate using an alkoxide catalyst, fractionation of the alcohol vapours is of little importance but with isopropanol the use of a fractionating column to condense the isopropanol but pass the methanol is advantageous. With b -chlorethanol, alkaline catalysts are inactivated, and hydrochloric, sulphuric or aryl sulphonic acids are best used with fractionation of the alcohol vapours. With "Carbitol" the boiling point is so high that a high temperature reaction with a sodium or zinc soap or trisodium phosphate or without a catalyst can be effected. In Examples: (1) methyl ricinoleate is refluxed with 4 molecular proportions of isopropanol containing sodium, methanol being removed, and a solution of the isopropyl ester in the excess of alcohol obtained. Some of the catalyst may be converted into soap which can be converted into the isopropyl alcohol by adding an esterifying catalyst at the end of the alcoholysis; (2) methyl ricinoleate and 1.5 molecular proportions of n-butanol are similarly reacted, vacuum being gradually applied to complete. The soap formed may be esterified as in (1), washed out with water, or directly esterified by an alkyl inorganic ester such as diethyl sulphate; (3) isopropyl ricinoleate and b -chlorethanol are refluxed with a catalyst comprising hydrochloric and toluene sulphonic acids made by hydrolysis of toluene sulphonyl chlorides; (4) methyl ricinoleate and 2-ethylhexanol are heated to 200 DEG C. with potassium ricinoleate to form the octyl ester. Refluxing under gradually increasing vacuum may be used and the zinc soap may replace the potassium. With an alkoxide catalyst, reaction is complete at 100 DEG C. Specification 543,604 also is referred to.