Isotherme d'adsorption du phénanthrène et de ses dérivés hydrogénés sur du nickel de Raney

1989 ◽  
Vol 67 (3) ◽  
pp. 365-368 ◽  
Author(s):  
François Bossányi ◽  
Chakib Ameziane Hassani ◽  
Hugues Ménard ◽  
Jean Lessard
Keyword(s):  
Raney Nickel ◽  
Adsorption Isotherms ◽  
Hydrogen Atoms ◽  
Position And Orientation ◽  
Derivatives Of

The adsorption isotherms of phenanthrene and its hydrogenated derivatives, of naphthalene, and of tetralin on Raney nickel have been determined by chromatographic studies. The adsorption of these molecules on Raney nickel depends on the number of π electrons and on the position and orientation of hydrogen atoms that can interfere with the interaction of the π electrons with the catalyst. Keywords: adsorption, phenanthrene, chromatographic studies.

Synthetical Applications of Activated Metal Catalysts. XVI. The Role of Hydrogen in the Formation of 2,2'-Bipyridyl from Pyridine under the Influence of Degassed Raney Nickel

1963 ◽  
Vol 16 (1) ◽  
pp. 14 ◽  
Author(s):  
WHF Sasse ◽  
CP Whittle
Keyword(s):  
Raney Nickel ◽  
Nickel Catalysts ◽  
Nickel Atom ◽  
Metal Catalysts ◽  
Published Data ◽  
Hydrogen Atoms ◽  
Adsorbed Pyridine

The efficiency of W7 Raney nickel catalysts degassed between 30 and 400�C in the preparation of 2,2'-bipyridyl has been examined. The highest activities are observed with catalysts which have been degassed at 200�C, and these catalysts arc up to 20% more efficient than catalysts previously used and degassed at 100�C. The results obtained are compared with published data concerning the hydrogen contents of degassed Raney nickel catalysts (Kokes and Emmett 1959, 1960). This shows that catalysts which are virtually free of hydrogen are only 25% less efficient than catalysts degassed at l00�C (containing 65 to 70% of their original hydrogen). Because of this finding a new mechanism is proposed in which the adsorbed pyridine is activated by the transfer of an electron from the catalyst. On stereochemical grounds it is proposed that meso-2,2'-dihydro-2,2'-bipyridyl with axially disposed hydrogen atoms at the 2,2'-positions and bonded via both nitrogen atoms to one nickel atom is the energetically most favoured intermediate.

SYNTHESES DE LA DL-PROLINE A PARTIR DE L'α-PIPERIDONE

1950 ◽  
Vol 28b (6) ◽  
pp. 245-255 ◽  
Author(s):  
Roger Gaudry ◽  
Louis Berlinguet
Keyword(s):  
Raney Nickel ◽  
Alkaline Solution ◽  
Low Pressure ◽  
Valeric Acid ◽  
Derivatives Of

By treatment of α-piperidone with sulphuryl chloride,β,β′-dichloro-α-piperidone was obtained. It was hydrolyzed to α,α′-dichloro-δ-amino-n-valeric acid, which was simultaneously reduced and cyclized to DL-proline, by low pressure hydrogenation, using Raney nickel, in alkaline solution. All the intermediate compounds were identified and characterized. The over-all yield of DL-proline is 33% calculated from α-piperidone.α-Piperidone was hydrolyzed to δ-amino-n-valeric acid, and the δ-phenylureido-n-valeric and δ-phthalimido-n-valeric acids were prepared. Halogenation of δ-phthalimido-n-valeric acid gave excellent yields of the α-bromo and α-chloro acids. These acids were hydrolyzed to the α-halogenated-δ-aminoacids. On treatment with alkali, they gave DL-proline in 56% and 50% yields respectively, from α-piperidone.Halogenation of δ-phenylureido-n-valeric acid gave the dibromo and the dichloro acids, which ring-close immediately into derivatives of α-piperidone.The different behavior of δ-benzoylamino, δ-phthalimido, and δ-phenylureido derivatives of n-valeric acid with halogens, or halogenating agents is noted.

Investigation of the mobility of methylene group hydrogen atoms in some derivatives of 2-iminothiazolidin-4-one

1967 ◽  
Vol 3 (2) ◽  
pp. 516-518
Author(s):  
I. I. Chizhevskaya ◽  
R. S. Kharchenko ◽  
N. N. Khovratovich
Keyword(s):  
Hydrogen Atoms ◽  
Derivatives Of ◽  
Methylene Group

Synthetical applications of activated metal catalysts. XXV. The hydrogenolysis of some phenyl derivatives of silicon by Raney nickel

1966 ◽  
Vol 19 (10) ◽  
pp. 1897 ◽  
Author(s):  
WHF Sasse ◽  
KO Wade
Keyword(s):  
Raney Nickel ◽  
Silicon Atom ◽  
Atmospheric Pressure ◽  
Nickel Catalysts ◽  
Metal Catalysts ◽  
Derivatives Of ◽  
Related Compounds ◽  
Raney Cobalt

Tetraphenylsilane and 11 related compounds have been cleaved by treatment at atmospheric pressure with Raney nickel catalysts to give mixtures of benzene and cyclohexane. Yields exceeding 90% are obtained with degassed Raney nickel and silanes. Silanols and siloxanes are less readily spilt. The presence of methanol in the reaction mixtures retards the fission of silicon-phenyl bonds. Tetracyclo-hexylsilane, cyclohexyltrimethylsilane, and hexa(n-hexyl)disiloxane did not react detectably with Raney nickel. Raney cobalt had no effect on tetraphenylsilane. A mechanism for the new reaction is discussed which involves chemisorption via the silicon atom, ejection of a phenyl anion, and hydrogenolysis of the absorbed triphenylsilyl species.

scholarly journals Hydroxyderivatives of levoglucosenone in reactions of enantioselective reduction of 1,3-diphenylpropan-1-one

2020 ◽  
Vol 63 (9) ◽  
pp. 19-25
Author(s):  
Anna N. Davydova ◽  
◽  
Bulat T. Sharipov ◽  
Farid A. Valeev ◽  
◽  
...  
Keyword(s):  
Aluminum Hydride ◽  
Point Of View ◽  
Chiral Ligands ◽  
Lithium Aluminum ◽  
Hydrogen Atoms ◽  
Enantioselective Reduction ◽  
Urgent Task ◽  
Partial Neutralization ◽  
Prochiral Ketones ◽  
Derivatives Of

The enantioselective reduction of prochiral ketones is an important method for the preparation of enanti-enriched secondary alcohols, which can serve as starting materials for optically active compounds. Chiral metal hydride reagents, such as lithium aluminum hydride (LiAlH4) and sodium borohydride (NaBH4), modified with chiral ligands, have been developed to effect enantioselective reduction. However, in most cases, derivatives are used to obtain chiral hydride reagents, which are rare and hardly available. Therefore, the search for more accessible and effective derivatives suitable for the modification of hydride reagents is an urgent task. Levoglucosenone is an optically pure enone of carbohydrate nature, readily available by pyrolysis of any cellulose-containing materials. Levoglucosenone is considered a promising bioplatform for both laboratory synthesis and industrial use. The prospect of the development of chemistry of levoglucosenone and its derivatives in industry makes it possible to pay attention to these compounds from the point of view of studying their possibilities as chiral inducers or auxiliaries. In this work, we studied the possibilities of chiral induction in the reduction reactions of 1,3-diphenylpropan-1-one with hydride reagents obtained by replacing hydrogens in LiAlH4 and NaBH4 with hydroxy derivatives of levoglucosenone. The reduction of 1,3-diphenylpropan-1-one with chiral aluminum hydride reagents proceeded with low enantioselectivity, mainly with a predominance of (S)-1,3-diphenylpropan-1-ol. It was found that the enantiomeric purity of the S-stereomer decreases with an increase in the substitution of hydrogen atoms in LiAlH4 by hydroxy derivatives of levoglucosenone. Reduction of 1,3-diphenylpropan-1-one with reagents obtained by partial neutralization of NaBH4 with hydroxy derivatives of levoglucosenone, on the contrary, predominantly leads to the formation of (R)-1,3-diphenylpropan-1-ol. The addition of AcOH and Bu4NCl to NaBH4 has a positive effect on the optical frequency of the R-alcohol. At the same time, enantioselectivity in the reactions was almost absent upon reduction of 1,3-diphenylpropan-1-one with reagents obtained by partial neutralization of BH3. The best results of enantioselective reduction were shown by unsaturated alcohols: (1S,4S,5R) -6,8-dioxabicyclo[3.2.1]oct-2-en-4-ol and (1S,4S,5R)-4-methyl-6,8-dioxabicyclo[3.2.1]oct-2-en-4-ol, of which (1S,4S,5R)-6,8-dioxabicyclo[3.2.1]oct-2-en-4-ol was the most effective. It is likely that an increase in the enantioselectivity of reactions carried out in the presence of hydroxy derivatives of levoglucosenone is possible by obtaining more bulky chiral ligands, provided that the double bond is retained.

Desulfuration of steroidal thians

1982 ◽  
Vol 47 (11) ◽  
pp. 3148-3159 ◽  
Author(s):  
Alexander Kasal
Keyword(s):  
Raney Nickel ◽  
Optimum Conditions ◽  
Unsaturated Esters ◽  
Aprotic Medium ◽  
Derivatives Of ◽  
By Products

The reaction of 4-thia-5-cholesten-3-one (X) with Raney nickel in protic medium affords alcohol III, while A-nor-5β-cholestan-3-one (XXIII), A-bisnor-2,5-secocholestane (XXXI) and the esters of the type XVIII are formed as by-products. When aprotic medium is used compounds XXIII and XXXI are the main products. During desulfuration with a less active Raney nickel the mentioned substances are accompanied by 5-unsaturated derivatives of the type I, XIV and XXIX. Optimum conditions for the preparation of either saturated alcohols of type III or of unsaturated esters of type XIV were found.

Universality among topological properties of electron density associated with the hydrogen–hydrogen nonbonding interactions

1992 ◽  
Vol 70 (2) ◽  
pp. 443-449 ◽  
Author(s):  
Jerzy Cioslowski ◽  
Stacey T. Mixon
Keyword(s):  
Electron Density ◽  
Functional Dependencies ◽  
Hydrogen Atoms ◽  
Topological Features ◽  
Second Derivatives ◽  
The Difference ◽  
Point Distance ◽  
Torsional Angles ◽  
Derivatives Of ◽  
Bond Ellipticity

Nonbonding repulsive interactions between hydrogen atoms, separated by less than ca. 2.18 Å and connected to two carbon atoms in the 1,4-positions, are associated with additional pairs of bond and ring critical points in the electron density, ρ(r), and the corresponding attractor interaction lines. Such topological features of ρ(r) are present in some planar benzenoid hydrocarbons, including chrysene, benzanthracene, and phenanthrene. They also appear in conformations of the biphenyl molecule with the torsional angles between the benzene rings lying within the range of 0°–27°. Properties such as the bond point – ring point distance, the difference in ρ(r) at the bond point and the ring point, and the bond ellipticity are found to follow universal functional dependencies with the hydrogen–hydrogen distance as the controlling variable. The same is true about the corresponding difference in the second derivatives of ρ(r) in the direction of the vector connecting the bond and ring points. Keywords: atoms in molecules, electron density, attractor interaction lines, steric repulsions.

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