Ferrocene catalyst

Highly enantioselective hydrosilylation of aliphatic and aromatic carbonyl compounds such as acetophenone, methyl phenethyl ketone 1813, or deuterobenz-aldehyde 1815 can be readily achieved with stericaUy hindered silanes such as o-tolyl2SiH2 or phenyl mesityl silane 1810 in the presence of the rhodium-ferrocene catalyst 1811 to give alcohols such as 1812, 1814, and 1816 in high chemical and optical yield [47] (Scheme 12.14). More recently, hydrosilylations of aldehydes... 

The yield for the chromium complex was lower, but the enantioselectivity was higher than for the corresponding ferrocene catalyst. 

The chiral vinylferrocene monomer 18 and the chiral copolymers 19a — e have been prepared for the first time. Insolubilization of the chiral ferrocene catalyst lowered the enantioselectivity to some extent compared with that of the soluble monomeric catalysts. Nevertheless, polymers 19a —e are usefull for the enantiose-lective synthesis of secondary alcohols. 

The reported procedure allows the transfer of aryl moieties to aromatic aldehydes affording diaryl methanols with excellent enantiomeric excesses in high yields (Table 8.2). It relys on the use of a readily available ferrocene catalyst and... 

Dibutyltin bisisooctyl thioglycolate catalyst, rocket propellants Ferrocene catalyst, rubber... 

A highly regiospecific (usually >98 2) S 2 reaction between a -trifluoromethylallyl acetates and secondary amines occurs in the presence of a Pd(OAc)2/DPPE (l,2-bis(diphenylphosphino)ethane) or a [Pd( r-allyl)(cod)]BF4/DPPF (l,l -bis (diphenylphosphino)ferrocene) catalyst, resulting in moderate to good yields. Yields are reduced markedly when sterically hindered amines are used, but the yield can be increased by changing the leaving group from acetate to f-butyl carbonate. The 5 2 product isomerizes to the 5 2 product when the [Pd( r-allyl)(cod)]BF4/DPPF catalyst is used. 

Recently, we have discovered [8], for the first time, that ferrocene (catalyst 1.1) is an efficient (pre)catalyst for several types of oxidative transformations, namely, the oxidation of alkanes and benzene by H2O2 or tert-butyl hydroperoxide. The oxidation of gaseous and liquid alkanes to alkyl hydroperoxides by H2O2 proceeds in MeCN at 50 °C. An obligatory cocatalyst is pyrazine-2-carboxylic acid (PCA, or Hpca, where H is a proton and pea is the anion of PCA). In the cyclohexane oxidation, the yield and TON after 1.5 h attained 32% and 1200, respectively. In the ethane oxidation, TON reached 970. Maximum yield (58% based on the alkane) was obtained for the n-butane oxidation after 4 h. 

In 2001, Fu s group [128] reported the application of Pd-triarylphosphane-ferrocene catalysts for the Suzuki-Miyaura reaction on aryl chloride substrates (Figure 1.40a). Activated aryl chlorides could be coupled at room temperature, while unactivated aryl chlorides, including sterically hindered and electron-rich substrates, at 70 °C. The triarylphosphane - which is air stable - was mixed with either Pd2(dba)j or Pd(OAc)2 with KjPO -HjO as base in toluene at room temperature, and very good yields were obtained. 

The preparation and structure determination of ferrocene marked the beginning of metallocene chemistry Metallocenes are organometallic compounds that bear cyclo pentadiemde ligands A large number are known even some m which uranium is the metal Metallocenes are not only stucturally interesting but many of them have useful applications as catalysts for industrial processes Zirconium based metallocenes for example are the most widely used catalysts for Ziegler-Natta polymerization of alkenes We 11 have more to say about them m Section 14 15... 

VGCFs have typical diameters of 100 nm - 100 pm with hollow cores [9]. Thus VGCFs are 10 - lO times thicker than CNTs. A preparation method for VGCFs was first developed by Endo [10,11] wbo decomposed benzene at 1150-1.300°C in an electric furnace in the presence of H2 (99.9% pure) as the carrier gas (see Fig. 1). Ultra-fine particles of Fe (ca. 10 nm diameter) or its compounds, such as Fe(N03)3 or ferrocene, were introduced into the chamber as a catalyst. 

Singer and co-workers have investigated the acylation reactions of ferrocene in ionic liquids made from mixtures of [EMIMJI and aluminium(III) chloride (Scheme 6.1-5) [9, 10]. The ionic liquid acts both as solvent and as source of the Friedel-Crafts catalyst. In mildly acidic (X(A1C13) > 0.5 [EMIM]I/A1C13, the monoacetylated ferrocene was obtained as the major product. In strongly acidic [EMIM]I/AlCl3 X(A1C13) = 0.67 the diacylated ferrocene was the major product. Also, when R = alkyl, the diacetylated product was usually the major product, but for R = Ph, the monoacetylated product was favored. 

The crude product from the above reaction mixt was fractionated into a distilled product (bp 200°/0.3 Torr) with an average molecular weight of 514 and a residue with an average molecular weight of 940. These were evaluated as catalysts and compared to prior art ferrocenes in a standard carboxy-terminated polybutadiene formula cured with MAPO. The results are shown in Table 31... 

Sayles (Ref 67) combined n-butylferrocene with l-(2,3-epoxyaliphatic) carboianes of at least 3 carbonations in the aliphatic chain to function both as burning rate catalysts and cross-linking agents for carboxylated polybutadiene and acrylate binders. The use of 1,2-bis(2,3-epoxy-piopyl) carborane and 1-(2,3-epoxypropyl) car-borane boosted the burning rate of a butyl-ferrocene propint from 1.2 to 1.9 inches/sec as the data in Table 32 indicates... 

The biradical catalysts described previously for double-base propints (Ref 80) are also effective for hydrocarbon propints. Table 34 shows how p,p,-biphenylene-bis(diphenylmethyl) compares to n butyl ferrocene as a catalyst in a carboxy-terminated polybutadiene. These catalysts are claimed to overcome all of the processing difficulties, chemical stability and volatility disadvantages attributed to catalysts based on ferrocene and carborane derivatives. Another somewhat similar functioning catalyst, the free radical compd, 2,2-diphenylpicrylhydrazyl,... 

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