Polymorphism of the Crystalline Methylchloromethane Compounds

Abstract

Polymorphism of the methylchloromethane compounds, (CH3),CC14-,, where n varies from 0 to 4, has been studied using lowtemperature X-ray diffraction techniques. Single crystals of both high and low-temperature phases were grown and crystal data were obtained for the various phases. The crystal structure of the phase of t-butyl chloride which is stable between -54 and -90" was determined. On the basis of the present investigation, the conclusion is reached that the hightemperature modifications are dynamically disordered, in agreement with the results of n.m.r. and dielectric studies.

Pressure Dependence of the Melting and Self Diffusion in 2,2-dimethylpropane, 2,2-dimethylpropionitrile, and 2-methylpropanol-2

“…The data for the melting of 2-methylpropanol-2 agree with results given in the literature [7], No data for the pressure dependence of the melting of 2,2-dimethylpropionitrile and 2,2-di methylpropane were found in the literature, and also the pressure dependence of the solid-solid tran sition between the brittle hexagonal low tempera ture phase of 2,2-dimethylpropane and the plastic face centred cubic phase [8] appears to be unknown.…”

Electron Mobilities and Ranges in Solid Neopentane: Effect of Liquid–Solid Phase Change

“…An early report (6) indicated that the mobility in solid n-hexane at -30" below the melting point was at least five times greater than that expected for electrons in the liquid a t the melting point. Neopentane would be a better candidate for study because electron mobility in the liquid is relatively high (9) and the material forms a plastic crystal (11) rather than a rigid solid upon freezing. Both of these properties increase the probability of obtaining a measurable electron conductance signal in the solid.…”

The formation of the plastic crystal phase in several pentaerythritol derivatives

“…Pentaerythritol, C(CH2OH)4, has been shown to undergo a transition at 452.7°K (Nitta & Watanab6, 1938) to just such a phase. As part of our attempts to define the sphericity of the molecular envelope that is required in order for plastic crystals to form (Rudman & Post, 1968;Rubin & Rudman, 1973), a series of substituted pentaerythritol compounds was selected for investigation.…”