GB870007A - Organosilicon liquids - Google Patents

Abstract

In making a liquid silioxane which is stable to oxygen, a mixture of (1) a liquid siloxane having Si-bonded hydrocarbon and/or halohydrocarbon radicals, and (2) an iron carboxylate containing from 4 to 18 C atoms, is heated in intimate contact with oxygen at a temperature above 200 DEG C. until the mixture will not form a precipitate when heated in the substantial absence of oxygen at a higher temperature. The first step is preferably conducted at 230 DEG to 315 DEG C. for a time (usually 2 to 4 hours) sufficient for the mixture to assume a deep reddish brown colour. The contacting with oxygen can be effected by bubbling oxygen through the liquid siloxane, or the mixture of the siloxane and iron salt can be caused to flow down a heated column packed with inert material while oxygen passes in the opposite direction. The iron salts may be used as solutions in hydrocarbon solvents, the solvent being removed, if desired, prior to the oxygenation step. The term "oxygen" includes pure oxygen, air and mixtures of oxygen with air and inert gases, e.g. helium and argon. Iron salts specified are the hexoate, 2-ethylhexoate, n-octoate, decoate, dodecoate, benzoate, phenyl-acetate, 3-methylcyclopentylbutyrate, cyclohexylcaproate, stearate and t-butylcyclohexylacetate, and are generally added in amount to provide from 0,006% to 0,03% of Fe calculated on the weight of the siloxane. Examples are given. Uses: as lubricants, greases, hydraulic fluids, heat transfer fluids and as heating baths for sterilizing surgical instruments.