PROGRESSIVE SYNTHESES OF OLIGOMERS OF METHYL VINYL ETHER AND THEIR TACTICITIES

In this work, the oligomers of methyl vinyl ether were synthesized by the successive addition of methyl vinyl ether to the corresponding dimethyl acetal according to Hoaglin's procedure; the steric structures were studied by PMR spectroscopy. In experiments, the four oligomers, 1-, 2-, 3- and 4-mers were progressively prepared in ether at room temperature using a catalytic amount of BF//3 multiplied by (times) OEt//2. PMR spectra of the oligomers were taken at 100 MHz on a JNM-MH-100 spectrometer (JEOL) at 35 degree C. The relative intensities of the peaks were determined by an electronic integrator built in the spectrometer, and also by cutting out and weighing each band area in Xerox copy of the spectrum. The fractions of the configurational dyads in dimer, trimer, and tetramer obtained are summarized. From the results, it is revealed that the addition mode of methyl vinyl ether is almost independent of the mol. wt of the preceding oligomer, and the dyad tacticities of the oligomers are nearly the same as the dyad tacticity of the polymer obtained under similar conditions to those of the preparation of oligomer. This suggests that the addition mode of the monomer to the growing end is almost the same during the polymerization of methyl vinyl ether independently of the mol. wt of growing chain.