Aromatization catalyst

Formic acid is a good reducing agent in the presence of Pd on carbon as a catalyst. Aromatic nitro compounds are reduced to aniline with formic acid[100]. Selective reduction of one nitro group in 2,4-dinitrotoluene (112) with triethylammonium formate is possible[101]. o-Nitroacetophenone (113) is first reduced to o-aminoacetophenone, then to o-ethylaniline when an excess of formate is used[102]. Ammonium and potassium formate are also used for the reduction of aliphatic and aromatic nitro compounds. Pd on carbon is a good catalyst[103,104]. NaBH4 is also used for the Pd-catalyzed reduction of nitro compounds 105]. However, the ,/)-unsaturated nitroalkene 114 is partially reduced to the oxime 115 with ammonium formate[106]... 

With palladium catalysts aromatic chlorides are rather unreactive, however, nickel is able to catalyze the reactions of these substrates, too. The water-soluble catalyst was generated in situ from the easily available [NiCl2(DPPE)] and an excess of TPPTS by reduction with Zn in mixtures of 1,4-dioxane and water. Although it had to be used in relatively large quantities (10 mol %), the resulting compound catalysed the cross-coupling... 

The ene reaction is strongly catalyzed by Lewis acids such as aluminum chloride and diethylaluminum chloride204 Coordination by the aluminum at the carbonyl group increases the electrophihcity of the conjugated system and allows reaction to occur below room temperature, as illustrated in Entry 6. Intramolecular ene reactions can be carried out under either thermal (Entry 3) or catalyzed (Entry 7) conditions 205 Formaldehyde in acidic solution can form allylic alcohols, as in entry 1. Other carbonyl ene reactions are carried out with Lewis acid catalysts. Aromatic aldehydes and acrolein undergo the ene reaction with activated alkenes such as enol ethers in the presence of Yb(fod)3 206 Sc(03SCF3)3 has also been used to catalyze ene reactions.207... 

Additional evidence to this scheme was reported applying temporal analysis of products. This technique allows the direct determination of the reaction mechanism over each catalyst. Aromatization of n-hexane was studied on Pt, Pt—Re, and Pd catalysts on various nonacidic supports, and a monofunctional aromatization pathway was established.312 Specifically, linear hydrocarbons undergo rapid dehydrogenation to unsaturated species, that is, alkenes and dienes, which is then followed by a slow 1,6-cyclization step. Cyclohexane was excluded as possible intermediate in the dehydrocyclization network. 

The aldol-type reaction of a cyclic enol ester, 5-methyl-2(3//)-furanone (4b), was carried out with three kinds of catalytic systems PdCl2 (PhCN)2-SnCl2, Ni(Cod)2/Ph3P-Zn, and Pd(OAc)2/PPh3-Zn. In the presence of the first catalyst, aromatic aldehydes condense with 4b to give ds-)3-acetyl-y-aryl-y-butyrolactones (47), but alkanals are mainly con-... 

Keywords Asymmetric hydrosilylation, optically active alcohols, amines, Chiral Titanocene Catalysts, Acyclic Imines, Cyclic Imines, Chiral Rhodium Catalysts, aromatic ketones... 

These tests indicate that, with the aluminum-silicate-supported catalyst, aromatics can be split with less ring hydrogenation than observed... 

Alcohol and aldehyde decarbonylation on Rh(l 11), activation of C-H, C-C, and C-0 bonds, 345-353 Alkane dehydroeyelization with Pt-Sn-alumina catalysts aromatic formation, 120 preparation condition effect, 119... 

Over nickel catalysts, aromatic carboxylic acids can be hydrogenated without difficulty as their sodium salts. Thus, e>-179 and m-toluic acids,180 m-hydroxybenzoic acid,181 and tetrephthalic acid182 were hydrogenated to the corresponding saturated acids in high yields over Raney Ni at elevated temperatures and pressures. Examples are shown in eqs. 11.47 and 11.48. o-Toluic acid and terephthalic acid afforded the trans acids predominantly under these conditions. 

Marder reported that the alkyl C-H bonds in benzylic compounds are selectively borylated with a rhodium catalyst. Aromatic borylation prodncts were only observed as minor by-products. Similar results were obtained by Miyaura with Pd/C (equation 28). ... 

The fat or oil can be hydrolyzed into fatty acids and glycerol by treatment with steam under elevated pressure and temperature. The reaction is reversible and is catalyzed by inorganic catalysts (ZnO, MgO, or CaO) and an acid catalyst (aromatic sulfonic acid). 

In the third procedure, due to Burgstahler et al., ° the basic additive is 2,6-dimethylpyridine. For aliphatic acyl chlorides, THF is used as solvent and 10% palladium on carbon or 5% Pd-BaS04 as catalyst. Aromatic acyl chlorides require benzene as solvent, 10% palladium on carbon/quinoline-S as catalyst and a raised temperature. 

Direct catalytic oxidative carbonylation to form acid anhydrides was achieved with arylmercuiy acetate. Palladium(II) salts are taken as catalysts. Aromatic compounds such as benzene, toluene, anisole, furan, thiophene and naphthalene can be converted catalytically with palladium(II) acetate and an excess of 1,2-dibromoethane to acid anhydrides in yields of 30- %. 

Evidence for the presence of organic cations was provided by bright red or purple colors observed immediately upon addition of the carbonyl compounds to the catalyst-aromatic mixtures, and by isolation of side products derived from hydride shifts to intermediate carbonium ions. Mechanistically, these reactions are visualized as proceeding by initial Bideal-like attack of aromatic on the adsorbed conjugate acid derived from the carbonyl compound, with the formation of an intermediate tert-benzylic carbinol ... 

In the presence of excess acetyl halide and a tin(II) catalyst aromatic acetals react with allyltrimethylsilane to give a-allylbenzyl halides in good yield by double substitution of the acetal alkoxy groups (Scheme 10.127) [365]. The indium-catalyzed tandem reaction using a hydrosilane-allylsilane system enables deoxygenative allylation of aromatic ketones [366]. 

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