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Synthesis and structure of poly(phenyl isocyanate)s bearing an optically active alkoxyl group
Author(s) -
Hino Kyoko,
Maeda Katsuhiro,
Okamoto Yoshio
Publication year - 2000
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/1099-1395(200007)13:7<361::aid-poc255>3.0.co;2-e
Subject(s) - chemistry , helix (gastropod) , polymer , isocyanate , polymer chemistry , specific rotation , monomer , polymerization , tetrahydrofuran , alkoxy group , circular dichroism , anionic addition polymerization , crystallography , polyurethane , stereochemistry , organic chemistry , solvent , alkyl , ecology , snail , biology
Novel optically active phenyl isocyanate derivatives ( 1 – 6 ) bearing an (R)‐sec ‐butoxy, (S) ‐2‐methylbutoxy or (S) ‐3,7‐dimethyloctyloxy group at the meta or para position on the phenyl ring were prepared and polymerized with an anionic initiator in tetrahydrofuran (THF). The resulting polymers from 1 , 2 , 4 and 6 showed much greater specific rotation than that of the corresponding monomers and an intense circular dichroism (CD) band in the main‐chain absorption region, indicating that these polymers have a predominantly one‐handed helical conformation in solution. On the other hand, the polymers obtained from 3 and 5 showed a much smaller specific rotation than that of the above polymers at room temperature. The polymers from 2 and 5 showed a remarkable change in optical activity with change in temperature, and the specific rotation of the polymers changed from a positive to a negative value with decrease in temperature. The CD band of the polymers in the absorption region due to the main chain changed from a positive to a negative peak with a change in specific rotation. These results indicate that poly‐ 2 and poly‐ 5 undergo a thermally induced helix–helix transition in THF. The temperature for the helix–helix transition of poly‐ 2 was independent of the degree of polymerization. Poly‐ 2 exhibited a reversible helix–helix transition in chloroform and diethyl ether and also in THF, whereas in toluene and dichloromethane such a transition was not observed. Copyright © 2000 John Wiley & Sons, Ltd.