A number of 2‐ and 3‐methoxy‐substituted‐4‐N.N‐diethylaminoazobenzenes have been prepared and their absorption maxima in ethanol and toluene compared with the corresponding 4‐N.N‐diethylaminoazobenzenes. Both the 2‐ and 3‐methoxy groups cause a bathochromic shift, but the bathochromic shift of a 3‐methoxy group depends on the substituents in the diazo component. With increasing electron‐withdrawing strength of the substituents in the diazo component a progressive enhancement of bathochromic shift appears. In toluene all 3‐methoxy‐substituted dyes absorb at longer wavelengths compared with the 2‐methoxy‐substituted dyes.

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.

ChemInform Abstract Both the 2-and 3-methoxy groups in (II) and (III) cause a bathochromic shift as compared to the corresponding (I), but the bathochromic shift of a 3-methoxy group in (III) depends on the substituents in the diazo component.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.