Abstract: The intermediate 2,2,6,6-tetrachloro (or tetrabromo) cyclohexanone is prepared by reacting chlorine (or bromine) with a cyclohexanol compound of the formula ##STR1## where each Y represents an atom of hydrogen or chlorine (or hydrogen or bromine) in the presence of, as catalyst, a certain organophosphorus compound.

Abstract: 2,2,6,6-Tetrachloro(or tetrabromo)cyclohexanone is prepared by reacting in the liquid phase chlorine or bromine with a cyclohexanone compound of formula ##STR1## where Y is hydrogen or chlorine (to produce the tetrachloro compound) or hydrogen or bromine (to produce the tetrabromo compound) in the presence as catalyst of an organophosphorus compound of formula ##STR2## where Z is chlorine or bromine; n is 0 or 1; and when n is 0, m is 0 or 2, R.sup.1 is alkyl or phenyl, and R.sup.2 and R.sup.3 are hydrogen, alkyl or phenyl; and when n is 1, m is 0, and R.sup.1, R.sup.2 and R.sup.3 are the same and each is ##STR3## alkyl or phenyl, or R.sup.1 is hydrogen and R.sup.2 and R.sup.3 are alkyl or phenyl;or a salt thereof.Each alkyl is of 1-10 carbon atoms.