Methylidene malonate process

Abstract

An improvement in the production of methylidene malonates is attained by use of specific reaction phase and/or separation phase polymerization inhibitors and combinations thereof.

1 . An improved process for the separation and isolation of methylidene malonates from a crude or unpurified methylidene malonate wherein the improvement comprises the addition of a separation phase polymerization inhibitor to a crude or unpurified methylidene malonate reaction product prior to or concurrent with the application of the separation or isolation step to said product, wherein the separation phase stabilizer comprises at least one anionic polymerization inhibitor and at least one free radical polymerization inhibitor. 
     
     
         2 . The improved process of  claim 1  wherein the anionic polymerization inhibitor comprises at least one primary anionic polymerization inhibitor, at least one secondary anionic polymerization inhibitor or a combination thereof. 
     
     
         3 . The improved process of  claim 1  wherein the separation phase stabilizer is also added to the materials resulting from the separation or isolation process. 
     
     
         4 . The improved process of  claim 3  wherein at least a portion of the separation phase stabilizer is added to the collection vessel for the separated or isolated methylidene malonate before initiating the separation or isolation process. 
     
     
         5 . The process of  claim 2  wherein the primary anionic polymerization inhibitor is a strong acid. 
     
     
         6 . The process of  claim 2  wherein the primary anionic polymerization inhibitor is selected from trifluoroacetic acid sulfuric acid, maleic acid, perchloric acid and chlorosulfonic acid 
     
     
         7 . The improved method of  claim 1  wherein the separation process comprises a sequence of at least two distillations on a crude methylidene malonate product with the first distillation comprising the isolation of the liquid crude methylidene malonate from any non-liquid components in the crude product and the second distillation comprising a re-distillation of the product of the first distillation. 
     
     
         8 . The improved method of  claim 1  wherein the separation process comprises a sequence of at least three distillations on a crude methylidene malonate product with the first distillation comprising the isolation of the liquid crude methylidene malonate from any non-liquid components in the crude product, the second distillation comprising a re-distillation of the product of the first distillation and the third or subsequent distillation comprising the distillation of those fractions from the preceding distillation containing at least 50% by weight of methylidene malonate. 
     
     
         9 . The improved method of  claim 1  wherein the initial separation of the liquid methylidene malonate is by a method other than distillation and the method further comprises one or more additional purification steps, at least one of which is a distillation step. 
     
     
         10 . A process for the separation and isolation of methylidene malonates from a crude methylidene malonate comprising:
 a) adding a separation phase polymerization inhibitor to a crude or unpurified methylidene malonate reaction product;   b) adding at least a portion of a separation phase polymerization inhibitor to the collection vessel used in the separation and/or isolation step;   c) conducting the separation and/or isolation step to thereby collect the separated or isolated methylidene malonate in the collection vessel, wherein the separation phase stabilizer comprises at least one anionic polymerization inhibitor and at least one free radical polymerization inhibitor.   
     
     
         11 . The process of  claim 10  wherein additional separation phase stabilizer is added to the materials resulting from the separation or isolation process. 
     
     
         12 . The process of  claim 10  wherein a series of separation and/or isolation processes are conducted, each repeating the steps of  claim 10  until the desired degree of purity is attained. 
     
     
         13 . The process of  claim 11  additional separation phase stabilizer is added to the materials resulting from final separation or isolation process. 
     
     
         14 . The improved process of  claim 10  wherein the anionic polymerization inhibitor comprises at least one primary anionic polymerization inhibitor, at least one secondary anionic polymerization inhibitor or a combination thereof. 
     
     
         15 . The process of  claim 10  wherein the primary anionic polymerization inhibitor is selected from trifluoroacetic acid, sulfuric acid, maleic acid, perchloric acid and chlorosulfonic acid 
     
     
         16 . The process of  claim 10  wherein the separation process comprises a sequence of at least two distillations on a crude methylidene malonate product with the first distillation comprising the isolation of the liquid crude methylidene malonate from any non-liquid components in the crude product and the second distillation comprising a re-distillation of the product of the first distillation. 
     
     
         17 . The process of  claim 10  wherein the separation process comprises a sequence of at least three distillations on a crude methylidene malonate product with the first distillation comprising the isolation of the liquid crude methylidene malonate from any non-liquid components in the crude product, the second distillation comprising a re-distillation of the product of the first distillation and the third or subsequent distillation comprising the distillation of those fractions from the preceding distillation containing at least 50% by weight of methylidene malonate. 
     
     
         18 . The process of  claim 10  wherein the initial separation of the liquid methylidene malonate is by a method other than distillation and the method further comprises one or more additional purification steps, at least one of which is a distillation step. 
     
     
         19 . The process method of  claim 10  wherein the crude methylidene malonate is produced by an adduct process. 
     
     
         20 . The improved method of  claim 10  wherein the crude methylidene malonate is produced by a non-adduct process.