Method of preparation of fluorocarbon compounds

Claim 1

In the preparation, by the reaction of a perfluoroalkylethanol and pyromellitic dianhydride and subsequent conversion of pendent carboxyl groups to the alkyl ester-(CO 2 B) r , of a fluorocarbon compound having the formula ##STR4## wherein the attachment of the fluorinated radicals and the radicals CO 2 B to the nucleus is in asymmetrical positions with respect to rotation about the axis through the center of the nucleus wherein "X" is fluorine, or perfluoroalkoxy of 1 to 6 carbon atoms, and m has arithmetic mean between 2 and 20; n is zero or unity; "W" and "Y" are alkylene, cycloalkylene or alkyleneoxy radicals of combined chain length from 2 to 20 atoms; (CF 2 ) m and "Y" have each at least 2 carbon atoms in the main chain; "Z" is oxygen and p is 1, or "Z" is nitrogen and p is 2; q is an integer of at least 2 but not greater than 5; "B" is CH 2 RCHOH or is CH 2 RCHOCH 2 RCHOH where "R" is hydrogen or methyl, or "B" is CH 2 CH(OH)CH 2 Q where Q is halogen, hydroxy, or nitrile; or " B" is CH 2 CH(OH)CH 2 OCH 2 CH(OH)CH 2 Q; and r is an integer of at least 1 but not greater than q; and X(CF 2 ) m , W and Y are straight chains, branched chains or cyclic; and wherein the substituent chains of the above general formulas are the same or different, the improvement comprising removing most of the impurities from the fluorocarbon mass with heat and vacuum after the final washing step, then adding an emulsifier to the fluorocarbon compound mass so that the mass can be handled as a liquid concentrate rather than a tacky solid.