Catalytic Hydrogenation with Amorphous and Crystalline Pd8 0Si2 0

1981 ◽  
Vol 8 ◽  
Author(s):  
Bill C. Giessen ◽  
Sabri S. Mahmoud ◽  
David A. Forsyth ◽  
Markus Hediger
Keyword(s):  
Double Bond ◽  
Catalytic Hydrogenation ◽  
Metallic Glasses ◽  
Hydrogen Deuterium Exchange ◽  
Reaction Conditions ◽  
Crystalline Phases ◽  
Hydrogenation Catalysts ◽  
Double Bond Migration ◽  
Hydrogenation Reactions ◽  
Hydrogen Deuterium

ABSTRACTSeveral metallic glasses in the form of ribbons were screened for activity as hydrogenation catalysts. Pd80Si20 and (Ni50Fe50)80B20 showed activity in reducing cyclohexene. Pd 80 Si20 was further examined for differences between the glassy and crystalline phases in the selectivity shown during hydrogenation reactions of n-hexenes, phenylethyne, α-pinene, and cyclododecene. No significant differences were found for catalytic selectivity in regard to cis-trans isomerization, double bond migration, and stereochemistry of addition under the reaction conditions used. Minor differences were observed in hydrogen-deuterium exchange.

scholarly journals Double Bond Migration and Dehydrogenation of Squalene on Hydrogenation Catalysts.

1956 ◽  
Vol 10 ◽  
pp. 439-444 ◽  
Author(s):  
Johannes Dale ◽  
Torstein Årtun ◽  
H. I. Waterman ◽  
N. A. Eliasson ◽  
B. Thorell
Keyword(s):  
Double Bond ◽  
Hydrogenation Catalysts ◽  
Double Bond Migration

scholarly journals The catalytic isomerization of buten-1

1941 ◽  
Vol 178 (972) ◽  
pp. 106-117 ◽  
Keyword(s):  
Double Bond ◽  
Hydrogen Pressure ◽  
Square Root ◽  
Double Bond Migration ◽  
Rate Determining Step ◽  
Catalytic Isomerization ◽  
Rate Of Reaction ◽  
Hydrogenation Reactions ◽  
Kinetics Of ◽  
Catalytic Exchange

It has been shown that butene-1 undergoes isomerization to butene-2 on a nickel catalyst in the presence of hydrogen. B y using deuterium, this double-bond migration has been examined simultaneously with the exchange and hydrogenation reactions. The kinetics of double-bond migration and hydrogenation at 65° C were found to be identical, the rate of reaction in both cases being proportional to the square root of the butene pressure and to the square root of the hydrogen pressure. Energies of activation for the three reactions were measured over the temperature range 76-126° C and the following values found: Exchange 9.0 kcal. Hydrogenation 2.5 ,, Double-bond migration 5.9 ,, At the lowest temperatures, the rate of double-bond migration was about six times that of exchange. These facts are in agreement with the theory that the catalytic exchange between olefines and deuterium takes place through the formation of an associative complex. The rate-determining step in the double-bond migration is the second, fast step of the exchange reaction, viz.

Sweet Poisons: Synthetic Strategies towards Tutin Glycosides

2017 ◽  
Vol 70 (3) ◽  
pp. 301 ◽  
Author(s):  
Duong Nhu ◽  
Lesley Larsen ◽  
Nigel B. Perry ◽  
David S. Larsen ◽  
Bill C. Hawkins
Keyword(s):  
Double Bond ◽  
Major Product ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Reaction Conditions ◽  
Double Bond Migration ◽  
Epoxide Opening ◽  
Glycosylation Reaction ◽  
Cationic Palladium

The polycyclic, polyoxygenated picrotoxane tutin was subjected to various glycosylation reaction conditions in an effort to synthesise β-linked tutin glycosides, recently found in toxic honeys. Cationic palladium-mediated glycosylation of tutin was successful; however, the α-linked tutin tetrabenzyl glucoside was obtained as the major product (5 : 1, α : β). Hydrogenolysis of the benzyl ether protecting groups resulted in concomitant tutin double-bond migration. Epoxide opening and rearrangement were observed upon acetylation of the tutin glucoside.

Reactions directed towards the synthesis of 5-(β-hydroxyethyl)-2-isopropylcyclohexanone

1978 ◽  
Vol 31 (7) ◽  
pp. 1629 ◽  
Author(s):  
R Murphy ◽  
R Prager
Keyword(s):  
Double Bond ◽  
Partial Migration ◽  
Reaction Conditions ◽  
Double Bond Migration ◽  
Bond Rearrangement

Reduction of perillaldehyde by lithium in ammonia gives products the structures of which depend on reaction conditions. Shisool (p-menth-8- en-7-ol) undergoes double-bond migration in the presence of acids. The corresponding aldehyde, with dimethylsulfonium methylide, forms an oxiran which is comparatively unreactive, double-bond rearrangement or reduction accompanying the opening of the oxiran. The conversion of shisool into 5-(β-hydroxyethyl)-2-isopropylcyclohexanone was frustrated by only partial migration of the double bond.

Utility of the Cleavage of Nitrosamides for the Preparation of Chiral Acids after Chromatographic Separation of their Diastereomeric Amides

1977 ◽  
Vol 32 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Franz P. Schmidtchen ◽  
Peter Rauschenbach ◽  
Helmut Simon
Keyword(s):  
Double Bond ◽  
Carboxylic Acids ◽  
Chromatographic Separation ◽  
Optical Resolution ◽  
Double Bonds ◽  
Reaction Conditions ◽  
Double Bond Migration ◽  
Enantiomerically Pure ◽  
Amide Derivatives ◽  
Derivatives Of

A method for optical resolution of chiral acids is described. It consists of the conversion of racemic acids to diastereomeric amides, their chromatographic separation and subsequent deamidation via the nitrosamide route. Reaction conditions for cleavage of amide derivatives of phenylalanine and methylbenzylamine are given. No or only negligible racemization of carboxylic acids, chiral in α-position takes place under those conditions. The extent of Ε,Ζ-isomerization of double bonds is very small, as is the extent of double bond migration from the Δ3-position into conjugation with the carboxyl function. Enantiomerically pure R- or S[2-3H]2-methylbutanoic acid and (-)methyl-3(p-chlorophenyl)-2-chloropropionate (Bidisin®) were prepared by this procedure.

One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

2018 ◽  
Vol 15 (3) ◽  
pp. 380-387
Author(s):  
Xia Zhao ◽  
Xiaoyu Lu ◽  
Lipeng Zhang ◽  
Tianjiao Li ◽  
Kui Lu
Keyword(s):  
Double Bond ◽  
Efficient Method ◽  
Room Temperature ◽  
Sulfonyl Chloride ◽  
Antibacterial Activities ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

Some Analogs of 4-(2',4'-Difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic Acid: Synthesis and Antiinflammatory Activity

1995 ◽  
Vol 60 (6) ◽  
pp. 1026-1033 ◽  
Author(s):  
Miroslav Kuchař ◽  
Václav Vosátka ◽  
Marie Poppová ◽  
Eva Knězová ◽  
Vladimíra Panajotovová ◽  
...  
Keyword(s):  
Double Bond ◽  
Antiinflammatory Activity ◽  
Acid Synthesis ◽  
Reaction Conditions ◽  
Methyl Group ◽  
Oxobutanoic Acid

Analogs of 4-(2',4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid (I, flobufen), containing a double bond (II, IV, V, VII, VIII) or a methyl group in position 3 (VI) were prepared. Their antiinflammatory activity was evaluated and compared with that of flobufen. None of the mentioned analogs reached the activity of the standard. Isomerization of the unsaturated derivatives is connected with a shift of the double bond, Z-E transformation or lactonization. Reaction conditions and spectra of the compounds prepared are described.

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