The chemical process accompanying the hydrogenation of fats I. Geometrical isomerization
Summary1. It has been shown for numerous examples that the catalytic hydrogenation of fats is accompanied by the cis-trans isomerization of the radicals of the unsaturated acids.2. A scheme is proposed which explains the mechanism of the isomerization through a process of the hydrogenation-dehydrogenation of the olefinic compounds.
Modern State of the Multiplet Theor of Heterogeneous Catalysis
Publisher Summary This chapter reviews the modern state of the multiplet theory of heterogeneous catalysis. The multiplet theory deals with numerical values of bond lengths and bond energies, as well as with the geometrical form of reacting molecules and the crystal lattices of catalysts. This allows definite results to be obtained for many reactions on an atomic level. This is how the multiplet theory differs from a number of other theories on catalysis. The theory of the structure of matter is based on both electronic theory and quantum mechanics—the basis for the multiplet theory. Bond lengths and energies represent a stable complex of electronic properties essential for catalysis. The multiplet theory proceeds from the premise that catalysis is a chemical phenomenon and that covalent bonds require catalytic activation.
The Catalytic Exchange of Hydrocarbons with Deuterium
Publisher Summary This chapter reviews the catalytic exchange of hydrocarbons with deuterium. Exchange reactions are a unique class of chemical reactions, and the chapter focuses on the methods of interpretation of experimental data that are relevant to the study of exchange reactions and to the ways in which these may be classified. The simplest method of estimating activities of different metals for the exchange reaction is to compare the temperature or range of temperatures required to bring about similar rates of reaction on each of the metals. The comparison of rates of reaction at a single fixed temperature is less satisfactory, because it involves considerable extrapolation of the experimental data and the unjustifiable assumption that the activation energy remains constant over a wide range of temperature. Although it has been stressed that the rate of an exchange reaction is governed by an adsorption/desorption process, it is probable that the main single factor governing the reactivity of different hydrocarbons on different metals is the ease of chemisorption of the hydrocarbon on the catalyst.