Adams catalyst reactions

Cyanohydrin (52b 5 g mp 160-164°) is dissolved in acetic acid (200 ml) and placed in a 2-liter hydrogenation flask. Adams catalyst (0.75 g) is added (for 100 g cyanohydrin use 7.5 gof catalyst) and the mixture is hydrogenated until the theoretical amount of hydrogen is taken up (477 ml). The catalyst is removed by filtration, the filtrate is transferred to a 600 ml beaker provided with a stirrer and thermometer, treated with water (20 ml) and cooled to 0° (ice-salt). A solution of sodium nitrite (10 g) in water (30 ml) is added dropwise with stirring at 0°. The reaction mixture is then stirred for additional 2 hr at room temperature, treated with water (100 ml) and, after standing overnight, the precipitate is collected by filtration. The product is dissolved in ether (50 ml), the ether solution is washed sequentially... 

To 20 g of the above compound dissolved in 300 ml 95% ethanol In a Parr reaction vessel is added 1.5 g Adams catalyst, platinum dioxide, and the mixture shaken under hydrogen at 50 psi for 1 hour at ambient temperature. The mixture Is then filtered and the ethanol removed on a standard rotary evaporator. The resulting oil is dissolved in 200 ml ether and slowly added to 1,200 ml ether with continuous stirring. The product separates as crystals which are removed after 15 to 30 minutes by filtration. The compound melts at 148°C to 147°C and needs no further purification. 

Friedel-Crafts reaction Adams, Roger. 230 Adams catalyst, 230 Addition reaction, 137... 

Direct hydrogenation of key intermediate 248 over the Adams catalyst and subsequent lithium aluminum hydride reduction yielded the two stereoisomeric alcohols 256 and 257, which were separately transformed to ( )-corynantheal (258) and ( )-3-epicorynantheal (259), respectively, by Moffatt oxidation, followed by Wittig reaction with methyltriphenylphosphonium bromide and, finally, by demasking the aldehyde function (151, 152). 

Reflux 6.9 g triphenylphosphine and 6.6 g lauryl bromide (or equimolar amount of homolog) in 40 ml xylene for 60 hours. Remove solvent and wash residue with 5X20 ml ether (by decanting) to get 11 g lauryl triphenylphosphonium bromide (I). To a stirred suspension of 5.6 g (0.011M)(I) in 50 ml ether add 0.01M butyllithium solution (see Organic Reactions 8,258(1954) for preparation). Stir Vz hour at room temperature and slowly add 1.66 g 3,5-dimethoxybenzaldehyde (preparation given elsewhere here) in 10 ml ether over Vi hour. After 15 hours, filter, wash filtrate with water and dry, evaporate in vacuum. Dilute residue with pentane, filter and remove solvent. Dissolve the residual oil in 25 ml ethyl acetate and hydrogenate over O.lg Adams catalyst at one atmosphere and room temperature for 2 hours. Filter and evaporate in vacuum to get the 5-alkylresorcinol dimethyl ether which can be reciystallized from pentane and demethylated as described elsewhere here. 

The selectivity in favor of the desired monobenzylated product was found to be >99% and the immobilized Pt02 was found to be 4-5 times more active than the commercial Adams catalysts. In solution or in immobilized form, the PtOz colloid is effective in the hydrogenation of carbonyl compounds or of olefins. Recently, the heterogeneous catalytic amination of aryl bromides by immobilized Pd(0) particles has been reported [163], Secondary amines such as piperidine and diethyl amine are used in the amination of aryl bromides and the reaction proceeds with good turnover numbers and regio-control. The catalysts can be reused repeatedly without loss of activity or selectivity after filtration from the reaction mixture. 

Carbon reacts also with other sulfur-containing compounds with resulting fixation of sulfur. Reaction of various forms of carbon with hydrogen sulfide was reported by Baraniecky, Riley, and Streeter (126) and by Polansky, Knapp, and Kinney (128). The reaction of carbon blacks with hydrogen sulfide and with sulfur was studied extensively by Studebaker (86). At 150°, the increase in sulfur content was proportional to the quinone content as measured by catalytic hydrogenation using Adams catalyst (see page 203). 

Scheme 14, Reaction conditions i, CH3COCI ii, H2, Adams catalyst.

Platinum dioxide, also known as Adams catalyst, is used commercially in many hydrogenation reactions at ordinary temperatures, such as reduction of olefinic and acetylenic unsaturation, aromatics, nitro, and carbonyl groups. 

Because of the possibility of racemization during the transesterification reaction (strong basic conditions) alternative methods are reported. These include transesterification in the presence of the KF/18-crown-6 ether 461 or the use of titanium tetraalkoxides. 471 The methods are efficient and represent a route to any required dialkyl ester using diphenyl esters as starting materials. Diphenyl groups can also be removed by hydrogenation in the presence of platinum dioxide (Adams catalyst) to provide the free phosphonic acid moiety directly)46 ... 

Platinum in a finely divided form is obtained by the in situ reduction of hydrated platinum dioxide (Adams catalyst) finely divided platinum may also be used supported on an inert carrier such as decolourising carbon. Finely divided palladium prepared by reduction of the chloride is usually referred to as palladium black. More active catalysts are obtained however when the palladium is deposited on decolourising carbon, barium or calcium carbonate, or barium sulphate. Finely divided ruthenium and rhodium, usually supported on decolourising carbon or alumina, may with advantage be used in place of platinum or palladium for some hydrogenation reactions. 

Quaternary phenanthridinium compounds are reduced to the corresponding A-alkyldihydrophenanthridines by hydrogenation over Adams catalyst. The reaction forms part of the modified Emde sequence284 shown below. 

The catalysts usually encountered in this reaction are platinum oxide and Raney nickel. Cope and Hancock synthesized several alkyl-aminoethanols, using both catalysts (88). Although they prepared the compounds with Adams catalyst, they found Raney nickel to be also suitable at elevated temperatures and pressures. An 86% yield of 2-sec-butylaminoethanol was obtained from methyl ethyl ketone and... 

Phenylethylamine has been made by a number of reactions, many of which are unsuitable for preparative purposes. Only the most important methods, from a preparative point of view, are given here. The present method is adapted from that of Adkins,1 which in turn was based upon those of Mignonac,2 von Braun and coworkers,3 and Mailhe.4 Benzyl cyanide has been converted to the amine by catalytic reduction with palladium on charcoal,5 with palladium on barium sulfate,6 and with Adams catalyst 7 by chemical reduction with sodium and alcohol,8 and with zinc dust and mineral acids.9 Hydrocinnamic acid has been converted to the azide and thence by the Curtius rearrangement to /3-phenyl-ethylamine 10 also the Hofmann degradation of hydrocinnamide has been used successfully.11 /3-Nitrostyrene,12 phenylthioaceta-mide,13 and the benzoyl derivative of mandelonitrile 14 all yield /3-phenylethylamine upon reduction. The amine has also been prepared by cleavage of N- (/3-phenylethyl) -phthalimide 15 with hydrazine by the Delepine synthesis from /3-phenylethyl iodide and hexamethylenetetramine 16 by the hydrolysis of the corre-... 

C24H31N2O5I3, which corresponds to addition of one molecule of iodine to the methiodide. Hydrogenation of cimicidine by use of Adams catalyst yields a dihydro derivative, obtained as its dihydrate from methanol and characterized as its picrate and hydrochloride. The reaction of cimicidine with alkaline hydrogen peroxide is also different from that of haplophytine the product is an almost nonbasic, acidic substance of composition C23H28N2O6 (1, 3). 

The variety of reaction products can be demonstrated by the following examples. Alcohols usually form with platinum oxide catalysts e.g., in the case of furfuryl alcohol with Adams catalyst in ethanol, at least seven reaction products are obtained ... 

The unsubstituted 1,3,4-thiadiazole (3, R = H) was described in 1956 by Goerdeler et al. They transformed 2-amino-1,3,4-thiadiazole (4, R = H) into the 2-bromo compound (5, R = H) by a Sandmeyer reaction, and by hydrogenation of the latter with Adams catalyst the parent compound of the series was obtained as a colorless solid, m.p. 42-43°, b.p. 204-205°. Jensen and Pedersen prepared the same... 

A platinum-based catalyst, such as Adams catalyst, is an alternative to nickel and palladium, and is more active. For example, when the reaction in equation (24) is carried out in the presence of a plati-nium catalyst, the nitro group is also reduced. The hydrogenolysis of 2-butene oxide and propylene oxide proceeds at a slightly lower temperature than when using nickel, and for propylene oxide the... 

Catalytic hydrogenation of fluoro- and difluOTO-m- and tran -butenedioic acids and their esters frequently affords products only of hydrogenolysis, especially when platinum oxide (Adams catalyst) is used. Hydrogenolysis is favored in polar solvents, and is found to be more effective when rhodium or nickel rather than palladium are used as the catalysts (Table 2). Hydrogenolysis takes place prior to the saturation of the double bonds fluoro- and 2,3-difluoro-succinic acids do not suffer any loss of fluorine under the same reaction conditions. ... 

Secondary enamines derived from 3-ethylaminopyridine and isobutanal have been treated with a series of reducing agents. Whereas LiAlH4 and NaBH had no effect, hydrogenation in the presence of Adams catalyst was effective leading to mixtures of reduction and fragmentation products in ratios which were dependent on the reaction temperature. Loss of methoxy group was also observed, when present in the substrate (Scheme 121). 

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