Methyl, alcohol halides

The SnI mechanism is generally accepted to be correct for the reaction of tertiary and secondary alcohols with hydrogen halides It is almost certainly not correct for methyl alcohol and primary alcohols because methyl and primary carbocations are believed to be much too unstable and the activation energies for their formation much too high for them to be reasonably involved The next section describes how methyl and primary alcohols are converted to their corresponding halides by a mechanism related to but different from S l... 

Similarly, sodium methoxide (NaOCHj) is a suitable base and is used in methyl alcohol. Potassium hydroxide in ethyl alcohol is another base-solvent combination often employed in the dehydrohalogenation of alkyl halides. Potassium ferf-butoxide [K0C(CH3)3] is the prefened base when the alkyl halide is primary it is used in either terf-butyl alcohol or dimethyl sulfoxide as solvent. 

Methylamines can be synthesized by alkylating ammonia with methyl halides or with methyl alcohol. The reaction with methanol usually occurs at approximately 500°C and 20 atmospheres in the presence of an... 

The Mobil process as discussed still uses syngas in its initial step. Olah has shown,79 however, that it is possible to convert methane directly by selective electrophilic halogenation to methyl halides and through their hydrolysis to methyl alcohol [Eq. (1.12)]. When bromine is used, the HBr byproduct of the reaction is readily reoxidized to bromine, allowing a catalytic process in which bromine acts only as a redox catalyst [Eq. (1.13)] ... 

It is even not necessary to hydrolyze methyl halides to methyl alcohol as methyl halides themselves readily condense over bifunctional acid-base catalysts such as zeolite or W03 on A1203 to ethylene (and propylene) and subsequently to higher hydrocarbons (gasoline, aromatics) ... 

The preparation of acetic acid represents a special case. Olah and coworkers as well as Hogeveen and coworkers have demonstrated that CO can react with methane under superacidic conditions, giving the acetyl cation and by subsequent quenching acetic acid or its derivatives (see Section 7.2.3). Monosubstituted methanes, such as methyl alcohol (or dimethyl ether), can be carbonylated to acetic acid.115 Similarly, methyl halides undergo acid-catalyzed carbonylation.115,116 Whereas the acid-catalyzed reactions can be considered as analogs of the Koch reaction, an efficient Rh-catalyzed carbonylation of methyl alcohol in the presence of iodine (thus in situ forming methyl iodide) was developed by Monsanto and became the dominant industrial process (see Section 7.2.4). 

It is reported that trimethylamine in combination occurs in large amounts in beet-root residues 2 and can be obtained from them by the action of caustic soda it occurs also in herring brine.3 From both of these sources, however, the substance is obtained in an impure state and can be purified only by rather tedious methods. This is indicated by the fact that trimethylamine has always been an expensive substance. Synthetic methods for its production are by the action of methyl iodide on ammonia 4 by the distillation of tetramethylammo-nium hydroxide 6 by the action of magnesium nitride upon methyl alcohol 6 by the action of zinc upon trimethyloxy-ammonium halides 7 by the action of formaldehyde upon ammonium chloride under pressure 8 by the action of ammonium chloride upon paraformaldehyde.9 Of these syn-... 

Methyl magnesium halides react with most steroid ketones with a very pronounced preference for formation of the tertiary alcohol with an equatorial methyl group (Table 15). Methyl... 

ARna 12 148 ARb 12 282 AA.,, 0 773 AA 0 472. The molecular heat of combustion at constant volume is 430,800 calories, and work on the dielectric constant has been carried out by Matthews, and studies of the absorption spectra by Crymble. The complex MeHg- has been isolated by electrolysing methyl mercuric halides in liquid ammonia solution. It forms a fine black deposit on the cathode, and may be obtained in the form of flakes if the process be carried out in water or alcohol solution. The latter form appears to be more stable than the former, which decomposes into mercury and... 

Lead triphenyl methyl is prepared from lead triphenyl bromide and an excess of methyl magnesium halide. It crystallises from benzene in rhomboidal crystals, M.pt. 60 C., becoming turbid at 220 C. and decomposing at 200 C. In benzene or chloroform it is very soluble, less soluble in ether, sparingly in cold 94 per cent, alcohol. Alcoholic silver nitrate from an alcohol solution of the lead compound precipitates yellow silver phenyl-silver nitrate. 

Solvolysis in methyl alcohol converts an alkyl halide to an alkyl methyl ether. 

Methyl alcohol Alkyl halide Dialkyloxonium halide Alkyl methyl ether Hydrogen halide... 

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