Strong alkaline medium

The detailed mechanism of battery electrode reactions often involves a series of chemical and electrochemical or charge-transfer steps. Electrode reaction sequences can also include diffusion steps on the electrode surface. Because of the high activation energy required to transfer two electrons at one time, the charge-transfer reactions are beheved to occur by a series of one electron-transfer steps illustrated by the reactions of the 2inc electrode in strongly alkaline medium (41). 

Arenediazonium ions are stable in acidic or slightly alkaline solution in moderate to strong alkaline medium they are converted into diazohydroxides 4 ... 

It has been demonstrated that beta-hydroxynitrosamines such as NDE1A may undergo retroaldol-type reactions in strongly alkaline medium to form nitrosamlnes of lower molecular weight (19, 20). In some cases the nitrosamlnes formed from the retroaldol reaction are more potent animal carcinogens than is NDE1A. 

The organic coating at the metal interface is modified chemically by the strong alkaline medium that is generated under the coating. 

Direct preparation of azo compounds in good yields is accomplished by treatment of nitro compounds with lithium aluminum hydride [576], with magnesium aluminum hydride [577], with sodium bis(2-methoxy ethoxy)aluminum hydride [575], with silicon in alcoholic alkali [331] or with zinc in strongly alkaline medium [578], Hydrazobenzene was obtained by controlled hydrogenation of nitrobenzene in alkaline medium (yield 80%) [572] and by reduction with sodium bis 2-methoxyethoxy)alumium hydride (yield 37%) [544],... 

Phase-transfer catalysed N-alkylation of diphenylphosphinic amide (I) is totally unsuitable in the case of easily hydrolysable organic halides, especially those containing additional functional groups (i.e. carbonyl or carboalkoxyl) which decompose readily in strongly alkaline medium. To circumvent the difficulty connected with simultaneous mono- and dialkylation of (I) under anhydrous conditions, N-(t-butyloxycarbonyl) diethyl phosphoroamidate (X), a doubly-protected ammonia derivative, was devised as a useful and superior substitute of phthalimide in the Gabriel-type synthesis of amines. 

Nitric acid esters can be used as nitrating agents in the presence of sulphuric acid and in some cases in a strongly alkaline medium. 

Isatinates, obtained from the alkaline hydrolysis of isatin derivatives, are the precursors of the quinoline-4-carboxylic acids. These compounds are prepared by the Pfitzinger reaction from isatins in the presence of enolizable keto compounds in strongly alkaline medium, such as 8N KOH. In these solutions, isatinates condense with the keto compound and subsequently cyclize to the quinoline products. Recently, a modified procedure has been described, using acidic conditions. This methodology was subsequently applied to a concise manner for the preparation of derivatives of camptothecin, a topoisomerase I inhibitor23 (Scheme 115). 

The oxidation of formaldehyde by octacyanotungstate(V) ions in strong alkaline medium has been investigated, the reaction stoicheiom-etry being... 

Two parallel processes appear to be occurring rate-determining proton abstraction from the imidazolium ion by D2O and by OD to give the ylide at C-2 (137) followed by deuteration there (Scheme 66). The pD profile for 4-substitution can be accounted for by an additional path involving proton abstraction from the imidazole neutral molecule. In strongly alkaline medium imidazoles with no nitrogen substituent exchange more readily... 

Vat dyes. The vat dyes are insoluble complex polycyclic molecules based on the quinone structure (keto-forms). They are reduced with sodium hydrosulfite in a strongly alkaline medium to give soluble leuco forms that have a great affinity for cellulose. After the reduced dye has been absorbed on the fiber, the leuco forms are reoxidized to the insoluble keto forms. The dyeings produced in this way have high wash and light-fastness. An example of a vat dye is vat blue 4 (indan-threne) [5]. 

In either case, the sugar is liberated in its reducing form and is subject to all of the reactions which may occur in a strongly alkaline medium. 

Aqueous casting slips of satisfactory properties can be prepared from non-plas1 substances (e.g. oxides, nitrides) by controlling their pH Fig. 160 shows the effe of pH on viscosity of a—AI2O3 suspension of 5 pm particle size. In this case, a suitab fluidity is achieved in an acid or strongly alkaline medium. Substances that a hydrolyzed by water (e.g. MgO) can be shaped by casting a suspension in alcohol... 

As the alcohol is not formed, there is no need to use sterically hindered alkoxides. This reaction is usually carried out in pentane or in an excess of alkene at 0 to 10 °C and is recommended for the preparation of thermally unstable 1,1-dichlorocyclopropanes. An interesting modification for the synthesis of 1,1-dichlorocyclopropanes which eliminates strongly alkaline medium, utilizes trimethylsilyl trichloroacetate and potassium fluoride in the presence of a catalyst (a quaternary ammonium salt or a crown ether),... 

The Phthaleins. All phthaleins are rather insoluble in water but very soluble in alcohol. Most of them are colorless in acid medium (lactone form), while the alkaline form is colored (red, violet, blue, green) and possesses the quinone phenolate structure. In strongly alkaline medium the color gradually fades due to the transformation of the quinone phenolate into the colorless carbi-nol form. These structural changes will be discussed in detail in Chapter Seven. The velocity with which the colors of various phthaleins fade in alkaline medium has been measured by A. Thiel and coworkers, and the velocity constants determined. 

Ammonia is usually determined after being separated from a strongly alkaline medium and then absorbed in dilute H2SO4 or HCl. It is sometimes possible to carry out the indophenol reaction without separating the ammonia (e.g., in natural waters). In the presence of EDTA, moderate quantities (0.1-0.5 mg) of Ca, Mg, and A1 do not interfere. The addition of tartrate prevents the precipitation of hydrolysable metals. Phosphate interferes in the colour reaction [23]. 

The most time-honored and certainly dependable method for serum, urine, and tissue copper determination is that described by Eden and Green in 1940 (E3). Wet ashing with a combination of sulfuric, perchloric, and nitric acids is followed by the deionization of iron with citrate and/or pyrophosphate in strongly alkaline medium. Diethyldithiocarbamate is the color reagent and the complex is extracted into amyl alcohol. Provided blanks can be kept low, which can be achieved only by applying extreme care to avoid contamination of the many reagents, copper can be determined reliably in 0.5-1.0 ml of serum. While this method undoubtedly represents a great improvement over previous methods (M4, T5), it is somewhat cumbersome nevertheless it has proved its worth in many hands and has been the basis of a number of modifications and applications. 

Treatment of ultracurine A with sodium borohydride in strongly alkaline medium (pH 11) yields reduction product 4 (82), an extremely acid-sensitive compound, which in neutral solution exhibits a u.v. spectrum typical of the super-... 

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