Method of preparing naphthenic acids

摘要

A method for preparing naphthenic acids consists in that a petroleum fraction is oxidized at a temperature of 135 DEG -140 DEG C. in the presence of catalyst consisting of manganese naphthenate and potassium naphthenate; the obtained mixture of organic oxygen-containing compounds containing naphthenic and hydroxynaphthenic acids is diluted with an organic solvent, and the hydroxynaphthenic acids are precipitated and separated; the solution of the organic oxygen-containing compounds freed from hydroxynaphthenic acids in said organic solvent is treated with an aqueous solution of sodium hydroxide; thus obtained aqueous solution of sodium naphthenates is separated; said aqueous solution of sodium naphthenates is treated with diethyl sulphate at a temperature of 90 DEG -95 DEG C. to isolate ethyl naphthenates from which a fraction of ethyl naphthenate boiling out in a temperature range of 75 DEG -170 DEG C. is separated by rectification in vacuum of 3 mm Hg; the isolated fraction of ethyl naphthenates is treated with an aqueous solution of sodium hydroxide and the end product is isolated by the action of mineral acids.