2-Styrylpyridine methiodide

One or both of the carbocyclic aromatic rings in stilbenes or azobenzenes can be replaced by heterocycles. Examples include 2-styrylpyridine methiodide (138) and 4,4 -azopyridine (139) (53JCS1281). 

Irradiation of /m -2-styrylpyridine produces the m-isomer. trans-2 Styrylpyridine hydrochloride, irradiated in water, gives not only its cis isomer but also a dimer hydrochloride. Irradiation of /m -2-styrylpyridine methiodide in benzene suspension yields the bis-methiodide of a dimer, whereas in water it gives the rw-isomer and subsequently the dimer. re y-2-Styrylpyridine methiodide heated at its melting point produces the trans methiodide. Two stereoisomers of the dimer are known ... 

Conversion of mw -2-styrylpyridine methiodide into the rw-isomer by irradiation of the aqueous solution is very rapid compared with the dimeri-zationi " 316,... 

In an earlier report [46], it was shown that 2-styrylpyridine methiodide in water... 

Isomerization of unsaturated nitrogen-containing organic compounds, containing C=C double bonds, has been investigated less intensely than the isomerization of other related unsaturated compounds. Photoisomerization has been reported upon irradiation of a benzene solution of aqueous solution of its hydrochloride, and of the methiodide salt under nitrogen atmosphere. The corresponding cis-isomers are formed.308,309... 

Ultraviolet irradiation of the methiodide or hydrochloride of 2-styryl-pyridine (XCIII) in the solid state results in transformation of the trans-isomers to the corresponding dimers (XCVa, b) on the other hand irradiation in benzene solution gives both isomerization and dimerization.309 Dimer (XCVa) was produced in low yield on irradiation of XCIII in the powdered form in the presence of air.308 This is in contrast to the reported stability of XCIII toward photodimerization.109 Similar dimerizations have been reported in the case of 2,4-dichloro-3-cyano-6-styrylpyridine,164 2-styrylquinaldine (XCV) and frans-4,4 -diguanyl-stilbene bis(2-hydroxyethane sulfonate) (stilbamidine) (XCIV).82,83... 

We have reported [44] the photochemical behavior of a number of 2- and 4-styrylpyridines and their corresponding methiodides which were studied in order to gain insight into the behavior of analogous polymers by means of the model systems. 

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