Mechanism of NCA Polymerization. VIII. The Base-Initiated Polymerization of β-Amino Acid NCAs
作者:
HansR. Kricheldorf,
Rolf Mülhaupt,
期刊:
Journal of Macromolecular Science: Part A - Chemistry
(Taylor Available online 1980)
卷期:
Volume 14,
issue 3
页码: 349-377
ISSN:0022-233X
年代: 1980
DOI:10.1080/00222338008056718
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The polymerization of β-alanine NCA, D, L-cis-2-aminocyclo-butane-1-carboxylic acid NCA, D, L-cis-2-amino-4-cyclohexane-1-carboxylic acid NCA, and D, L-cis-2-aminocyclohexane-1-carboxylic acid NCA was carried out in various solvents by use of triethylamine or pyridine as catalysts. The addition of these bases to a NCA solution leads to deprotonation of the NCAs and to the formation of large amounts of β-isocyanatocarboxylate ions which are detectable in the IR spectra. These isocyanates cause side reaction which prevent the formation of high molecular weight β-polyamides under all conditions studied. The role of electrophilic cocatalysts such as N-acylamino acid NCAs and chlorophenyl isocyanate was investigated. In contrast to the base-initiated polymerization of α-amino acid NCAs, the polymerization of β-amino acid NCAs is inhibited by the addition of electrophilic cocatalysts. Thus, the activated monomer mechanism is not operating in the case of β-amino acid NCAs. Various N-acyl β-amino acid NCAs were synthesized by addition of β-amino acid NCAs onto reactive isocyanates.
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