Diphenylacetic acid, standardization

Butyllithium, purchased from Aldrich Chemical Company, Inc., was standardized by titration with diphenylacetic acid. Butyllithium solutions with concentrations less than 1.5 M may result in drastically reduced diastereomeric excesses and should be avoided. 

The submitters used butyllithium in hexane available from Janssen Chimica and standardized before use by titration against a solution of benzylic alcohol in toluene and cuproine (2,2 -biquinoline). The checkers used butyllithium (1.6 M in hexane) available from Aldrich Chemical Company, Inc., which was standardized before use by titration with diphenylacetic acid in THF. 

Frankfurt, Germany and standardized by titration with diphenylacetic acid. 

The seobutyllithium was purchased from Alfa Products, Ventron Corp., and standardized by double titration or diphenylacetic acid titration. Other alkyllithium bases such as butyllithium and methyllithium cannot be substituted for the stronger sec-butyllithium since larger amounts of bomylene are formed because of incomplete dianion formation. Careful attention must be paid to stoichiometry in this reaction failure to do so also results in increasing the amount of bomylene formed. 

Lafontaine, D. Mailhot, C. Vermeulen, M. Bissonnette, B. Lambert, C. Influence of chewable sucralfate or a standard meal on the bioavailability of naproxen. Clin.Pharm., 1990, 9, 773-777 [pharmacokinetics LOQ 1 pg/mL diphenylacetic acid (IS)]... 

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