Methylidene malonate process

Abstract

Novel improved processes for the production and isolation of methylidene malonates via direct and indirect adduct processes.

1 . An improved flash distillation process for the separation and isolation of methylidene malonates from a crude 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 subjecting the material to flash distillation, 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 at least a portion of a separation phase polymerization inhibitor is added to the still pot or vessel in which the crude material is to be flash vaporized prior to initiating flash distillation. 
     
     
         3 . The improved process of  claim 2  wherein at least a portion of a separation phase polymerization inhibitor is also added to the collection vessel for the methylidene malonate prior to initiating flash distillation. 
     
     
         4 . The improved process of  claim 3  wherein additional separation phase stabilizer is also added to the materials resulting from the flash distillation process. 
     
     
         5 . The improved process of  claim 1  wherein at least a portion of a separation phase polymerization inhibitor is also added to the collection vessel for the methylidene malonate prior to initiating flash distillation. 
     
     
         6 . The improved process of  claim 1  wherein a separation phase stabilizer is also added to the materials resulting from the separation or isolation process. 
     
     
         7 . 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. 
     
     
         8 . The improved process of  claim 1  wherein the primary anionic polymerization inhibitor is a strong acid. 
     
     
         9 . The improved process of  claim 1  wherein the primary anionic polymerization inhibitor is selected from trifluoroacetic acid, sulfuric acid, maleic acid, perchloric acid and chlorosulfonic acid 
     
     
         10 . The improved process of  claim 1  wherein the product of the flash distillation is subjected to one or more additional distillation steps, each involving the presence of a separation phase stabilize in the product to be distilled as well as in the resultant product, whether, in the latter case, added the product following distillation, to the collection vessel prior to distillation, or both. 
     
     
         11 . A flash distillation method for separating and/or isolating methylidene malonates from a crude or unpurified methylidene malonate comprising:
 a) adding a separation phase polymerization inhibitor to a crude or unpurified methylidene malonate reaction product to be subjected to flash distillation;   b) slowly adding the methylidene malonate material to the still pot or vessel of a flash distillation apparatus; and   c) collecting the resultant methylidene malonate.   
     
     
         12 . The method of  claim 11  wherein at least a portion of a separation phase polymerization inhibitor is also added to the collection vessel for the methylidene malonate prior to initiating flash distillation. 
     
     
         13 . The method of  claim 11  wherein at least a portion of a separation phase polymerization inhibitor is also added to the still pot or vessel of the flash distillation apparatus in which the methylidene malonate material is to be vaporized prior to initiating flash distillation. 
     
     
         14 . The method of  claim 11  wherein the still pot or vessel is heated to from 170° C. to 210° C. 
     
     
         15 . The method of  claim 11  wherein the crude methylidene malonate is subjected to solvent stripping prior to conducting flash distillation. 
     
     
         16 . The method of  claim 11  wherein the separation phase polymerization inhibitor is selected from a combination of sulfuric acid and hydroquinone or a combination of maleic acid and hydroquinone. 
     
     
         17 . The method of  claim 11  where in the product of the flash distillation is up-stabilized following completion of the flash distillation. 
     
     
         18 . The method of  claim 11  wherein the product of the flash distillation is subjected to one or more additional separation and/or isolation processes: said product containing a separation phase polymerization inhibitor. 
     
     
         19 . The method of  claim 18  wherein the subsequent separation and/or isolation process(es) is/are distillations. 
     
     
         20 . The method of  claim 19  wherein the collection vessel(s) used in the subsequent distillation step(s) have added thereto at least a portion of a separation phase polymerization inhibitor prior to initiating the distillation.