GB590784A - A process for the production of fatty acids with conjugated double bonds and their esters of polyhydric alcohols - Google Patents

Abstract

Unsaturated fatty acids whose double bonds are not conjugated are converted into the corresponding acids with conjugated double bonds by passing the vapours of the acids whether or not mixed with the vapours of other saturated or unsaturated fatty acids, over one of the isomerization catalysts listed below or over a mixture of such catalysts, at a temperature at least as high as the boiling point of the acids at the prevailing pressure but below the decomposition temperature of the acids. The catalysts may be used as such or may be on suitable supports such as kieselguhr, silica, silicates, silicon, carbon, graphite, or oxides or carbonates of metals. The catalysts mentioned are amorphous silica, activated fuller's earth, silicates or oxides of metals (other than those of alkali metals), metals (other than the alkali and alkaline earth metals). If the fatty acids from linseed oil or similar drying oils are treated in the manner described, then on esterification with glycerine or other polyhydric alcohol, an oil results which dries and may be polymerized faster than the original drying oils. Other fatty acid mixtures mentioned are the fatty acids obtained from dehydrated castor oil or menhaden fish oil. In examples, (a) the vapours of linseed oil fatty acids are passed at reduced pressure over amorphous silica or over a mixture of Cr2O3 and Al2O3 (b) the vapours of dehydrated castor oil fatty acids are passed at reduced pressure over metallic nickel precipitated on silica and (c) the vapours of soyabean oil fatty acids are passed at reduced pressure over bentonite or activated fuller's earth; in the latter instance the resulting fatty acids are esterified with glycerine to give a drying oil from which a varnish may be prepared by adding cobalt naphthenate.ALSO:Unsaturated fatty acids whose double bonds are not conjugated are converted into the corresponding acids with conjugated double bonds by passing the vapours of the acids whether or not mixed with the vapours of other saturated or unsaturated fatty acids, over one of the isomerisation catalysts listed below or over a mixture of such catalysts, at a temperature at least as high as the boiling point of the acids at the prevailing pressure but below the decomposition temperature of the acids. The catalysts may be used as such or may be on suitable supports such as kieselguhr, silica, silicates, silicon, carbon, graphite, or oxides or carbonates of metals. The catalysts mentioned are amorphous silica, activated fuller's earth, silicates or oxides of metals (other than those of alkali metals), metals (other than the alkali and alkaline earth metals). If the fatty acids from linseed oil or similar drying oils are treated in the manner described, then on esterification with glycerine or other polyhydric alcohol, an oil results which dries and may be polymerized faster than the original drying oils. Other fatty acid mixtures mentioned are the fatty acids obtained from dehydrated castor oil or menhaden fish oil. In examples: (a) the vapours of linseed oil fatty acids are passed at reduced pressure over amorphous silica or over a mixture of Cr2O3 and Al2O3; (b) the vapours of dehydrated castor oil fatty acids are passed at reduced pressure over metallic nickel precipitated on silica and (c) the vapours of soyabean oil fatty acids are passed at reduced pressure over bentonite or activated fuller's earth; in the latter instance the resulting fatty acids are esterified with glycerine to give a drying oil from which a varnish may be prepared by adding cobalt naphthenate.