Compounds by sodium

Reduction of carbonyl compounds can be carried out in an aqueous medium by various reducing reagents. Among these reagents, sodium borohydride is the most frequently used. The reduction of carbonyl compounds by sodium borohydride can also use phase-transfer catalysts (Eq. 8.4),10 inverse phase-transfer catalysts,11 or polyvinylpyridines12... 

Azoxybenzene was synthesized in 85% yield by reduction of nitrobenzene with sodium arsenite [221]. Nitrotoluenes and 2,5-dichloronitrobenzene were converted to the corresponding azoxy compounds by heating to 60-90° with hexoses (yields up to 74%) [316. Some ring-substituted nitrobenzenes were converted to azoxy compounds, some other to azo compounds by sodium bis 2-methoxyethoxy)aluminum hydride [575]. 

Reduction of aryl esters.1 Alkyl benzoates are reduced to 1,4-dihydro compounds by sodium in THF NH3 if 1 2 equivalents of water is present before addition of the metal (equation I). The presence of water can be useful for reduction of other aromatic systems (equation II). 

This reaction can be employed to remove a primary amino group from an aromatic compound, especially. when the ordinary method of direct reduction of the diazonium compound by sodium stannite or alcohol is not applicable. Although in the application of this method the hydrazine can be prepared as the hydrochloride, and reduced in the same solution, yet it is better to isolate the free base and oxidise it separately, since in the oxidation of the hydrochloride there is a tendency for the hydrazine radical to be replaced by chlorine. 

Zadmard, R., Saidi, M.R., Bolourtchian, M. and Naldishab, L., Microwave-assisted reduction of beta-trimethylsilyl carbonyl compounds by sodium borohydride, Phosphorous, Sulphur Silicon Relat. Elem., 1998, 143, 63-66. 

There is also a test method (ASTM E-256) for the determination of chlorine in organic compounds by sodium peroxide bomb ignition that is also worthy of reference. The method is intended for application to samples of organic materials containing more than 0.5% chlorine, and the assumption is that halogens other than chlorine will not be present. 

ASTM E-256. Standard Test Method for Chlorine in Organic Compounds by Sodium Peroxide Bomb Ignition. 

An interesting example, and the one where these ideas were first applied,40 is the Birch reduction of aromatic compounds by sodium in liquid ammonia containing alcohol. These reactions seem to take place by two successive electron transfers, each followed by capture of a proton, i.e. 

Berberines are reported to be reduced to dihydroberberines rather than the tetrahydro-compounds by sodium bis(2-methoxyethoxy)aluminium hydride.80 Partial reduction of coralynium salts affords the tertiary dienamine (55), autoxida-tion of which, at pH 8, yields the betaine (56) this can be oxidized by peracids to 6 -acetylpapaveraldine (57), obtainable directly from the dienamine (55) by photolysis in the presence of air. The diketone reacts with hydrazine to give the 1,2-diazine (58).81... 

According to more recent research hydrazobenzene and hydrazotoluene can also be used as hydrogen donors to oxygen. The azobenzene or azotoluene resulting from oxidation are reduced to the initial hydrazo- compounds by sodium amalgam. 

The reduction of diorgano ditellurium compounds by sodium borohydride is applicable to both dialkyl, divinyl and diaryl ditellurium compounds (Table 2 p. 166). 

Aryl tellurium halides are easily reduced to diaryl ditellurium compounds by sodium sulfide7, sodium disulfite8, zinc in refluxing toluene9, or hydrazine hydrate10 (p.273). 

Arenetellurinic anhydrides are reduced to diaryl ditellurium compounds by sodium sulfide nonahydrate2 or dipotassium disulfite3. 

This can be done in two steps, provided the intermediate is stable, but, because the instability of many imines makes them hard to isolate, the most convenient way of doing it is to form and reduce the imine in a single reaction. The selective reduction of iminium ions (but not carbonyl compounds) by sodium cyanoborohydride makes this possible. When NaCNBH3 is added to a typical imine-formation reaction it reacts with the products but not with the starting carbonyl compound. Here is an example of an amine synthesis using reductive amination. 

The differentiation of inorganic As(III) and As(V) can be achieved by exploitation of the pH sensitivity of the reduction of arsenic compounds by sodium tetrahydroborate(III), as adapted to analyses by the AgDDC spectrophotometric procedure. ... 

The statements made above concerning the replacement of a diazogroup by hydrogen are also applicable to this reaction. If it is desired to prepare an amido-compound from an amido-free compound, and if the direct reduction of the diazo-compound by sodium stannous oxide or alcohol (see page 210) has been shown to be impracticable, then, as above, the hydrochloric add salt of the corresponding hydrazine is prepared, the free hydrazine is liberated, and oxidised with caustic soda. The amido-free substance is not always easily volatile, as in the example dted. In a case of this kind, the oxidation may be effected in an open vessel the reaction product is obtained tither by filtering or by extracting with ether. It may be pointed out here that it is more convenient to separate the hydrazine from the hydrochloric add salt, and subject this to oxidation. If a hydrochloric add salt of a hydrazine is oxidised it may happen that the hydrazine radical will be replaced by chlorine ... 

Reduction of alkyl or aryl halides. Reduction of organic halogen compounds by sodium borohydride proceeds more rapidly in DMSO than in anhydrous diglyme.8... 

Sulfonation of nitroso compounds by sodium hydrogen sulfite leads to amino sulfonic acids by simultaneous reduction.1240 194 When aromatic nitro compounds are subjected to this reaction, sulfonation in the ring is accompanied by formation of arylamine-JV-sulfonic acids (arylsulfamic acids), which on acid fission also give amino sulfonic acids this reaction, known in the literature as the Piria reaction, has been reviewed in papers by Hunter and his co-workers.195... 

Ferric Pyrophosphate—(Fej)a(Pa07)s—745.6—is precipitated by decomposition of a solution of a ferric compound by sodium pyrophosphate an excess of the Na salt dissolves the precipitate when warmed, and, on evaporation, leaves scales of a double salt, (Fea)j(PaOT)3, Na8(Pj07)a -I- 20 Aq. 

With silica as a support and sodium borohydride as a reducing agent, cyclohexanol has been prepared from cyclohexanone in less than 3 min using a scientific microwave unit (Scheme 6.9). The reduction of carbonyl compounds by sodium borohydride is traditionally time consuming. It can take 2-4 h to reach completion, this equating to a whole laboratory period, and usually another lab period is required for product isolation and characterization. Using the microwave procedure, the entire experiment can be completed in one 2.5 h session. The reaction was performed in closed tubes... 

This reaction was first reported by Wooster in 1937d and subsequently by Hiickel et al in 1939, for the reduction of aromatic compounds by sodium in liquid ammonia with water however, no structural information was provided. It was Birch who extended Wooster s protocol in 1944 and since then had extensively explored the reduction of benzene and aromatic derivatives with alkali metal (i. e Li, Na, K) in liquid ammonia in the presence of an alcohol (as the proton donor) to produce corresponding cyclohexa-1,4-diene derivatives." Therefore, the reduction of aromatic compounds by alkali metal in liquid ammonia in the presence of alcohol is generally known as the Birch reduction or metal-ammonia reduction. In addition, this reaction is also referred to as the Birch reaction, and in one instance is cited as the Birch-Hiickel reduction. ... 

Iron and ruthenium carbonyls induce reductive carbonyl at ion o-f nitro compounds by sodium methoxide[[87j ... 

Draw the structure of the product that results from complete reduction of the following compounds by sodium borohydride. 

Reduction of the organomercury compound by sodium borohydride, NaBH, replaces HgOAc by H. 

The complexing role of fluoride ions in the reduction of refractory metals is now well known for the metal recovery [12]. The technology of extracting tantalum in molten salts is based on the formation of K2TaF7, obtained by reaction of HF on the oxide Ta205 extracted from raw materials [14] before the reduction of this compound by sodium in the liquid phase ... 

Vinyl azides, which can be obtained from olefins, are converted in high yield into the corresponding carbonyl compounds by sodium sulphide in methanol." The mercury(ii)-catalysed hydrolysis of the vinyl chloride (32) shows an interesting solvent dependence in dichloromethane, acetic acid, benzene, or acetonitrile the yield of (33) is almost quantitative and no trace of (34) is observed, whereas in methanol 83% (34) and 6% (33) are obtained [equation (7)]." ... 

E. Santaniello, F. Ponti, and A. Manzocchi. Reduction of carbonyl compounds by sodium borohydride absorbed on alumina. Synthesis, 1978, 891. 

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