Compound useful in detecting ion and method of preparing it

摘要

A novel compound is disclosed having the structure <IMAGE> (I) in which R is lower alkyl and X is halogen or pseudohalogen. Also disclosed in a novel process for preparing the compound which comprises the steps of combining a compound having the structure <IMAGE> in which X is a halogen or pseudohalogen, and a compound having the structure <IMAGE> (III) in which R is lower alkyl and A is lower alkylidene to produce a first reaction mixture; adjusting the pH of the first reaction mixture to at least about 8 to produce a second reaction mixture; and recovering the compound or its salt from the second reaction mixture.