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Nickel preparation

Raney nickel A special form of nickel prepared by treating an Al-Ni alloy with NaOH solution. The nickel is left in a spongy mass which is pyrophoric when dry. This form of nickel is a most powerful catalyst, especially for hydrogenations. [Pg.341]

Deuteration at C-12 by desulfurization of 12-thioketals with Raney Nickel preparation of the ethylene thioketal, 172 desulfurization of the mercaptal, 173... [Pg.495]

Ni° means nickel prepared in situ by reduction of nickel salts, or a Ni° complex containing easily displaceable ligands. 6 Disiamvlborane. Quadricyclane can be employed in place of dicyclopentadiene with which it is in equilibrium. [Pg.203]

To a stirred solution of 45g 3,5-dimethoxybenzoyl chloride and 17.4g thiophen in 300 ml benzene at 0° C, add dropwise 10.5g freshly distilled stannic chloride. Stir one hour at room temperature and add 200 ml 3% aqueous HC1. Separate the benzene layer and wash the aqueous layer with benzene. Dry and evaporate in vacuum the combined benzene layers and distill the red residue (250° C bath/4.5) to get 45g 2-(3,5-dimethoxybenzoyl) thiophen(I). Recrystallize from petroleum ether. Add a solution of 21 g AICI3 in 160 ml ether to a stirred suspension of 6.1 g lithium aluminum hydride in 140 ml ether. After 5 minutes add a solution of 39g(I) in 300 ml ether at a rate giving a gentle reflux. Reflux and stir 1 hour cool in an ice bath and treat dropwise with 50 ml water, then 50 ml 6N aqueous sulfuric acid. Separate the layers, extract the aqueous layer with 3X100 ml ether and dry, evaporate in vacuum the combined ether layers. Can distill the residue (230° C bath/5mm) to get 27g oily 2-(3,5-dimethoxybenzyl) thiophen (II). Recrystallize from petroleum ether. Reflux a solution of 5g (II) in 700 ml ethanol with W-7 Raney Nickel prepared from Ni-Al alloy (see Org. Synthesis Coll. Vol 111,176(1955)) for 6 hours. Filter, evaporate in vacuum and can distill (140/0.01) to get about 2.2g oily olivetol dimethyl ether which can be reduced to olivetol as described elsewhere here. -... [Pg.45]

Gut, Prins and Reichstein 62 methyl 3-methylthio-4,6-benzylidene-/S-D-idoside (LXX) with a four-fold quantity of Raney nickel (prepared from an eight-fold quantity of alloy) gave methyl 3-desoxy-4,6-benzyli-dene-/S-D-idoside (LXXI) in 92% yield use of a large excess of nickel resulted in simultaneous debenzylidenation. [Pg.34]

Hydrogenation using Raney nickel is carried out under mild conditions and gives cis alkenes from internal alkynes in yields ranging from 50 to 100% [356, 357, 358, 359, 360]. Half hydrogenation of alkynes was also achieved over nickel prepared by reduction of nickel acetate with sodium borohydride (P-2 nickel, nickel boride) [349,361,362] or by reduction with sodium hydride [49], or by reduction of nickel bromide with potassium-graphite [363]. Other catalysts are palladium on charcoal [364], on barium sulfate [365, 366], on... [Pg.43]

A method for the conversion of unsaturated aliphatic aldehydes to saturated aldehydes is a gentle catalytic hydrogenation. Palladium is more selective than nickel. Hydrogenation over sodium borohydride-reduced palladium in methanol at room temperature and 2 atm reduced crotonaldehyde to butyralde-hyde but did not hydrogenate butyraldehyde [57]. Nickel prepared by reduction with sodium borohydride was less selective it effected reduction of crotonaldehyde to butyraldehyde but also reduction of butyraldehyde to butyl alcohol, though at a slower rate [57]. Hydrogenation of 2,2,dimethyl-... [Pg.97]

Nickel prepared by reduction of nickel chloride with sodium borohydride was used for desulfurization of diethyl mercaptole of benzil. Partial desulfurization using 2 mol of nickel per mol of the mercaptole gave 71% yield of ethylthiodesoxybenzoin while treatment with a 10-fold molar excess of nickel over the mercaptole gave 61% yield of desoxybenzoin (benzyl phenyl ketone) 937. ... [Pg.131]

DESULFURIZATION WITH RANEY NICKEL Preparation of Aldehydes from Thiol Esters [1101]... [Pg.205]

Since RNi contains a large amount of aluminum and 2-hydroxy acid is a strong chelating reagent, one difference between RNi and RNiA could be ascribed to their difference in aluminum contents. Table XII (49) shows the correlation between the aluminum content and the EDA of those catalysts modified with tartaric acid. The aluminum content of RNi was decreased by pretreatment with hydroxy acid. Moreover, reduced nickel prepared from NiO (HNi-1) gives an effective modified catalyst and its pretreatment with hydroxyacid does not affect its EDA. [Pg.234]

Ru, Pt > Os > It.177 A slightly different order of activity Pd > Ni > Rh > Ru > Os, Ir, Pt is based on the isomerization of hexenes.178 Platinum is generally the preferable catalyst if isomerization is to be avoided, whereas palladium is the metal of choice in isomerization. The most active Raney nickel preparations rival palladium in their isomerizing activity. [Pg.187]

Fig. 14. Comparison of the current-voltage curves of a smooth nickel cathode and two different Raney-nickel-coated cathodes posessing comparable loading and effective surface (a) smooth nickel. Raney nickel prepared from two different precursors (b) plasma-sprayed NiAh, (c) NiAU cold rolled together with Mond nickel. Fig. 14. Comparison of the current-voltage curves of a smooth nickel cathode and two different Raney-nickel-coated cathodes posessing comparable loading and effective surface (a) smooth nickel. Raney nickel prepared from two different precursors (b) plasma-sprayed NiAh, (c) NiAU cold rolled together with Mond nickel.
Nickel affords selective catalysts for the hydrogenation of alkenes, dienes, and alkynes. When catalyzed by C. A. Brown s P-2 nickel, prepared by the reduction of Ni(0Ac)2 with NaBH in ethanol, the individual rates as well as the competitive rates appear to be sensitive to the alkene structure as judged by the reported initial rates of hydrogen addition (ref. 23). Alkene isomerization is relatively slow. Except for the most reactive alkenes such as norbornene, the individual hydrogenations seem to be first order in alkene. This indicates that alkenes are more weakly bound to Ni than to Pt or Pd. Similar selectivities are reported by Brunet, Gallois, and Caubere for a catalyst prepared by the reduction of Ni(0Ac)2 with NaH and t-amyl alcohol in THF (ref. 27). [Pg.28]

An explanation for this difference in selectivity of the Ni catalysts is suggested by the studies of Okamoto et al. who correlated the difference in the X-ray photoelectron spectra of various nickel catalysts with their activity and selectivity in hydrogenations (ref. 28,29). They find that in individual as well as competitive hydrogenations of cyclohexene and cyclooctene on Ni-B, cyclooctene is the more reactive while the reverse situation occurs on nickel prepared by the decomposition of nickel formate (D-Ni). On all the nickel catalysts the kinetically derived relative association constant favors cyclooctene (ref. 29). The boron of Brown s P-2 nickel donates electrons to the nickel metal relative to the metal in D-Ni. The association of the alkene with the metal is diminished which indicates that, in these hydrocarbons, the electron donation from the HOMO of the alkene to an empty orbital of the metal is more important than the reverse transfer of electron density from an occupied d-orbital of the metal into the alkene s pi orbital. [Pg.29]

STRUCTURE AND CATALYTIC PROPERTIES IN HYDROGENATION OF VALERONITRILE OF RANEY NICKEL PREPARED FROM Cr AND Mo DOPED Ni2A13 ALLOYS. [Pg.113]

The time required for the hydrogenation was 2.5 hours with a very active nickel catalyst, and longer with a less active catalyst. Raney nickel prepared according to Reference 2 is a particularly active catalyst and gives excellent results in this preparation. [Pg.34]

In the very early studies on catalysis little attention was paid to the influence of factors (c), (d), and (e). It is notable, however, that Fricke and co-workers (118,119) did connect the pyrophoric nature of copper and of nickel preparations with their lattice distortions and dispersion. [Pg.228]

Mauret and Alphonse reported that a finely divided nickel prepared by reduction of nickel halide with magnesium in ethanol was more selective for semihydrogenation of both mono- and disubstituted acetylenes than Raney Ni or those obtained by reduction in THF.86 With the nickel produced in ethanol, the rate of hydrogen uptake after 1 equiv was almost nil in the case of 3-hexyne, and 98-99% of cA-3-hexene along with only 1-2% of hexane was produced. [Pg.165]

Raney Nickel Preparation (Caution Raney nickel is pyrophoric when dry.) Raney nickel is produced by reacting nickel-aluminum alloy with sodium hydroxide. Each Raney nickel pellet is prepared individually, and each is enough catalyst for one determination. To produce one Raney nickel pellet, accurately weigh 1 g of nickel-aluminum alloy powder (50% Ni, 50% Al), place it in a 50-mL centrifuge tube, and chill it in an ice bath. Slowly add 5 mL of water to the tube, and let it stand for 10 min. Then, slowly add 10 mL of 2.5 N sodium hydroxide, and allow the mixture to react for 30 min. Cap the tube, and place it in a 50° water bath for 2 h. Centrifuge the mixture at 1000 rpm for 10 min, and discard the supernatant liquid. Wash the pellet twice with 15 mL of water and twice with 15 mL of isopropanol, centrifuging between each wash. Store the catalyst under isopropanol for no longer than 2 weeks. [Pg.87]

Note Properly dispose of unused Raney Nickel Preparation by transferring it to a 250-mL Erlenmeyer flask, and placing it in a fume hood. Add 20 mL of 60% (w/v) hydrochloric acid, and allow complete digestion... [Pg.87]

Note Properly dispose of the unused Raney Nickel Preparation by transferring it to a 250-mL Erlenmeyer... [Pg.9]

Procedure Test a representative portion of the sample. Accurately weigh 15 to 20 g of the sample, and place it on the bottom of the boiling flask. Discard the isopropanol from the Raney Nickel Preparation, add 10 mL of 95% isopropanol, mix, and place the mixture in the sample oil. Attach the water condenser and the nitrogen line to the boiling flask and adjust the gas flow to 4 psi through the sample. Place a heating mantle under the... [Pg.9]

Supported nickel catalysts, the analogues Raney nickel prepared from amorphous alloys of Ni-Al with a metalloid such as B or P, and supported Rh catalysts are some of the alternatives currently under study. [Pg.95]


See other pages where Nickel preparation is mentioned: [Pg.535]    [Pg.142]    [Pg.20]    [Pg.34]    [Pg.8]    [Pg.107]    [Pg.450]    [Pg.799]    [Pg.7]    [Pg.21]    [Pg.59]    [Pg.617]    [Pg.198]    [Pg.229]    [Pg.87]    [Pg.555]    [Pg.590]    [Pg.29]    [Pg.367]    [Pg.198]   
See also in sourсe #XX -- [ Pg.18 , Pg.88 ]

See also in sourсe #XX -- [ Pg.19 ]




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Benzylic nickel halides preparation

Nickel carbonyl preparation

Nickel catalyst, Raney, in preparation

Nickel catalyst, Raney, in preparation of 2,2 -bipyridine

Nickel catalyst, prepared from

Nickel catalysts preparation

Nickel complexes electrochemical preparation

Nickel complexes preparation

Nickel dioxide preparation

Nickel phthalocyanine preparation

Nickel sample preparations

Nickel sulfide catalysts preparation

Nickel tetracarbonyl preparation

Nickel, electrolytic preparation

Nickel, electrolytic preparation properties

Nickel, electrolytic preparation sources

Nickel, surface preparation

Nickel-activated carbon catalysts preparation

Nickel-alumina catalyst preparation

Nickel-copper alloys preparation

Nickel-kieselguhr catalysts preparation

Preparation Raney nickel

Preparation Urushibara nickel

Preparation highly reactive nickel

Preparation nickel borides

Preparation of Metallic Nickel Powders and Their Reaction with 4-Nitrobenzyl Chloride

Preparation of Nickel Carbonyl

Preparation of Nickel(III) Oxide

Preparation of Nickel, Cobalt, or Chromium Chloride

Preparation of Potassium Bis (biureto)nickelate (III)

Preparation of Raney Nickel Catalyst

Preparation of Reduced Iron (Cobalt, Nickel)

Preparation of activated nickel

Preparation of metallic nickel

Preparation of the heterogeneous catalyst nickel-on-charcoal

Preparation typical nickel slurry

Preparation variables for new nickel catalysts modified with tartaric acid

Raney nickel Catalysts, Preparation

Typical Preparation of Activated Nickel

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