17072-61-6Relevant academic research and scientific papers
Dissociation and Aromatization of a Semibenzene. Reactions of Triphenylmethyl and Methyl Isobutyryl Radicals
Engel, Paul S.,Chen, Yanqiu,Wang, Chengrong
, p. 3073 - 3079 (2007/10/02)
Semibenzene 4, which can be regarded as the recombination product of triphenylmethyl and methyl isobutyryl radicals (5), affords exactly these intermediates on thermolysis or inefficiently on direct photolysis.Recombination and disproportionation of these dissimilar radicals proceeds with a much lower barrier than the dimerization of triphenylmethyl.Whereas thiophenol or triplet 9-fluorenone aromatize 4, thermolysis in the presence of 1,4-cyclohexadiene allows trapping of 5 and oligomeric radical 13.From the measured heat of aromatization (22.0 kcal/mol), the C-H bond dissociation enthalpy of 4 and its analogue lacking the side chain ("p-isotriphenylmethane") is calculated to be 54 kcal/mol, the lowest value known for any closed-shell, neutral hydrocarbon.Exposure of 4 to the atmosphere causes rapid autoxidation to hydroperoxide 19, which thermolyzes in the GC to aromatic ketones and phenols instead of undergoing a 1,2-aryl shift.
Thermal Degradation of Polymers. III Thermal Degradation of a Compound which Models the Head-to-Head Linkage in Poly(methyl methacrylate)
Holland, Kelvyn A.,Rae, Ian D.
, p. 687 - 692 (2007/10/02)
As a model for a poly(methyl methacrylate) chain which contains a head-to-head unit, the thermal degradation of tetramethyl 2,4,5,7-tetramethyloctane-2,4,5,7-tetracarboxylate has been studied.The meso compound degraded at 210 deg to give seven products which have been characterized by spectroscopic techniques and synthesized by unambiguous routes.The products resulted from reactions which followed thermal rupture of the central C-C bond of the model compound, thus supporting the proposal that head-to-head units are important in the thermal degradation of poly(methyl methacrylate).
The Self-Reactions of 1-Methoxycarbonyl-1-methylethyl and Higher Ester Radicals: Combination vs Disproportionation and Oligomeric Products from Secondary Reactions
Bizilj, Snezna,Kelly, David P.,Serelis, Algirdas K.,Solomon, David H.,White, Kathleen E.
, p. 1657 - 1673 (2007/10/02)
The geminate self-reactions of the title methyl, ethyl and butyl ester radicals (2a-c), formed by decomposition of the corresponding azo precursors (1a-c) in the presence of stable nitroxide radical scavengers, were found on the basis of product analysis to comprise combination and disproportionation in the ratios 56 : 44 (methyl), 58 : 42 (ethyl) and 47 : 53 (butyl).In the absence of radical scavengers, extensive oligomerization is observed.Hydrogenation and degradation were used in conjunction with g.l.c.-m.s. to deduce the identities of the dimeric, trimeric and tetrameric products, which were in most cases subsequently confirmed by isolation and n.m.r. analysis.Of particular interest is the highly regioselective disproportionation of radical (3) to give dimethyl 4-methylpent-1-ene-2,4-dicarboxylate (8), and the further reaction of (8) with (2a) to form branched oligomers (10) and (15).
