Dimethyl formaldehyde

An important extension of these reactions is the Mannich reaction, in which aminomethyl-ation is achieved by the combination of formaldehyde, a secondary amine and acetic acid (Scheme 24). The intermediate immonium ion generated from formaldehyde, dimethyl-amine and acetic acid is not sufficiently reactive to aminomethylate furan, but it will form substitution products with alkylfurans. The Mannich reaction appears to be still more limited in its application to thiophene chemistry, although 2-aminomethylthiophene has been prepared by reaction of thiophene with formaldehyde and ammonium chloride. The use of A,iV-dimethyf (methylene) ammonium chloride (Me2N=CH2 CF) has been recommended for the iV,iV-dimethylaminomethylation of thiophenes (83S73). 

Cyanogen chloride Cyclohexane Diethyl ether Dimethyl formaldehyde Dimethyl sulfate Dimethyl sulfide Epichlorohydrin Ethyl acetate Ethyl benzene Ethylene glycol Fluorine... 

Indeed, on Pd/SiO adsorbed formaldehyde was characterized with dimethyl- or diethylsulfate in the form of formaldehyde dimethyl or diethyl acetal, respectively. The highest concentration of formaldehyde (10 mol.(g of cat) )) was observed when only CO was added to the prereduced Pd catalyst (42). With an excess of hydrogen as well as on more active magnesium containing catalyst, only trace amounts of adsorbed formaldehyde were detected. Its low concentration on these catalytic surfaces may result from rapid conversion of adsorbed formaldehyde into methoxy moieties (Table I). 

Formaldehyde dimethyl acetal (dimethoxy methane, methylal, formal) [109-87-5] M 76.1,... 

Formaldehyde dimethyl acetal (dimethoxy methane, methylal, formal) [109-87-5] M 76.1, m -108 , b 41-42 /736mm, 41-43 /atm, 42-46 /atm, d ° 0.8608, n2D° 1.35335. It is a volatile flammable liquid which is soluble in three parts of H2O. It is readily hydrolysed by acids. Purify by drying... 

J.-M. Lassaletta and R. FemSndez, Michael addition of formaldehyde dimethyl-hydrazone to nitroolefins. A new formyl anion equivalent, Tetrahedron Lett. 33 3691 (1992). 

Ogura [296, 297] has proposed other interesting uses of MMTS (also known as FAMSO, for formaldehyde dimethyl dithioacetal S-oxide) and also of the two following dithioacetal monosulfones ... 

Acetal and ketal carbon nuclei are shielded relative to the parent functions. Their shifts occur at 105 + 5 ppm, reflecting the change from sp2 carbonyl to sp3 dialkoxy carbons. Increasing the number of alkoxy groups successively enhances the associated carbon shift. But the effects are not additive when comparing the data of formaldehyde dimethyl-acetal, triethyl orthoformate and tetramethyl orthocarbonate. 

KETONES N.O-Dimethylhydroxylamine hydrochloride. N,N,-Diphenyl-/>-mcthoxyphenylchloromethyleniminum chloride. Formaldehyde dimethyl dithioacetal S.S-dioxidc 4-Fonmyl l methylpyridiniuni bcnzencsullonatc. l.ithi[Pg.651]

METHYL CARBOXYLATES Formaldehyde dimethyl dithioacetal S,S-dioxide. 

Conventional uses of methanol account for 90% of present consumption and include formaldehyde, dimethyl terephthalate, methyl methacrylate, methyl halides, methylamines and various solvent and other applications. Newer uses for methanol that have revitalized its growth and outlook include a new technology for acetic acid, single cell protein, methyl tertiary butyl ether-(MTBE), and water denitrification. Potential uses for methanol include its use as a carrier for coal in pipelines, as a source of hydrogen or synthesis gas used in direct reduction of iron ore, as a direct additive to or a feedstock for gasoline, peak power shaving and other fuel related possibilities. Table II lists the world methanol demand by end use in 1979. 

The organolithium compound (214) is obtained by treatment of the tetrathiafulvalene (5) with lithium diisopropylamide (LDA). This lithium compound (214) can further react with carbon dioxide, ethyl chloroformate, acetyl chloride, formaldehyde, dimethyl sulfate, and triethyloxonium hexafluorophosphate to produce the correspondingly substituted tetrathiafulvalenes (215) (79JOC1476). 

Arnold s demonstration" that oxocarbenium ion intermediates can be formed through homobenzylic ether radical cation fragmentation reactions shows that mild oxidizing conditions can be used to prepare important reactive intermediates. Scheme 3.2 illustrates a critical observation in the development of an explanatory model that allows for the application of radical cation fragmentation reactions in complex molecule synthesis. In Arnold s seminal work, cleavage of the benzylic carbon-carbon bond in substrate 1 is promoted by 1,4-dicyanobenzene (DCB) with photoirradiation by a medium-pressure mercury vapor lamp. With methanol as the solvent, the resulting products were diphenylmethane (2) and formaldehyde dimethyl acetal (3). 

Scleclivitics of around 90% at formaldehyde conversions of over 80% are claimed. Commercial developments require the building of an integrated complex, since neither of the two fccd-siocks, methyl propionate and formaldehyde dimethyl acetal,are available in the market. 

Preparation. The reagent is prepared in 78 % yield by oxidation of formaldehyde dimethyl mercaptal with 30 % hydrogen peroxide in acetic acid. ... 

Formaldehyde dimethyl dithioacetal 5-oxide (FAMSO 113) and its ethyl analog are widely used as synthetic carbonyl equivalents. - Addition of the lithio derivative of (113) to aldehydes and ketones followed by acidic hydrolysis is a preparative method for a-hydroxy aldehyde derivatives (equation 27). A chiral analog of (113), (5)-formaldehyde di-p-tolyl dithioacetal 5-oxide (114), can be synthesized from (-)-mentyl (/ )-p-toluenesulfinate. °° The reaction of the lithio derivative of (5)-(114)... 

Only very few examples of acetal ultraviolet absorption spectra are known. With 1,3-dioxane (101), 1,3-dioxolane (102), formaldehyde dimethyl acetal (103a), acetaldehyde dimethyl acetal (103b), and pivalaldehyde dimethyl acetal (104), it is remarkable that absorption sets in below 200 nm, that is, at shorter wavelengths than ethers, and is lower (Table 2). This could be... 

The photolysis of acetals has hitherto found scant attention. 1,3-Dioxolane has been studied by Roqultte (102) who used the full light of a medium-pressure Hg arc. The liquid phase photolysis (X 185 nm) of formaldehyde dimethyl acetal has been undertaken in the reviewers laboratory (103a). 

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