Methylating agent

FS(0)20CH3. Colourless liquid, b.p. 94°C. Functions as a powerful methylating agent, even for amides and nitriles which are not attacked by conventional alkylating agents like dialkyl sulphates. 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

Arguably the key step in the MGC process is the conversion of a-hydroxyisobutyramide to methyl a-hydroxyisobutyrate using methyl formate as the methylating agent. Methyl formate is made commercially by MGC via vapor-phase dehydrogenation of methanol (72). 

The reaction is mn for several hours at temperatures typically below 100°C under a pressure of carbon monoxide to minimise formamide decomposition (73). Conversions of a-hydroxyisobutyramide are near 65% with selectivities to methyl a-hydroxyisobutyrate and formamide in excess of 99%. It is this step that is responsible for the elimination of the acid sludge stream characteristic of the conventional H2SO4—ACH processes. Because methyl formate, and not methanol, is used as the methylating agent, formamide is the co-product instead of ammonium sulfate. Formamide can be dehydrated to recover HCN for recycle to ACH generation. 

Detoxifica.tlon. Detoxification systems in the human body often involve reactions that utilize sulfur-containing compounds. For example, reactions in which sulfate esters of potentially toxic compounds are formed, rendering these less toxic or nontoxic, are common as are acetylation reactions involving acetyl—SCoA (45). Another important compound is. Vadenosylmethionine [29908-03-0] (SAM), the active form of methionine. SAM acts as a methylating agent, eg, in detoxification reactions such as the methylation of pyridine derivatives, and in the formation of choline (qv), creatine [60-27-5] carnitine [461-06-3] and epinephrine [329-65-7] (50). 

Methyl bromide finds use as a methylating agent in the syntheses of agricultural and dmg chemicals. It is also used in ionization chambers, for degreasing wool, and for extracting oil from nuts, seeds, and flowers. 

Methylation. Methylating agents such as methyl sulfate and methyl iodide react with coumarin in the presence of sodium hydride to give methyl 2-methoxycinnamate [15854-58-7] (29). 

Methylamines are commonly formed by reacting the amine with a methylating agent such as Mel or dimethyl sulfate. 

Te-Methyl-2-phenylbenzotelluroniumazole perchlorate 20 behaves as a strong methylating agent in reactions with O- and N-nucleophiles (92MI1). 

One of the most important applications of diazomethane depends on its ability to replace a mobile hydrogen atom by a methyl group. In comparison with other methylation agents, diazomethane occupies a rather special place this is, in part, because only rather strongly acidic protons are replaced. Because of the simple method of working up the reaction mixture, the reaction is especially well applicable for sensitive compounds and for small amounts. If tautomeric or potentially tautomeric compounds are treated with diazomethane, two... 

The general equation (1) for the methylation of a sufficiently acidic compound Z—H with diazomethane show s that the reaction formally takes place in two steps. Diazomethane docs not itself contain a methyl group, thus the first step, Eq. (2), must involve the loss of a proton from Z—-H and that it is taken up by diazomethane to give the corresponding cation CHa—which is the actual methylating agent ... 

As alkylating agent an alkyl halide, alkyl tosylate or dialkyl sulfate is used in most cases the latter type of reagent is often used in the preparation of methyl and ethyl ethers by employing dimethyl sulfate and diethyl sulfate respectively. Dimethyl sulfate is an excellent methylating agent, but is acutely toxic as well as carcinogenic." ... 

Diazomethane is a yellow gas that is toxic and explosive but that may be handled safely in solution in ether. It reacts immediately with an acid to liberate nitrogen and form the methyl ester. Its reaction with alcohols to form methyl esters requires catalysis by a Lewis acid. The procedures illustrate the use of this reagent as a methylating agent (see Chapter 17, Section III, for preparation of diazomethane). 

The major use of methyl chloride is to produce silicon polymers. Other uses include the synthesis of tetramethyl lead as a gasoline octane booster, a methylating agent in methyl cellulose production, a solvent, and a refrigerant. 

Reaction of 1,4-diazocinediones with methylating agents leads to different products depending on the conditions. With dimethyl sulfate, the annulated derivative 6 gives JV-methylation selectively 7 however, on reaction with diazomethane, a mixture of the O- and iV-methylated products is obtained.9... 

Antiproliferative agents Methylating agents Chlor-oethylating agents... 

Mesolimbic System/Reward System Metabolic Syndrome Metabotropic Glutamate Receptors Metabotropic Receptor Metalloprote(in)ases Methicillin-resistant Staphylococci iV-Methyl D-aspartate Receptors Methylating Agents... 

Prepd by the action of methylating agents (methyl chloride, bromide, iodide, or sulfate) on aniline. This procedure gives a mixt with dime thy laniline which is difficult to separate by distn (see below for sepn procedure) (Refs 1,... 

Acyl-l-aryl-3-methyltriazenes are potential prodrugs of the methylating agents l-aryl-3-methyl-triazenes. The groups of Iley and Rosa (Iley et al., 1989 Carvalho et al., 1993) studied therefore the base- and acid-catalyzed hydrolysis of such acylated triazenes. 

The trifluoromethyl-tin bond is, however, much less stable chemically (24). Reaction of, e.g., (CF3)2SnBr with an excess of the relatively covalent, methylating agent (CHaljCd results in the very slow substitution for one of the Sn-CFg bonds, but the reaction of CFaSnBr3 with an excess of the more powerful, more ionic reagent methyllithium results in the displacement of all of the ligands, and the formation of (CH3)4Sn as shown in Equations 16 and 17. 

Our result, therefore, suggests that the methylating agent formed from NOPPA is similar in reactivitjr to that formed from NDMA, and would support the hypothesis of Kruger (13) that NMPA may be the methylating agent formed from NOPPA. 

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