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ω-Cyano-functionalized polystyrene has been prepared in 87% isolated yield using the general functionalization methodology based on anionic polymerization, silyl hydride functionalization, and hydrosilylation with allyl cyanide. First, an ω-silyl hydride-functionalized polystyrene was prepared quantitatively from poly(styryl)lithium by reaction with dimethylchlorosilane in hydrocarbon solution. Then the silyl hydride-functionalized polystyrene was added to allyl cyanide using Karstedt’s Pt(0) hydrosilylation catalyst. This general functionalization methodology was also used to develop a new synthesis of in-chain functionalized polymers. First, an in-chain, silyl hydride-functionalized polystyrene was prepared quantitatively from the reaction of excess poly(styryl)lithium with dichloromethylsilane in hydrocarbon solution. The excess poly(styryl)lithium was reacted with ethylene oxide to form an easily separable, hydroxyl-functionalized polystyrene. Then the purified, in-chain silyl hydride-functionalized polystyrene was added to allyl cyanide using Karstedt’s Pt(0) hydrosilylation catalyst. The resulting in-chain, cyano-substituted polystyrene was isolated in 58% yield. The silyl hydride- and cyano-functionalized polystyrenes were characterized by SEC, FTIR, 1H and 13C NMR, and MALDI-TOF mass spectrometry. [ABSTRACT FROM AUTHOR]

Poly(styryl)lithiums (Mn1500−2200 g/mol) in benzene were reacted with propylene sulfide (1.3−3 equiv) to prepare the corresponding thiol chain-end-functionalized polymers. The resulting polymers were characterized by thin layer chromatography, elemental analysis, 1H, 13C, and DEPT NMR spectroscopy, and MALDI-TOF mass spectrometry. Analysis of the resulting polymers by MALDI-TOF mass spectrometry indicates that reaction occurs by a ring-opening mechanism, in contrast to precedents showing that the reaction of organolithium compounds with propylene sulfide occurs by a sulfur extrusion mechanism. Poly(styryl)lithium was also reacted with 1.3 equiv of ethylene sulfide. The results from MALDI-TOF mass spectrometry show that the structure of the polymer corresponds to the product resulting from a ring-opening mechanism analogous to the reaction of propylene sulfide with poly(styryl)lithium. More oligomerization was observed for functionalizations with 1.3 equiv of ethylene sulfide (34.6%) compared to propylene sulfide (3.8%). The experimental results are consistent with quantitative thiol functionalization for reactions of poly(styryl)lithium with thiiranes. [ABSTRACT FROM AUTHOR]

The regiochemistry of the nickel-catalyzed polymerization of 2,5-dichlorobenzophenone in the presence of excess zinc and triphenylphosphine with (PBP-B) and without added coligand, 2,2'-bipyridine (PBP-A), has been re-examined. The carbonyl region of the 13 C NMR spectra have been interpreted by analysis of dimeric models for the H–T, H–H and T–T units in the polymer, i.e. 2,3'-bisbenzophenone, 2,2'-bisbenzophenone and 3,3'-bisbenzophenone. Based on the NMR spectral assignments for these model compounds, it has been concluded that PBP-B has few if any H–H units, whereas these units are present in significant amounts in PBP-A. Based on these results, it is proposed that what determines the conjugation length in the UV-vis spectra of PBPs is the occurrence of H–H units along the polymer backbone and not the percentage of H–T units in the chains. [ABSTRACT FROM AUTHOR]