ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Asymmetric-selective (or stereoelective) polymerization of racemic α-methylbenzyl acrylate (2a) was studied with Grignard reagent/(-)-sparteine and its modified catalyst system in toluene. All catalyst svstems polymerized preferentially the (R)-monomer over the (S)-monomer. The Grignard reagent/(-)-sparteine system showed very low activity and gave the polymer only in a few per cent yield at -78°C. The addition of secondary amines such as piperidine and diethylamine to the catalyst system improved not only the activity but also the selectivity. The optical purity of the polymer initially formed with the cyclohexylmagnesium bromide/(-)-sparteine/diethylamine system at - 78°C was 84%, and at about 80% polymer yield almost optically pure monomer was recovered. Asymmetric selectivity decreased with an increase of temperature. The dyad tacticity of the polymer was determined by 1H NMR spectroscopy. There was no clear correlation between the selectivity and tacticity. The role of the amines in the catalyst systems was investigated by 1H NMR spectroscopy.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1981.021821020
Permalink