Method for preparing .alpha.-naphthol

Details Method for preparing .alpha.-naphthol Method for preparing .alpha.-naphthol

1979-06-08

1980-12-02

Lone, Werren B.

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

Organic compounds

Oxygen containing

C07C 3704

Patent

active

042373239

ABSTRACT:
A method for preparing .alpha.-naphthol according to the present invention comprises sulphonation of naphthalene with an equimolar amount of a concentrated sulphuric acid at a temperature ranging from 30.degree. to 85.degree. C. for a period of from 60 to 120 minutes in the presence of acetic anhydride whereafter .alpha.in an amount of from 0.5 to 1.5 mole per mole of naphthalene. The resulting naphthalene-.alpha.-sulphonic acid is fused with an alkali taken in an amount of 3-4 moles per mole of naphthalene-.alpha.-sulphonic acid at a temperature ranging from 180.degree. to 285.degree. C. for a period of from 10 to 30 minutes. The resulting melt consisting of the alkali metal .alpha.-naphtholate and the alkali metal sulphite is mixed with a polar solvent; the resulting mixture is acidified with a mineral acid taken in an amount equimolar relative to the alkali metal .alpha.-naphtholate, whereafter.alpha.-naphthol is separated from the resulting suspension. The method according to the present invention makes it possible to increase the yield of .alpha.-naphthol up to 98% of the theoretical amount and produce .alpha.-naththol with a purity of up to 99.5%.

REFERENCES:
patent: 1949243 (1934-02-01), Cotton
patent: 1962137 (1934-06-01), Cotton
patent: 2025197 (1935-12-01), Cotton
Erros et al., "Chemistry and Processes for the Production of Aromatic Compounds", Khimia Publishers, Leningrad, 1971, p. 73.

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