Process for preparing pure alkyl 1-hydroxy-2-naphthoates

Details Process for preparing pure alkyl 1-hydroxy-2-naphthoates Process for preparing pure alkyl 1-hydroxy-2-naphthoates

1984-03-01

1985-06-04

Killos, Paul J.

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acids and salts thereof

560 56, C07C 5143

Patent

active

045216177

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.

REFERENCES:
patent: 4057576 (1977-11-01), Bachmann et al.
patent: 4415750 (1983-11-01), Volk et al.

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