Process for producing decachlorooctahydro-1,3,4-metheno-2H-cyclobuta-(c,d)-pentalen-2-one

A process for producing decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(c,d)-pentalen-2-one in at least 95% yield, which comprises:

• a. reacting hexachlorocyclopentadiene and sulfur trioxide at a temperature between about 95.degree.C. and about 120.degree.C., at a pressure of between 50 p.s.i.g. and 300 p.s.i.g., in the presence of a catalytic quantity of an antimony compound selected from the group consisting of trivalent and pentavalent antimony halides, oxides and oxy acids, the mole ratio of sulfur trioxide to hexachlorocyclopentadiene being between about 1.5 and 2, to form a reaction product thereof;
• said reacting step being further characterized in that an admixture of the hexachlorocyclopentadiene and the antimony compound is first formed, the sulfur trioxide is added to said admixture to form the reaction mixture, the reaction temperature is maintained below 105.degree.C. during addition of the sulfur trioxide, and the reaction mixture is reacted until it turns to a black color;
• b. hydrolyzing the reaction product from step (a) in at least about 5 parts by weight of an aqueous solution containing dissolved caustic alkali and having a pH of at least 9, per part by weight of reaction mixture, said hydrolysis being carried out at a temperature between about 85.degree.C. and about 115.degree.C. for 60 to 120 minutes until all solids have gone into solution;
• c. acidifying the hydrolysis mixture from step (b) with sulfuric acid to pH 5.4-5.6;
• d. digesting the acidified hydrolysis mixture at pH 5.4-5.6, at a temperature between about 85.degree.C. and about 105.degree.C. for 1-4 hours, until the decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(c,d)-pentalen-2-one is completely precipitated as a crystalline product;
• and
• e. recovering the crystalline product from the digestion mixture.

A process for producing decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(c,d)-pentalen-2-one in at least 99% yield, which comprises:

• a. reacting hexachlorocyclopentadiene and sulfur trioxide at a temperature between about 95.degree.C. and about 105.degree.C., at a pressure of between 85 p.s.i.g. and 115 p.s.i.g., for about 1-2 hours in the presence of a catalytic quantity of an antimony compound selected from the group consisting of trivalent and pentavalent antimony halides, the mol ratio of sulfur trioxide to hexachlorocyclopentadiene being between about 1.5 and 2, to form a reaction product thereof;
• said reacting step being further characterized in that an admixture of the hexachlorocyclopentadiene and the antimony compound is first formed, the sulfur trioxide is added to said admixture to form the reaction mixture, the reaction temperature is maintained below 105.degree.C. during addition of the sulfur trioxide, and the reaction mixture is reacted until it turns to a black color;
• b. hydrolyzing the reaction product from step (a) in at least about 5 parts by weight of an aqueous solution containing dissolved caustic alkali and having a pH of about 9.5 to 10.5, per part by weight of reaction mixture, said hydrolysis being carried out at a temperature of about 90.degree.-96.degree.C. for 60 to 120 minutes until all solids have gone into solution;
• c. acidifying the hydrolysis mixture from step (b) with sulfuric acid to pH 5.4-5.6;
• d. digesting the acidified hydrolysis mixture at pH 5.4-5.6, at a temperature between about 85.degree.C. and about 105.degree.C. for 1-4 hours, until the decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(c,d)-pentalen-2-one is completely precipitated as a crystalline product;
• and
• e. recovering the crystalline product from the digestion mixture.