1,2,3-Triazabutadiene. XXII. Photochemie der 1-(Carbmethoxy-aryl)- und 1-(Carboxy-aryl)-3-(3-alkyl-benzthiazolinyliden-(2))-triazene als potentielle CEL-Farbstoffe

Abstract

1,2,3-Triazabutadienes. XXII. Photochemistry of 1-(Carbmethoxy-aryl)- and 1-(Carboxy-aryl)-3-(3-alkyl-benzthiazolinyliden-(2))-triazenes as potential CEL-dyes 1-(Carbmethoxy-aryl)-3-(3-alkyl-benzthiazolinyliden-(2))-triazenes (ester-triazenes) (1) were synthesized by coupling of substituted 3-alkyl-2-imino-benzthiazolines-(1,3) with 2-, 3- and 4-carbmethoxy-benzenediazonium salts. The Z-isomers obtained can be transformed into the E-isomers 2 photochemically or by heating. In the presence of acids the E-ester-triazenes are protonated. From the E-ester-triazenes the potassium-salts (4) can be produced by alkaline ester hydrolysis. With hydrochloric acid the E-triazene-potassium salts (4) can be transformed into the protonated (at the N(1)-Atom) E-acid-triazenes (5). Their photochemical properties are identical with those of the protonated E-ester-triazenes (3). The 1-(carboxy-aryl)-3-(3-alkyl-benzthiazolinyliden-(2))-triazenes (E-acid-triazenes) (6) can be obtained from the protonated derivates by deprotonation in the presence of water. The photochemical behaviour of the E-acid-triazenes (6) and of the E-triazene-potassium-salts (4) depends on the position of the carboxy-group (2-position: photolysis, 3- and 4-position: photoisomerization). The uv/vis-spectroscopical and photochemical properties of the triazene-derivates in solution and in polymeric layers are discussed.