41044-64-8Relevant academic research and scientific papers
The Thermolysis of 2,2-Dimethyl-1-vinylcyclobutane
Chickos, James S.,Frey, H. Monty
, p. 365 - 370 (2007/10/02)
The kinetics of thermolysis of 2,2-dimethyl-1-vinylcyclobutane have been investigated as a function of temperature from 263 to 301 deg C.Primary products produced in the reaction include isobutene and butadiene, 4,4-dimethylcyclohexene, 2-methylhepta-1,6-diene, and cis-2-methylhepta-1,5-diene. trans-2-Methylhepta-1,5-diene and 2,4-dimethylhexa-1,5-diene are produced from cis-2-methylhepta-1,5-diene by way of a 3,3-sigmatropic rearrangement.The reaction obeys first-order kinetics and is unaffected by surface.Activation energies (kcal mol-1) and (logA/s-1) for the overall decomposition and for formation of the primary products are 45.73 +/- 0.3 (14.427 +/- 0.12), 47.71 +/- 0.7 (15.087 +/- 0.3), 44.35 +/- 1.6 (12.53 +/- 0.6), 45.0 +/-1.3 (12.24 +/- 0.5), and 38.38 +/- 1.7 (10.785 +/- 0.7), respectively.The regiochemistry observed in fragmentation and in the 1,3-sigmatropic rearrangement of the starting material is discussed in terms of substituent effects found in other cyclobutane and vinylcyclobutane thermolyses.The fragmentation process and the isomerization to 4,4-dimethylcyclohexene and 2-methylhepta-1,6-diene is believed to proceed through the intervention of 6-methylhept-1-ene-3,6-diyl. cis-2-Methylhepta-1,5-diene is formed from a concerted 1,5-sigmatropic rearrangement of the starting material.The factors which affect the stereochemistry of the 1,5-hydrogen shift are discussed.
Secondary Deuterium Isotope Effects in the Thermolysis of 2,2-Dimethyl-1-vinylcyclobutane
Chickos, James S.
, p. 1109 - 1112 (2007/10/02)
Secondary deuterium isotope effects for the thermolysis of 2,2-dimethyl-1-vinyl-3,3,4,4-tetradeuteriocyclobutane are reported.A value of kH/kD (262.2 deg C) for the overall decomposition of the starting material of 1.018 +/- 0.008 was determined and values of 1.06 +/- 0.04, 0.95 +/- 0.04, 0.95 +/- 0.08 and 0.98 +/- 0.1 are reported for fragmentation to butadiene and 2-methylpropene, and for rearrangement to 4,4-dimethylcyclohexene, cis-2-methylhepta-1,5-diene, and 2-methylhepta-1,6-diene, respectively.The isotope effects are discussed in terms of the potential energy surfaces proposed for 1,4-biradicals.It is concluded from these results and the isotope effect observed in thermolysis of cyclobutane that most of the effect in cyclobutane results from cleavage of the first bond, and that the subsequent surface for fragmentation is relatively flat.
