| abstract |
Prepn. of N,N'-disubstd. p-quinonediimines of formula (I) by oxidising the corresp. N,N'-phenylenediamines in an alkali/alcoholic soln. (esp. using O2 opt. in admixt. with N2) is claimed, as are also the use of (I) to stabilise (meth)aryloxy gp.-contg. organosilanes of formula (II) and compsns. comprising the organosilane together with (I) and opt. also the corresp. N,N'-disubstd. p-phenylenediamine and/or a specified volatile sterically-hindered phenol. R1 and R2 = phenyl gp., 3-8C alkyl and/or cyclohexyl; R3 = H or Me; R4 and R5 = 1-4C alkyl; and m = 0, 1 or 2. |