Abstract:
The present invention is directed to compositions comprising fluorinated 4-oxo-chroman-carboxylates, particularly fluorinated 4-oxo-chroman-7-carboxylate, and a process for making the same. The compounds are useful as intermediates in the production of agricultural chemicals, and also as chain terminators in condensation polymerization reactions, particularly when it is desired to provide a polymer having a relatively low surface energy.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to compositions comprising fluorinated 4-oxo-chroman-carboxylates and methods for making the same. The compounds are useful as intermediates in the production of agricultural chemicals, and also as chain terminators in polyester polymerization. 
     BACKGROUND 
     Fluorinated materials have many uses. In particular, they are used in the in polymer-related industries, and, more particularly, in fiber-related industries, to impart soil, water and oil resistance, and improved flame retardancy. Generally, these materials are applied as a topical treatment, but their effectiveness decreases over time due to material loss via wear and washing. They can also find use in agricultural end-uses such as herbicides, fungicides and the like. 
     There is a need to provide materials that have improved soil and oil resistance in general, as well as materials that maintain such properties over time. By incorporating fluorinated aromatic diesters into polymer backbones, more permanent soil, water and oil resistance, as well as improved flame retardancy, can be achieved. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention is a fluorinated 4-oxo-chroman-carboxylate or carboxylic acid represented by structure (I): 
                                
wherein:
     R is H, C 1 -C 10  alkyl, C 5 -C 15  aryl, or C 6 -C 20  arylalkyl;   each R 1  is independently C 1 -C 10  alkyl, C 5 -C 15  aryl, C 6 -C 20  arylalkyl, or halogen;   X is O or CF 2 ; and   Rf is (CF 2 ) n , wherein n is an integer within the range of 1-10   

     Another aspect of the present invention is a process, comprising combining in a reaction vessel a hydroxyaromatic diester or diacid with a perfluorovinyl compound in the presence of a basic catalyst to form a reaction mixture, sealing the reaction vessel, and stirring the reaction mixture under the autogenous pressure of the perfluorovinyl compound to effect reaction; wherein the hydroxy aromatic diester or diacid is represented by the structure (II) 
     
       
                 
         
             
             
         
      
         
         wherein R is H, C 1 -C 10  alkyl, C 5 -C 15  aryl, or C 6 -C 20  arylalkyl; 
         each R 1  is independently C 1 -C 10  alkyl, C 5 -C 15  aryl, C 6 -C 20  arylalkyl, or halogen; 
         and wherein the perfluorovinyl compound is represented by the structure (III) 
       
    
                                
wherein X is O or CF 2 ; and
     Rf is (CF 2 ) n , and wherein n is an integer within the range of 1-10   

    
    
     DETAILED DESCRIPTION 
     Disclosed herein are fluorinated 4-oxo-chroman-carboxylates and processes for making the compounds. The compounds have the formula: 
                                
wherein:
     each R is independently H, C 1 -C 10  alkyl, C 5 -C 15  aryl, or C 6 -C 20  arylalkyl;   each R 1  is independently H, C 1 -C 10  alkyl, C 5 -C 15  aryl, C 6 -C 20  arylalkyl, or halogen;   each X is independently O or CF 2 ; and   each Rf is independently (CF 2 ) n , wherein each n is independently an integer within the range of 1-10.   The substituents on the benzene ring in the above formulas can be attached to the benzene ring at any point, thus making it possible to have ortho-, meta- and para-substituents as defined above.   

     In one embodiment of the compound R is H. 
     In an alternative embodiment of the compound, R is C 1 -C 10  alkyl, C 5 -C 15  aryl, or C 6 -C 20  arylalkyl. In a further embodiment, R is methyl. 
     In one embodiment of the compound R 1  is H. 
     In one embodiment of the compound, X is O. In an alternative embodiment of the compound, X is CF 2 . 
     In one embodiment of the compound Rf is CF 2 . In an alternative embodiment of the compound, (CF 2 ) 2 . 
     In one embodiment of the compound, the carboxylate group is located at position 7. 
     In one embodiment of the compound R is methyl, each R 1  is H, X is O and n=2. 
     In another aspect, the invention provides a process comprising combining in a reaction vessel a hydroxyaromatic diester or diacid with a perfluorovinyl compound in the presence of a basic catalyst to form a reaction mixture, sealing the reaction vessel, and stirring the reaction mixture under the autogenous pressure of the perfluorovinyl compound to effect reaction; wherein the hydroxy aromatic diester or diacid is represented by the structure (II) The reaction can be performed at elevated temperature. 
     
       
                 
         
             
             
         
      
         
         wherein R is H, C 1 -C 10  alkyl, C 5 -C 15  aryl, or C 6 -C 20  arylalkyl; 
         each R 1  is independently C 1 -C 10  alkyl, C 5 -C 15  aryl, C 6 -C 20  arylalkyl, or halogen; 
         and wherein the perfluorovinyl compound is represented by the structure (III) 
       
    
                                
wherein X is O or CF 2 ; and
     Rf is (CF 2 ) n , and wherein n is an integer within the range of 1-10   

     Suitable solvents include, but are not limited to, dimethyl formamide, carbon tetrabromide, or tetrahydrofuran Any basic catalyst that is capable of deprotonating phenol is suitable. Suitable catalysts include but are not limited to potassium t-butoxide, potassium carbonate, or sodium carbonate, 
     The progress of the reaction can be monitored by thin layer chromatography or proton NMR. The reaction can be terminated by the addition of acid such as HCl. In one embodiment of the compound of the process the process further comprises diluting the reaction product with a solvent (typically methylene chloride, chloroform, carbon tetrachloride, THF or 1,4-dioxane) followed by washing with additional acid and water. In a further embodiment, the thus washed product is dried, concentrated under reduced pressure, and dried again under vacuum. The resulting final product can be isolated by any convenient method, such as, for example, column chromatography. 
     In one embodiment the hydroxy aromatic diester or diacid is a hydroxyaromtic diester. In a further embodiment, the hydroxy aromatic diester is dimethyl 2-hydroxy terephthalate. 
     In one embodiment of the process R is H. 
     In an alternative embodiment of the process, R is C 1 -C 10  alkyl, C 5 -C 15  aryl, or C 6 -C 20  arylalkyl. In a further embodiment of the process R is methyl. 
     In one embodiment of the process R 1  is H. 
     In one embodiment of the process, X is O. In an alternative embodiment of the process, X is CF 2 . 
     In one embodiment of the process Rf is CF 2 . In an alternative embodiment of the process, Rf is (CF 2 ) 2 . 
     In one embodiment of the process R is methyl, each R 1  is H, X is CF 2 , and Rf is (CF 2 ) 2 , and the aromatic diester is 2-hydroxy dimethyl terephthallate. 
     EXAMPLES 
     The following chemicals and reagents were used as received from Sigma-Aldrich, Milwaukee, Wis.:
         potassium t-butoxide   dimethyl formamide   carbon tetrabromide (tetrabromomethane)   1,4-dimethyl-2-hydroxy terephthalate   methylene chloride
 
Perfluoroprop-1-ene was used as received from SynQuest Labs., Alachua, Fla.:
       

     Example 1 
     (Methyl 2,2,3-trifluoro-4-oxo-3-(trifluoromethyl)chroman-7-carboxylate) 
     
       
                 
         
             
             
         
      
     
     In a dry box, dimethyl formamide (50.00 mL) and carbon tetrabromide were added to a reaction flask equipped with a stirring bar. To this solution in the reaction flask was added 1,4-dimethyl-2-hydroxy terephthalate (5.25 g, 0.025 mol) to form a homogeneous reaction solution. To this homogeneous reaction solution in the reaction flask was added potassium t-butoxide (0.77 g, 0.0069 mol). Perfluoroprop-ene (9.375 g, 0.0625 mol) was then added to the reaction flask to form a reaction mixture. The reaction mixture was stirred for 24 hours. The reaction was terminated by the addition of 2 mL of 10% HCl to the reaction mixture. The resulting reaction solution was diluted with methylene chloride (250 mL) and then washed with 10% HCl (2×100 mL) and then with water (3×100 mL). The resulting reaction product was then dried over anhydrous sodium sulfate, concentrated at reduced pressure and then dried under vacuum. Column chromatography afforded the desired product, methyl 2,2,3-trifluoro-4-oxo-3-(trifluoromethyl)chroman-7-carboxylate), as a white solid (0.71 g, 8.6% yield, Rf: ˜0.50 methylene chloride/hexane 91:1)). 
     Example 2 
     (Methyl 2,2,3-trifluoro-4-oxo-3-(trifluoromethyl)chroman-7-carboxylate) 
     
       
                 
         
             
             
         
      
     
     In a dry box, 1,4-dimethyl-2-hydroxy terephthalate (5.25 g, 0.025 mol) was weighed into a round bottom reaction flask, equipped with a stirring bar. To this material in the reaction flask was added dimethyl formamide (250.00 mL) and potassium t-butoxide (0.77 g, 0.0069 mol), forming a reaction mixture. To this reaction mixture was added perfluoroprop-1-ene (9.375 g, 0.0625 mol). The resulting reaction mixture was stirred for ˜24 hours. The reaction was terminated by the addition of 10% HCl (2 mL). The resulting reaction product was diluted with methylene chloride and then washed with 10% HCl (2×100 mL) and then with water (2×100 mL), forming an organic phase and an aqueous phase. The s separated organic phase was dried over anhydrous sodium sulfate, filtered and then concentrated at reduced pressure and then column chromatographed to 3.71 (45.24% yield) of the desired material, identified by NMR, as methyl 2,2,3-trifluoro-4-oxo-3-(trifluoromethyl)chroman-7-carboxylate.