Manufacture of methylstyrene

Claim 1

A METHOD OF PRODUCING A MIXTURE OF META- AND PARA-METHYLSTYRENES FROM TOLUENE AS A STARTING MATERIAL, WHICH METHOD COMPRISES ETHYLATING TOLUENE IN THE PRESENE OF A FRIEDEL-CRAFTS CATALYST TO FORM A MIXTURE COMPRISING UNREACTED TOLUENE AND THE THREE ISOMERIC MONOETHYLTOLUENES TOGETHER WITH POLYETHYLTOLUENES, SEPARATING THE ETHYLATION MIXTURE BY FRACTIONAL DISTILLATION TO OBTAIN A FRACTION RICH IN TOLUENE, A FRACTION RICH IN ORTHO-ETHYLTOLUENE, A FRACTION WHICH IS RICH IN A MIXTURE OF METAETHYLTOLUENE AND PARA-ETHYLTOLUENE AND WHICH CONTAINS NOT MORE THAN 0.5 PER CENT BY WEIGHT OF ORTHO-ETHYLTOLUENE, AND A FRACTION WHICH IS RICH IN POLYETHYLTOLUENES RECYCLING TO THE ETHYLATION REACTION THE FRACTION RICH IN TOLEUNE, TH FRACTION RICH IN ORTHO-ETHYLTOLUENE AND THE FRACTION RICH IN POLYETHYLTOLUENES, VAPORIZING THE FRACTION RICH IN THE META- AND PARA-ETHYLTOLUENE AND PASSING THE VAPORS THROUGH A DEHYDROGENATION ZONE AT A REACTION TEMPERATURE TO FORM A MIXTURE COMPRISING UNREACTED META- AND PARA-ETHYLTOLUENES AND META- AND PARAMETHYLSTYRENES, COOLING THE EFFLUENT VAPORS TO CONDENSE THE AROMATIC PRODUCTS, AND SEPARATING THE CONDENSE PRODUCTS BY FRACTIONAL DISTILLATION TO OBTAIN A FRACTION RICH IN THE UNREACTED META- AND PARA-ETHYLTOLUENES AND ANOTHER FRACTION WHICH IS RICH IN META- AND PARA-METHYLSTYRENES AND CONTAINS NOT MORE THAN 0.5 PER CENT BY WEIGHT OF ORTHO-METHYLSTYRENE.

Claim 2

A METHOD OF PRODUCING A MIXTURE OF META- AND PARA-METHYLSTYRENES FROM TOLUENE AS A STARTING MATERIAL, WHICH METHOD COMPRISES ETHYLATING TOLUENE IN THE PRESENE OF A FRIEDEL-CRAFTS CATALYST TO FORM A MIXTURE COMPRISING UNREACTED TOLUENE AND THE THREE ISOMERIC MONOETHYLTOLUENES TOGETHER WITH POLYETHYLTOLUENES, SEPARATING THE ETHYLATION MIXTURE BY FRACTIONAL DISTILLATION TO OBTAIN A FRACTION RICH IN TOLUENE, A FRACTION RICH IN ORTHO-ETHYLTOLUENE, A FRACTION WHICH IS RICH IN A MIXTURE OF METAETHYLTOLUENE AND PARA-ETHYLTOLUENE AND WHICH CONTAINS NOT MORE THAN 0.5 PER CENT BY WEIGHT OF ORTHO-ETHYLTOLUENE, AND A FRACTION WHICH IS RICH IN POLYETHYLTOLUENES RECYCLING TO THE ETHYLATION REACTION THE FRACTION RICH IN TOLEUNE, TH FRACTION RICH IN ORTHO-ETHYLTOLUENE AND THE FRACTION RICH IN POLYETHYLTOLUENES, VAPORIZING THE FRACTION RICH IN THE META- AND PARA-ETHYLTOLUENE AND PASSING THE VAPORS THROUGH A DEHYDROGENATION ZONE AT A REACTION TEMPERATURE TO FORM A MIXTURE COMPRISING UNREACTED META- AND PARA-ETHYLTOLUENES AND META- AND PARAMETHYLSTYRENES, COOLING THE EFFLUENT VAPORS TO CONDENSE THE AROMATIC PRODUCTS, AND SEPARATING THE CONDENSE PRODUCTS BY FRACTIONAL DISTILLATION TO OBTAIN A FRACTION RICH IN THE UNREACTED META- AND PARA-ETHYLTOLUENES AND ANOTHER FRACTION WHICH IS RICH IN META- AND PARA-METHYLSTYRENES AND CONTAINS NOT MORE THAN 0.5 PER CENT BY WEIGHT OF ORTHO-METHYLSTYRENE.