Hydrogenolysis selective

This behavior depended on the surface atomic M/Cu ratio and resulted from an electron transfer from Cu to the second metal. Bimetallic Cu-Pt and Cu-Au nanoparticles prepared in the same way but on a charcoal support 

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Tetrafluoropyrimidine was converted to the antiaeoplastic 5-fluorouracil (5-FU) by a novel process based on the sequence partial exchange chlorination (61% yield), selective hydrogenolysis ia triethylamine (71% yield) and hydrolysis (85—93% yield) (464). 

By reversibly blocking position 3 with a diphenylmethyl group (72, 73), Prystas and Sorm also prepared 6-azauridine. The diphenylmethyl group was removed after ribosidization (74) by selective hydrogenolysis. The crystalline 6-azauridine obtained was identical with 6-azauridine prepared enzymatically. ... 

Process development for the selective hydrogenolysis of CCI2F2 (CFC-12) into CH2F2 (HFC-32)... 

Selective Hydrogenolysis of Esters and Acids to Aldehydes and Alcohols... 

Several supported metalhc catalysts were evalrrated for the selective hydrogenolysis of glycerol. Initially, the reactions were performed tmder acidic conditions in order to promote the formation of 1,3-PDO. Rutheniirm-based catalysts were found to be the most active catalysts but significant amount of tmdesired products resulted from C-C cleavages were detected. On the contrary, Rh/C catalysts were found selective to C-O cleavages. As far as the selectivity to 1,3-PDO was concerned, we previously reported that the addition of iron salts in the medium improved the l,3-PDO/l,2-PDO selectivity (11). A systematic study on the influence of additives was therefore carried out in the present investigation. Mineral and organic acids were evaluated for this purpose (Table 35.1). 

It was envisioned that selective hydrogenolysis of the cyclopropane ring in polycyclopropanone could produce polyacetone as shown in Equation 4. There is precedent for the selective cyclopropane ringopening of the least substituted cyclopropane carbon-carbon bonds... 

Selective hydrogenolysis of the benzyl ether group was performed in the presence of an N-Boc protecting group. In this case, 10 Pd/C (0.45 mol/mol) and HC02NH4 (6.5 mol/mol) was warmed at reflux in acetone for 30 minutes (Scheme 4.55).258... 

Desulfoxidation was achieved using Ra-Ni in ether. This was followed by selective hydrogenolysis of the benzyl group on W2 Ra-Ni under a hydrogen atmosphere in EtOH.420-422 Desulfoxidation had to be performed in ether use of ethanol as the solvent in desulfoxidation led to cleavage of a C-7-C-8 bond (Scheme 4.123). 

During hydrogenation of vinylic chlorides, both saturation of the double bond and hydrogenolysis of the C-Cl bond take place.433 35 Also, selective hydrogenolysis of chlorine occurs in the presence of fluorine atoms on a Pd/C catalyst (Scheme 4.125).436... 

The possibility of a controlled degradation of polystyrene in copolymer [ethylene styrene] has been examined by selective hydrogenolysis of appended groups, minimizing the cleavage of the main chain [62]. 

Hydrogenolysis of esters to aldehydes or alcohols is difficult to attain either by homogeneous or heterogeneous catalysis. In fact, high temperatures and high pressures are required to achieve the reaction, leading to a non-selective hydrogenolysis with formation of acids, alcohols, CO2, CO and hydrocarbons. 

Selective hydrogenolysis of bromodeoxylactones can also be achieved by catalytic reduction in the presence of an acid acceptor (triethylamine). Thus, reaction of 2,6-dibromo-2,6-dideoxy-D-mannonolactone (2) (Scheme 2) under... 

Selective Hydrogenolysis of Sugar Alcohols over Structured Catcdysts... 

A unique information with respect to the use Pd on HZSM-5 in a selective hydrogenolysis has been disclosed.501 The transformation of methylcyclohexane to n-alkanes with two or more carbon atoms is a useful transformation since these products are desirable components in synthetic steam-cracker feedstock. It was shown that these compounds are not obtained on catalysts with high (0.2 or 1%) Pd loading or without Pd. But on Pd on H-ZSM-5, with Pd content in the range of 10-100 ppm, the desired products are formed with high ( 78%) selectivity. 

Benzoic Acid (14), Selective Hydrogenolysis of 4-Fluorobenzoic Acid with Raney Nickel Typical Procedure 117... 

This conversion of a 1,2-diol to an epoxide has been used as an approach to 2-arylpropanoic acids, members of the nonsteroidal antiinflammatory drugs (NSAIDS) family of drugs.163 However, the sequence can be shortened by a selective hydrogenolysis, as illustrated for naproxen (20) (Scheme 9.24).164... 

In contrast, selective hydrogenolysis of glycerol to 1,3-propanediol by means of chemo catalysis is still a challenging task. Although several attempts do exist with, for example, Pt/W03/Zr02 or Ir-ReOx/Si02 catalysts [48, 49], the enzyme-catalyzed route using bacterial strains is more efficient [42] and has been commercialized (see Table 2.2.1). 

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