Quat. benzothiazole salts prepn., intermediates for cyanine dyes - avoids the use of sultone(s)

摘要

Quat. salts of formula (I) are prepd. by heating at >80 degrees C a heterocyclic base of formula (II) with a hydroxysulphonic acid. HOR4SO3H, and removing the water from the reactial as it is formed. In the formalae, X is -0-; -Se-; .-S-; -NR- or -CR(R) where R is H or 1-4C alkyl, R1 is H, CH3 or C2H5. R2 and R3 are each H or substituent gps. or together form an opt. substd. benzene nucleus; R4 is a 1-4C opt. substd. alkylene chain, n is O or 1, and when n is 1, R1 can not be H. (I) are intermediates partic. for the prepn. of optically sensitive cyanine dyes. The process avoids the use of carcinogene sultanes to synthesise (I).