Abstract
The glucose/valine reaction was investigated as an exampie of a reaction between organic solids. The reactions between glucose and other amino acids were studied in less detail. Both, the kinetics of the reaction and the chemical composition of the products were investigated. Contrary to previous results, dry crystals of glucose and valine reacted readily at a temperature below the melting point of either reactant. Increase of humidity appeared to decrease the rate of reaction. Water, CO2 and isobutyraldehyde were the major gaseous products. The rate of reaction was followed by measurement of pressure change on a vacuum line and also by measurement of weight loss on a thermogravimetric balance, The kinetic curves obtained on both systems were of sigmoid shape and seemed to be similar. The reaction did not go to completion. The activation energy obtained was 34 Kcal/sole and did not vary with particle size. The approximate "orders" of reaction were 0.5 and 1.0 with respect to valine and glucose. Observation by optical microscope and electron microscope suggested the reaction might occur on the surface of glucose and photographs taken showed a build up of inert product which hinders further reaction. Analysis of reaction products showed that (X-amino acids and glucose react to give water, CO2 and the aldehyde containing one fewer carbon atoms than the amino acid, Carbon-l4 labelling showed the CO2 to arise from the carboxyl group of the amino acid. A number of minor products were partly or wholly identified. There was some evidence that the glucose was being degraded as well as reacting with valine" Efforts were made to find out the kinetic rules for the reactions of this kind, and the data were fitted with varying degrees of success to equations suggested by Avrami and Erofeyev and others" A mechanism of reaction involving the Strecker degradation was outlined. The mass spectra of several hexoses and some pentoses and disaccharides were obtained and analysed. No molecular ion peaks were obtained and the most abundant ions generally appeared at mass numbers 73, 60, and 31, The differences between the sugars were insufficient for this to be an acceptable method of analysis.