THERMAL DECOMPOSITION OF 1,1,3,3-TETRAMETHYLCYCLOBUTANE

The thermal decomposition of 1,1,3,3-tetmrnethylcyclobutane has been studied in the pressure region 7.65-42.8 mm at 435.7° and over the temperature range 415-455°. The reaction yielding two molecules of isobutylene as the primary product is a first-order process which occurs homogeneously, and the rate does not seem to be affected significantly by the addition of nitric oxide or propylene. Experiments near 10-mm pressure in the 40° temperature range indicate that the activation energy for the decomposition is 64.8 ± 0.3 kcal/mole. The first-order rate constant may be expressed as k = (1.74 ± 0.02) × 1016 exp(–64,800/RT) sec−1. Occurring simultaneously with the decomposition, there is a slow structural isomerization to yield 2,4,4-trimethyl-1-pentene. When the results of this study are compared with previous data for the decomposition of cyclobutane, it is found that 1,1,-3,3-tetramethylcyclobutane reacts about 0.83 times as fast as cyclobutane. © 1969, American Chemical Society. All rights reserved.