| 摘要 |
<p>Dyes of formula:- where Z, Z' complete a heterocycle of benzothiazole, benzolselenazole, naphhthothiazole, or naphthoselenazole; R is H or lower alkyl, R' is (subst) alkyl; n is 1-3; are prepd. by reacting a alkoxyalkene of formula:- with the required 2-methylheterocycloammonium salt in the presence of a base to give a mixt. of two symmetric carbocyanins which is then treated at 60-80 degrees C with an alcoholic soln. of an alcoholate (sodium methylate, ethylate) or contd. alkali metal hydroxide (KOH) to ppte the corresponding ethylidene bases of formulae:- Compound (III) is separated off with solvent (acetone) then the residue refluxed with an excess aq. soln. of a weak org. acid (60% acetic) to regenerate ethyl-meso-subst-dyes and cooled to crystallise (I) with (II) remaining sol.</p> |
