TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The process (M1) is performed at a pressure higher than ambient pressure and/or with a condenser or a cooled trap or both in the off-gas line. The reaction between the starting material and elemental fluorine is performed at a pressure 3-12 bar. The formed difluoroethylene carbonate, trifluoroethylene carbonate and tetrafluoroethylene carbonate are isolated and stored. The formed difluoroethylene carbonate, trifluoroethylene carbonate and tetrafluoroethylene carbonate are contacted only with resistant material. In the method (M2), difluoroethylene carbonate, trifluoroethylene carbonate and tetrafluoroethylene carbonate are not contacted with glass, ceramics, aluminium parts parts containing aluminium alloys; and are contacted with stainless steel, Inconel, Hastelloy or polymeric materials. The polymeric materic material is perfhiorinated. Preferred Reactants: The starting material is ethylene carbonate or fluoroethylene carbonate; or difluoroethylene carbonate selected from 4,4-difluoeroethylene carbonate, cis-4,5-difluoroethylene carbonate and/or trans-4,5-difluoroethylene carbonate; or mixture containing at least two compounds selected from ethylene carbonate, fluoroethylene carbonate, 4,4-difluoroethylene carbonate, cis-4,5-difluoroethylene carbonate and trans-4,5-difluoroethylene carbonate. The resistant material is stainless steel or organic polymeric material. EXAMPLE - A reactor with gas inlets and gas outlet was applied with starting material, ethylene carbonate. Fluorine was introduced in the form of a mixture consisting of fluorine (10 vol.%) and nitrogen (90 vol.%) through a metal diffuser. Additionally, nitrogen was introduced separately into the reactor. The temperature of the reaction mixture was kept in a range of +7 degrees C from the average temperature. The reactor pressures were 0.02 bar (comparative) and 2.5 bar (test). The amount of trifluoroethylene (F3EC) was 13.6/4.7 (%) for test/comparative. The total amount of trans-F2EC, 4,4-F2EC, and cis-F2EC was 74.9/67.8 (%). The results indicated that that use of a pressure higher than ambient pressure led to higher yield toward di-, tri- or tetrafluoroethylene, and also avoided the loss of volatile products as of the above products.