Process for making diaryl sulfones

Abstract

A process for preparing diaryl sulfones, such as 4,4′-dichlorodiphenylsulfone is disclosed. The process comprises contacting an aryl compound with sulfur trioxide to provide a benzene sulfonic acid. The benzene sulfonic acid is coupled to additional aryl compound in the presence of a catalyst. During the coupling step, the additional aryl compound is continuously added while water is removed.

1 .- 82 . (canceled) 
     
     
         83 . A process for preparing a sulfone of the formula 
       
         
           
           
               
               
           
         
         wherein X 1  and X 2  are independently H, halogen, or C 1 -C 6  alkyl, wherein each hydrogen atom in C 1 -C 6  alkyl is independently optionally substituted with a halogen or C 1 -C 6  alkyl; the process comprising 
         a. contacting a reactant of the formula 
       
       
         
           
           
               
               
           
         
       
       wherein X 1  is a H, halogen, C 1 -C 6  alkyl, wherein each hydrogen atom in C 1 -C 6  alkyl is independently optionally substituted with a halogen or C 1 -C 6  alkyl, with sulfur trioxide to provide a first product mixture comprising the sulfonic acid to provide a sulfonic acid of the formula 
       
         
           
           
               
               
           
         
       
       and
 b. a coupling step comprising contacting the sulfonic acid formed in step (a) with an aryl compound of the formula 
 
       
         
           
           
               
               
           
         
       
       wherein X 2  is a H, halogen, or C 1 -C 6  alkyl, wherein each hydrogen atom in C 1 -C 6  alkyl is independently optionally substituted with a halogen or C 1 -C 6  alkyl, in the presence of a catalyst selected from the group consisting of aluminum oxide, antimony oxide, zirconium oxide, bismuth oxide, boric anhydride, boric acid, ferric oxide, stannic oxide, titanium oxide, titanium sulfate, zinc oxide, iodine, lithium iodide, and silica,
 wherein resulting water is removed during the coupling step (b) by distillation, and 
 wherein the coupling step (b) is performed in the absence of a dehydrating reagent. 
 
     
     
         84 . The process of  claim 83 , wherein step (a) is performed at a temperature in the range of about 30° C. to about 100° C. 
     
     
         85 . The process of  claim 84 , wherein the coupling step (b) is performed at a temperature in the range of about 180° C. to about 240° C. 
     
     
         86 . The process of  claim 85 , wherein X′ and X′ are Cl. 
     
     
         87 . The process of  claim 85 , wherein the crude yield of the coupling step (b), as determined by the sulfone relative to the sulfonic acid, is about 60% to about 95%. 
     
     
         88 . The process of  claim 85 , wherein the purified yield of the coupling step (b), as determined by the sulfone relative to the sulfonic acid, is about 50% to about 85%. 
     
     
         89 . The process of  claim 85 , wherein the coupling step (b) is initiated under anhydrous conditions. 
     
     
         90 . The process of  claim 85 , wherein the coupling step (b) is initiated with less than about 10 wt % water. 
     
     
         91 . The process of  claim 85 , wherein the resulting water is removed continuously during the coupling step (b). 
     
     
         92 . The process of  claim 85 , wherein step (a) is performed in a first reaction vessel and the product mixture produced by step (a) is transferred to a second reaction vessel after the first step for use in step (b). 
     
     
         93 . The process of  claim 85 , wherein the concentration of water throughout the coupling step (b) is less than about 10 wt % water. 
     
     
         94 . The process of  claim 85 , wherein the concentration of the catalyst relative to all components of the coupling step, when the coupling step (b) is initiated, is about 0.7 wt % to about 1.1 wt %. 
     
     
         95 . The process of  claim 85 , wherein the coupling step results in less than 20% of a 2,4′ isomer of the formula 
       
         
           
           
               
               
           
         
         wherein X 1  and X 2  are independently H, halogen, or C 1 -C 6  alkyl, wherein each hydrogen atom in C 1 -C 6  alkyl is independently optionally substituted with a halogen or C 1 -C 6  alkyl, as determined by the 2,4′ isomer relative to all sulfone products. 
       
     
     
         96 . The process of  claim 85 , wherein the coupling step results in less than 20% of a 3,4′ isomer of the formula 
       
         
           
           
               
               
           
         
         wherein X 1  and X 2  are independently H, halogen, or C 1 -C 6  alkyl, wherein each hydrogen atom in C 1 -C 6  alkyl is independently optionally substituted with a halogen or C 1 -C 6  alkyl, as determined by the 3,4′ isomer relative to all sulfone products. 
       
     
     
         97 . The process of  claim 85 , wherein the aryl compound in coupling step (b) is added to the sulfonic acid continuously at the same time that water is removed continuously from the sulfonic acid. 
     
     
         98 . The process of  claim 85 , wherein the aryl compound in coupling step (b) is added to the sulfonic acid continuously at the same time that wet chlorobenzene is removed continuously from the sulfonic acid. 
     
     
         99 . The process of  claim 85 , wherein the aryl compound in coupling step (b) is added at a flow rate of about 1.5 mL/min. 
     
     
         100 . The process of  claim 85 , wherein the coupling step (b) is performed at a pressure of about 30 psi to about 60 psi. 
     
     
         101 . The process of  claim 85 , further comprising extracting the sulfone after the coupling step (b). 
     
     
         102 . The process of  claim 85 , further comprising crystallizing the sulfone.