The vaporization of TiO, Ti203, Ti30B and Ti02 has been studied by the Knudsen effusion method, and the solid phases investigated by high temperature X-ray diffraction technique. TiO, Ti02 (rutile) and Ti203 do not undergo any structural change up to their melting points. Ti305 has a low temperature structure and a high temperature structure (above 1600 °K.). TiO(s) vaporizes to TiO(g), AH% = 134.6 kcal./mole, Ti02(s) to Ti02(g), AH% = 138.9 kcal./mole. 203 decomposes on vaporization to TiO(g) + Ti02(g), the heat of reaction being AH% = 296.0 kcal./mole.

The photochemical bromination of methane was studied in the temperature range 423–503°K and found to proceed through the following chain mechanism: (1)    Br2+hν=Br+Br(2)    Br+CH4=CH3+HBr(3)   CH3+Br2=CH3Br+Br(4)  CH3+HBr=CH4+Br(5) Br+Br+M=Br2+M.Bromination of methyl bromide is analogous and from 7.5 to 10 times more rapid in this temperature range. Hydrogen bromide inhibits bromination of methane but not of methyl bromide. Thermal bromination was studied at 570°K and found to follow the same mechanism as photochemical reaction, except that bromine atoms are produced thermally. The activation energy of photochemical bromination of methane is 17.8 kcal./mole and that of methyl bromide is 15.6 kcal./mole. Varying efficiencies of different molecules as third bodies in the homogeneous recombination of bromine atoms are discussed. Configurations of activated complexes have been assigned and by statistical mechanical calculations shown to be reasonable. Activation energies and other data have been combined to arrive at a value for the C–H bond strength in methane of 102 kcal./mole at room temperature.

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Cyclization Kinetics of Aliphatic í-/3-Chloroethylamin es 281 tion to light results in a magnetic change which could be interpreted as being due to appreciable dissociation.A considerable degree of free radical formation is observed with 2,2'-dibenzothiazyl disulfide. The concentration of the thiol radicals in toluene has been measured up to 150°.

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