Methyl alcohol reagent

Material Safety Data Sheet Methyl Alcohol, Reagent ACS, 99.8% (GC). Department of Chemistry, Iowa State University. http //avogadro.chem.iastate.edu/MSDS/methanol.htm (accessed on October 17, 2005). 

Cellobiose was prepared first by Skraup and Konig by the saponification of the octaacetate with alcoholic potassium hydroxide, and the method was improved by Pringsheim and Merkatz.3 Aqueous barium hydroxide also has been employed for the purpose, and methyl alcoholic ammonia has been used extensively for the hydrolysis of carbohydrate acetates. The method of catalytic hydrolysis with a small quantity of sodium methylate was introduced by Zemplen,i who considered the action to be due to the addition of the reagent to the ester-carbonyl groups of the sugar acetate and the decomposition of the addition compound by reaction with alcohol. The present procedure, reported by Zemplen, Gerecs, and Hadacsy, is a considerable improvement over the original method (see Note 2). 

The reaction of Grignard reagents with the keto group of 5a-cholestan-3-one (7) was first described in 1937/ In a later study, Barton obtained the two epimeric tertiary alcohols (8) and (9), in a ratio of 40 60 by exposing (7) to the action of methyl Grignard reagent. 

In some cases products of rearrangement are obtained either partially or exclusively on treatment of Grignard reagents with epoxides. Thus, reaction of the 2/ ,3/ -epoxide (14) with methyl Grignard reagent affords a mixture of two epimeric secondary A-nor alcohols (15) in 80% yield and the tertiary hydroxy compound, 2a-methyl-5a-cholestan-2/f-ol (16) in 15 % yield. ... 

The facile and selective oxidation of both primary and secondary hydroxy groups with certain nucleotides led Pfitzner and Moffatt (48) to explore the scope of the carbodiimide-methyl sulfoxide reagent with steroid and alkaloid alcohols. Relatively minor differences were apparent in the rate of oxidation of epimeric pairs of 3- and 17- hydroxy steroids whereas the equatorial lLx-hydroxyl group in several steroids was readily oxidized under conditions where the axial epimer was unreactive [cf. chromic oxide oxidation (51)]. 

The main drawback to this reaction is the toxicity of diazomethane and some of its precursors. Diazomethane is also potentially explosive. Trimethylsilyldia-zomethane is an alternative reagent,42 which is safer and frequently used in preparation of methyl esters from carboxylic acids.43 Trimethylsilyldiazomethane also O-methylates alcohols.44 The latter reactions occur in the presence of fluoroboric acid in dichloromethane. 

The low yields, which are observed among styrenyl adducts, reflect a combination of the poor reactivity of the styrene at the low temperature of the reaction. For example, the combination of t-butyl Grignard with the 2,4-bis-OBoc-benzyl alcohol 15 affords the corresponding benzopyran 50 in only 50% yield even when carried out in the presence of 5-10 equivalents of the styrene (method H, Fig. 4.27).27 Yields for substituted benzopyran styrene adducts are still lower (method G, Fig. 4.27). For example, addition of methyl lithium to 2,4-bis-OBoc-benzylaldehyde 5 followed by the addition of the dienophile and magnesium bromide affords benzopyran 51 in a paltry 27% yield. Method F is entirely ineffective in these cases, because the methyl Grignard reagent competes with the enol ether and with styrene 1,4-addition of methyl supercedes cycloaddition. 

Nef prepared acetol in several ways, the more important of which depended upon the reaction between bromoacetone and potassium or sodium formate or acetate, and the subsequent hydrolysis of the ester by methyl alcohol.1 2 Acetol is also formed, together with pyruvic acid, by the direct oxidation of acetone by Baeyer and Villiger s acetone-peroxide reagent.3... 

This reagent is very much used and It is best to keep a stock. Dissolve 25 g. of potassium hydroxide sticks in 100 c.c. of methyl alcohol by warming or by leaving over night in the cold potassium hydroxide in ethyl alcohol soon resinifies. Remove carbonate by filtration and determine the KOH content by titration. 

Uses Manufacture of vanillin, Michler s ketone, methyl violet, and other dyes solvent reagent for methyl alcohol, hydrogen peroxide, methyl furfural, nitrate, and formaldehyde chemical intermediate stabilizer reagent. 

Dr. Basolo We know what the facts are with 0H but are much less certain why these are the facts. There is no doubt that 0H is the poorest of all these reagents towards Pt(II). The hydroxide ion does not compete with the solvent water, nor does methoxide ion compete with methyl alcohol, even at concentrations of 0.5Af anion. 

Limitations and interferences. The Karl Fischer reagent is composed of pyridine, sulfur dioxide, and iodine dissolved in either methyl alcohol or ethylene glycol monomethyl ether. Substances which react with any of these components will interfere. For example, Karl Fischer reagent will react with aldehydes or ketones in the presence of Methyl alcohol. 

Methylnitramine decomposes explosively in contact with concentrated sulfuric acid. If the substance is dissolved in water, and if concentrated sulfuric acid is added little by little until a considerable concentration is built up, then the decomposition proceeds more moderately, nitrous oxide is given off, and dimethyl ether (from the methyl alcohol first formed) remains dissolved in the sulfuric acid. The same production of nitrous oxide occurs even in the nitrometer in the presence of mercury. If methylnitramine and a small amount of phenol are dissolved together in water, and if concentrated sulfuric acid is then added little by little, a distinct yellow color shows that a trace of nitric acid has been formed. The fact that methylnitramine gives a blue color with the diphenylamine reagent shows the same thing. 

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