Poly-butadienes ozonolysis

Negative ions FAB mass spectrum of poly(butadiene) ozonolysis products. (Reprinted with permission from Ref. 76, Copyright 1999, American Chemical Society.)... 

With the synthetic dienes the situation may be much less simple. In the case of the simplest structure, poly butadiene, a variety of ozonolysis products may be obtained as indicated below (Table 5.1). With other diene homopolymers such as polyisoprene, polypiperylene and copolymers such as SBR the range of possible products is clearly much greater. 

Yakubchik and his co-workers (1956, 1959 and 1962) have preferred to separate the acid derivatives by means of partition chromatography and compared the results with those obtained from an artificial mixture of those acids expected to be present. In the case of Ziegler-Natta catalyzed polybutadienes with less than 1% 1,2- units the presence of 1,4-1,2-1,4 sequences was indicated by the identification of some 1,2,4-butane tricarboxylic acid. Examination of their chromatograms suggests, at most, just a trace of any hexane tetra-carboxylic acid so that only a very small amount, if any, of 1,4-1,2-1,2-1,4 structures were present. Furthermore, no trace of any 1,2,3-propane tricarboxylic acid was found so there was no positive sign of any branching at the a-methylene position. On the other hand in the case of rubidium-catalyzed poly butadienes, which, like other polybutadienes prepared by the use of alkali metal catalyst systems, have a high 1,2- content, both hexane tetracarboxylic acid and 1,2,3-propane tricarboxylic acid were present in the ultimate products of ozonolysis. 

Figures 12.8 and 12.9 show chromatographic separation of the ozonolysis products from poly butadienes having different amounts of 1,2 structure, as measured by IR or NMR spectroscopy. Figure 12.10 shows the relationship of 1,2 content to the amount of 3-formyl-l,6 hexane-dial in the ozonolysis products.

Ebdon and coworkers22 "232 have reported telechelic synthesis by a process that involves copolymerizing butadiene or acetylene derivatives to form polymers with internal unsaturation. Ozonolysis of these polymers yields di-end functional polymers. The a,o>dicarboxy1ic acid telechelic was prepared from poly(S-s tot-B) (Scheme 7.19). Precautions were necessary to stop degradation of the PS chains during ozonolysis. 28 The presence of pendant carboxylic acid groups, formed by ozonolysis of 1,2-diene units, was not reported. 

Montaudo, G., Scamporrino, E., and Vitalini, D., Structural Characterization of Butadiene/Styrene Copol5nners by Fast Atom Bombardment Mass Spectrometry Analysis of the Partial Ozonolysis Products, Mactomolecules, 24, 376 (1991). Wilczek-Vera, G., Danis, P.O., and Eisenberg, A., Individual Block Length distributions of Block Copol5nners of poly(alfa methyl styrene)-block-poly(st5rrene) by MALDI-TOF Mass Spectrometry, Macromolecules, 29, 4036 (1996). 

Partial degradation induced by an ozonolysis process was used to produce low molar mass oligomers, and FAB-MS was applied for the identification of the ozonolysis-formed oligomers, from polpsoprene, poly(chloroprene), and butadiene/acrylonitrile and butadiene/st5n-ene copol5mier samples. ... 

Draw the structure of the product of ozonolysis of rnr t-poly(l,3-butadiene) under oxidation workup conditions. 

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