ANALYTICAL CHEMISTRY
1114 Examination of a Propylene Polymer. Limited success hap been achieved in extending the iodine-olefin procedure to an olefintype analysis of a complex olefin mixture. A propylene polymer was selected because it is thought to consist largely of tri- and tetrasubstituted olefins which are detectable by the iodine-olefin procedure I t n a s ’thought best to analyze such a complex olefin mixture by a combination infrared and iodine-olefin method. This takeq advantage of the certainty with which the simpler olefin types can he determined bv infrared spectroscopy. The infrared method used is essentially equivalent to that published by Saier and other% (9), except that a 0 1-mm. cell and n-heptane w r e used. The matrix used for the iodine-olefin procedure, including the overlaps for the olefins determined by infrared analysis, is give? in Table V.
The propylene polvmer used was prepared by polymerization of propylene over UOP sohd phosphoric acid catalyst. Its average molecular weight was approximately Clo as determined by boiling range. The analysis obtained is given in Table VI. The low total obtained in Table VI is believed to be due to the lack of tri- and tetrasubstituted olefins with branched-chain R groups for calibration. It has been pointed out that blanching of the R groups of the simpler olefin types generally decreaws the absorptivity, e‘. It is possible that this effect iq even more pronounced for the tri- and tetrasubstituted olefin^. T h r propylene polymer is thought to contain principally theqe high11 branched structures This type analysis is the first spectroscopic determination that the RzC=CRZ type of olefin is present in propylene polymei Further, the RzC=CHR type is shown to be a major constituent This confirms infrared evidence based on a broad. geneial abSOI’ptiOn in the 800- to 850- cm.-l region.
Table I-. Matrix for Combined Infrared and Iodine Complex Methods for Olefin-Type 4nalysis cis-
RHC= CHR 295 317 337
E 11 6 3 1
Molecular Absorptivity e ’ transRzC= R?C= RHC= CHR CR, CHR 17 1 86 113 86 22 3 270 2 6 3 x 192
RCH= CH? 5 5 0 9 0 3
RICE CH2
248 127 31
Table YI. Analysis of Propylene Polymer Olefin Type RCH=CHz
R?C=CHga trans-RCH=CHRa
Percentage 2.4 7.0
cis-RCH=CHR
RL!=CHR RzC=CR% Total a Determined by infrared analysis . .-
~
~
LITERATURE CITED
(1) Anderson. J. .I.,Jr., and Seyfried, K. D.. .%N.I., J . A m . CAenz. Soc., 74, 458 (1952). (3) Benesi, H.A , , and Hildebrand. J. H., I h i d . , 71, 2703 (1949) (4) Fenske, M. R., Braun. W. G.. Wiegand, R. V., Quiggle, D.. McCormick, R. H., and Rank, D. H.. AN.
