Selectivity, hydrogenation over

Crosman, A. and Holderich, W. F. Selective hydrogenation over immobilized rhodium diphosphine complexes on aluminated SBA-15, J. Catal., 2005, 232, 43-50. 

Resorcinol as mono sodium salt is selectively hydrogenated over Ni-kieselguhr to the sodium salt of dihydroresorcinol, which on acidification gives cyclohexane-1,3-dione in high yield (eq. 11.27).141,142 The same selective hydrogenation [10 g (0.091... 

Unsaturated nitriles are converted smoothly to the saturated compounds by selective hydrogenation over palladinized charcoal or by chemical reduction. " The reaction is of special value in the preparation of a variety of substituted cyano compounds from the olefinic nitriles obtained in cyanoacetic ester condensations (method 387). 

Nishiyama N, Ichioka K, Park DH, Egashira Y, Ueyama K, Gora L, Zhu WD, Kapteijn F, and Moulijn JA. Reactant-selective hydrogenation over composite silicaUte-l-coated Pt/Xi02 particles. IndEng Chem Res 2004 43(5) 1211-1215. 

The possibility of performing enantio-selective hydrogenation over heterogenous catalysts is based on the fact that a chiral additive can govern the way a... 

The type 1 and type 2 trisaccharide derivatives 265 and 264 were each converted into the free azido carboxylic acid in quantitative yields by selective hydrogenation over 5% palladium-on-carbon in ethyl acetate. Zemplen saponification gave the trisaccharide derivatives 268 and 269 (91 and 85%, respectively). Transfer of fucose from GDP-fucose, catalyzed by human milk -3/4- fucosyltransferases, to the type 1 and type 2 acceptors 268 (Scheme 44) and 269 (Scheme 45) proceeded at rates comparable to those of the natural substrates and afforded tetrasaccharides 270 and 274 in quantitative yields. From the azido tetrasaccliarides 270... 

Selective Hydrogenation over Supported Metal Catalysts... 

Unsaturated acids and esters including fatty acids derivatives are also selectively hydrogenated over homogeneous catalysts , e.g., Ir(CO)Cl(PPh3)2 catalyzes the hydrogenation of styrene, ethylacrylate at 10 Pa and 80-120°C . ... 

The y, 5-double bond of a conjugated keto-diene may be selectively hydrogenated over catalysts, offering useful synthetic applications. Hydrogenation of dienone 16 affords 17 as an intermediate in the total synthesis of steroids. The disubstituted double bond is reduced more readily than the tetrasubstituted double bond in a nonpolar solvent to prevent participation of the carbonyl groups ... 

Preferential reduction of an a,)3-unsaturated ketones C=C bond is more easily accomplished than preferential reduction of the C=0 bond. However, a keto group can be hydrogenated in preference to a C=C bond after the appropriate choice of the catalyst, usually Pt or Ru . Additives such as FeCl2 (a carbonyl reduction promoter) and zinc acetate (a double bond saturation inhibitor) may be used in conjunction with platinum oxide . The less hindered ketone in 6 is selectively hydrogenated over Pt02 [equation... 

P Kluson, J Had Z Belholav L Cerveny. Selective hydrogenation over ruthenium catalysts prepared by sol-gel method. Appl Catal A 149 331 -339,1997. 

The selective hydrogenation of alkynes to alkenes has an industrial application in the hydrogenation of low concentrations of alkynes and dialkenes in alkene streams obtained from the steam cracking of petroleum fractions. The impurities are selectively hydrogenated over a Pd catalyst to produce pure alkenes. 

Firstly, we have the acetone aldol self-condensation reaction over basic sites to give diacetone alcohol (DAA). Dehydration of this alcohol yeilds mesityl oxide (MSO) winch, in turn, can be selectively hydrogenated over reduced metal sites to finally give methyl isobutyl ketone (MIBK). In addition to the aldol condensation route, the acetone carbonyl functional group can also be directly hydrogenated over reduced metal sites yielding 2-propanol. Other reaction by-products such as methane, propane, diisopropyl ether and diisobutyl ketone have been detected in some experiments, but in very low amounts, lower than 2% of the total reaction products. 

Though conceptually simple, photochemical E to Z isomerization of double bonds is not an efficient approach for accessing geometrically pure alkenylboronic esters [253, 258]. Alkynylboronic esters, however, can be selectively hydrogenated over Lindlar s catalyst [276]. 1,4-Dioxane was found to be the optimal solvent for providing (Z)-l-... 

The shortest synthesis of (5Z,9Z)-indolizidine 223AB (1566) was reported in 2007 by Ma and coworkers (Scheme 223, first two lines) In this approach the copper(I) complex of the chiral bis(oxazoline) ligand 1772 catalyzed the enantioselective addition of hept-l-yn-3-one to the N-acylpyridinium salt 1773, producing the (2S)-dihydropyridine adduct (+)-1774 in 70% yield and an ee of 91%. Selective hydrogenation over... 

Nishiyama, N., Ichioka, K., Park, D.-H. et al. (2004) Reactant selective hydrogenation over composite silicalite-l-coated Pt/TiO particles. Industrial and Engineering Chemistry Research, 43, 1211-1215. 

Furlong B, Hightower JW, Chan TY-L, Sarkany A, Guczi L. 1,3-Butadiene selective hydrogenation over Pd/alumina and CuPd/alumina catalysts. Appl Catal A Gen. 1994 117 41. 

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