THE PYROLYSIS OF TRIMETHYLINDIUM

Abstract

The pyrolysis of trimethylindium has been studied in a toluene carrier flow system from 550 °K to 781 °K using total pressures from 6.0 to 33.5 mm. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, propane, and ethylbenzene formed and in a number of cases by direct indium analysis. The decomposition occurs in three steps: [Formula: see text]At all temperatures reaction [2] follows rapidly after reaction [1]. Reaction [3] occurs at a measurable rate only at temperatures sufficiently high that reactions [1] and [2] are completed in a very small fraction of the contact time. At lower temperatures the InCH3 produced deposits in the reaction zone as a white film of (InCH3)n.Both k1 and k3 decline rapidly if the toluene-to-alkyl ratio is decreased below 150. In an unseasoned vessel, the decomposition is markedly dependent on surface conditions. In the unpacked conditioned vessel the reaction is at least 89% homogeneous in the first bond region and 97% homogeneous in the third bond region. Both k1 and k3 depend on the total pressure in the system, the dependence of k1 being very slight. A least squares analysis of the experimental results gives: [Formula: see text]at 13.0 mm. E1 may be directly related to D[(CH3)2In—CH3]. A rough calculation based on unimolecular pressure effects indicates that D[In—CH3] is probably about 2 kcal/mole greater than E3.