Preparation of hydroxy aromatic compounds from halogenated aromatic compounds.
US Patent 3413341
Abstract
Haloaromatic compds. are hydrolyzed in good yield in aq. medium with, preferably, Na or K acetate or propionate as hydrolyzing agent and Cu or Cu2O as catalyst at 200-350°, and at pH 3-6, under pressure sufficient to keep reactants in the liq. phase. Thus, in a 1 l. Cu-coated autoclave, a mixt. of 0.4 mole a-chloronaphthalene, 0.6 mole Na propionate, 1.13 mole EtCO2H, 500 ml. H2O, and 4 g. Cu2O was heated 7 hrs. at 275° with agitation and worked up to give 87% a-naphthol. This method gives a good yield irrespective of the no. and kind of halogen atoms to be replaced, and of other substituents on the aromatic nucleus; proceeds under milder conditions; forms fewer byproducts; and requires only .apprx.1 mole equiv. of OH ion for each halogen atom replaced. Yields above 90-5% may be obtained if unreacted and incompletely reacted material is recycled. A no. of examples were given to illustrate the method and study process variables for a range of halobenzenes and naphthalenes, esp. chlorotoluenes, chlorophenols, and dichlorobenzenes.
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