Styryls

An alkyi group occupying the 4-position of the thiazole ring may condense if the 5-position is substituted. 2-Acetamido-4-methy]-5-nitrothiazole (80) and p-cyanobenzaldehyde when refluxed with small amounts of piperidine yield the 4-styryl derivative (81) (Scheme 57) (238, 239). 

In styryl compounds, a part of the methine chain is replaced by a phenyl group. Their name is based on the nuclei from which they are issued 3-ethyl-5-methyl-2-(p-dimethylaminostyryl)thiazolium iodide (Scheme 7). 

A mesophenyl-substituted trimethine cyanine has been identified as a by-product in syntheses leading to styryl dyes it is also obtained when the anhydrobase reacts with the styryl dye (26). 

Unquaternized dyes, substituted by styryl groups in positions 4 and 5, have been used to prevent steric hindrance (115). 

Until now, no final conclusion seems to have been reached as to the origin and amplitude of the phenomenon. The nature of the alkyl group fixed on the nitrogen atoms does not influence the position of but substituents of different kinds produce, for trimethine thiazolocyanine as well as styryl derivatives (116), a bathochromic shift in the order ... 

A rigidized molecule obtained when the two a-carbons of the trimethine chain are linked by a dimethylene bridge cannot be planar. According to the resonance concept, its stability increases as a bathochromic effect of 41 nm is observed (122). The of the bistyryl dye obtained by the substitution of the -proton in the chain of a styryl dye by a dialkylamino group is nearly the same as for the parent styryl dye (123). 

Styryl derivatives have been patented as sensitizers (76) and other methine dyes for sensitization in direct photothermoGraphic material (134). 

Many methine cationic dyes, styrylic (141), pyrrolic. or amino-substituted (142) derivatives of thiazolium, possess interesting anthelmintic properties (143). This last class has been used as accelerators of the catabolism and activators of cellular exchanges (144). 

VII. Classification and List of Thiazolocyanine Dyes TABLE 1121 A, STYRYL DYES... 

Ozonolysis of 2-styryl-4-methylthiazole followed by oxidation of the intermediate carbonyl compound with peracetic acid yields 4-methyl-2-thiazolecarboxylic acid (30). 

As mentioned previously, aldehydes can be prepared by Stephen s method of reduction of nitriles by stannous chloride (37, 91). Polaro-graphic reduction of thiazolecarboxylic acids and their derivatives gives lower yields of aldehydes (58). Ozonolysis of styrylthiazoles, for example, 2-styryl-4-methylthiazole, followed by catalytic reduction gives aldehyde with 47% yield of crude product (30). 

Diethylamino)phenyl]-4,5-dihydro-l-phenyl-lH-pyra2ol-3 -yl]ethenyl]-N,N-diethylben2enamine, (5-(p-diethyl aminophenyl)-l-phenyl-3-(p-diethylamino-styryl)pyra2oline) [57609-72-0]... 

ALKANOLAMNES - ALKANOLAMINES FROM OLEFIN OXIDES AND AL ONIA] pol 2) l-Phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl] pyrazoline [57609-72-0]... 

Styryl Derivatives of Benzene and Biphenyl. Othei compounds based on the styryl gioup weie piepaied to lengthen the conjugated system of stilbene. 

As the quinone stabilizer is consumed, the peroxy radicals initiate the addition chain propagation reactions through the formation of styryl radicals. In dilute solutions, the reaction between styrene and fumarate ester foUows an alternating sequence. However, in concentrated resin solutions, the alternating addition reaction is impeded at the onset of the physical gel. The Hquid resin forms an intractable gel when only 2% of the fumarate unsaturation is cross-linked with styrene. The gel is initiated through small micelles (12) that form the nuclei for the expansion of the cross-linked network. 

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