A study has been made of the reductive carbonylation of 2,4-dinitrotoluene (2,4-DNT) to 2,4-diisocyanotoluene (2,4-TDI) with catalysis either by [Pd(isoquinoline)2], in the presence of Fe2O3 and MoO3 or of Fe2(MoO4)3 as cocatalysts, or by Pdo complexes without cocatalysts. In the case of catalytic systems based upon [Pd(isoquinoline)2Cl2] the reaction can be carried out at about 200°C and under 200 atm of CO to produce 2,4-TDI with high conversions and acceptable selectivities. Pd0 complexes as catalysts good conversions can be achieved at much lower temperatures (100-120° C) but with a low selectivity when a higher pressure of CO is used (300 atm or more). An investigation of the reductive carbonylation of nitrobenzene to phenylisocyanate as a model system, together with a study of the thermal stability of [Pd(isoquinoline)2Cl2] in the presence of CO, has provided evidence that the actual active catalyst could be a reduced (probably zerovalent) form of palladium stabilised by the nitroaromatic substrate or by some of the products formed from it as ligands.

Catalysis by palladium salts / R. Ugo, R. Psaro, M. Pizzotti, P. Nardi, C. Dossi, A. Andreetta, G. Capparella. - In: JOURNAL OF ORGANOMETALLIC CHEMISTRY. - ISSN 0022-328X. - 417:1-2(1991), pp. 211-233.

Catalysis by palladium salts

R. Ugo;R. Psaro;M. Pizzotti;
1991

Abstract

A study has been made of the reductive carbonylation of 2,4-dinitrotoluene (2,4-DNT) to 2,4-diisocyanotoluene (2,4-TDI) with catalysis either by [Pd(isoquinoline)2], in the presence of Fe2O3 and MoO3 or of Fe2(MoO4)3 as cocatalysts, or by Pdo complexes without cocatalysts. In the case of catalytic systems based upon [Pd(isoquinoline)2Cl2] the reaction can be carried out at about 200°C and under 200 atm of CO to produce 2,4-TDI with high conversions and acceptable selectivities. Pd0 complexes as catalysts good conversions can be achieved at much lower temperatures (100-120° C) but with a low selectivity when a higher pressure of CO is used (300 atm or more). An investigation of the reductive carbonylation of nitrobenzene to phenylisocyanate as a model system, together with a study of the thermal stability of [Pd(isoquinoline)2Cl2] in the presence of CO, has provided evidence that the actual active catalyst could be a reduced (probably zerovalent) form of palladium stabilised by the nitroaromatic substrate or by some of the products formed from it as ligands.
Settore CHIM/03 - Chimica Generale e Inorganica
JOURNAL OF ORGANOMETALLIC CHEMISTRY
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/182026
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