Nickel treatment

The successful preparation of Il,ll-d2-5l5-androstan-3o -oh and 11,11-d2-(25R)-5a-spirostane in 83% and 91% isotopic purity by Raney nickel treatment of the 11,1 l-d2-12-ethylene thioketal derivatives further confirms the low degree of isotope scrambling with C-12 keto steroids. 

The required 1-oxa-l,3-diene precursor was synthesized according to the synthesis design (Scheme 8). Cycloadditon with enol ether furnished exclusively the endo-isomer. Raney nickel treatment in refluxing ethanol yielded in one step the desired tetrahydropyran derivative in a favorable 6 1 cis/trans ratio. Transformation into the lactone and ring closure with potassium tert.-butoxide afforded (+)-ramulosin. 

Sulfur-containing heterocyclic rings are readily desulfurized by treatment with Raney nickel. Thus the 1,2,4-thiadiazine (146) is fully desulfurized and cleaved to give (147) (67CB2159). Similarly, Raney nickel treatment of (148) gives RO2CNHNHCO2R... 

Finished hydrogenated vegetable oils contain less than 1 mg/kg nickel. Treatment of the finished oil with citric or phosphoric acid followed by bleaching should result in nickel levels of less than 0.2 mg/kg. 

Using data from other alkaloids, the NMR data enabled substantial progress to be made in the placement of the esterifying ester groups, but in these compounds the cathate bridge provided a novel feature. In the cases of both E3 and E4 this dilactone bridge could be opened by hydrogenolysis over palladium or by Raney nickel treatment to form 55 and 56, respectively. A new methyl resonance appeared in the NMR spectrum, and the new phenolic hydroxyl was characterized by a reversible bathochromic shift in the UV spectrum on the addition of... 

Thiolate ions react with a-(alkylthio)carbonyl compounds to afford disulfides and the corresponding reduced ketone (equation 26). The reaction apparently involves direct nucleophilic attack by thiolate on the sulfur atom of the alkylthio group. Other soft bases, such as cyanide ion, thiourea and tertiary phosphines, also effect this conversion. Raney nickel of course readily desulfurizes a-alkylthiocarbonyl compounds. The reaction is quite selective for example, the ester, ketone and alkenic moieties of (43) are unaffected by the Raney nickel treatment (equation 27). Raney nickel reduction of (44) is reported to proceed with retention of configuration in ethanol and with inversion in acetone. Telluride salts also desulfurize a-alkylthio ketones. ... 

The reaction of chiral aminals of the monohydrazone of glyoxal 6.49 with organolithium reagents is stereoselective. After Raney nickel treatment, followed by protection of the amine and hydrolysis, a-aminoaldehydes are obtained with an excellent enantiomeric excess [302]. Reaction of organomagnesium reagents with 6.49 in toluene, followed by the same treatment, gives the other enantiomer [1196] (Figure 6.41). 

Amino acid sequencing was performed (304) by initial Raney nickel treatment of cortinarin A followed by partial hydrolysis and degradation of the resulting linear peptide employing dansylation of the terminal amino acid. Dansyl amino acids were identified by comparison with standards using two-dimensional TLC on polyamide plates. The amino acid sequence was also determined by the mass spectrometry method (Scheme 61). The sequence reported (330) in 1986 appeared to be a reversal of that shown previously (304). 

Similar studies were carried out by American researchers [10]. In the field experiments, nickel was applied in the form of nickel chloride instead of the nickel sulphate used by Casalicchio and coworkers. Tests were carried out using two different nickel treatments in the soil into which musk melon was directly seeded as follows ... 

Reduction. Raney Nickel treatment of thioacetals is a standard method for carbony 1-to-methylene reduction." In the presence of Triethylamine, (1) reduces azides to primary amines (eq 14). Under the acidic conditions employed for thioacetal formation, this reduction does not occur (eq 8). " Reduction of peptidic disulfides to dithiols can be conveniendy accomplished with (1). ... 

Other compounds which may be found in crude oil are metals such as vanadium, nickel, copper, zinc and iron, but these are usually of little consequence. Vanadium, if present, is often distilled from the feed stock of catalytic cracking processes, since it may spoil catalysis. The treatment of emulsion sludges by bio-treatment may lead to the concentration of metals and radioactive material, causing subsequent disposal problems. 

Fortunately, in the presence of excess copper(II)nitrate, the elimination reaction is an order of magnitude slower than the desired Diels-Alder reaction with cyclopentadiene, so that upon addition of an excess of cyclopentadiene and copper(II)nitrate, 4.51 is converted smoothly into copper complex 4.53. Removal of the copper ions by treatment with an aqueous EDTA solution afforded in 71% yield crude Diels-Alder adduct 4.54. Catalysis of the Diels-Alder reaction by nickel(II)nitrate is also... 

Gassman and co-workers developed a synthetic route from anilines to indoles and oxindoles which involves [2.3]-sigmatropic rearrangement of anilinosul-fonium ylides. These can be prepared from Ai-chloroanilines and ot-thiomcthyl-ketones or from an aniline and a chlorosulfonium salt[l]. The latter sequence is preferable for anilines with ER substituents. Rearrangement and cyclizalion occurs on treatment of the anilinosulfonium salts with EtjN. The initial cyclization product is a 3-(methylthio)indole and these can be desulfurized with Raney nickel. Use of 2-(methylthio)acetaldehyde generates 2,3-unsubstituled indoles after desulfurization[2]. Treatment of 3-methylthioindoles with tri-fiuoroacetic acid/thiosalieylie acid is a possible alternative to Raney nickel for desulfurization[3]. 

Upon treatment with suitable cobalt complexes, methylbutynol cyclizes to a 1,2,4-substituted benzene. Nickel complexes give the 1,3,5-isomer (196), sometimes accompanied by linear polymer (25) or a mixture of tetrasubstituted cyclooctatetraenes (26). 

Nickel carbonyl is volatile, has Htde odor, and is extremely toxic. Symptoms of dangerous exposure may not appear for several days. Effective medical treatment should be started immediately. The plant should be designed to ensure containment of nickel carbonyl and to prevent operator contact. 

Direct hydrohquefaction of biomass or wastes can be achieved by direct hydrogenation of wood chips on treatment at 10,132 kPa and 340 to 350°C with water and Raney nickel catalyst (45). The wood is completely converted to an oily Hquid, methane, and other hydrocarbon gases. Batch reaction times of 4 hours give oil yields of about 35 wt % of the feed the oil contains about 12 wt % oxygen and has a heating value of about 37.2 MJ /kg (16,000 Btu/lb). Distillation yields a significant fraction that boils in the same range as diesel fuel and is completely miscible with it. 

Steels iu the AISI 400 series contain a minimum of 11.5% chromium and usually not more than 2.5% of any other aHoyiag element these steels are either hardenable (martensitic) or nonhardenable, depending principally on chromium content. Whereas these steels resist oxidation up to temperatures as high as 1150°C, they are not particularly strong above 700°C. Steels iu the AISI 300 series contain a minimum of 16% chromium and 6% nickel the relative amounts of these elements are balanced to give an austenitic stmcture. These steels caimot be strengthened by heat treatment, but can be strain-hardened by cold work. 

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