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Topochemical reactions of boron nitride

University of British Columbia

An absorption complex or compound between boron nitride and chromyl chloride was discovered and studied in some detail. The method used to prepare the boron nitride had some effect on the composition of the complex but for a given sample of boron nitride the equilibrium composition for temperatures from 0°C to 160°C was constant. The kinetics of formation were studied at 24.1°C, 67.1°C, and 117.0°C. The reaction was interpreted as diffusion controlled with two diffusion coefficients--each for a certain concentration range. The corresponding two energies of activation were 5.0 and 6.1 kcal. These are of the same order of magnitude as for similar processes. X-ray studies of the complex showed a strong reflection line at the same place as for the main layer separation in boron nitride itself. There could have been a small amount of reflection due to a greater layer spacing, but it was not detected. Water hydrolyses the chromyl chloride in the complex, leaving the original boron nitride and a solution of dichromate and HCl. Carbon tetrachloride would not dissolve out the chromyl chloride from the complex. Similar complexes of chromyl chloride with disulfides of molybdenum, tungsten and uranium and of cupric and aluminum chlorides with boron nitride were discovered but the kinetics of their formation were not studied. The theory of formation of lamellar compounds is discussed.

Text

2012-02-28

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http://hdl.handle.net/2429/40976

Chemistry

University of British Columbia

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