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Isospecific, Chain Shuttling Polymerization of Propylene Oxide Using a Bimetallic Chromium Catalyst: A New Route to Semicrystalline Polyols
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-08-08 , DOI: 10.1021/jacs.7b00194
M. Ian Childers 1 , Andrew K. Vitek 2 , Lilliana S. Morris 1 , Peter C. B. Widger 1 , Syud M. Ahmed 1 , Paul M. Zimmerman 2 , Geoffrey W. Coates 1
Affiliation  

Hydroxy-telechelic poly(propylene oxide) (PPO) is widely used industrially as a midsegment in polyurethane synthesis. These atactic polymers are produced from racemic propylene oxide using chain shuttling agents and double-metal cyanide catalysts. Unlike atactic PPO, isotactic PPO is semicrystalline with a melting temperature of approximately 67 °C. Currently there is no practical route to hydroxy-telechelic isotactic PPO using racemic propylene oxide as the monomer. In this paper, hydroxy-telechelic isotactic PPO is synthesized from racemic propylene oxide with control of molecular weight using enantioselective and isoselective bimetallic catalysts in conjunction with chain shuttling agents. The discovery of an easily accessible bimetallic chromium catalyst is reported for this transformation. Diol, triol, and polymeric chain shuttling agents are used to give hydroxy-telechelic isotactic PPO of varying functionality and structure. Detailed quantum chemical studies are used to reveal the polymerization mechanism and origin of stereoselectivity.

中文翻译:

使用双金属铬催化剂进行环氧丙烷的等规链穿梭聚合:半结晶多元醇的新途径

羟基遥爪聚(环氧丙烷)(PPO)在工业上广泛用作聚氨酯合成的中间段。这些无规聚合物是使用链穿梭剂和双金属氰化物催化剂由外消旋环氧丙烷生产的。与无规 PPO 不同,全同立构 PPO 是半结晶的,熔化温度约为 67 °C。目前还没有使用外消旋环氧丙烷作为单体制备羟基遥爪等规 PPO 的实用途径。在本文中,使用对映选择性和等选择性双金属催化剂以及链穿梭剂,由控制分子量的外消旋环氧丙烷合成羟基遥爪等规 PPO。据报道,对于这种转化,发现了一种易于获得的双金属铬催化剂。二醇、三醇、和聚合物链穿梭剂用于提供具有不同功能和结构的羟基遥爪等规 PPO。详细的量子化学研究用于揭示立体选择性的聚合机制和起源。
更新日期:2017-08-08
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