Functionalization of Poly(styryl)lithium with Styrene Oxide

Abstract

The functionalization of poly(styryl)lithium with styrene oxide as a route to functional polymers was investigated. When the reaction was performed in benzene at room temperature, analysis of the products by SEC and column chromatography indicated the presence of functional polymer (83.5 wt %), along with unfunctionalized polymer (9.0 wt %), dimeric product (5.6 wt %), and trimeric product (0.1 wt %). The structure of the dimeric product was determined to be head-to-head dimer from both 13C NMR analysis and MALDI−TOF MS and was proposed to result from an electron-transfer mechanism. The dimeric product was eliminated when the functionalization was effected in the presence of tetrahydrofuran (>15 mol equiv). Under these conditions >99 wt % functionalized polymer was obtained as determined by column chromatography and MALDI−TOF MS. Addition of PSLi to the epoxide can occur by addition to the least hindered carbon or by addition to the most hindered carbon. Analysis of the regiochemistry of the chain end was performed by both 13C NMR and APT 13C NMR spectroscopy. It was determined that the product obtained in the presence of tetrahydrofuran contained 53 mol % of the product resulting from addition to the least hindered carbon and 47 mol % resulting from addition to the most hindered carbon.

Macroporous Helical Silica Immobilizing Cobalt-Salen Complex Catalyzed Asymmetric Hydrolytic Kinetic Resolution of Epoxides

“…For 1,2-epoxybutane, this comparison was basically retained except for one test (entry 23). For 1,2-epoxyhexane, this relation depended on catalysts (entries [26][27][28][29][30]. Therefore, the present system showed potentials on preparation of chiral epoxides.…”

“…The Co-salen complexes were immobilized into helical silica. In view of application of chiral epoxide and diol compounds in polymer [26] and pharmaceutical [27], the HKR of styrene oxide, 1,2-epoxybutane and 1,2-epoxyhexane were carried out using helical silica-supported Co-salen complexes. In particular, the possible synergy of helical silica with Co-salen complex would be discussed.…”

Synthesis and characterization of copolymers with the same proportions of polystyrene and poly(ethylene oxide) compositions but different connection sequence by the efficient Williamson reaction

“…The quantitative reaction between polymeric organolithium and epoxides is used to design functionalized polymers due to the high aggregation degree of lithium alkoxides and their inability to initiate further polymerization . Herein, the functionalized precursors of PS‐OH with one hydroxyl group at the ω end were synthesized by capping poly(styryl)lithium (PS − Li + ) with EO.…”

A Road Less Traveled to Functional Polymers: Epoxide Termination in Living Carbanionic Polymer Synthesis

“…The formation of these undesired macromolecules can be almost fully suppressed by adding THF as a Lewis base, leading to reduced association of living polymer chain ends. In this case, high degrees of functionalization (>99%) can be obtained 51, 52. The regiochemistry of this reaction is affected by steric (polymer chain) and electronic (electron‐delocalization) factors 53.…”