123200-59-9Relevant academic research and scientific papers
Determination of the Relative Rates of Addition of Styrene and Acrylonitrile to the 1-(1,3-Diphenylpropyl) and 1-(3-Cyano-1-phenylpropyl) Radicals. Evidence for a Penultimate Effect in Radical Copolymerization
Cywar, Douglas A.,Tirrell, David A.
, p. 7544 - 7553 (2007/10/02)
1,1'-Azobis(1,3-diphenylpropane) (1b) and 4,4'-azobis(4-phenylbutyronitrile) (1c) were prepared in overall yields of 10percent and 1.2percent, respectively, both starting from Ba(13)CO3 (99 atom percent).Analysis of end-group concentrations in styrene-acrylonitrile (SAN) copolymers prepared with 1b as initiator allows accurate determination of the relative rates of addition of these monomers (kS/kA) to the 1-(1,3-diphenylpropyl) radical (2b); similarly, analysis of SAN copolymers prepared with 1c allows determination of kS/kA for the 1-(3-cyano-1-phenylpropyl)radical (2c).Significantly different preferences of the radicals for addition of styrene and acrylonitrile were observed; we obtain kS/kA=0.21 +/- 0.01 for 2b and KS/kA=0.52 +/- 0.03 for 2c.These results show that kS/kA for 1-(1-phenylalkyl) radicals is sensitive to substitution γ to the radical center and provide strong support for the existence of a penultimate unit effect in SAN copolymerization.The results are consistent with the penultimate model analysis of SAN copolymerization by Hill, O'Donnell, and O'Sullivan.
Self-Reactions of 1,3-Diphenylpropyl and 1,3,5-Triphenylpentyl Radicals:Models for Termination in Styrene Polymerization
Schreck, Vicki Anne,Serelis, Algirdas K.,Solomon, David H.
, p. 375 - 393 (2007/10/02)
Quantitative determination of the products from thermal decomposition of 1,1',3,3'-tetraphenylazopropane (2) and 1,1',3,3',5,5'-hexaphenylazopentane (5) shows that the respective derived title radicals (1) and (4) undergo self-reactions with a similar preference for combination over disproportionation.The proportion of combination increases from 87 to 93percent (Ec-Ed=9.6+/-1.2kJ mol-1 and ΔSc-ΔSd=43+/-7 JK-1mol-1) for (1), and from 86 to 93percent (Ec-Ed=10.6+/-1.4kJ mol-1 and ΔSc-ΔSd=45+/-6 JK-1mol-1) for (4) over the temperature range 80-161 deg.The relevance of these results to the termination mechanism in the radical polymerization of styrene is discussed.Some minor by-products (28)-(30) which arise by addition of 1,3-diphenylpropyl (1) to 1,3-diphenylpropene (14)/(15) have also been detected.The syntheses of the azo compounds (2) and (5), the former as separate, pure meso- and rac-diastereomers (2m) and (2r), and their various expected decomposition products are described.
