to ethylene was obtained as a by product the obtained crude product was distilled under reduced pressure 10 mmhg and a fraction at 70 u00b0 c to 74 u00b0 c was collected to obtain 814 g 4 94 mol yield 91 of hcc 250fb at a purity of 98 or more a 1 000 ml four necked flask equipped with a thermometer and a condenser tube was charged with 540 g 3 0 mol of hcc 250fb obtained in step 1 630 g of a 40 aqueous koh solution and 10 g of a phase transfer catalyst aliquat 336 the reaction was allowed to proceed under stirring at 80 u00b0 c in an oil bath for 3 hours after completion of the reaction the resulting product was cooled and distilled under reduced pressure 10 to 20 mmhg and a fraction at 67 7 u00b0 c to 81 9 u00b0 c was collected to obtain 390 g 2 68 mol yield 89 3 of a mixture of hcc 1240zf and hcc 1240za with a hcc 1240zf hcc 1240za ratio of 62 38 a 500 ml flask equipped with a high pressure mercury vapor lamp a magnetic stirrer and two gas ports was charged with 265 g of a mixture of the 1 1 3 trichloropropene hcc 1240za and 3 3 3 trichloropropene hcc 1240zf obtained in step 2 and allowed to cool to 0 u00b0 c in an ice bath while the content was irradiated with ultraviolet light stirring was performed and chlorine gas was introduced at 20 to 120 ml min from one of the gas ports to the area above the liquid surface of the content the reaction mixture was intermittently sampled and analyzed by gas chromatography to measure the degree of chlorination after 3 hours the trichloropropene was.