Salt substitute, sodium laboratory

The most important reaction of esters is their conversion by a carbonyl-group substitution reaction into carboxylic acids. Both in the laboratory and in the body, esters undergo a reaction with water—a hydrolysis—that splits the ester molecule into a carboxylic acid and an alcohol. The net effect is a substitution of -OC by -OH. Although the reaction is slow in pure water, it is catalyzed by both acid and base. Base-catalyzed ester hydrolysis is often called saponification, from the Latin word sapo meaning "soap." Soap, in fact, is a mixture of sodium salts of long-chain carboxylic acids and is produced by hydrolysis with aqueous NaOH of the naturally occurring esters in animal fat. 

An unspecified process had been operated for 20 years using synthetic sodium carbonate powder (soda-ash) to neutralise the hydrogen chloride as it was formed by interaction of the amine and chloro compound in a non-aqueous (and probably flammable) solvent in a steel reactor. Substitution of the powdered sodium carbonate by the crystalline sodium carbonate—sodium hydrogencarbonate double salt ( trona, natural soda ) caused a reduction in the rate of neutralisation, the reaction mixture became more acid, and attack on the steel vessel led to contamination by iron. These changed conditions initiated exothermic side reactions, which eventually ran out of control and caused failure of the reactor. Subsequent laboratory work confirmed this sequence and showed that presence of dissolved iron(III) was necessary to catalyse the side reactions. 

The hydrolysis of amides and nitriles may be conducted not only in acid solution but also in the presence of alkali. When dealing with substances soluble in water only with difficulty, it is customary to use alcohol as a solvent. In the latter instance, in connection with acid hydrolysis, the organic acid formed in the reaction is partially converted into an ester, whereas ammonia, or a substituted ammonia, will be present in the form of a salt with the inorganic acid used. When the hydrolysis is conducted in the presence of alkali, the organic acid is present as the sodium or potassium salt, whereas the amine is liberated and, if volatile, may be lost when the reaction mixture is refluxed. Type experiments are illustrated in connection with the laboratory work, page 146. 

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