Patent GB-663364-A (GB)
Title: Process for the production of perchlorethylene
IPC: C07C17/06
Filed: 1947-12-17
Abstract: <PICT:0663364/IV (b)/1> The gas mixture obtained by the combustion of acetylene and chlorine in the process of the parent Specification is submitted to fractional condensation so as to recover as a single fraction the constituents having a boiling point lying between 120 DEG  and 78 DEG  to 80 DEG  C.  The condensation may be effected by washing the gaseous combustion products with a liquid which is miscible with the condensate and which is produced during the combustion.  Thus the separation of the constituents boiling above 120 DEG  C. may be effected by spraying perchlorethylene into the combustion gases. In this way the combustion gases are cooled down to 120 DEG  C. whilst a part of the added liquid perchlorethylene vaporizes.  The high boiling constituents such as hexachlorbenzene are dissolved in or entrained by the perchlorethylene and after cooling the perchlorethylene the high boiling products separate out. The separation of the main reaction product (perchlorethylene) as a fraction boiling between 120 DEG  and 78 DEG  to 80 DEG  C. can be effected by bringing the residual gases into contact with solid bodies or preferably with a liquid of low vapour pressure which is immiscible with the condensate and does not react therewith and which is maintained at 78 DEG  to 80 DEG  C.  The uncondensed gases are then cooled down to room temperature so that the constituents boiling below 78 DEG  to 80 DEG  C. are separated out, or the gases are sprayed with cold water to absorb the hydrogen chloride and condense the products boiling below 78 DEG  to 80 DEG  C.  In the drawing a mixture of chlorine and acetylene from the mixing device 1 is burnt in the chamber 6 as described in the parent Specification. The combustion gases flow upwardly over the Raschig rings in the column 10 which are sprayed with perchlorethylene from the rose 11.  Part of the perchlorethylene vaporizes whilst another part flows out of the column through a perforated plate 12.  The gases boiling above 120 DEG  C. are entrained in the out-flowing perchlorethylene which issues from the chamber at 14 via the bubble cap 13.  By cooling in the condenser 15 the entrained high boiling constituents especially hexachlorbenzene are separated out and retained by the filter 16 whilst the perchlorethylene is returned to the rose 11.  The separation of perchlorethylene from the gases issuing at 19 is effected by passing the gases into column 20 filled with Raschig rings down which sulphuric acid at a temperature of 78 DEG  to 80 DEG C. flows.  The perchlorethylene together with the acid flows into a separating vessel 23 and the perchlorethylene is collected through overflow 24.  The sulphuric acid is removed at 25 and led back to the column 20 via a thermostat 27.  The constituents boiling below 78 DEG to 80 DEG  C. are condensed by introducing the gases issuing at 29 into an absorber 30 sprayed with cold water.  The hydrogen chloride is absorbed and the heavier condensate (carbon tetrachloride) removed at 32, the aqueous acid being removed at 31.ALSO:The gas mixture obtained by the combustion of acetylene and chlorine in the process of the parent Specification is submitted to fractional condensation so as to recover as a single fraction the constituents having a boiling point lying between 120 DEG C. and 78 DEG  to 80 DEG C.  The condensation may be effected by washing the gaseous combustion products with a liquid which is miscible with the condensate and which is produced during the combustion, thus the separation of the constituents boiling above 120 DEG C. may be effected by spraying perchlorethylene into the combustion gases. In this way the combustion gases are cooled down to 120 DEG C. whilst a part of the added liquid perchlorethylene vaporizes.  The high boiling constituents such as hexachlorbenzene are dissolved in or entrained by the perchlorethylene and after cooling the perchlorethylene the high boiling products separate out.  The separation of the main reaction product (perchlorethylene) as a fraction boiling between 120 DEG C. and <PICT:0663364/III/1> 78 DEG  to 80 DEG C. can be effected by bringing the residual gases into contact with solid bodies or preferably with a liquid of low vapour pressure which is immiscible with the condensate and does not react therewith and which is maintained at 78 DEG  to 80 DEG C.  The uncondensed gases are then cooled down to room temperature so that the constituent boiling below 78 DEG  to 80 DEG C. are separated out, or the gases are sprayed with cold water to absorb the hydrogen chloride and condense the products boiling below 78 DEG  to 80 DEG C.  In the drawing a mixture of chlorine and acetylene from the mixing device 1 is burnt in the chamber 6 as described in the parent Specification.  The combustion gases flow upwardly over the Raschig rings in the column 10 which are sprayed with perchlorethylene from the rose 11.  Part of the perchlorethylene vaporizes whilst another part flows out of the column through a perforated plate 12.  The gases boiling above 120 DEG C. are entrained in the outflowing perchlorethylene which issues from the chamber at 14, via the bubble cap 13.  By cooling in the condenser 15 the entrained high boiling constituents especially hexachlorbenzene are separated out and retained by the filter 16 whilst the perchlorethylene is returned to the rose 11.  The separation of perchlorethylene from the gases issuing at 19 is effected by passing the gases into column 20 filled with Raschig rings down which sulphuric acid at a temperature of 78 DEG  to 80 DEG C. flows.  The perchlorethylene together with the acid flows into a separating vessel 23 and the perchlorethylene is collected through overflow 24.  The sulphuric acid is removed at 25 and led back to the column 20 via a thermostat 27.  The constituents boiling below 78 DEG to 80 DEG C. are condensed by introducing the gases issuing at 29 into an absorber 30 sprayed with cold water.  The hydrogen chloride is absorbed and the heavier condensate (carbon tetrachloride) removed at 32 the aqueous acid being removed at 31.