Controlled Synthesis of Polyenes by Catalytic Methods. Progress Report for the period December 1, 1989 - November 30, 1992

Technical Report · Mon Nov 30 00:00:00 EST 1992

DOI:https://doi.org/10.2172/5225994· OSTI ID:5225994

Schrock, R R

A more direct approach to polyenes by the direct polymerization of acetylenes has been achieved. We were able to show that polymerization of acetylene itself can be controlled with a well- characterized alkylidene catalyst, but only if a base such as quinuclidine is present in order to slow down the rate of propagation relative to initiation. (Quinuclidine may also stabilize vinylalkylidene intermediates formed in the reaction). Unfortunately, living polyenes'' were no more stable than isolated polyenes, and so this approach had its limitations. Direct polymerization of acetylene by Mo(CH-t-Bu)(NAr)(O-t-Bu){sub 2} was more successful, but inherent polyene instability was still a problem. The most important result of the past grant period is the finding that dipropargyl derivatives (HC=CCH{sub 2}XCH{sub 2}C=CH; X = CH{sub 2}, C(CO{sub 2}R){sub 2}, SiR{sub 2}, etc.), which have been reported to be cyclopolymerized by various classical catalysts by as yet unknown mechanisms, are polymerized by Mo(CH-t-Bu)(NAr)(OCMe(CF{sub 3}){sub 2}){sub 2} in dimethoxyethane. We speculate that intramolecular formation of a five-membered ring in the product of {alpha} addition is fast enough to yield another terminal alkylidene on the time scale of the polymerization reaction, while a six-membered ring is formed in a reaction involving a more reaction terminal alkylidene. Either intermediate alkylidene, but most likely the terminal alkylidene, could react with additional monomer to lead to growth of a chain having dangling'' triple bonds that eventually could be employed to form crosslinks.

• Research Organization: Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-86ER13564
• OSTI ID: 5225994
• Report Number(s): DOE/ER/13564-11; ON: DE92015286
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKYNES
POLYMERIZATION
POLYENES
CHEMICAL PREPARATION
COPOLYMERS
MOLYBDENUM COMPLEXES
ORGANOMETALLIC COMPOUNDS
PROGRESS REPORT
CHEMICAL REACTIONS
COMPLEXES
DOCUMENT TYPES
HYDROCARBONS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201 - Chemical & Physicochemical Properties
Copolymers
Progress Report
400201* - Chemical & Physicochemical Properties