Borohydride, sodium salts

A novel reduction of a vinyl sulphone has been published by Ueno, Kojima and Okawara200 who have found that 2-(alkylsulphonyl)benzothiazoles can be reduced by aqueous sodium borohydride to form the sodium salts of alkylsulphinic acids, in good... 

Toxic pollutants found in the mercury cell wastewater stream include mercury and some heavy metals like chromium and others stated in Table 22.8, some of them are corrosion products of reactions between chlorine and the plant materials of construction. Virtually, most of these pollutants are generally removed by sulfide precipitation followed by settling or filtration. Prior to treatment, sodium hydrosulfide is used to precipitate mercury sulfide, which is removed through filtration process in the wastewater stream. The tail gas scrubber water is often recycled as brine make-up water. Reduction, adsorption on activated carbon, ion exchange, and some chemical treatments are some of the processes employed in the treatment of wastewater in this cell. Sodium salts such as sodium bisulfite, sodium hydrosulfite, sodium sulfide, and sodium borohydride are also employed in the treatment of the wastewater in this cell28 (Figure 22.5). 

Early use of the low-molecular-weight quaternary ammonium borohydrides in hydrocarbon solvents showed little advantage over the use of sodium borohydride in aqueous or alcoholic media. Although the ammonium salts in benzene appealed to be capable of effecting all the normal reductions exhibited by the sodium salt in water, they appeared to be generally less reactive. This is well illustrated by the recrystallization of tetra-n-butylammonium borohydride from acetone, if the operation is performed rapidly [5,6],... 

Kinetic studies established that tetra-n-butylammonium borohydride in dichloromethane was a very effective reducing agent and that, by using stoichiometric amounts of the ammonium salt under homogeneous conditions, the relative case of reduction of various classes of carbonyl compounds was the same as that recorded for the sodium salt in a hydroxylic solvent, i.e. acid chlorides aldehydes > ketones esters. However, the reactivities, ranging from rapid reduction of acid chlorides at -780 C to incomplete reduction of esters at four days at 250 C, indicated the greater selectivity of the ammonium salts, compared with sodium borohydride [9], particularly as, under these conditions, conjugated C=C double bonds are not reduced. 

A difference in the reactivities and selectivities between tetra-n-butylammonium borohydride and sodium borohydride in the reduction of conjugated ketones is well illustrated with A1-9 2-octalone (Scheme 11.3) [17], Reduction with the sodium salt in tetrahydrofuran is relatively slow and produces the allylic alcohol (1) and the saturated alcohol (2) in a 1.2 1 ratio whereas, in contrast, tetra-n-butylammonium borohydride produces the non-conjugated alcohol (3) (50%) and the saturated alcohol (2) (47%), with minor amounts of the ketone (4), and the allylic alcohol (1) [16]. It has been proposed that (3) results from an initial unprecedented formation of a dienolate anion and its subsequent reduction. 

The neutralization values were influenced by reduction with strong reducing agents, lithium aluminum hydride, sodium borohydride, and amalgamated zinc plus hydrochloric acid (35, 46). For the most part, the consumption of NajCOj and of NaOEt decreased in equivalent amounts. This is further confirmation of the assumption that lactones of the fluorescein type or of the lactol type are present. The reaction with sodium ethoxide was shown to be no true neutralization, that is, exchange of H+for Na+, at all, but an addition reaction w ith the formation of the sodium salt of a semi-acetal or ketal ... 

Potassium borohydride may be prepared by reacting potassium hydroxide with sodium borohydride. The salt precipitates from an aqueous solution of sodium borohydride with addition of potassium hydroxide ... 

Sodium Hydrosulfide Solution Sodium Bisulfite Sodium Borate Sodium Borohydride Sodium Cacodylate Hexadecyl Sulfite, Sodium Salt Sodium Chlorate Sodium Chromate Sodium Chromate Sodium Cyanide... 

The optimum process for converting aqueous solutions of the sodium salt of R-aminoketone (X) to dilevalol DBTA salt resulted from a study of such parameters as reaction solvent, temperature, mole equivalents of sodium borohydride, mole equivalents of DBTA and crystallization conditions. The reduction process, which essentially yielded a 1 1 mixture of RR and SR compounds, was monitored by HPLC (Scheme 8). The plant equipment layout is shown in Figure 2. The process containment equipment (Krauss Mallei Titus system) used for the filtration, washing and drying steps is shown in Figure 3. 

A. Reductions with Sodium Borohydride Quinolinium salts are converted by sodium borohydride to the corresponding 1,2,3,4-tetrahydroquinolines as the major product. Usually, however, small amounts of 1,2-dihydroquinoline can be... 

Reduction of acid chlorides to aldehydes One of the most useful synthetic transformations in organic synthesis is the conversion of an acid chloride to the corresponding aldehyde without over-reduction to the alcohol. Until recently, this type of selective reduction was difficult to accomplish and was most frequently effected by catalytic hydrogenation (the Rosenmund reduction section 6.4.1). However, in the past few years, several novel reducing agents have been developed to accomplish the desired transformation. Among the reagents that are available for the partial reduction of acyl chlorides to aldehydes are bis(triphenylphosphine)cuprous borohydride , sodium or lithium tri-terf-butoxyaluminium hydride, complex copper cyanotrihydridoborate salts °, anionic iron carbonyl complexes and tri-n-butyltin hydride in the presence of tetrakis(triphenylphosphine)palladium(0). ... 

Naphtho[l,8-c]-l,2-diselenole 4 was reduced with sodium borohydride to provide the sodium salt 48 that was subsequently alkylated or arylated by reaction with a suitable electrophile (Scheme 1) <1995T12239, 1996J(P1)1783, 1996CC371, 1998JOC8790, 1999JOC6688>. Thus, treatment with an excess of 1,3-dibromopropane gave compound 49 <1996J(P1)1783>. 

Sodium 1-methylethanetellurolate and hexadecanetellurolate were obtained from sodium hydrogen telluride and the appropriate alkyl halide in THF or THF/ethanol. The sodium hydrogen telluride was prepared from tellurium and sodium borohydride in water. Equimolar amounts of disodium telluride combined with aliphatic carboxylic acid chlorides in tetrahydrofuran at — 30" and with aromatic carboxylic acid chlorides in tetrahydrofuran at 0° to give sodium tellurolates that have an acyl group bonded to the tellurium atom. These tellurolates, the sodium salts of tellurolocarboxylic acids, are dark-red substances that were obtained in almost quantitative yields. 

The reduction of aldoses/ketoses occurs readily with sodium borohydride and during the reaction the pH increases to about 9 (O Scheme 19) [155]. For the reduction of aldonolactones in water the first step of the reduction has to be carried out at a pH around 5 in order to avoid ring-opening of the lactone to the corresponding sodium salt which will not react with sodium borohydride. The pH control can be achieved by performing the reduction in the presence of an acidic ion-exchange resin, e. g., Amberlite IR-120 [156]. In this way, it is possible to stop the reduction at the aldose step. Alternatively, more sodium borohydride can be added and thereby increasing the pH to 9 by which the alditol is obtained (O Scheme 19). The reduction of aldonolactones to alditols can also be performed in anhydrous methanol or ethanol where hydrolysis of the lactone is not a side reaction [156]. 

The synthesis of the first half-metallocene bis(borohydrides) of lanthanide elements has been achieved by a reaction of the tetraisopropylcyclopentadienyl sodium salt NafCsHPr ) with Ln(BH4)3(THF)3 (Ln = Sm, Nd) at room temperature to afford the monocyclopentadienyl complexes (CsHPr 4)Sm(BH4)2(THF) and (CsHPr 4)Nd(BH4)2(THF) in 50-60% yield. These complexes are thermally stable and melt without decomposition at around 170 °C.307 Analogous compounds have also been synthesized with the use of the [CsMe4Prn] ligand.308... 

In contrast to allyl halides substituted with one ASG, the cyclopropanation reaction proceeds relatively smoothly when a second ASG is present. Generally, the best results are obtained with sodium borohydride, sodium cyanide, potassium cyanide, and the sodium salts of alcohols or thiols as the nucleophilic species (Table 22, entries 3-26). Even spiroalkanes can be synthesized with the nucleophiles described above (Table 23). Examples illustrating this route are the conversion of a tetracyclic enamino ester with potassium cyanide to the corresponding electrophilic cyclopropane 2, and the facile one-pot synthesis of 1,1 -bis(hydroxymethyl)cyclo-propanes 3 by reduction of halogenated alkylidene malonates with lithium aluminium hydride. ... 

CHROMIC ACID, DIPOTASSIUM SALT (7778-50-9) Noncombustible, but many chemical reactions can cause fire and explosions. A powerful oxidizer. Violent reaction with many substances, including combustible materials, reducing agents, organic materials, finely divided metals, ammonium nitrate, ammonium perchlorate, fluorine, hydrazine, hydrazinium nitrate, hydroxylamine, iron powder, nitric acid, potassium iodide, sodium borohydride, sodium bromide, sodium tetraborate and its decahydrate, tungsten, and zirconium dusts. Mixture with sulfuric acid forms chromic acid. Incompatible with ethylene glycol, iron, tungsten. 

Reid et al. (454) reinvestigated the synthesis of the zirconium and hafnium borohydrides. The reaction of diborane with zirconium tetrachloride dissolved in tetrahydrofuran (THE) does not give a boron-containing product, whereas the reaction of diborane with an ether solution of zirconium tetraethoxide gives the desired metal borohydx ide although it is difficult to separate from the borate ester coproduct. The reaction of Katz (246) was run with potassium fluorozirconate in preference to the sodium salt because the potassium salt reacted more readily,... 

On the other hand, the number of highly reactive chemicals that advance from the sta of laboratory curiosities to commercial items is constantly increasing, Some of these are sodium hydride (NaH), lithium aluminum hydride (LiAlH ), lithium borohydride (LiBH ), aluminum and beryllium borohydride, Al(BH4)3 and BefBH ), the sodium salt of nitromethane sodium methane nitronate or if one prefers sodium nitro methanate (HjCNOgNa), - and barium carbide (BaCg)/ all of which can flame on contact with water. Again, it must be stressed that particle size and other conditions of exposure may determine whether there is flaming or merely a violent reaction on exposure to water, air, or both. 

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