Dinitração regiosseletiva de difenil-alcanos, um método simples usando reagente suportado

Abstract

1,ω-bis(p-nitro-phenyl)alkanes are chemical intermediates that can, through their derivatives, amines and isocyanates, lead to a large quantity of bis-nitrogenated symmetric compounds, for example bis-sydnones, and can also be important for the synthesis of macromolecules, such as polyurethanes and polyimides, liquid crystals, etc.. But the obtention of para,para’-dinitro compounds from the correspondents diphenylalkanes, employing nitration in homogeneous conditions, leads to yields of only about 20%. This work shows that better results can be reached when the nitration of diphenylalkanes is made using the supported reagent claycop – cupric nitrate deposited on montmorillonite K10 (or Brazilian bentonite) – in the presence of acetic anhydride, where the p,p’ isomer is obtained with yields around 50% or better. For comparative purposes, zeolite β was used as catalyst in the nitration of 1,4-diphenylbutane: the result was similar to that obtained with the supported reagent.