Dimethyl direct carbonation

Raw stock for the direct synthesis of methylchlorosilanes, methylchlo-ride, has such impurities as moisture, methyl alcohol, oxygen, sulfur dioxide, methylenechloride, dimethyl ether, carbon oxide and dioxide, etc. Most of them negatively affect the synthesis of methylchlorosilanes harmful impurities are chemisorbed on the active centres of contact mass and foul the copper catalyst, which naturally inhibits the reaction of methyl-chloride with contact mass. A similar situation is observed in the direct synthesis of ethylchlorosilanes. 

The conventional electrochemical reduction of carbon dioxide tends to give formic acid as the major product, which can be obtained with a 90% current efficiency using, for example, indium, tin, or mercury cathodes. Being able to convert CO2 initially to formates or formaldehyde is in itself significant. In our direct oxidation liquid feed fuel cell, varied oxygenates such as formaldehyde, formic acid and methyl formate, dimethoxymethane, trimethoxymethane, trioxane, and dimethyl carbonate are all useful fuels. At the same time, they can also be readily reduced further to methyl alcohol by varied chemical or enzymatic processes. 

Dimethyl sulfate (16 g) is added to a mixture of dimethyl carbonate (400 g) and deuterium oxide (1(X) g) in a 1 liter flask. Two reflux condensers and a drying tube are attached in series (initial rapid evolution of carbon dioxide may entrain some liquid), and the reaction mixture is heated under reflux for 72 hr. The methanol-OD is distilled directly from the reaction flask through a 30 cm Vigreux column. Redistillation from a small amount of sodium yields 275 g of pure methanol-OD bp 66-66.5° isotopic purity, 98.6%. ... 

Directed lithiation of aromatic compounds is a reaction of broad scope and considerable synthetic utility. The metalation of arenesulfonyl systems was first observed by Gilman and Webb and by Truce and Amos who reported that diphenyl sulfone is easily metalated at an orf/io-position by butyllithium. Subsequently, in 1958, Truce and coworkers discovered that metalation of mesityl phenyl sulfone (110) occurred entirely at an orf/io-methyl group and not at a ring carbon, as expected. Furthermore, refluxing an ether solution of the lithiated species resulted in a novel and unusual variation of the Smiles rearrangement and formation of 2-benzyl-4,6-dimethyl-benzenesulfinic acid (111) in almost quatitative yield (equation 78). Several other o-methyl diaryl sulfones have also been shown to rearrange to o-benzylbenzenesulfinic acids when heated in ether solution with... 

Complex 169 is very susceptible to electrophilic attack, as shown in Scheme 32. The protonation of 169 with PyHCl gave back 166. In this reaction, the assistance of one of the oxygens as the primary site of the protonation cannot be excluded. The alkylation with MeOTf, unlike in the case of 161 (see Scheme 29),22 occurs at the alkylidene carbon as well, forming the 2,3-dimethyl-2-butene-W derivative 167, which was obtained also by the direct synthesis given in Scheme 31. 

Bajugam and Flitsch [217] have described the synthesis of glycosylamines from mono-, di-, and trisaccharides by direct microwave-assisted Kochetkov amination (Scheme 6.110). The reaction was found to be effective with just a fivefold excess (w/w) of ammonium carbonate with respect to the sugar, as compared to the 40-or 50-fold excess needed under thermal conditions. All transformations were completed within 90 min in dimethyl sulfoxide as solvent, maintaining the vessel temperature at an apparent 40 °C using the heating-while-cooling technique (see Section 2.5.3). 

Introduction of trimethylsilyl substituents attached directly to the ot-carbon atom of a-(benzotriazol-l-yl)alkyl thioethers provide new opportunities. Thus, treatment of lithiated monosubstituted a-(benzotriazol-l-yl)alkyl thioethers with chlorotrimethylsilane produces a-(trimethylsilyl)alkyl thioethers 837. In reactions with hexamethyl-disilathiane and cobalt dichloride, thioethers 837 are converted to thioacylsilanes 838 that can be trapped in a Diels-Alder reaction with 2,3-dimethylbutadiene to form 2-alkyl-4,5-dimethyl-2-trimethylsilyl-3,6-dihydro-27/-thiopyrans 839 (Scheme 133) <2000JOC9206>. 

The reactions in which the methyl ketone loses a primary proton are all fast reactions, and the direction of the reaction is determined by the fact that an electron-releasing alkyl group slows down the removal of the secondary proton from the methylene group. On the other hand a slow reaction, like the base-catalyzed reaction of ketones with dimethyl sulfate in ether, gives a product corresponding to the removal of a proton from the more alkylated carbon.418... 

Namely, the reaction of 2-thioxothiazolidin-4-one N-hexanoic acid (116) with 2,5-dimethyl-l-phenylpyrrol-3-carboxaldehyde (117) in methanol under the catalytic action of ethylenediamine diacetate (EDDA) yields 5-[(2,5-dimethyl-l-phenylpyrrol-3-yl)methylidene]-2-thioxothiazolidin-4-one N-hexanoic acid (118) in 79% yield. The hydroxamate derivative of 118 is prepared by reacting this compound with 0-(tetrahydro-2H-pyran-2-yl)hydroxylamine followed by treatment with p-toluenesulfonic acid in methanol to afford compound 121 in 60% yield. Esterification of compound 118 is carried out by using methyl iodide in acetonitrile in the presence of sodium carbonate to give compound 120. The 5-(cyclohexyl)methylidene analogue (119) is obtained in 42% yield by direct reaction of compound 116 with cyclohexanecar-boxaldehyde in methanol under the catalytic action of EDDA. 

Reactions of a,(3-unsaturated acylzirconocene chlorides with stable carbon nucleophiles (sodium salts of dimethyl malonate and malononitrile) at 0°C in THF afford the Michael addition products in good yields (Scheme 5.38). Direct treatment of the reaction mixture with allyl bromide in the presence of a catalytic amount of Cul -2LiCl (10 mol%) in THF at 0 °C gives the allylic ketone in a one-pot reaction. This sequential transformation implies the electronic nature of a,P-unsaturated acylzirconocene chloride to be of type E as shown in Scheme 5.37. 

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