Spectrophotometric and fluorimetric determination of amines
Thirteen procedures are described in this report for the colorimetric and fluorimetric determination of amines. In the presence of an appropriate base, ,3,5-trinitrobenzene condenses with nitromethane to give a red Meisenheimer—type complex which allows determination of alkylamines and quaternary ammoniums. The nobility of the hydrogen atom (or atoms) bonded to the amino nitrogen atom of primary and secondary alkyland arylamines, allows derivatives which permit general or selective determinations. Primary and secondary alkyland arylamines are so estimated through the formation of N-substituted derivatives of p-nitrophenylazobenzamide or of 2,4-dinitroaniline (according to another procedure, only primary aklylamines afford the latter derivatives). Primary alkyland arylamines react with succinic dialdehyde to give a pyrrole derivative which is then developed with p-dimethylaminobenzaldehyde and they also yield fluorescent derivatives with fluorescamine. Primary and secondary alkylamines produce fluorescent 4-amino derivatives with 7-nitrobenzofurazan. Secondary alkylamines are selectively determined as N-substituted derivatives of 2-chloro-3-(2-aminoethenyl)-5,6dicyano-1,4-benzoquinone, or of 4-aminoor 4,5-diamino-1,2-benzoquinone. Only primary arylamines condense with glutaconic dialdehyde to yield a colored Schiff's base. Diazo coupling with p-nitrophenyldiazonium ion allows the estimation of all classes of arylamines. Tertiary aklylamines and quaternary ammoniums develop a color with cis-aconitic anhydride in the presence of acetic anydride, whereas only tertiary aklylamines develop a fluorescence with a mixture of aconitic acid and acetic anhydride.