Di:phenylamine and derivs. prodn. from corresp. N=cyclohexylidene aniline

摘要

Prodn. of diphenylamines (I) is carried out by dehydrating N-cyclohexylidene-anilines (II) at 250-500degC, using a catalyst (III) contg. 0.05-5, pref. 0.05-4, esp. 0.1-3 (wt.)% Rh, up to 90% of which may be replaced by Pd, Pt and/or Ir, with addn. of 1-6% alkali metal hydroxide (IV) and 1-6% alkali metal sulphate (V), both w.r.t. (III). R1 = H, 1-6 C alkyl, 1-2 C alkoxy, 3-6 C cycloalkyl, benzyl or aryl; R2 = H, 1-6 C alkyl or 1-2 C alkoxy; R5 = H, 1-6 C alkyl, 1-6 C alkoxy, 3-6 C cycloalkyl, benzyl, aryl, OH, NH2, 1-6 C alkylamino, di-1-6-C-alkylamino, aryloxy or arylamino; R6 = H, 1-6 C alkyl, 1-6 C alkoxy, OH, NH2 or 1-6 C alkylamino; R3, R4, R7 and R8 independently = H or 1-2 C alkyl; aryl = phenyl or 5-6-membered heteroaryl attached in the 2-, 3- or 4-position and with 1 or 2 N, O and/or S heteroatom(s). The prepn. of (II) (not claimed) is described in the text (see below). Pref. (III) has a support of Al2O3 or Al spinel, opt. treated with Cr and Mn, which has a surface area of over 100 M2/g.