Acetic acid, transition metal complexes

Because of the high nucleophilicity and reactivity of diazoalkanes, catalytic decomposition occurs readily, not only with a wide range of transition metal complexes but also with Brpnsted or Lewis acids. Well-established catalysts for diazodecomposition include zinc halides [638,639], palladium(II) acetate [640-642], rhodium(II) carboxylates [626,643] and copper(I) triflate [636]. Copper(II)... 

In homogeneous catalytic systems we witnessed a new process for the production of acetic acid from methanol and carbon monoxide using a transition metal complex, thus displacing the earlier process employing ethylene as the starting material. The use of immobilized enzymes makes possible the commercial conversion of glucose into fructose. 

Trost exploited the annulation of electron rich phenols and alkynoates to obtain coumarins in the presence of transition metal complexes. Ethyl propiolate and 3,4,5-trimethoxyphenol were coupled in formic acid in the presence of a palladium complex and sodium acetate to give 5,6,7-trimethoxycoumarin via a net C-H insertion in acceptable yield (4.42.). The coupling, characteristic of electron rich phenols, was also catalyzed by other transition metals, such as platinum or silver.56... 

The choice of metal halides, especially those of Groups III-V, in the syntheses of molecular complexes is related with their high Lewis acidity and so their capacity to form stable adducts (Sec. 1.2.1). However, this does not mean that molecular complexes cannot be obtained on the basis of weaker Lewis acids, for instance nitrates or acetates of transition metals. 

Liquid phase oxidation of hydrocarbons by molecular oxygen forms the basis for a wide variety of petrochemical processes,3 "16 including the manufacture of phenol and acetone from cumene, adipic acid from cyclohexane, terephthalic acid from p-xylene, acetaldehyde and vinyl acetate from ethylene, propylene oxide from propylene, and many others. The majority of these processes employ catalysis by transition metal complexes to attain maximum selectivity and efficiency. 

On the scene of industrial chemistry, too, many sizable advances have occurred. Among them are processes for production of vinyl acetate from ethyl-ene/02/acetic acid over a heterogeneous Pd-catalyst the manufacture of acetic acid by carbonylation of methanol using a transition metal complex homoge-... 

Carbonylation of methanol catalyzed by soluble Group IX transition metal complexes remains the dominant method for the commercial production of acetic acid. The Monsanto process stands as one of the major success stories of homogeneous catalysis, and for three decades it was the preferred technology because of the excellent activity and selectivity of the catalyst. It has been demonstrated by workers at Celanese, however, that addition of iodide salts can significantly benefit the process by improving the catalytic reaction rate and catalyst stability at low water concentrations. Many attempts have been made to enhance the activity of... 

The reaction of transition-metal complexes and strained carbocycles has been examined most extensively with Pt(II) complexes and cyclopropane derivatives. Chloroplatinic acid and cyclopropane react in acetic anhydride at RT to give a stable, polymeric compound, [PtCl2(C3H6)]4(I), in 50-70% yield ... 

Gagn6 et al. developed polymer active sites that additionally contained a receptor (recognition sites) displayed in the outer sphere of the metal center (reactive site). The Suzuki reaction of /)-bromoanisole with phenyl boronic acid and the allylation of dimethyl malonate with allyl acetate were both chosen to assess the presence and/or effect of the crown-ether in crown-ether-molecular imprinting polymer-palladium complex. The results showed that molecular imprinting can be used to functionalize the second-coordination sphere of a transition metal complex and subsequently affect its catalytic behavior. 

C-H o-bond activation of hydrocarbons by transition metal complexes is of considerable importance in modern organometallic chemistry and catalytic chemistry by transition-metal complexes [1], because a functional group can be introduced into alkanes and aromatic compounds through C-H o-bond activation. For instance, Fujiwara and Moritani previously reported synthesis of styrene derivatives from benzene and alkene via C-H o-bond activation of benzene by palladium(ll) acetate [2]. Recently, Periana and his collaborators succeeded to activate the C-H o-bond of methane by the platinum(ll) complex in sulfuric acid to synthesize methanol [3], Both are good examples of the reaction including the C-H o-bond activation. 

Examples in which the cation of the ionic liquid contains the transition metal complex for catalysis have also been published. For example, Forbes and coworkers [63] synthesized a Rh-containing ionic liquid cation by replacing an acetate ligand at the Rh center by a carboxyhc acid functionalized imidazolium moiety. The modified dirhodium(ii) dimer of this kind was applied as an effective catalyst in the intermolecular cydopropanation reaction of styrene using ethyl diazoacetate. 

The carbonylation of methanol to give acetic acid is catalyzed by Group Vni transition metal complexes, especially rhodium, cobalt, and nickel ... 

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