Reaction XXXVI.—Condensation of Carbon Tetrachloride with Phenols and simultaneous Hydrolysis

Reaction XXXVI. Condensation of Carbon Tetrachloride with Phenols and simultaneous Hydrolysis (Tiemann-Reimer). (B., 10, 2185.)—This reaction is closely analogous to that of the formation of hydroxy-aldehydes by means of chloroform and caustic alkali (see p. 104). A mixture of a phenol, carbon tetrachloride and caustic soda or caustic potash solution is boiled. Condensation occurs, chiefly in the para-position, but small amounts of the ortho-acids are also formed. The product, after the excess of carbon tetrachloride has been removed, is saturated with carbon dioxide and the unchanged phenol extracted with ether. The hydroxy acids are then precipitated by acidification with hydrochloric acid. 

A variation of this method consists in heating carbon tetrachloride with potassium phenolate under pressure with sufficient alcohol to give a clear solution. The product in this case is mostly the orfAo-acid (cf. Reaction XXXIV. (q)), 

Reaction XXXVII. Action of finely divided Metals on Halogen Adds. 

Of the metals mentioned silver gives the best results, while iodo- and then bromo- give better yields than chloro-acids. 

This synthesis has one rather anomalous application, when a-bromo-isobutyric acid (or its ethyl ester) is heated with silver, some tetramethyl-succinic acid is produced in the ordinary way (B., 23, 297 26, 1458). But there also appears trimethylglutaric acid (A., 292, 220). To explain the unexpected formation of this acid, it has been assumed that a portion of the a-bromoisobutyric acid gives up HBr to form methylacrylic acid. This latter then forms j3-bromoisobutyric acid, and the silver withdraws bromine from the a- and /3 acids, whereby the residues unite to tri-methyl-glutaric acid (B., 22, 48, 60). A similar explanation applies to some other syntheses in which tetramethylsuccinic and trimethylglutaric acids appear together. 

---