Process for removal of homogeneous catalyst group VIII metals from process streams

Claim 2

A process for removing homogenous triphenylphosphine substituted Group XIII metal catalysts selected from RhCl(P.0. 3 ) 3 , IrH 3 (P.0. 3 ) 3 , IrH(CO)(P.0. 3 ) 3 , PdCl 2 (P.0. 3 ) 2 , naphthyl BrNi(P.0. 3 ) 2 , Br 2 Ni(P.0. 3 ) 2 from toluene solvent-containing reaction process streams, which comprises adding about 2 to about 12 moles of an organic sulfur compound containing a carbon sulfur double bond selected from N-benzyl-dithiocarbamoylglycine, β-dithiocarbamylpropionic acid, thiohydantoin, thiourea, ammonium dithiocarbamate, thiobarbituric acid, thiosemicarbazide, rhodamine or 2-mercapto-4-aminopyrimidine, per mole of said Group VIII metal, warming to 50° to 100° C. for from 2 to 10 hours, cooling to 0° to 5° C. and separating the metal-organic sulfur complex that forms.

Claim 3

In a process for preparing ivermectin which comprises the steps of: (a) hydrogenating avermectin Bla in the presence of tris-(triphenylphosphine)rhodium (I) chloride in an organic solvent selected from benzene, toluene, o-, m- or p-xylene, tetrahydrofuran and methylene chloride; (b) evaporating the organic solvent; (c) dissolving the residue in ethanol; (d) treating the ethanol solution with formamide and water to cause crystallization of the product; wherein the improvement comprises after the hydrogenation step (a) and before the evaporation step (b), adding about 2 to about 12 moles of an organic sulfur compound containing a carbon sulfur double bond selected from the group consisting of N-benzyldithiocarbamoylglycine, β-dithiocarbamylproprionic acid, thiohydantoin, thiourea, ammonium dithiocarbamate, thiobarbituric acid, thiosemicarbazide, rhodamine or 2-mercapto-4-aminopyrimidine, per mole of tris-(triphenylphosphine)rhodium (I) chloride; warming to 50° to 100° C. for from 2 to 10 hours; cooling to 0° to 5° C. and separating the rhodium-organic sulfur complex that forms.

Claim 4

In a process for preparing ivermectin which comprises the steps of: (a) hydrogenating avermectin Bla in the presence of tris-(triphenylphosphine)rhodium (I) chloride in an organic solvent selected from benzene, toluene, o-, m- or p-xylene, tetrahydrofuran and methylene chloride; (b) evaporating the organic solvent; (c) dissolving the residue in ethanol; (d) treating the ethanol solution with formamide and water to cause crystallization of the product; wherein the improvement comprises after the hydrogenation step (a) and before the evaporation step (b), adding about 2 to about 12 moles of an organic sulfur compound containing a carbon sulfur double bond selected from the group consisting of N-benzyldithiocarbamoylglycine, β-dithiocarbamylproprionic acid, thiohydantoin, thiourea, ammonium dithiocarbamate, thiobarbituric acid, thiosemicarbazide, rhodamine or 2-mercapto-4-aminopyrimidine, per mole of tris-(triphenylphosphine)rhodium (I) chloride; warming to 50° to 100° C. for from 2 to 10 hours; cooling to 0° to 5° C. and separating the rhodium-organic sulfur complex that forms.

Claim 5

The process of claim 1, wherein the organic sulfur compound is thiourea or thiohydantoin.

Claim 6

The process of claim 3 wherein the organic sulfur compound is thiourea.

Claim 7

The improved process of claim 2 wherein the organic sulfur compound is thiourea or thiohydantoin.

Claim 8

The improved process of claim 5 wherein the organic sulfur compound is thiourea.