The synthesis of precursors to conjugated polymers

Davis, Heather (1998) The synthesis of precursors to conjugated polymers. Masters thesis, Memorial University of Newfoundland.

[img] [English] PDF - Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.

Download (6Mb)

Abstract

Poly(benzo[c]thiophene) (PBcT) was prepared by Wudl et al in 1984 from the monomer benzo[c]thiophene (BcT) and was found to have a bandgap of 1.0 eV, the lowest bandgap polymer reported at that time. Since this finding, very few substituted BcTs have been prepared. -- Two substituted BcTs, 5,6-dioxymethlenebenzo[c]thiophene 56 and 5,6-bis(methylcarboxylate)benzo[c]thiophene 57), were prepared using adapted literature procedures in four and six steps, respectively, in good yields. In the case of 57 a novel monomer, several approaches were taken, one of which led to the discovery of NBS and silica as a rather unique benzylic brominating agent. -- Other compounds of interest included terheterocycles, 1,3-dithienylbenzo[c]thiophenes 85. The following compounds, 5,6-dimethoxythiophthalic anhydride 105, 5,6-methylenedioxyphthalaldehyde 112 and 5,6-ethylenedioxyphthalic acid 171, were prepared as potentially useful precursors for the synthesis of substituted terheterocycles. Compound 105 was prepared by the hydroxymethylation of 3,4-dimethoxybenzoic acid 117 followed by the reaction with sulfur. Upon its isolation, it was reacted with two equivalents of 2-thienyllithium and also with one equivalent of 2-thienyllithium followed by methyliodide to form 1-thienoyl-2-methylthiacaronyl-5,6-dimethoxybenzene 108. Compund 112 was prepared in four steps starting from piperonal and 171 was prepared by a Diels-Alder reaction of a 3,4-disubsituted thiophene, EDT 157, and dimethylacetylene dicarboxylate. The literature synthesis of 157 gave disappointing results, but modifications to this procedure led to a significant improvement in the yield of this important thiophene.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/9376
Item ID: 9376
Additional Information: Bibliography: pages 125-131.
Department(s): Science, Faculty of > Chemistry
Date: 1998
Date Type: Submission
Library of Congress Subject Heading: Polymerization; Monomers

Actions (login required)

View Item View Item

Downloads

Downloads per month over the past year

View more statistics