Styrenes dicyano

Penultimate effects have been observed for many comonomer pairs. Among these are the radical copolymerizations of styrene-fumaronitrile, styrene-diethyl fumarate, ethyl methacrylate-styrene, methyl methacrylate l-vinylpyridine, methyl acrylate-1,3-butadiene, methyl methacrylate-methyl acrylate, styrene-dimethyl itaconate, hexafluoroisobutylene-vinyl acetate, 2,4-dicyano-l-butene-isoprene, and other comonomer pairs [Barb, 1953 Brown and Fujimori, 1987 Buback et al., 2001 Burke et al., 1994a,b, 1995 Cowie et al., 1990 Davis et al., 1990 Fordyce and Ham, 1951 Fukuda et al., 2002 Guyot and Guillot, 1967 Hecht and Ojha, 1969 Hill et al., 1982, 1985 Ma et al., 2001 Motoc et al., 1978 Natansohn et al., 1978 Prementine and Tirrell, 1987 Rounsefell and Pittman, 1979 Van Der Meer et al., 1979 Wu et al., 1990 Yee et al., 2001 Zetterlund et al., 2002]. Although ionic copolymerizations have not been as extensively studied, penultimate effects have been found in some cases. Thus in the anionic polymerization of styrene t-vinylpyri-dine, 4-vinylpyridine adds faster to chains ending in 4-vinylpyridine if the penultimate unit is styrene [Lee et al., 1963]. 

Kambour RP, Gruner CL (1978) Effects of polar group incorporation on crazing of glassy polymers styrene-acrylonitrile copolymer and a dicyano bisphenol polycarbonate. J Polym Sci Polym Phys 16(4) 703—716... 

The condensation of DAMN with 1,2-diimino-l, 2-dimethoxyethane (70) gives 2-amino-5,6-dicyano-3-methoxypyrazine (71) (385), but as in the condensation of DAMN with DISN the control of acid concentration is critical. The condensation of DAMN with chloroacetone or pyruvaldehyde has been shown to give 23-dicyano-5-methylpyrazine (385) and DAMN with methylsulfinylmethyl phenyl ketone refluxed in ethanol gave 23-dicyano-5-phenylpyrazine (386a). A, 7V -Dichlorodi-iminosuccinonitrile (a2DISN) (72) reacts with some olefins to give pyrazines. Thus with styrene (73, R = Ph, R = H) in benzene it gave 23-dicyano-5-phenyl-pyrazine (74, R = Ph, R = H). Similar reactions were observed with /J-methyl-styrene and 23-dihydropyran (387). 

Diiminosuccinonitrile (DISN) (10) reacts exothermically with ds-l,2-dimethoxy-ethylene (62) in acetonitrile to give 5,6-dicyano-2,3-dimethoxy-l,2,3,4-tetrahydro-pyrazine (63) (386, 1596). Styrene and p-halogenostyrenes reacted with DISN in acetonitrile at room temperature to form 2-amino-3-(2 -arylaziridin-r-yl)maleonitrile (64) (50-80%), whereas the more electron-rich p-methoxystyrene and 2-vinylfuran gave 5-aryl-2,3-dicyano-l,4,5,6-tetrahydropyrazine(65)(60-80%).p-Methylstyrene gave both types of products (1597). 

Cycloadditions only proceeding after electron transfer activation via the radical cation of one partner are illustrated by the final examples. According to K. Mizono various bis-enolethers tethered by long chains (polyether or alkyl) can be cyclisized to bicyclic cyclobutanes using electron transfer sensitizer like dicyanonaphthalene or dicyano-anthracene. Note that this type of dimerization starting from enol ethers are not possible under triplet sensitization or by direct irradiation. Only the intramolecular cyclization ci the silane-bridged 2>. s-styrene can be carried out under direct photolysis. E. Steckhan made use of this procedure to perform an intermolecular [4+2] cycloaddition of indole to a chiral 1,3-cyclohexadiene. He has used successfully the sensitizer triphenylpyrylium salt in many examples. Here, the reaction follows a general course which has been developed Bauld and which may be called "hole catalyzed Diels-Alder reaction". 

Dehydrogenation of some aromatic steroids with 2,3-dichloro-5,6-dicyano-benzoquinone (DDQ) affords styrene analogues. Neoergosterol (252) gives the 14-ene (253) rapidly at room temperature, and is more slowly transformed into the 14,16-diene (254). The first step provides a further illustration of the... 

R. P. Kambour and C. L. Gruner, Effects of Polar Group Incorporation on Crazing of Glassy Polymers Styrene-Acrylonitrile Copolymer and a dicyano Bisphenol Polycarbonate , J. Polym. Sci., Polym. Phys. 16, 703-716 (1978). 

The same group have also used [Fe(S2CNEt2)3] alone as a catalyst for the reverse ATRP polymerization of vinyl monomers, including MMA and styrene, using diethyl 2,3-dicyano-2,3-diphenylsuccinate as a radical initiator... 

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