Shiichiro Teranishi

Aromatic substitution of olefins. VI. Arylation of olefins with palladium(II) acetate

Olefins react with benzene derivatives to produce aryl-substituted olefins uia direct substitution of the aromatic compound for hydrogen on the double bond of the olefin in the presence of palladium salts and reduced palladium metal. The reaction may be made catalytic with respect to the palladium salts by using cupric acetate or silver acetate, and air as reoxidants. The reaction provides an extremely convenient method for the synthesis of a wide variety of olefinic compounds. xtensive studies on reactions of olefins in the presE ence of transition metal compounds have been carried out. Much less is known about arylation of olefins with transition metal compounds. Most recently, Heck described interesting arylation reactions of olefins with arylating agents such as arylmercuric halides in the presence of group VI11 metal salts, and showed that palladium salts are the most generally useful, with rhodium and ruthenium salts next best. We have reported a novel method of synthesizing stilbene derivatives by substitution of aromatic compounds for hydrogen on the double bond of the styrenepalladium chloride ~ o m p l e x . ~ In the course of our work, palladium acetate was found to be the most effective for the direct arylation of olefins with aromatic compounds in the presence of acetic acid. The present paper reports a study of substitution reaction of olefins with benzene derivatives by means of palladium salts, especially palladium acetate. A preliminary communication of a portion of this work has been given.4 ( I ) On leave of absence from Ube Industries, Ltd., Ube, Japan. (2) (a) R. F. Heck, J . Amer. Chem. Soc., 90, 5518 (1968); (b) R .F. Heck, ibid., 90, 5526 (1968); (c) R. F. Heck, ibid., 90, 5531 (1968); (d) R. F. Heck, ibid., 90, 5535 (1968); (e) R. F. Heck, ibid., 90, 5542 (1968). (3) (a) I. Moritani and Y. Fujiwara, Tefrahedron L e f f . , 1119 (1967); (b) Y . Fujiwara, I. Moritani, and M. Matsuda, Tetrahedron, 24, 4819 (1968). (4) Y. Fujiwara, I. Moritani, M. Matsuda, and S . Teranishi, Tetrahedron Lett., 633 (1968). Results and Discussion In previous papers3 we described our initial work on the reactions of the styrene-palladium(I1) chloride complex with benzene derivatives to give stilbenes. It was noted that for this arylation on a P-carbon atom of styrene, the presence of a carboxylic acid such as acetic is essential because the reactants form a homogeneous solution and the reaction proceeds best in this solvent. Further, it was found that when sodium acetate was added, the yield was greatly increased. Palladium(I1) acetate has been found to be the most generally useful, with palladium(I1) chloride-sodium acetate next best for the direct arylation of olefins with benzene derivatives. The aromatic substitution of olefins takes place in homogeneous solutions of reactant olefin and palladium(I1) acetate (equal mole equivalents to olefin) in a solution of the aromatic compound (large excess) and acetic acid. The solution is stirred in the presence of air for a few minutes to several hours (8 hr usually), to give from 10% to ca. 90% yield of arylated products, with reduced metallic palladium and a very small amount of acetates. With unsymmetrical olefins, the aryl group generally adds predominantly to the less substituted carbon atom of the double bond because of steric hindrance of the substituents. This is consistent with that observed in the Heck arylation.2 Although cis and trans mixtures are formed, no mixtures resulting from arylation in both directions to unsymmetrical olefins have been found. Increasing substitution on the olefinic carbons decreases the reactivity of the olefin in the palladium acetate arylation reaction. For example, the reaction of triphenylethylene with benzene and a palladium acetate catalyst gave tetraphenylethylene in low yield (13 %),5 while styrene reacts with benzene to afford trans-stilbene in almost quantitative yield. Results are given in Table I. (5) Yields of arylation products given in this paper are based on the amount of palladium salt utilized. Journal of the American Chemical Soc ie t y J 91:25 December 3, 1969

Surface state and catalytic activity and selectivity of nickel catalysts in hydrogenation reactions: III. Electronic and catalytic properties of nickel catalysts

Abstract Various nickel catalysts (nickel-boride, nickel-phosphide, Raney-nickel, Urushibara-nickel, and decomposed-nickel) were investigated to examine the relationships between catalytic and electronic properties of nickel catalysts modified by component elements (boron, phosphorus, aluminum, and zinc) in the catalysts. Based on the X-ray photoelectron spectroscopic results, a parameter Δ q was tentatively proposed to characterize the electronic properties of the catalysts. The specific activity (activity per surface area of nickel metal) for hydrogenation reaction, the adsorption equilibrium constant of acetophenone, the resistivity against poisoning, and the characteristic selectivities in hydrogenation of 1,2-butylene oxide were found to be summarized in terms of the parameter Δ q . It is suggested that Δ q is a useful parameter to reflect the electronic properties of the nickel catalysts.

Surface structure of CoOMoO3Al2O3 catalysts studied by X-ray photoelectron spectroscopy

X-Ray photoelectron spectroscopic studies of oxidic and sulfided CoOue5f8MoO3Al2O3 catalysts revealed the chemical species, the surface structure of the catalysts, and the promoting effect of Co. It was found from the Mo(3d)Al(2s) and Co(2p)Al(2s) intensity ratios that the surface structure of the oxidic catalysts was highly sensitive to the preparation method. Bilayer structures are proposed for the catalysts prepared by sequential impregnations, while a separate phase structure is suggested to be plausible for the catalysts prepared by a simultaneous impregnation. On sulfidation the surface structure of the CoOue5f8MoO3Al2O3 catalysts was not essentially altered under atmospheric pressure, compared to that of the oxidic precursor catalysts, although Co and Mo were sulfided. The oxidic catalysts mainly consist of Co3O4 and pseudo-CoAl2O4, the fraction of Co3O4 increasing with Co content and depending on the preparation method. On the basis of the observation that both the extent of sintering and the sulfidation degree of Mo are depressed by Co, it is suggested that the stabilization effect of Co (most likely pseudo-CoAl2O4) for Mo monolayers is operative during hydrodesulfurizations, thus holding the Mo effective for the reactions.

Active states of rhodium in rhodium exchanged Y zeolite catalysts for hydrogenation of ethylene and acetylene and dimerization of ethylene studied with X-ray photoelectron spectroscopy

Abstract Rh-Y zeolite catalysts were investigated with X-ray photoelectron spectroscopy (XPS) techniques. It was found, for the first time, that Rh (I) was formed in Rh-Y zeolites as a significantly stable intermediate during the reduction of Rh(III) to Rh metal by heat treatment in vacuum. It was revealed that Rh(I) in Rh-Y zeolites was active for the hydrogenation and the dimerization of ethylene, whereas Rh metal was active for the hydrogenation of both ethylene and acetylene. Strong correlations were established between homogeneous Rh complex catalysts and Rh-Y catalysts both in the active oxidation states of Rh and the effect of additives on the reactions. Furthermore, XPS was successfully applied to define not only the chemical nature but also the structure of Rh in zeolites. The structure of Rh in Rh-Y zeolite was suggested to correlate strongly with the chemical nature of Rh.

A coordinatively unsaturated, polymer-bound palladium(0) complex. Synthesis and catalytic activities

Abstract A coordinatively unsaturated palladium(0) complex was prepared by the reduction of a polymer-bound palladium(II) chloride complex, which was prepared by the reaction of poly-4-diphenylphosphinomethylstyrene with palladium chloride, with hydrazine in ethanol in the presence of triphenylphosphine. Catalytic activities of the polymerbound palladium(0) complex were examined for three representative types of palladium(0)-induced reactions involving oxidative addition of halides to the metal: (i) vinylic hydrogen substitutions with aryl halides, (ii) acetylenic hydrogen substitutions with aryl halides, (iii) vinylic halogen substitutions with Grignard reagents. Use of the catalyst resulted in formation of corresponding products in good yields. The catalytic activity is comparable to that of analogous homogeneous catalysts, yet is not remarkably lowered on being recycled.

Stabilization effect of Co for Mo phase in CoMoAl2O3 hydrodesulfurization catalysts studied with X-Ray photoelectron spectroscopy

Abstract The promotional effects of Co in Coue5f8Mo Al 2 O 3 hydrodesulfurization (HDS) catalysts were studied by means of X-ray photoelectron spectroscopy. The higher MoO 3 -content Mo Al 2 O 3 catalysts (10 and 20 wt% MoO 3 ) contain mobile Mo, which migrates from the pores to the outermost surface layers of the catalysts and segregates to form less active crystalline MoS 2 during the HDS reaction, while in the case of Mo Al 2 O 3 (5 wt% MoO 3 ) catalyst: no migration of Mo was observed. It is revealed that the Co in Coue5f8Mo Al 2 O 3 catalyst inhibits the migration and segregation of Mo and that it keeps Mo effective for the HDS reaction, since no surface enrichment of Mo was observed. It is concluded that stabilization of the Mo monomolecular layer is the main role of Co. The active species of Mo is suggested to have the composition of S/Mo(IV) = 1 on the basis of the sulfur contents of the catalysts under the mild HDS reaction conditions.

Effect of preparation variables on enantioselectivity of supported nickel catalysts modified with tartaric acid

Abstract Enantioselective hydrogenation of methyl acetoacetate to methyl 3-hydroxybutyrate on various supported nickel catalysts modified with ( R,R )-tartaric acid was studied under mild reaction conditions in order to examine the effects of preparation variables on the enantioselectivity and activity of resulting catalysts. The selectivity of the supported nickel catalysts was strongly dependent on the precipitation conditions. The effect of reduction conditions on the selectivity depended on the kind of support. Even Ni-alumina catalysts, when reduced under relatively mild conditions, had high enantioselectivity although their hydrogenation activity was low. Ni-silica catalysts, precipitated under optimum conditions and reduced at 400–500 °C for 1–3 h, were much more active than the other catalysts with similar, high enantioselectivity. Various extents of the selectivity of supported nickel catalysts were explained in terms of the effect of preparation conditions on the crystallite size distributions of nickel.

Preparation chemistry of precipitated NiSiO2 catalysts for enantioselective hydrogenation

Abstract Effects of preparation conditions on chemical composition and reducibility of precipitated precursors of Niue5f8SiO 2 catalysts were studied using thermal gravimetric analysis. The proportion of NiCO 3 in the precursor decreased as the preparation conditions became severe and the reducibility of the precursor decreased with a decrease in the NiCO 3 content, suggesting stronger metal-support interaction of SiO 2 with Ni(OH) 2 than with NiCO 3 . The X-ray diffraction measurements showed that the mean crystallite size of nickel in H 2 -reduced catalysts increased with increasing NiCO 3 content in the precursor. The activity and selectivity of the modified catalysts in enantioselective hydrogenation of methyl acetoacetate depended on the proportion of NiCO 3 in the precursor and were explained in terms of crystallite size distribution of nickel in the catalysts.

Surface state and catalytic activity and selectivity of nickel catalysts in hydrogenation reactions: IV. Electronic effects on the selectivity in the hydrogenation of 1,3-butadiene

Abstract The hydrogenation of 1,3-butadiene was carried out over various unsupported Ni catalysts: nickel-boride, Raney-nickel, decomposed-nickel, nickel-phosphide, and nickel treated with H2S. It was found that the butene distributions characteristic of the catalysts were explainable in terms of the electron density of Ni metal and the reaction mechanism proposed by Wells and co-workers. It is suggested that there are critical electron densities of Ni metal at which catalytic properties change significantly.

Highly selective oxidation of secondary hydroxyl functions using the VO(acac)2-tBuOOH SYSTEM

Abstract The VO(acac) 2 - t BuOOH system shows high oxidation reactivity for secondary alcohols to give ketones.