THE THERMAL DECOMPOSITION OF t-BUTYL NETHYL ETHER

Summary The rates of the thermal decomposition of t-butyl methyl ether have been measured in the range 433-495'. The reaction products are isobutene and methanol, and the kinetic form is first order. The Arrhenius equation describes the variation of rate with temperature. The reaction behaviour is consistent with a unimolecular mechanism. Comparison of the results with those obtained for the production of isobutene from various t-butyl compounds indicates that the reaction has some degree of heterolytic character. In a recent review of molecular decompositions in the gas phase Maccoll and Thomas noted that while interesting examples of molecular decompositions are found to occur among vinyl ethers the known decompositions of alkyl ethers are predominantly free-radical chain-mechanisms.l Laidler and McKenney in reviewing the pyrolysis of ethers point out that in addition to the well-studied decompositions of dimethyl and diethyl ethers, the decompositions of methyl ethyl, ethyl propyl, dipropyl, and methyl butyl ethers involve the presence of free radicals and are inhibited by nitric oxide;2 they also draw attention to the suggestion3 of Stimson and Watson that the traces of isobutane found among the products of the hydrogen-bromide-catalysed decomposition of t-butyl methyl ether may be due to a free-radical uncatalysed decomposition of this ether involving the steps :