Reduction with alcohols

Reductions with alcohols other than t-butyl alcohol are carried out using the general procedure given above and replacing the -butyl alcohol by an equivalent amount of the other alcohol. 

Electrocatalytic regeneration of NADH has also been performed at polymer-modified electrodes with pendent [(r/s-Cs M cs) R h( bpy )C1]1 55,56 and [Rh(terpy)2]3+ 57 complexes, and coupled to enzymatic reduction with alcohol dehydrogenase.55,57... 

Hirai, H., Nakao Y., and Toshima, N., Preparation of colloidal transition-metals in polymers by reduction with alcohols or ethers, J. Macromol. Sci. Chem. A, 13, 727, 1979. 

Another way to statin side chains, via the intermediate syn-(i K,5,S )-6-chloro-hexanoate, employs regioselective and (K)-specific reduction with alcohol dehydrogenase (ADH) from Lactobacillus brevis to yield the intermediate (5S)-6-chloro-3-ketohexanoate from the 3,5-diketo acid (Wolberg, 2001) (Figure 13.16). Further reduction of (5S)-6-chloro-3-ketohexanoate to syn-(3R,5S)-6-chlorohexanoate is afforded chemically with NaBH4/B(OMe)Et2. 

Alone, the compound is of no interest as an explosive, for 1,3,5-trichlorobenzene is too expensive as a starting material. It is prepared by the chlorination of aniline followed by diazotization and reduction with alcohol. Nevertheless it may be used for the preparation of explosives with certain specially valuable properties, for example, an initiating substance - trinitrotriazidobenzene - (Vol. Ill) or for the very powerful high explosive - trinitrotrimethylnitroaminobenzene (Vol. III). It was used in Germany as an insecticide. 

While the use of zeolites as catalysts for C=0 reduction with alcohols as a reductant goes back to the eighties, stereoselective versions of this reaction have been developed more recently. In this so-called MPV (Meerwein-Ponndorf-Verley) reaction, the reactant carbonyl compound and the reducing alcohol coordinate simultaneously on a Lewis acid centre. In the reduction of 4-t-butylcyclohexanone, the trans product would normally be thermodynamically favored. However, the cis alcohol isomer is economically much more interesting. Van Bekkum and coworkers discovered that in the constrained pores of an Al- or Ti-Beta zeolite, more than 95 % of the product has the cis configuration (59) ... 

Molybdenum Sulphates.— Reduction of a solution of molybdic acid in sulphuric acid by means of hydrogen sulphide is stated to yield the compound M0O3.M0O0.2SO3 as a black substance, soluble in water to an unstable brown solution reduction with alcohol is said to yield soluble blue crystals of the sulphate 7MoO3.2MoO3.7SO3.aq. 

Manning, Ball, and Menis (162) have carried out polarographic and coulometric reductions of molybdenum (VI) in a nitrilotriacetic acid medium and have applied their findings to the analysis of thorium-uranium oxide mixtures. The determination of molybdenum in steel using coulometric techniques has been reported by Ibrahim and Nair (163) who reduced molybdenum at —0.40 V vs. SCE in a sodium acetate buffered chloride medium. Chromium interference can be removed by pre-reduction with alcohol. The catalytic effect of lower oxidation states of molybdenum in the reduction of perchlorate has been used as an indirect electro-analytical method for the determination of perchlorate (159, 164). 

Ethylamine, monoethylamine, CH3CH2NH2-B.p. 19 C. Prepared by reduction of acetonitrile or by heating ethyl chloride with alcoholic ammonia under pressure. It is a strong base and will displace ammonia from ammonium salts. Forms a crystalline hydrochloride and also crystalline compounds with various metallic chlorides. 

Piperitone is of considerable technical im portance. It is a colourless oil of a pleasant peppermint-like smell. (-)-Piperilone has b.p. 109-5-110-5 C/I5mm. Piperitone yields thymol on oxidation with FeCl. On reduction with hydrogen in presence of a nickel catalyst it yields menthone. On reduction with sodium in alcoholic solution all forms of piperitone yield racemic menthols and womenthols together with some racemic a-phel)andrene. 

SchifT s bases A -Arylimides, Ar-N = CR2, prepared by reaction of aromatic amines with aliphatic or aromatic aldehydes and ketones. They are crystalline, weakly basic compounds which give hydrochlorides in non-aqueous solvents. With dilute aqueous acids the parent amine and carbonyl compounds are regenerated. Reduction with sodium and alcohol gives... 

Extremely dry (or super-dry ) ethyl alcohol. The yields in several organic preparations e.g., malonic ester syntheses, reduction with sodium and ethyl alcohol, veronal synthesis) are considerably improved by the use of alcohol of 99-8 per cent, purity or higher. This very high grade ethyl alcohol may be prepared in several ways from commercial absolute alcohol or from the product of dehydration of rectified spirit with quicklime (see under 4). 

Direct Borohydride Reduction of Alcohols to Alkanes with Phosphonium Anhydride Activation N-Proovlbenzene. To a solution of 5.56 g (20 mmol) of triphenylphosphine oxide in 30mL of dry methylene chloride at CfC was added dropwise a solution of 1.57 mL (10 mmol) of triflic anhydride in 30mL of dry methylene chloride. After 15 min when the precipitate appeared, a solution of 1.36g (10 mmol) of 3-phenyl-1-propanol in 10 mL of dry methylene chloride was added and the precipitate vanished in 5 min. An amount of 1.5g (40 mmol) of sodium borohydride was added as a solid all at once and the slurry was stirred at room temperature for... 

Reduction with sodium in alcohol was unsuccessful (54). The introduction of lithium aluminium hydride has provided an elegant method for the reduction of thiazole esters to hydroxythiazoles for example, ethyl 2-methyl-4-thiazolecarboxylate (11 with lithium aluminium hydride in diethyl ether gives 2-methyl-4-(hydroxymethyl)thiazole (12) in 66 to 69% yield (Scheme 7) (53),... 

Reduction with aluminium isopropoxide by the Meerwein-Pondorf procedure yields the alcohol (56, 57, 112). 

Reduction to alcohols (Section 15 2) Aide hydes are reduced to primary alcohols and ketones are reduced to secondary alcohols by a variety of reducing agents Catalytic hydrogenation over a metal catalyst and reduction with sodium borohydride or lithium aluminum hydride are general methods... 

Reduction with lithium aluminum hydride (Sec tion15 3) Lithium alumi num hydride cleaves es ters to yield two alcohols... 

The concentration of chromic acid can be determined from its reduction by alcohols under conditions when the kinetics are pseudo-first-order in analyte. One approach is to monitor the absorbance of the solution at a wavelength of 355 nm. A standard solution of 5.1 X lO " M chromic acid yields absorbances of 0.855 and 0.709 at, 100 s and 300 s, respectively, after the reaction s initiation. When a sample with an unknown amount of chromic acid is analyzed under... 

AHylestrenol (37) is prepared from (32), an intermediate in the synthesis of norethindrone. Treatment of (32) with ethanedithiol and catalytic boron trifluoride provides a thioketal. Reduction with sodium in Hquid ammonia results in the desired reductive elimination of the thioketal along with reduction of the 17-keto group. Oxidation of this alcohol with chromic acid in acetone followed by addition of aHyl magnesium bromide, completes the synthesis... 

The compound can be prepared from 2,4,6-trinitrophenol (picric acid [88-89-1]) by reduction with sodium hydrosulfide (163), with ammonia —hydrogen sulfide followed by acetic acid neutralization of the ammonium salt (164), with ethanolic hydrazine and copper (165), or electrolyticaHy with vanadium sulfate in alcoholic sulfuric acid (159). Heating 4,6-dinitro-2-benzamidophenol in concentrated HQ. at 140°C also yields picramic acid (166). 

Sulfonic acids are prone to reduction with iodine [7553-56-2] in the presence of triphenylphosphine [603-35-0] to produce the corresponding iodides. This type of reduction is also facile with alkyl sulfonates (16). Aromatic sulfonic acids may also be reduced electrochemicaHy to give the parent arene. However, sulfonic acids, when reduced with iodine and phosphoms [7723-14-0] produce thiols (qv). Amination of sulfonates has also been reported, in which the carbon—sulfur bond is cleaved (17). Ortho-Hthiation of sulfonic acid lithium salts has proven to be a useful technique for organic syntheses, but has Httie commercial importance. Optically active sulfonates have been used in asymmetric syntheses to selectively O-alkylate alcohols and phenols, typically on a laboratory scale. Aromatic sulfonates are cleaved, ie, desulfonated, by uv radiation to give the parent aromatic compound and a coupling product of the aromatic compound, as shown, where Ar represents an aryl group (18). 

Reduction of Alcohols or Ketones. The reaction of alcohols and ketones with chlorine and base to give chloroform is well known (30). 

After washing with chlorhexidine skin cleanser for 15 seconds, a 99.9% reduction of transient contaminants was achieved (216). Chlorhexidine is sometimes combined with alcohol to achieve the rapid reduction obtained with alcohol and the residual effect of chlorhexidine. It is substantive to the skin, and repeated use results in lower levels of bacteria on the skin. 

Reduction with Metals and Metal Hydrides. Practically any ester can be reduced by Na—C2H OH, Li or Na—NH, LiAlH, LiBH, or NaBH to give alcohols in excellent yield (35,36). Carbon-carbon double bonds are usually preserved using these reducing reagents. 

Reductive cleavage to alcohols by catalytic hydrogenation (64HC(19-1)188) has largely given way to reduction with hydride reagents (Section 5.05.3.4.3(t)u)). 

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