Bromine-Methanol

Anodic hydroxylation/methoxylation of furans has an exact chemical counterpart in the well-known bromine/methanol reaction, and the choice of method is not always easily made. One can compare the two methods particularly easily in syntheses of the flavoring component, the pyrone maltol 121, from the furan 122 since one group used the electrolytic method299 and another the chemical method.300... 

The bromine/methanol (18.1.1.4) oxidation of furans to give 2,5-dialkoxy-2,5-dihydrofurans and the cycloaddition of singlet oxygen (18.7) are discussed elsewhere in this chapter. 2,5-Dialkoxy-2,5-dihydrofurans can also be obtained by electrochemical oxidation in alcohol solvents or conveniently by oxidation with magnesium monoperoxyphthalate in methanol. Reaction of furan with lead(IV) carboxylates produces... 

In an unusual reaction, a furan derivative has been cyclized with hydrazine to give, after aerial oxidation in alkali, 6,9-dihydroxybenzo[ ]phthalazine-5,10-dione in excellent yield (Equation (40)). Normally furans need to be converted into unsaturated 1,4-dicarbonyl derivatives (bromine/ methanol, followed by hydrolysis) prior to reaction with hydrazine to give pyridazines, but in this case the carbonyl groups activate the furan to attack by hydrazine <93JHC1597>. 

The electrochemical or bromine/methanol oxidations of furans to give 2,5-dialkoxy-... 

Bowman and coworkers (1990) have reported a violent explosion in preparing a bromine-methanol solution useful in semiconductor etching. The mixture is exothermic, showing initial increases in temperature, which then decreases at varying rates. The authors have reported that a second temperature increase occurred at higher bromine concentrations, causing explosion at a 50% volume mixture. 

Free iron. By bromine/methanol or copper sulfate extraction, followed by ICP determination of Fe. 

As part of their studies, Bruening and coworkers [15] examined the effects of common etching procedures on the work function of CdSe. They observed that the bromine/methanol etch increases the work function while a subsequent hydrazine treatment then reduces it. Because the bromine/methanol etch leaves an elemental Se residue on the surface, the authors suggest that the higher work function of Se relative to CdSe may account for the increase in work function. They noted that such etching effects lead to ir-reproducible surfaces and can produce substantial variations in adsorption properties [15]. 

Sudhaker Nayak HV, Vasu KI, Prasad YVRK (1980) Texture dependent stress corrosion failure of commercial titanium sheets in bromine-methanol solution. J Mater Sci 15 1265-1275. doi 10.1007/BF00551816... 

This method is convenient for fabrication of GRIN lenses, where the required refractive index gradient is obtained by point diffusion [114]. Refractive microlenses with arbitrary geometry may be fabricated by photolithography so that first masks and etching are used to form a mesa or multiple-step structure directly in the substrate, and then additional etching is used (bromine-methanol for HgCdTe or InSb) to round it into a spherical or aspheric surface [115]. 

One of the modifications of this approach is the use of a combination of mechanical and chemomechanical polishing, for instance, by simultaneous action of abrasive and bromine-methanol for lenses in Ge, CdTe, and InP [126]. 

The results of initial attempts (46) to solve the problem by the use of chemical methods of separation, such as gaseous chlorine or bromine/ methanol, for example, do not stand up to critical evaluation any more than those relating to the determination of oxygen in unalloyed aluminium. The bromine-methanol process in particular is subject to a serious systematic error, since it ultimately responds to aluminium amounts, present in the undissolved silicon component of the alloy, as if they were Al O, and thus reports them as oxygen. 

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