Supercritical fluids in chemistry

Abstract

Dedicated the memory of Akademician Valery Vasilievich Lunin, a friend, colleague, teacher, founder and leader of the research into application of supercritical fluids in chemistry. This review analyzes the rapidly developing applications of supercritical fluids, mainly supercritical carbon dioxide, in catalysis, chemistry of high-molecular-weight compounds, and medicinal chemistry in Russia and abroad. It considers the methods of catalyst preparation based on impregnation of inorganic and organic supports with metal-containing compounds, immobilization of organometallic and metal complex reagents in matrices of oxide and polymer supports, and deposition processes employing supercritical fluids. An analysis is presented of the prospects for applying CO2 and some organic compounds, such as aliphatic alcohols, in sub- and supercritical states as reactants and (or) solvents for catalytic reactions of hydrocarbon isomerization and cracking, hydrogenation, dehydrogenation, oxidation, etc., including the asymmetric reactions. The review discusses processes of synthesizing and modifying polymer materials for various purposes, including aerogels, foams, and composites impregnated with photochromes, in a supercritical fluid medium. Special attention is paid to supercritical one-pot processes, which make the techniques of obtaining new materials simpler, less expensive, and more efficient. The work investigates the effect of supercritical CO2 on the morphology, gas separation characteristics, and dielectric properties of polymers. One of the promising applications of supercritical fluids in medicine is the use in transplantology and pharmacology, for example, for the preparation of drug polymorphs with higher bioavailability. The review also provides an overview of the recent data on the use of EPR spectroscopy for studying the properties of supercritical fluids, including those exhibited in the vicinity of the critical point and identifying the intermediates of chemical reactions in such media. The bibliography includes 1151 references.