Catalysis by palladium salts: XIII. The reductive carbonylation of nitroaromatic compounds to isocyanates with PdII and Pd0 complexes as homogeneous catalysts

摘要: Abstract A study has been made of the reductive carbonylation 2,4-dinitrotoluene (2,4-DNT) to 2,4-diisocyanotoluene (2,4-TDI) with catalysis either by [Pd(isoquinoline) 2 ], in presence Fe O 3 and MoO or (MoO 4 ) as cocatalysts, Pd o complexes without cocatalysts. In case catalytic systems based upon Cl ] reaction can be carried out at about 200°C under 200 atm CO produce 2,4-TDI high conversions acceptable selectivities. 0 catalysts good achieved much lower temperatures (100-120° C) but a low selectivity when higher pressure is used (300 more). An investigation nitrobenzene phenylisocyanate model system, together thermal stability CO, provided evidence that actual active catalyst could reduced (probably zerovalent) form palladium stabilised nitroaromatic substrate some products formed from it ligands.