Selective hydrogenation of chloronitrobenzenes with an MCM-41 supported platinum allyl complex derived catalyst

Abstract

A platinuin precatalyst (1) has been prepared by reacting [(eta(3)-C(3)H(5))(4)Pt(4)Cl(4)] with surface functionalized MCM-41 with pendant -(CH(2))(3)NH(CH(2))(2)NH(2) groups. For the hydrogenation of o-, m- and p-chloronitrobenzenes to the corresponding chloroanilines, 1 is found to be a highly active catalyst with good selectivities for them-and p-isomers. Its performance is superior to that of its palladium analogue and far superior to that of commercial (5%) Pt/C or (5%) Pt/Al(2)O(3). Comparison of solid state and solution NMR data and other evidences indicate that on treatment with the functionalized MCM-41 support; [(eta(3)-C(3)H(5))(4)Pt(4)Cl(4)] loses the ally! ligand. XPS data show that in the fresh catalyst Pt is present in the 2+ oxidation state. Based on these and analytical data, co-ordination by surface diamine and hydroxo groups to Pt(2+) in 1 is suggested. In the used catalyst both Pt(2+) and Pt are present but the amount of metallic platinum is similar to 16% of the total. (C) 2011 Elsevier B.V. All rights reserved.