Elucidation of the fine structure of poly(vinyl chloride) by hydrogenation and ¹³C‐NMR analysis of low molecular weight fractions

Abstract

SynopsisThe following experiment was performed based on the assumption that the characteristic structural features of high molecular weight poly(viny1 chloride) (PVC) should be present to the same extent in its low molecular weight fractions. Two PVC fractions of molecular weight, 1500 and BOO, respectively, (0.1496 of total polymer) were isolated from bulk PVC (M,, 32,000) by extraction with methanol. This extract was transformed into paraffins by a new hydrogenation method using an excess of Raney nickel in order to facilitate identification. W -N M R spectral data of the paraffins showed that almost 2 out of lo00 carbon atoms were linked to a side chain with more than five carbon atoms, and 5 out of 1000 carbon atoms were methyl branched. Gas chromatography-mass spectrometry (GC-MS) analyses confirmed that the low molecular weight paraffins consisted of a sequence of even-numbered homologs. These findings suggest indirectly that the surprisingly low degradation temperature of PVC is due to the arrangement of the chlorine atoms rather than to the branching of the alkyl chain.

Isolation and Structural Characterization of Tetrameric Oligomers of Vinyl Chloride

“…NMR data for isomer 1: dH (400 MHz, CDC13) 5.78 (2H, m, J 13, Hab), 4.40 (1H, m, Hc), 4.23 (1H, m, Hd), 4.05 (2H, d, J 6.4, Hee-), 3.82 (1H, dd, J 12, 4, Hf), 3.67 (1H, dd, J12, 4, Hg), 2.57 (2H, m, Hhi), 2.26 (1H, m, Hj), 2.00 (1H, m, Hk).…”

“…NMR data for isomer 2: dH (400 MHz, CDC13) 5.80 (2H, m, J 13, Hab), 4.26 (1H, m, Hc), 4.10 (1H, m, Hd), 4.05 (2H, d, J 6.2, Hee'), 3.83 (1H, dd, J 12, 4, Hf), 3.77 (1H, dd, J12, 4, Hg), 2.61 (2H, m, Hhi), 2.43 (1H, m, Hj), 2.22 Mass spectral data for isomer 2: found, (M -HC1)+ 211.9926 (C8Hn35Cl3 requires 211.9926), 177 (M -2C1)+, 141 (M -3C1)+. The and 13C NMR spectra of the two isomers clearly indicate that the structure of the VC tetramer isomers are two diastereomers of the structure shown as structure 3. Cl Cl 3…”