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Title: Controlled synthesis of polyenes by catalytic methods. Progress report, December 1, 1989--November 30, 1992

Abstract

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.more » 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.« less

Authors:
Publication Date:
Research Org.:
Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10152711
Report Number(s):
DOE/ER/13564-11
ON: DE92015286
DOE Contract Number:  
FG02-86ER13564
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: [1992]
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; POLYENES; CHEMICAL PREPARATION; ALKYNES; POLYMERIZATION; PROGRESS REPORT; MOLYBDENUM COMPLEXES; ORGANOMETALLIC COMPOUNDS; COPOLYMERS; 400201; CHEMICAL AND PHYSICOCHEMICAL PROPERTIES

Citation Formats

Schrock, R.R. Controlled synthesis of polyenes by catalytic methods. Progress report, December 1, 1989--November 30, 1992. United States: N. p., 1992. Web. doi:10.2172/10152711.
Schrock, R.R. Controlled synthesis of polyenes by catalytic methods. Progress report, December 1, 1989--November 30, 1992. United States. doi:10.2172/10152711.
Schrock, R.R. Wed . "Controlled synthesis of polyenes by catalytic methods. Progress report, December 1, 1989--November 30, 1992". United States. doi:10.2172/10152711. https://www.osti.gov/servlets/purl/10152711.
@article{osti_10152711,
title = {Controlled synthesis of polyenes by catalytic methods. Progress report, December 1, 1989--November 30, 1992},
author = {Schrock, R.R.},
abstractNote = {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.},
doi = {10.2172/10152711},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jul 01 00:00:00 EDT 1992},
month = {Wed Jul 01 00:00:00 EDT 1992}
}

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