“…135 If diethylene glycol is used as the heating medium, along with one or two equivalents of quinoline, isolation of the product is facilitated because the decarboxylated product is more readily extracted from the tarry residues.136 A hot solution of quinoline containing cupric oxide has provided 4-, 5-, 6-, and 7-nitroindoles in yields of 51, 71, 38, and 78%, respectively, from the corresponding nitroindole-2-carboxylic acid.128 Copper powder in hot quinaldine readily decarboxylates 5,6-dialkoxy- these conditions$12 whereas only tar is obtained if boiling quinoline and copper bronze are 6-Dimethylaminoindole-2-carboxylic acid, when heated in glycerol, is converted to 6-dimethylaminoindole in 88.5 % yield,431 but quinaldine and copper powder is reported to be a better system for the decarboxylation of 4-, 5-, and 6-benzyloxyindole-2-carboxylic acid4,' than is hot glycerol.427 Merely heating the acid above its melting point is quite satisfactory in a number of cases. Molecules which are sensitive to high temperatures and to the more vigorous conditions of hot quinoline, are apparently more advantageously decarboxylated by heating them to or slightly above their melting point.…”