SOLUBILITY IN ALCOHOLS AND ALCOHOLYSIS REACTIONS OF CARBONATES, SULFIDES, CYANIDES, AND PHOSPHATES OF ALKALI METALS

Abstract

The published data on the solubilities of lithium, sodium, potassium, rubidium and cesium carbonates; sodium bicarbonate; sodium sulphide; potassium and sodium cyanides; orthophosphates, hydro- and dihydroorthophosphates of potassium and sodium, as well as sodium pyrophosphate in methanol, ethanol, 2-propanol, 2-methyl-1-propanol, benzyl alcohol, ethylene glycol, methyl cellosolve and glycerol have been considered and collected. A little bit information for salts has been taken from the most common solubility handbooks, but most of data was selected from scientific articles. There is an acid-base equilibrium with the formation of the corresponding alcoholates in the systems "potassium or sodium carbonate/methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether", "sodium sulphide/methanol, ethanol, 2-propanol, 2-methyl-1-pro-panol, benzyl alcohol", "potassium cyanide/methanol, ethylene glycol, glycerol", "potassium or sodium orthophosphate/ethylene glycol", and "sodium pyrophosphate/ethylene glycol". The mechanism of the reaction of alcoholysis and the formation of alcoholates from the alkali metal salts and alcohols is based on the distribution of the components in phases. Analysis of all phases in the alcohol solutions of alkali metal salts proved the presence of an alcoholysis reaction in some salt/alcohol systems. The concentrations of dissolved salts in alcoholate-generating systems are significantly lower than those determined by the gravimetric method without taking into account the alcoholysis reaction and are considered in the common handbooks "solubilities of the corresponding salts in alcohols". A classification of inorganic alkali metal salts reacting with alcohols in the alcoholysis reaction has been proposed. The analysis of literature data showed that along hydroxides and alkali metal salts, the hydrides, organometallic compounds, acetylenides, nitrides, amides (including alkyl amides) as well as azides can react with alcohols to form alkoxides by alcoholysis reaction. Alcoholysis of salts can be considered as a promising method for the production of alkali metal alkoxides in which the salt is used instead of metal or hydroxide.