Synthesis of heterocyclic quinones containing bridgehead nitrogen atom from 2-aminonaphtho[2,3-d]thiazole-4,9-dione.

Imidazonaphthothiazole derivatives 3-6 were prepared by treatment of 2-aminonaphtho[2,3-d]-thiazole-4,9-dione(1) with phenacyl bromide, chloroacetic acid, diethyl oxalate and 2,3-dichloroquinoxaline respectively. The reaction of 1 with ethyl acrylate, ethyl acetoacetate and diethyl malonate gave the corresponding naphthothiazolopyrimidine derivatives 8-11.

Determination of Ag(I) with chemically modified carbon paste electrode based on 2,3-dicyano 1,4-naphthoquinone.

The utility of carbon paste modified with 2,3-dicyano 1,4-naphthoquinone (CYNQ) for the voltammetric determination of Ag(I) is demonstrated. The method is based on the formation of Ag(I) complex with CYNQ by accumulation from the aqueous solution to the electrode surface without an applied potential. Using the medium exchange technique, the electrode was transferred to another media followed by linear-scan voltammetric measurements.