Volhard, Jacob (1834-1910)

German chemist who devised various significant methods of organic synthesis, and a method of quantitatively analysing for an element via silver chloride. Bromides can also be determined using this technique. Volhard was born in Darmstadt and studied at Giessen. He held professorial appointments at three German universities: Munich 1864-79, Erlangen 1879-82, and Halle 1882-1910. During the 1860s Volhard developed methods for the syntheses of the amino acids sarcosine (N-methylaminoethanoic acid) and creatine, and the heterocyclic compound thiophen; he also did research on guanidine and cyanimide. Volhard's method of preparing halogenated organic acids has become known as the Hell-Volhard-Zelinsky reaction, in which the acid is treated with chlorine or bromine in the presence of phosphorus. The reaction is also useful for syntheses because the substituted halogen atom(s) can easily be replaced by a cyanide group (by treatment with potassium cyanide), which in the presence of an aqueous acid and ethyl alcohol (ethanol) yields the corresponding malonic ester (diethylpropandioate), from which barbiturate drugs can be synthesized.