Process for stabilizing hydrocyanation catalyst

Abstract

The invention provides a method of forming a phosphonate diester compound from a ligand hydrolysis product (LHP) of a phosphite ligand used in a nickel-phosphite hydrocyanation catalyst, such as for conversion of 3-pentenenitrile to adiponitrile, which serves to eliminate acidic LHP compound for a hydrocyanation reaction milieu where the acidic LHP can catalyze further catalyst ligand destruction. The invention further provides phosphonate disester compounds prepared by alkylation of diarylphosphite LHP in the presence of a nickel-phosphite catalyst comprising a bidentate ligand, and a continuous hydrocyanation process for production of adiponitrile wherein catalyst ligand breakdown is inhibited through inactivation of ligand hydrolysis products towards further breakdown. A method of stabilizing a hydrocyanation catalyst is provided.

1 - 10 . (canceled) 
     
     
         11 . A phosphonate disester compound of formula (I) 
       
         
           
           
               
               
           
         
       
       wherein
 each Ar is independently an unsubstituted or a mono-substituted or a multi-substituted aryl group, wherein any aryl group can be substituted with independently selected (C1-C4)alkyl, hydroxyl, a phosphite ester group, or phosphonate ester group; or, 
 the two Ar groups are bonded to each other to provide an unsubstituted or substituted biaryl group, wherein the biaryl group is unsubstituted or is independently mono-substituted or multi-substituted with independently selected (C1-C4)alkyl, hydroxyl, a phosphite ester group, or a phosphonate ester group; and, 
 R is a 2-butenyl, 3-butenyl, 2-cyanobutyl, 3-cyanobutyl, 4-cyanobutyl group, or is one of a group of isomers of a cyanononenyl group wherein the group of isomers includes double bond and cyano group positional isomers. 
 
     
     
         12 . The compound of  claim 11  wherein R is 2-butenyl or 3-butenyl. 
     
     
         13 . The compound of  claim 11  wherein R is 2-cyanobutyl, 3-cyanobutyl, 4-cyanobutyl, or is a cyanooctenyl. 
     
     
         14 . The compound of  claim 11  wherein both Ar groups are (C1-C4)alkyl substituted phenyl, or wherein both Ar groups taken together are (C1-C4)alkyl multisubstituted biphenyl, or wherein one Ar group is (C1-C4)alkyl substituted phenyl and one Ar group is a (C1-C4)alkyl multisubstituted biphenyl further substituted with a hydroxyl. 
     
     
         15 . The compound of  claim 11  wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
       wherein R is defined as in  claim 11 . 
     
     
         16 . A continuous hydrocyanation process for production of adiponitrile, comprising use of a nickel-phosphite catalyst comprising nickel and a ligand mixture comprising one or more monodentate phosphite ligand and the bidentate phosphite ligand of formula (IVA) 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are both mono-ortho-substituted aryls and the aryls are ortho-substituted with one respective (C1-C10)alkyl or (C1-C10)alkoxy, provided that respective meta- and para-positions of the R 1  and R 2  aryls can be unsubstituted or substituted; R 6  and R 10  are a (C1-C10)alkyl or a (C1-C10)alkoxy, R 3 , R 4 , R 5  and R 7 , R 8 , R 9  are each independently hydrogen, a (C1-C10)alkyl or a (C1-C10)alkoxy, provided that at least one of R 3 -R 5 , and at least one of R 7 -R 9 , is a (C1-C10)alkyl or a (C1-C10)alkoxy; wherein the process exhibits reduced degradation of the catalyst relative to an amount of degradation of a second nickel-phosphite catalyst under comparable conditions wherein the ligand mixture comprises only one or more monodentate phosphite ligands, or, comprising bidentate ligands not including a compound of formula (IVA), the process comprising:
 (a) charging the catalyst, 3-pentenenitrile, a Lewis acid, HCN, and water, to a reaction zone under conditions suitable for hydrocyanation to occur; 
 (b) withdrawing reactor effluent comprising a hydrocyanation product and recovered catalyst from the reaction zone; 
 (c) contacting the reactor effluent with an extraction solvent to separate recovered catalyst from hydrocyanation product; and 
 (d) recharging a portion of the recovered catalyst and a portion of makeup catalyst to the reaction zone, sufficient to maintain substantially constant over a period of time a ratio of an amount of active catalyst to an amount of an amount of 3-pentenenitrile added over the period of time, 
 wherein a relative portion of makeup catalyst is reduced compared to a relative portion of makeup catalyst used in carrying out a comparable process wherein the ligand mixture comprises only monodentate phosphite ligands or comprises a bidentate ligand not including the compound of formula (IVA). 
 
     
     
         17 . The process of  claim 16  wherein a portion of makeup catalyst recharged to the reaction zone of the catalyst comprising the bidentate phosphite ligand of formula (IVA) is less than a portion of makeup catalyst charged to the reaction zone of the catalyst comprising only one or more monodentate phosphite ligands or comprising a bidentate ligand not including the compound of formula (IVA). 
     
     
         18 . The process of  claim 16  wherein bidentate phosphite ligand of formula (IVA) is Ligand 3 
       
         
           
           
               
               
           
         
       
       or Ligand 4 
       
         
           
           
               
               
           
         
       
       or a mixture thereof, and wherein reduced degradation of the catalyst occurs compared to the degradation of the catalyst that occurs in carrying out a comparable process wherein the ligand mixture does not include Ligand 3 or Ligand 4. 
     
     
         19 - 28 . (canceled) 
     
     
         29 . A method of stabilizing a hydrocyanation catalyst with respect to hydrolytic ligand decomposition under reaction conditions effective for hydrocyanation of a pentenenitrile in the presence of a Lewis acid and water, the catalyst comprising a nickel-phosphite complex comprising nickel and one or more triarylphosphite ligand, the method comprising addition of a bidendate phosphite ligand to the nickel-phosphite complex, the bidentate ligand of formula (IV) 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are each independently an unsubstituted or substituted monovalent aryl group; each of R 3 -R 10  is independently selected from the group consisting of hydrogen and (C1-C10) alkyl, or wherein two adjacent R 3 -R 10  groups together form an optionally substituted fused aryl ring. 
     
     
         30 . The method of  claim 29  wherein for the bidentate phosphite ligand of formula (IV), R 1  and R 2  are both mono-ortho-substituted aryls, wherein the R 1  and R 2  aryl groups are each ortho-substituted with one respective (C1-C10)alkyl or (C1-C10)alkoxy group, provided that respective meta- and para-positions of the R 1  and R 2  aryls can be unsubstituted or substituted. 
     
     
         31 . The method of  claim 29  wherein for the bidentate phosphite ligand of formula (IV), R 6  and R 10  are not hydrogen. 
     
     
         32 . The method of  claim 29 , wherein for the bidentate phosphite ligand of formula (IV), at least one of R 3 -R 5 , and at least one of R 7 -R 9 , is not hydrogen. 
     
     
         33 . The method of  claim 29 , wherein for the bidentate phosphite ligand of formula (IV), R 5  and R 6  together form an optionally (C1-C10)alkyl or a (C1-C10)alkoxy substituted fused phenyl ring, and wherein R 9  and R 10  together form an optionally (C1-C10)alkyl or a (C1-C10)alkoxy substituted fused phenyl ring. 
     
     
         34 . The method of  claim 29 , wherein for the bidentate phosphite ligand of formula (IV), R 1  and R 2  are both mono-ortho-substituted aryls and the aryls are ortho-substituted with a respective (C1-C10)alkyl or a (C1-C10)alkoxy, provided that respective meta- and para-positions of the R 1  and R 2  aryls can be unsubstituted or substituted; R 6  and R 10  are a (C1-C10)alkyl or a (C1-C10)alkoxy, and at least one of R 3 -R 5 , and at least one of R 7 -R 9 , is a (C1-C10)alkyl or a (C1-C10)alkoxy. 
     
     
         35 . The method of  claim 29  wherein the pentenenitrile is 3-pentenenitrile. 
     
     
         36 . The method of  claim 29  wherein R 1  and R 2  are 2,4-xylyl. 
     
     
         37 . The method of  claim 29  wherein the bidentate phosphite ligand of formula (IV) is 
       
         
           
           
               
               
           
         
       
       or is 
       
         
           
           
               
               
           
         
       
     
     
         38 . The compound of  claim 11 , wherein R is one of a group of isomers of a cyanononenyl group wherein the group of isomers includes double bond and cyano group positional isomers. 
     
     
         39 . The compound of  claim 15 , wherein R is 2-butenyl or 3-butenyl. 
     
     
         40 . The compound of  claim 15 , wherein R is 2-cyanobutyl, 3-cyanobutyl, 4-cyanobutyl, a cyanooctenyl, or is one of a group of isomers of a cyanononenyl group wherein the group of isomers includes double bond and cyano group positional isomers.