GB361042A - Improvements in the manufacture and production of lactates and salts of other hydroxy fatty acids - Google Patents

Abstract

Salts of a -hydroxy fatty acids such as lactic acid are obtained by treating the reaction product formed by condensing an aldehyde such as acetaldehyde with hydrocyanic acid and saponifying the resulting nitrile by means of a strong inorganic acid, with a base or a compound of a base which forms an insoluble salt with the acid used for the saponification, and a readily soluble salt with the a -hydroxy fatty acid. Suitable salt-forming compounds when sulphuric acid has been used for the saponification are compounds of lead, and when hydrochloric acid has been used, compounds of lead, mercury, or silver are suitable. Examples are given. Specification 300,040, [Class 2 (iii), Dyes &c.], is referred to.ALSO:Salts of a -hydroxy fatty acids, especially calcium and ammonium lactates, are obtained by treating the reaction product formed by condensing an aldehyde such as acetaldehyde with hydrocyanic acid and saponifying the resulting nitrile by means of a strong inorganic acid, with a base or compound of a base which forms an insoluble salt with the acid used for the saponification, and a readily soluble salt with the a -hydroxy fatty acid. Suitable salt-forming compounds when sulphuric acid has been used for the saponification are those of the alkaline-earth metals or lead, and when hydrochloric acid has been used as the saponifiying agent compounds of lead, mercury, or silver are suitable. When lactic acid has been formed by the saponification of its nitrile with sulphuric acid, enough lime may be added to the reaction mixture to form both the soluble calcium lactate, which may subsequently be converted to the ammonium salt, and the insoluble calcium sulphate, which is removed by filtration; or only enough lime to form calcium sulphate may be added, so that the ammonia set free may combine with the lactic acid to form ammonium lactate, which is thus obtained directly. In an alternative method, when the nitrile has been saponified in the presence of an inert diluent in which the ammonium salt of the saponifying acid which is formed is insoluble, according to the method of Specification 300,040, [Class 2 (iii), Dyes &c.], and this ammonium salt has been removed by filtration, the a -hydroxy fatty acid remaining behind may be converted into its ammonium salt by passing gaseous ammonia into the solution. If the saponifying acid has been used in excess, this excess is first precipitated, for example, by adding ammonia or ammonium carbonate, and then filtered off together with the ammonium salt formed by the saponification. Ammonia is led into the solution and the ammonium salt of the a -hydroxy fatty acid formed is precipitated by cooling, if necessary, after distilling off some of the solvent. In one example, in which dioxane is used as the diluent, after filtering off the ammonium lactate formed as above, and evaporating the filtrate a residue of lactic anhydride is left which is converted to ammonium lactate by boiling with milk of lime and subsequent conversion of the calcium lactate formed with ammonium carbonate. Other examples are given.