Search

INTRODUCTION In principle, the heat capacity curve of a solid substance can give information about the dependence of energy absorption on temperature of the crystal lattice, and hence on the mechanism of any phase changes which occur therein. In practice, however, the amount of information is limited (a) by the fact that a considerable contribution to the measured Cp comes from the term f32VTja; (b) by the lack of an adequate theory of the heat capacities of complex crystals. In certain cases, though, considerable insight can be obtained by diluting the lattice of a compound which undergoes a phase transition with a second kind of molecule or ion, and observing the effect on the nature and magnitude of the transition. The added component has usually been one which itself has no transitions', but a few studies have been made of mixed crystals both of whose components exhibit solid transitions2, when the phenomena are naturally more complex. This paper concerns heat capacity measurements on mixtures of ethylene dichloride and dibromide, both of which undergo solid transitions, and form a continuous series of mixed crystals.

Yield-dose curves obtained from isotope dilution and paper chromatographic methods reveal that glucose and fructose are primary products of gamma -irradiation of aqueous sucrose solutions, together with smaller amounts of glucosone and gluconic acid. Glucuronic acid, 2-oxogluconic acid, arabinose, and two- and three-carbon aldehydic fragments arise in secondary processes. In the final stages carbon dioxide and formic acid are formed. Hydrogen peroxide is produced continuously. The amounts of volatile and non-volatile acid formed, and changes in optical rotation and absorption spectra, were determined. Thus, the degradation of sucrose is related to two types of oxidative scission of the disaccharide linkage. (auth)

The Paper reports the results of a careful determination of the temperature-dependence of the rate of hydrolysis of t-butyl chloride in water at 1 degree intervals between 0 and 20C. (Author)

The degradation of D-fructose in aqueous solution by Co/sup 60 gamma - radiation was examined by measuring the changes in acidity, absorption spectra, and optical rotation with dose. Hydrogen peroxide and carbon dioxide formation were measured. Paper chromatographic and radioactive tracer methods revealed that the main products were glucosone 2-oxogluconic acid, oxalic acid, and two- carbon aldehydic fragments. Isotope dilution and absorption spectra indicate the formation of three-carbon aldehydic fragments. By following the yield-dose curves for the main products, the primary and secondary products are identified. These products are considered to arise from at least three types of degradation process: (a) oxidation of the primary alcohol group at position 1 to form glucosone, which is then converted into 1-oxogluconic acid (there is also evidence of a similar process occurring at position 6); (b) direct scission between C/sub 2/ and C/sub 3/ to form two- and four-carbon aldehydic fragments which are subsequently oxidized; (c) symmetrical scission of the molecule to form glyceraldehyde and glycerosone. (auth)