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Stable solutions of tetraethylammonium superoxide can be prepared in aprotic solvents by electrochemical generation. This has provided a basis for a chronopotentiometric study of the kinetics for the nucleophilic displacement by superoxide of halide from alkyl halides to give peroxide radicals. The reaction is first order in superoxide and occurs with 1:1 stoichiometry. The pseudo-first-order rate constants at 28°for a series of butyl chlorides in dimethyl sulfoxide follow: n-butyl chloride, 3.2 X 10-1 sec-1; sec-butyl chloride, 0.6 X 10-1 sec-1; and ¿-butyl chloride, 0.4 X 10-1 sec-1. The rates of reaction for the butyl bromides and iodides are too rapid for quantitative evaluation of their rate constants.

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In an effort toward providing a more active learning environment, these authors present a revised approach for introductory chemistry labs.

Isotropic ESR spectra of · SiH2F, · SiHF2, and · SiF3 are reported. The radicals were produced by radiolysis of H3SiF, H2SiF2, and HSiF3 in an SF6 matrix. The hyperfine parameters in gauss are: for · SiH2F, aH=34.6, aF=55.2; for · SiHF2, aH=89.9, aF=77.8; and for · SiF3, aF=136.6, aSi=(−) 498.0. The large 29Si hyperfine constant for · SiF3 shows that the radical is strongly pyramidal, probably as a result of the high ionic character of the Si–F bonds. The proton hyperfine constants are believed to be positive and the parallel of · SiHF2 with · HPO2− (aH=82.5 G) is noted. The radical (CH3)2SiF · was also produced in liquid phase photolysis experiments and has the parameters aH=4.53 and aF=65.21 G.