Dichlorine reaction with, phosgene

The presence of tetrachloromethane inhibits the formation of phosgene, and this has been ascribed to its action as an inert third body for the recombination of chlorine atoms to form dichlorine, thus inhibiting both the formation of [COClj- and its reaction with Cl-[1328] ... 

The reaction of carbon monoxide with lead(II) chloride is illustrated in Table 5.2 [168]. Thermal decomposition of the lead salt to give dichlorine, followed by reaction with carbon monoxide, could be responsible for the phosgene formation [781]. 

The most investigated com X>und is CeOCl, studied both as a pure material and as a compound formed in situ in the reaction of CeOj with phosgene it has been suggested (although it seems rather unlikely) that reaction between CeOCl and COClj does not actually occur, but that the product derives from equilibrium amounts of carbon monoxide and dichlorine present [307,1087,1088]. The reaction of PrOCI with phosgene has also been the subject of a kinetic study [305]. 

As is common for many of the reactions with metal oxides and phosgene, the reaction rate goes through a maximum at ca. 650 C, drops to a minimum at ca. 850 C, and then starts to rise again (see Fig. 9.10). This is reasonably explained in terms of phosgene dissociation into carbon monoxide and dichlorine (see Chapter 8) becoming appreciable at above 600 C,... 

According to Atkinson et al., highly active charcoal effects the conversion of a mixture of CO and Cl 2 at a temperature below 50 "C [89]. Other workers, however, have found that commercial charcoals, supplied for phosgene manufacture, do not catalyse the CO/Clj reaction, even at temperatures as high as 100 "C. After treatment with dichlorine the catalyst was active above 80 C [ICI72]. 

The thermal synthesis of phosgene involves the reaction of carbon monoxide with dichlorine Equation (5.1) induced by purely thermal, as opposed to catalytic (Section 5.1.3), means. 

The extent of thermal dissociation of phosgene at 0.5, 1.0 and 10 bar pressure (0.05, 0.1 and 1 MPa, respectively) has been calculated [1764] based on the accepted ideal gas thermodynamic values [359aa], and is illustrated in Fig. 5.3, whilst the enthalpy of formation for this reaction has been based on actual measurements of the equilibrium constant in the temperature range of 645-725 K by heating together carbon monoxide and dichlorine [218], see Section 6.1. The equilibrium reaction depicted in Equation (5.1) has been measured experimentally both by dissociation of phosgene and by association of carbon monoxide and dichlorine [216]. At 603, 553 and 503 C, the dissociation was found to be 91, 80 and 67%, respectively, in reasonable agreement with the values based on the ideal gas calculations illustrated in Fig. 5.3. At temperatures above 800 C, the dissociation is essentially complete [216]. 

The reaction of CCl with CO is reported to result in the formation of considerable quantities of phosgene [1824a], and it is interesting to speculate upon the carbon monoxide behaving as a thermodynamic sink for dichlorine in the well-known and industrially operated reaction [2165] ... 

In the reaction of sulfur(II) chloride with carbon monoxide, the co-product S2CI2, formed in addition to phosgene, may be reconverted using dichlorine into active SClj [142],... 

The reaction of oxygen atoms with CCl, results in the formation of phosgene, in addition to dichlorine, CO and COj [2088a]. The primary reactions in this system are... 

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