Preparation of thionyl chloride and phosphorus oxyhloride from sulfur dioxide
AssigneeGreat Lakes Chemical Corporation
InventorJohn E. Hill
Life of this patent
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Abstract
A process to manufacture high purity thionyl chloride and phosphorus oxychloride utilizing a fluctuating flow of sulfur dioxide. Chlorine, sulfur dioxide, and phosphorus trichloride are reacted in a process that limits the amount of sulfuryl chloride and/or phosphorus trichloride remaining in the product stream. Cl.sub.2 and SO.sub.2 are first reacted to form SO.sub.2 Cl.sub.2, which, in turn, is reacted with excess PCl.sub.1 to form the products, POCl.sub.3 and SOCl.sub.2. Any excess PCl.sub.3 is then reacted with additional Cl.sub.2 and SO.sub.2 to form additional product. Alternatively, Cl.sub.2, SO.sub.2, and PCl.sub.13 are reacted directly to form POCl.sub.3 and SOCl.sub.2 without the formation of any SO.sub.2 Cl.sub.2 intermediate by utilizing a continuous stirred loop reactor.
Claims15
A process for preparing thionyl chloride and phosphorus oxychloride, comprising the steps of:
- (a) recirculating sulfuryl chloride through a reaction loop, said reaction loop including a reservoir and a catalyst for promoting the formation of sulfuryl chloride;
- (b) dissolving chlorine into the sulfuryl chloride being recirculated through the reaction loop;
- (c) dissolving sulfur dioxide into the sulfuryl chloride being recirculated through the reaction loop;
- (d) continuously circulating the sulfuryl chloride containing dissolved chlorine and dissolved sulfur dioxide through the reaction loop to convert the sulfur dioxide to sulfuryl chloride;
- (e) reacting phosphorus trichloride with a stoichiometric deficient amount of the sulfuryl chloride formed in step (d) to produce a first mixture of thionyl chloride, phosphorus oxychloride, and phosphorus trichloride;
- and
- (f) contacting said first mixture of thionyl chloride, phosphorus oxychloride, and phosphorus trichloride with sulfur dioxide and chlorine to convert phosphorus trichloride in said first mixture to thionyl chloride and phosphorus oxychloride, thereby providing a second mixture consisting of thionyl chloride and phosphorus oxychloride.
A process for preparing sulfuryl chloride, comprising the steps of:
- (a) recirculating sulfuryl chloride through a reaction loop, said reaction loop including a reservoir and a catalyst for promoting the formation of sulfuryl chloride;
- (b) dissolving chlorine into the sulfuryl chloride being recirculated through the reaction loop;
- (c) dissolving sulfur dioxide into the sulfuryl chloride being recirculated through the reaction loop;
- and
- (d) continuously circulating the sulfuryl chloride containing dissolved chlorine and dissolved sulfur dioxide through the reaction loop for a time and at a temperature effective to convert substantially all of the sulfur dioxide and chlorine to sulfuryl chloride.
A process for preparing thionyl chloride and phosphorus oxychloride, comprising the steps of:
- (a) recirculating thionyl chloride and phosphorus oxychloride through a reaction loop, said reaction loop including a reservoir and a reaction zone;
- (b) dissolving a fluctuating amount of sulfur dioxide into the thionyl chloride and phosphorus oxychloride being recirculated through the reaction loop;
- (c) introducing phosphorus trichloride and chlorine into the thionyl chloride and phosphorus oxychloride being recirculated through the reaction loop, said phosphorus trichloride and chlorine introduced in about stoichiometric amounts for reaction with the sulfur dioxide present from step (b);
- and (d) recirculating the reaction mixture through the reaction loop for a time and at a temperature effective to convert the phosphorus trichloride, chlorine, and sulfur dioxide to phosphorus oxychloride or thionyl chloride.
Dependencies are inferred from the claim text.