Abstract: A method and installation for separating and purifying a crude mixture containing hydroquinone, resorcinol and possibly tars and/or catechol, comprising the following steps: —a possible distillation stage (I) in order to obtain a catechol head, —the foot (I) or crude mixture undergoes distillation (II) in order to obtain a fraction that is rich in resorcinol, —the foot of (II) undergoes distillation (III) in order to obtain a fraction that is rich in hydroquinone, whereupon said rich fractions are refined (IV or V). Preferably, one or several stages in which tar is removed (I,I?) precede stage (I) or (II).

Abstract: Chlorophenols are prepared by thermally dehydrochlorinating a corresponding chlorocyclohexanone in the presence of a catalyst having the formula: ##STR1## wherein A is phosphorus or arsenic, R.sub.1 and R.sub.2, which are identical or different, are each hydrogen, an alkyl radical having from 1 to 12 carbon atoms, a phenyl radical or a radical --NR.sub.4 R.sub.5, in which R.sub.4 and R.sub.5, which are identical or different, are each H or an alkyl radical having from about 1 to 5 carbon atoms, R.sub.3 is an alkyl radical having from 1 to 12 carbon atoms, a phenyl radical or a radical --NR.sub.4 R.sub.5, in which R.sub.4 and R.sub.5 are as defined above, and n is equal to 0 or 1.