Atom-efficient electrophilic aromatic nitration by dinitrogen pentoxide catalysed by zirconium(IV) 2,4-pentanedionate

• Published in: Organic & biomolecular chemistry 2004-01, Vol.2 (1), p.90-92
• Main Authors: Hill, Adrian J, Millar, Ross W, Sandall, John P B
• Format: Article
• Language: English
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/b311068k

An atom-efficient, non-acidic, catalytic process is described for the nitration of electron deficient arenes such as o-nitrotoluene using a dinitrogen pentoxide-zirconium(iv) 2,4-pentanedionate system in dichloromethane solvent. Kinetic studies showed the nitration process to be first-order with respect to the aromatic substrate and higher than first-order with respect to the catalyst. Addition of the catalyst at ca. 0.1-1 mol% compared with both N(2)O(5) and the organic substrate results in an increase in the first-order rate constant for nitration by a factor of approximately 5000 with a turnover number of at least 500. The orientation of the nitration products (2,4-/2,6-dinitrotoluenes) is consistent with attack of nitronium ion. The apparently high order of reaction with respect to the catalyst suggests a possible heterogeneous process.