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.

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.

Synthetical applications of activated metal catalysts. XXIII. The desulphurization of thianthren

1964 ◽  
Vol 17 (3) ◽  
pp. 366 ◽  
Author(s):  
GM Badger ◽  
P Cheuychit ◽  
WHF Sasse
Keyword(s):  
Raney Nickel ◽  
Metal Catalysts ◽  
Radical Intermediates ◽  
Raney Cobalt

��� The desulphurization of thianthren with a degassed (hydrogen-poor) Raney nickel has been shown to give benzene, biphenyl, dibenzothiophen, and a little triphenylene. Chromatography on a column of Raney cobalt has been used to separate a mixture of biphenyl and dibenzothiophen. The results have been discussed with reference to two radical intermediates (III and V, or VI).

Synthetical applications of activated metal catalysts. XXI. The formation of carbazole from aniline and related compounds in the presence of degassed Raney nickel

1964 ◽  
Vol 17 (3) ◽  
pp. 347 ◽  
Author(s):  
GDF Jackson ◽  
WHF Sasse
Keyword(s):  
Raney Nickel ◽  
Metal Catalysts ◽  
Related Compounds

Trace amounts of carbazole are formed by the action of W-7J Raney nickel on aniline, diphenylamine, 2,2'-diaminobiphenyl, and 2-aminobiphenyl. Aniline yields also N-cyclohexylaniline, diphenylamine, 2,2'-diaminobiphenyl, and 2-aminobiphenyl; 2,2'-diaminobiphenyl gave 2-aminobiphenyl also. Carbazole was not detectably affected by the catalyst. These results suggest that aniline is slowly converted to carbazole (a) by way of diphenylamine; (b) by way of 2,2'-diamino- biphenyl and 2-aminobiphenyl; and (c) by way of 2,2'-diaminobiphenyl. The last route appears to be the most efficient one.

scholarly journals Lignin and related compounds. II. Studies using ruthenium and Raney nickel as catalysts for lignin hydrogenolysis

1970 ◽  
Vol 48 (3) ◽  
pp. 477-479 ◽  
Author(s):  
J. M. Pepper ◽  
Y. W. Lee
Keyword(s):  
Raney Nickel ◽  
Nickel Catalysts ◽  
Spruce Wood ◽  
Catalytic Hydrogenolysis ◽  
Related Compounds

Five cyclohexyl compounds, derived from lignin, have been isolated and identified from the products of the catalytic hydrogenolysis of spruce wood over ruthenium and Raney nickel catalysts. One of these, 3-(4-hydroxy-3-methoxycyclohexyl)-1-propanol, a previously unreported compound, has been synthesized and characterized.

Synthesis of 5,7-dihydroxynaphthoquinone derivatives and their reactions with nucleophiles: Nitration of 2,3-dimethylnaphthalene and subsequent transformations

1976 ◽  
Vol 29 (10) ◽  
pp. 2247 ◽  
Author(s):  
HJ Banks ◽  
DW Cameron ◽  
MJ Crossley ◽  
EL Samuel
Keyword(s):  
Unusual Reaction ◽  
Nitro Derivatives ◽  
Reactions With Nucleophiles ◽  
Derivatives Of ◽  
Related Compounds ◽  
Benzenoid Ring

5,7-Dihydroxy-2,3-dimethyl-l,4-naphthoquinone (5) and related compounds have been synthesized. The quinone affords an accessible substrate for studying an unusual reaction with nucleophiles, which involves attack at the 8-position, i.e. at the benzenoid ring. An unsuccessful approach to (5) has led to tri- and tetra-nitro derivatives of 2,3-dimethylnaphthalene. Reduction of the former and subsequent conversions have given aminonaphthoquinone and perimidinone derivatives.

Sign in / Sign up

Export Citation Format

Share Document