Methyl sulfate methylation

Methyl sulfate, methylation of sugars by, history of, 1 Methylation... 

Beilstein Handbook Reference) AI3-52118 BRN 0635994 CCRIS 265 Dimethyl monosulfate Dimethyl sulfate Dimethyl sulphate Dimethylester kyseliny sirove Dimethylsulfaat Dimethylsulfat Dimetilsolfato DMS (methyl sulfate) Owumetylowy siarczan EINECS 201-058-1 HSDB 932 Methyl sulfate Methyle (sulfate de) NSC 56194 RCRA waste number U103 Sulfate de dimethyle Sulfate dimethylique Sulfato de dimetilo Sulfuric acid, dimethyl ester UNI 595. Liquid mp = -27° bpis = 76°, bp = 188° (dec) d = 1,3322 moderately soluble in H2O, organic solvents. 

Methyl bromide Dimethyl sulfate Na methyl sulfate Methyl methanesulfonate JViiV-methylnitrosourea JVj -methylnitrosourethan JViiV-methylnitroso-iV -nitroguanidine Dimethylnitrosamine Tetramethyl orthocarbonate... 

Carbon Disulfide Methyl Sulfate Methyl Sulfuric Acid... 

To a mixture of 50 ml of dry THF and 0.050 mol of l-tert.-butoxy-2-pentyne (prepared by ethylation of HC-CCH O-tert.-Ci,H9 in liquid ammonia was added 0.055 mol of butyilithium in about 35 ml of hexane in 10 min at -30°C. After stirring for 20 min at -25°C the solution was cooled to -50°C and 0.06 mol of methyl iodide was added in one portion, followed 10 min later by 50 ml of water. The aqueous layer was separated and extracted twice with diethyl ether. The solutions were dried over magnesium sulfate and concentrated in a water-pump vacuum. 

The most stable protected alcohol derivatives are the methyl ethers. These are often employed in carbohydrate chemistry and can be made with dimethyl sulfate in the presence of aqueous sodium or barium hydroxides in DMF or DMSO. Simple ethers may be cleaved by treatment with BCI3 or BBr, but generally methyl ethers are too stable to be used for routine protection of alcohols. They are more useful as volatile derivatives in gas-chromatographic and mass-spectrometric analyses. So the most labile (trimethylsilyl ether) and the most stable (methyl ether) alcohol derivatives are useful in analysis, but in synthesis they can be used only in exceptional cases. In synthesis, easily accessible intermediates of medium stability are most helpful. 

J. Rebek, Jr., (1987) first developed a new synthesis of Kemp s acid and then extensively explored its application in model studies. The synthesis involves the straightforward hydrogenation (A. Steitz, 1968), esterification and methylation of inexpensive 1,3,5-benzenetricar-boxylic acid (trimesic acid 30/100 g). The methylation of the trimethyl ester with dimethyl sulfate, mediated by lithium diisopropylamide (V. J. Shiner, 1981), produced mainly the desired aff-cis-1,3,5-trimethyl isomer, which was saponified to give Kemp s acid. 

Alkylation of bis(4-methyl-2-thiazolyl)urea (257) with dimethyl sulfate gives product 258 dimethylated on the ring nitrogens (Scheme 154) (488). Alkylation of l-alkyl-3-(2-thiazolyl)urea from its derived anion formed by NaH gives 259 (Scheme 155). 

The reactivity of sulfathiazoles has been reviewed (65). Methylation in alkaline solution with dimethyl sulfate gives only the ring methylated derivative (85). Mixtures of products are obtained with diazomethane as alkylating agent (see p. 37). Other alkyl halides in aqueous alkali lead also to ring-alkylated products (85. 251, 650. 669-671). 

Coproductioa of ammonium sulfate is a disadvantage of the formamide route, and it has largely been supplanted by processes based on the direct hydrolysis of methyl formate. If the methanol is recycled to the carbonylation step the stoichiometry corresponds to the production of formic acid by hydration of carbon monoxide, a reaction which is too thermodynamicaHy unfavorable to be carried out directly on an iadustrial scale. 

Reactions of the Hydroxyl Group. The hydroxyl proton of hydroxybenzaldehydes is acidic and reacts with alkahes to form salts. The lithium, sodium, potassium, and copper salts of sahcylaldehyde exist as chelates. The cobalt salt is the most simple oxygen-carrying synthetic chelate compound (33). The stabiUty constants of numerous sahcylaldehyde—metal ion coordination compounds have been measured (34). Both sahcylaldehyde and 4-hydroxybenzaldehyde are readily converted to the corresponding anisaldehyde by reaction with a methyl hahde, methyl sulfate (35—37), or methyl carbonate (38). The reaction shown produces -anisaldehyde [123-11-5] in 93.3% yield. Other ethers can also be made by the use of the appropriate reagent. 

Biacetyl is produced by the dehydrogenation of 2,3-butanediol with a copper catalyst (290,291). Prior to the availabiUty of 2,3-butanediol, biacetyl was prepared by the nitrosation of methyl ethyl ketone and the hydrolysis of the resultant oxime. Other commercial routes include passing vinylacetylene into a solution of mercuric sulfate in sulfuric acid and decomposing the insoluble product with dilute hydrochloric acid (292), by the reaction of acetal with formaldehyde (293), by the acid-cataly2ed condensation of 1-hydroxyacetone with formaldehyde (294), and by fermentation of lactic acid bacterium (295—297). Acetoin [513-86-0] (3-hydroxy-2-butanone) is also coproduced in lactic acid fermentation. 

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). 

Reaction conditions depend on the reactants and usually involve acid or base catalysis. Examples of X include sulfate, acid sulfate, alkane- or arenesulfonate, chloride, bromide, hydroxyl, alkoxide, perchlorate, etc. RX can also be an alkyl orthoformate or alkyl carboxylate. The reaction of cycHc alkylating agents, eg, epoxides and a2iridines, with sodium or potassium salts of alkyl hydroperoxides also promotes formation of dialkyl peroxides (44,66). Olefinic alkylating agents include acycHc and cycHc olefinic hydrocarbons, vinyl and isopropenyl ethers, enamines, A[-vinylamides, vinyl sulfonates, divinyl sulfone, and a, P-unsaturated compounds, eg, methyl acrylate, mesityl oxide, acrylamide, and acrylonitrile (44,66). 

All lation. Alkylating agents such as diaLkyl sulfates and alkyl hahdes react with ahphatic amine oxides to form trialkylalkoxyammonium quaternaries. For example (33), methyl iodide reacts with trimethyl amine oxide to form trimethylmethoxyammonium iodide... 

QuaterniZation. Quaternary ammonium compounds are formed by alkylation of alkyl, alkyl dimethyl, dialkyl, and dialkylmethyl fatty amines with methyl chloride, dimethyl sulfate, or benzyl chloride (1,3,7,12,29). 

V,/V-dimethy1amino)pheno1 (177). In addition, 3-aminophenol may be methylated with dimethyl sulfate under neutral conditions, or its hydrochloride salt heated with methanol at 170°C under pressure for 8 h to give the desired product (178). The compound is used primarily as an intermediate in the production of basic (Red 3 and Red 11) and mordant (Red 77) dyes. 

A Methylamino)phenol. This derivative, also named 4-hydroxy-/V-methy1ani1ine (19), forms needles from benzene which are slightly soluble in ethanol andinsoluble in diethyl ether. Industrial synthesis involves decarboxylation of A/-(4-hydroxyphenyl)glycine [122-87-2] at elevated temperature in such solvents as chlorobenzene—cyclohexanone (184,185). It also can be prepared by the methylation of 4-aminophenol, or from methylamiae [74-89-5] by heating with 4-chlorophenol [106-48-9] and copper sulfate at 135°C in aqueous solution, or with hydroquinone [123-31 -9] 2l. 200—250°C in alcohoHc solution (186). 

Fats, Oils, or Fatty Acids. The primary products produced direcdy from fats, oils, or fatty acids without a nitrile iatermediate are the quatemized amidoamines, imidazolines, and ethoxylated derivatives (Fig. 3). Reaction of fatty acids or tallow with various polyamines produces the iatermediate dialkylarnidoarnine. By controlling reaction conditions, dehydration can be continued until the imidazoline is produced. Quaternaries are produced from both amidoamines and imidazolines by reaction with methyl chloride or dimethyl sulfate. The amidoamines can also react with ethylene oxide (qv) to produce ethoxylated amidoamines which are then quaternized. 

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

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