Azobenzene 3-methoxy

In 1990, Baumeister et al. [127] described the crystal and molecular structure of 4-ethoxy-3 -(4-ethoxyphenyliminomethyl)-4 -(4-methoxy-benzoy-loxy)azobenzene. The molecules have a bifurcated shape. The phenyliminom-ethyl branch is bent markedly from the nearly linear three ring fragment, but is almost coplanar with the azobenzene moiety. They found that the molecular conformation is affected by an intramolecular interaction of the carboxylic and azomethine groups. The crystal packing was described in terms of a sheet structure with interdigitating rows of molecules. 

Metal complex dyestuffs derived from tetradentate azo compounds (147) have very limited commercial significance but merit brief discussion on chemical grounds. The first dyestuffs of this type to be used commercially contained the o-hydroxy-o -carboxymethyleneoxydiarylazo system, e.g. (148). These were dyed on cotton and aftertreated with a copper salt to produce the copper complex dyestuff which was reported71 to be a triannelated species (149). Formation of complexes of this type has been confirmed105 in the case of 2-hydroxy-5-methyl-2 -carboxymethyleneoxy-azobenzene, which yields the complex (150) on treatment with copper acetate under mild conditions. Under more severe conditions, however, the complex (151) is produced. Loss of the carboxymethyl group from dyes of this type has also been shown105 to occur under dyebath conditions. This may be compared with the demethylation of o-methoxy-o -hydroxydiarylazo compounds (Section 58,2.3. l(iii)(a)) under similar conditions. 

Column, bottom 1 cm azobenzene p-methoxy- Sudan Sudan... 

Name 2-Methyl-4 -methoxy-4-(4-ethoxybenzoyloxy) azobenzene Structure ... 

Scheme 6 Derivatives of azobenzene (X=N) and stilbene (X=CH) with methyl or methoxy (in the case of stilbene) Y groups are observed to dimerise within the cavity of 24...

Upon photolysis at 254 nm 1-methoxy- and l-cycloalkoxy-l,2,3-benzotriazoles (102) show rather different photolytic pathways homolytic cleavage of the N—O—R bond occurs, while a second path proceeds via nitrogen extrusion followed by an intramolecular H-abstraction leading to phenylnitrene (103). The latter dimerizes to give an azobenzene (104) (74JOC3788, 80JHC825). l-Benzyloxy-l,2,3-benzotriazole shows a similar behavior (80JHC1309). 

Fig. 27 Stability of volume gratings in thin films of the statistical copolymer 6 and block copolymer 7 with methoxy-azobenzene side-groups...

The refractive index modulation of the block copolymer lb carrying cyano-azobenzene side-groups is more than twice that of the methoxy-substituted block copolymer 14. In addition, lb exhibits a much higher sensitivity than 14. This is just a consequence of (7), in which the sensitivity increases with the refractive index modulation. Furthermore, 14 exhibits a continuous decay after the writing laser is turned off, similar to that shown in Fig. 27. Block copolymer lb, in contrast, even shows an increase by 15% within a few hours, and the refractive index modulation is stable for years. In this case, the so-called post-development is not due to a different morphology as discussed above. Rather, the liquid crystalline character of the... 

Fig. 33 Dynamic relaxation processes in block copolymer 7 containing the methoxy-substituted azobenzene, as observed by temperature-dependent holographic measurements between 295 and 323 K. (Adapted with permission from [115]. Copyright Wiley-VCH Verlag GmbH Co. KGaA)...

A very large increase in kjsc is observed with para-meth-oxy and -dimethylamino substituents (Table 5.7). This result is consistent with the solution phase photochemistry of para-methoxy and para-dimethylaminophenyl azides, which largely yield azobenzenes on photolysis. 

Reactions suitable for the kinetics aiming at the purpose mentioned above needs to satisfy one condition. The TST must be valid for a fairly wide range of pressure and temperature. Furthermore it is desirable that the reactant can be generated in situ and the reaction can be followed spectroscopically to obtain reliable rate constants. As the first set of reactions, thermal ZfE isomerization of three N-benzylideneanilines (benzaldehyde anUs), i.e. N-[4-(dimethylamino) benzylidene]-4-nitroaniline (DBNA), N-[4-(dimethylamino)benzylidene]-4-ethoxy-carbonylaniline (DBEA), and N-[4-(dimethylamino)benzylidene]-4-bromoaniline (DBBA), and two push-pull substituted azobenzenes, i.e. 4-(dimethylamino)-4 -nitroazobenzene (DNAB) and 4 -(dimethylamino)-2-methoxy-4-nitroazobenzene (DMNAB) as shown in Scheme 3.2 were selected. 

Fig. 6-3. Variation of R, values with alumina water content in thin- layet chromatography. CCI4 solvent. Solid and dashed lines, calculated from q., (6-S) and adsorbent parameters of Table 6-1 (W /F = 1.25, I = 1.1) n, azobenzene [experimental data. Ref. A, />-methoxy azobenzene [experimental data, (Ref. (/S)] , Sudan red...

The major product of photolysis of l-methoxy-l,2,3-benzotriazole (43) in benzene, methanol, and acetonitrile (but not cyclohexane) is azobenzene (44), although 1,2,3-benzotriazole (45) is also formed.28 The formation of these two... 

Hydrogen transfer from hydrazobenzene to benzofuroxan (622) results in azobenzene and o-benzoquinone dioxime (623). Compound (622) reacts with formaldehyde to yield the benzimidazolinone (624). Chlorobenzofuroxan aldehyde condenses with derivatives of hydroxylamine or hydrazine to yield oximes or hydrazones (625 R = OH, OMe, NHPh, NMe2, etc.), which rearrange thermally to indazoles (626). Treatment of 7-methoxy-4-nitro-benzofurazan 1-oxide with aqueous potassium hydroxide affords a mixture of the corresponding 7-hydroxy-compound (627) and the rearranged 5-hydroxy-4-nitrobenzofuroxan (628). ... 

Ichimura and coworkers synthesized two organosilanes, 4-methoxy-4 -(A-(3-triethoxysilylpropyl)carbamoylmethoxy)azobenzene (MTAB) and 4,4 -bis-(A-(3-triethoxysilylpropyl)carbamoylmethoxy)azobenzene (DTAB), using the condensation reaction between carboxylic acid and amine in the presence of dicyclohexylcarbodiimide (DCC Ueda et al., 1993). However, this synthetic route... 

Methoxy phcny lazo) -2-Naphthol Sudan Red G 1, 4 Diphenyl Toluidino Anthraquinone 2-(4-Dimethylamino Phen>4azo) Naphthalene 1-Amino Anthraquinone Fast red AI I, 4 EHmethylamino Anthraquinone, Fast blue B 4-Dimethylamino Azobenzene (for colored smoke mixtures) 1-Methylamino Anthraquinone... 

Azoamine red A. See 4 Methyl-2-nitroaniline Azoamine scarlet. See 2-Methoxy-5-nitroaniline Azobenzene, 4-amino-. See p-Phenylazoaniline Azobenzene-3,4 -disulfonic acid, 4-amino-. See Acid yellow 9... 

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