The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 04, 1985
Filed:
Mar. 01, 1984
Theodor Papenfuhs, Frankfurt am Main, DE;
Heinrich Volk, Bad Vilbel, DE;
Hoechst Aktiengesellschaft, , DE;
Abstract
A process for preparing pure alkyl 1-hydroxy-2-naphthoates of the formula ##STR1## in which R denotes lower alkyl, by adjusting, with mineral acid, to pH 5.5-6.5 an aqueous solution of monoalkali and/or dialkali metal salts of 1-hydroxy-2-naphthoic acid, then adding a surface-active compound (1) of the formula ##STR2## in which R, R.sub.1, R.sub.2 and R.sub.3 denote aliphatic radicals of 1-30 carbon atoms which are substituted and which can contain, in the terminal positions, ionic substituents, or hydroaromatic carbocyclic or cycloaliphatic radicals of 4-8 carbon atoms, and in which X.sup.(-) represents one equivalent of an inorganic or organic acid, or (2) of the formula ##STR3## in which R, R.sub.1, R.sub.2 and X.sup.(-) have the abovementioned meanings, the total number of the carbon atoms of R, R.sub.1 and R.sub.2 being at least 6 and 2 of the aliphatic radicals R, R.sub.1 and R.sub.2 being able to form, together with the sulfur atom, a heterocyclic ring, or (3) of the formula ##STR4## in which R, R.sub.1, R.sub.2, R.sub.3 and X.sup.(-) have the meanings given in the definition of the formula (II), the total number of the carbon atoms of R, R.sub.1, R.sub.2 and R.sub.3 being at least 8 and 2 or 3 of the aliphatic radicals R, R.sub.1, R.sub.2 and R.sub.3 being able to form, together with the phosphorus atom, a heterocyclic ring, in an amount of 0.5 to 5% by weight, relative to 1-hydroxy-2-naphthoic acid, separating off the precipitates at 50.degree. C.-100.degree. C., and esterifying the pure monoalkali metal 1-hydroxy-2-naphthoate present in aqueous solution with dialkyl sulfate at pH 5.5-6.5 between 30.degree. C. and 80.degree. C.