METHOD FOR SIMPLE TITRATION OF ORGANOLITHIUM REAGENTS IN ETHERS OR HYDROCARBONS USING METALATION OF N-BENZYLIDENEBENZYLAMINE AS COLORED REACTION

Organolithium compounds are useful reagents in organic synthesis. Generally, it is necessary to know their accurate concentration before their use in metalation and addition reactions; the most widely used methods for their analysis are the doubletitration procedure of Gilman and Cartledge1 and the compleximetric method of Watson and Eastham, in alkanes or benzene at room temperature2 or in ethers at -78 °C.49 Recently, a method was described which used the organolithium in a colored reaction of carbon lithiation: the colored indicator was diphenylacetic acid, whose dianion is yellow while the monoanion iscolorless.4 The organolithium was run from a syringe in the tetrahydrofuran solution of indicator until the end point was reached. © 1979, American Chemical Society. All rights reserved.