Reactions of phosgene with lanthanide oxide halides

3 LANTHANIDE AND ACTINIDE HALIDES AND OXIDE HALIDES 9.3.1 Reactions of phosgene with lanthanide oxide halides 

The lanthanum(III) oxide chlorides might all be expected to react similarly with phosgene  

Indeed, the ease of this reaction, as determined by the temperature range of the exothermic d.t.a. peak for heating LnOCl under phosgene, decreases from cerium to gadolinium [306,1087]  

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]. 

The reaction of lanthanum(III) oxide fluoride, a-LaOF, with phosgene has been investigated as a function of time and temperature (430, 500 and 680 C) by t.g.a., followed by product analysis and characterization by powder X-ray diffraction [113]. This is a much more thorough study than those described above for the lanthanide oxide chlorides, and the results are summarized in Fig. 9.9. All the fluoride ends up as LaF (thus no significant quantities of COCIF or COFj can be formed), and the major product at each temperature is LaOCl. The product analysis is consistent with the following sequential reactions occurring [113]  

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