Arenes Raney nickel

Reduction of arenes. Raney nickel (Mozingo type) in combination with 2-propanol (reflux) effects reduction of aromatic rings in 2-18 hours. Naphthalene is reduced in 18 hours to tetralin (90% yield) and cis- and ran -decalin (10% yield). Anisole is reduced in 110 hours to cyclohexyl methyl ether (90% yield). Nitrobenzene is reduced quickly to aniline and then further to cyclohexylamine and cyclohexylisopropylamine. 

Traditionally, monoqrclic arene hydrogenation is carried out in drastic conditions with heterogeneous catalysts [9-18] such as Rh/Al203 and Raney Nickel or metal sulfides. Nevertheless, some pure homogeneous systems have been reported [19-23]. 

Arene(tricarbonyl)chromium complexes, 19 Nickel boride, 197 to trans-alkenes Chromium(II) sulfate, 84 of anhydrides to lactones Tetrachlorotris[bis(l,4-diphenyl-phosphine)butane]diruthenium, 288 of aromatic rings Palladium catalysts, 230 Raney nickel, 265 Sodium borohydride-1,3-Dicyano-benzene, 279 of aryl halides to arenes Palladium on carbon, 230 of benzyl ethers to alcohols Palladium catalysts, 230 of carboxylic acids to aldehydes Vilsmeier reagent, 341 of epoxides to alcohols Samarium(II) iodide, 270 Sodium hydride-Sodium /-amyloxide-Nickel(II) chloride, 281 Sodium hydride-Sodium /-amyloxide-Zinc chloride, 281 of esters to alcohols Sodium borohydride, 278 of imines and related compounds Arene(tricarbonyl)chromium complexes, 19... 

Because diaryl telluriums can be prepared from aromatic hydrocarbons and tellurium followed by reduction of the diaryl tellurium dichlorides, the overall reaction sequence converts arenes to biaryls. The formation of benzene from diphenyl tellurium and Raney nickel was also reported3. 

All types of electrophiles have been used with 2-lithio-l,3-dithiane derivatives, including alkyl halides, sulfonates, sulfates, allylic alcohols, arene-metal complexes, epoxides, aziridines, carbonyl compounds, imines, Michael-acceptors, carbon dioxide, acyl chlorides, esters and lactones, amides, nitriles, isocyanates, disulfides and chlorotrialkylsilanes or stannanes. The final deprotection of the dithioacetal moiety can be carried out by means of different types of reagents in order to regenerate the carbonyl group by heavy metal coordination, alkylation and oxidation184 or it can be reduced to a methylene group with Raney-nickel, sodium or LiAIII4. 

Nicht durch Halogen-substituierte Nitro-arene werden bei Anwesenheit eines Palladium- Katalysators bzw. Raney-Nickel zu Diarylazo-Verbindungen reduziert (s. Bd. X/3, S. 352). 

Raney nickel and platinum, palladium, and rhodium catalysts have been used to accomplish the hydrogenation of polycyclic aromatics. Hydrogenation of fused polycyclic arenes leads to the cis- or fran -substituted cyclohexane derivatives. The cis product is usually obtained again this can be understood in terms of the mechanism proposed for aromatic hydrogenation (vide supra). 

Hydrogenolysis of aryl halides. Aryl halides are converted into arenes by hydrogenation in a 0.2 M solution of KOH in ethanol at room temperature and atmospheric pressure in the presence of Raney nickel. The reaction is subject to steric hindrance. ... 

Introduction of deuterium or tritium into aromatic compounds can also be carried out with a surprising degree of selectivity that is not seen in the equivalent thermal reaction. Thus reaction of / -bromoacetylbenzene with NaOD—D O in the presence of Raney nickel gives an 83% yield of the product resulting from direct displacement of the halide on exposure to ultrasound [185]. This is in stark contrast to the thermal reaction which gives a mixtures of products in which the trideuterated arene predominates (Scheme 84). 

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