Nickel complexes acetophenone

Prior preparation of the phenyl nickel complex (XXXV) is not necessary the desired product may be obtained by simply stirring bromo-benzene (XXXIII) (or iodobenzene), tetrakis(triphenylphosphine)nickel(0) (XXXIV), and the sodium salt of acetophenone at — 78°. From a consideration of the scheme, a catalytic effect by the nickel may be expected. Although this effect does exist, it has a poor efficiency thus, starting from 0.14 molar equivalents of the nickel complex (XXXV), a 250% yield of the phenylbenzyl ketone (XXXVII) may be obtained based on the nickel catalyst. 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

Aromatic ketones are often hydrogenated with the aim to prepare the corresponding aromatic alcohols - Acetophenone was chosen here as a reasonably complex molecule to effect a modelization of this family of catalytic hydrogenations. Previous papers have proved that Raney nickel is an effective catalyst in this type of reaction (refs. 1-4).Acetophenone is principally hydrogenated to 1-phenylethanol which is a very valuaole product of the perfumery industry. 

Catalytic activities of several platinum, palladium, nickel as well as rhodium complexes in hydrosilylation of acetophenone were briefly examined by using methyldichlorosilane, and the platinum(II) complex, [(PhMe2P)PtCl2]2 was found to be the most effective for this particular hydrosilane. Chlorotris(triphenylphos-phine)rhodium(I) (7) has no catalytic activity at all in sharp contrast to the case in which the hydrosilylation is carried out by using alkylhydrosilanes, R SiH4 ( = 1, 2 or 3), as described in the previous Section. 

The Suzuki coupling of 4-bromo-acetophenone with phenylboronic acid was achieved using Nil2(tmiy)2 with 19 to 58% aryl halide conversion and TONs of 630 to 1930. Amination of aryl chlorides was accomplished by using a nickel hydroimidazoline carbene complex (Equation (27)). ... 

Another example of asymmetric reduction of a polyketone was given by Schulz [185] who reported the quantitative reduction of polyvinyl-p-acetophenone by AlLiH4//-quinine complexes. The optical yield is very poor and was evaluated as 9%. Asymmetric hydro-genetion of ketone [186] or imino groups [187] was described by Plateh etal. The catalyst used was Raney nickel modified by /-glutamic or tartaric acid or by a macromolecular substrate (e.g. OA polyhydroxyesters). (More details are given by Dr Luisi in his chapter). The studied polymers were [186, 187] ... 

---