Process for dehalogenation of aryl and alpha-araliphatic halides
AssigneeCiba-Geigy Corporation
InventorStephen K. Boyer
Life of this patent
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Abstract
Process for the dehalogenation of aryl and alpha-araliphatic halides comprising contacting the aryl halide or alpha-araliphatic halide with hypophosphite salt, in the presence of a catalytic amount of a noble metal catalyst. This process is useful in the field of organic synthesis and for the removal of environmentally hazardous aryl and alpha-araliphatic halides, including polychlorinated biphenyls and dibenzo-p-dioxins.
Claims15
A process for the dehalogenation of a compound selected from a (carbocyclic or heterocyclic) aromatic halide and an alpha-(carbocyclic or heterocyclic) aromatic-aliphatic halide wherein said carbocyclic or heterocyclic aromatic group is selected from
- phenyl, naphthyl, biphenyl, anthracenyl, phenanthrenyl, quinolinyl, isoquinolinyl, carbazole, purinyl, pyridinyl, pyrimidinyl, pyrazolyl, imidazolyl, furanyl, oxazolyl, indolyl, benzofuranyl, benzoquinolinyl, and dibenzodioxinyl,
- each of said carbocyclic or heterocyclic aromatic groups being further unsubstituted or further substituted by a substituent selected from
- cyano, nitro, --NHR, --N(R).sub.2, --COOR, --CONHR, --CON(R).sub.2, --OR, --C(O)R, --OOCR, --NHC(O)R, --SO.sub.2 R, --NHCOOR, --SO.sub.3 R, --SR, and R,
- wherein R is hydrogen, or a phenyl which is unsubstituted or further substituted with a substituent selected from lower alkyl, lower alkoxy, carboxy, sulfoxy, amino, mono-lower alkylamino, di-lower alkylamino, cyano, lower alkanoyloxy, amido, mono-alkylamido, dialkylamido, hydroxy, and halo, or R is an aliphatic selected from lower alkyl or lower alkenyl, each of which is unsubstituted or substituted by lower alkoxy, carboxy, sulfoxy, amino, mono-lower alkylamino, di-lower alkylamino, cyano, lower alkanoyloxy, amido, mono-lower alkylamido, di-lower alkylamido, hydroxy or halo, or R is a phenyl-lower alkyl which is unsubstituted or substituted by lower alkoxy, carboxy, sulfoxy, amino, mono-lower alkylamino, di-lower alkylamino, cyano, lower alkanoyloxy, amido, mono-lower alkylamido, di-lower alkylamido, hydroxy or halo,
- said aliphatic portion of said alpha-(carbocyclic or heterocyclic) aromatic-aliphatic halide being lower alkyl which is unsubstituted or further substituted by lower alkoxy, carboxy, sulfoxy, amino, mono-lower alkylamino, di-lower alkylamino, cyano, lower alkanoyloxy, amido, mono-lower alkylamido, di-lower alkylamido, hydroxy or halo, and when said compound is polynuclear, the analogs thereof having at least one but not all of the nuclear rings partially or totally saturated, comprising:
- reacting said compound with a stoichiometric excess of a hypophosphite salt in the presence of a catalytic amount of a hydrogenation catalyst in an aqueous, aqueous/organic, or liquid alkanoic acid medium at a temperature between 0.degree. C. and the boiling point of the medium in the presence of a stoichiometric excess of a base.
A process for the dehalogenation of a compound selected from mono- and polyhalogenated biphenyl and p-dibenzodioxin which are further unsubstituted or substituted by a substituent selected from
- cyano, nitro, --NH(R), --N(R).sub.2, --COOR, --CONHR, --CON(R).sub.2, --OR, --C(O)R, --OOCR, --NHC(O)R, --SO.sub.2 R, --NHCOOR, --SO.sub.3 R, --SR, and --R,
- wherein R is hydrogen;
- or phenyl, lower alkyl, lower alkenyl, or phenyl-lower alkyl, each of which is unsubstituted or substituted by lower alkoxy, carboxy, sulfoxy, amino, mono-lower alkylamino, di-lower alkylamino, cyano, lower alkanoyloxy, amido, mono-lower alkylamido, di-lower alkylamido, hydroxy, or halo;
- or a phenyl substituted with lower alkyl;
- comprising:
- reacting said compound with a stoichiometric excess of a hypophosphite salt in the presence of a catalytic amount of a palladium on carbon catalyst in an aqueous, aqueous/organic, or liquid alkanoic medium, at a temperature between 0.degree. C. and the medium boiling point, in the presence of a stoichiometric excess of a base capable of neutralizing any H-halide which may be produced.
Dependencies are inferred from the claim text.