Formaldehyde dimethyl acetal

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... 

Once methanol is produced, it can be converted to an extensive range of materials. The following reactions illustrate some of the chemicals of major importance that can be made from methanol. Among these are dimethyl ether, acetic acid, methyl acetate, acetic anhydride, vinyl acetate, formaldehyde, and methyl tertiarybutyl ether (MTBE). 

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... 

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. 

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. 

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. ... 

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). 

On the basis of the formaldehyde dimethyl acetal results, summarized in Table 18, the quantum yields of the primary processes can be estimated (Scheme 14). It has been shown (103a) that... 

TABLE 18. Photolysis (185 nm) of liquid deaerated formaldehyde dimethyl acetal (15°). Products and quantum yields (103a)... 

Today, synthesis gas is mainly used for the production of ammonia (120 x 10 t/yr ) and methanol (30 X 10 t/yr ) followed by pure hydrogen for hydro-treating in refineries. Other current applications are in the production of higher alcohols by hydroformulation and a number of products including acetic acid, formaldehyde, dimethyl ether (DME), and methyl-tert-butyl ether (MTBE) in all cases methanol is used as a coreactant. 

However, the activity of TS-1 in the oxidation of benzene appeared to be very poor. TS-1 does not perform very well in two-phase systems, so that only solvents able to homogenize the hydrophobic substrate and the aqueous hydrogen peroxide can be used. Even in this case, using solvents such as acetone, acetonitrile or tert-butanol, the selectivity to phenol rapidly dropped at very low benzene conversion, mainly due to the formation of dioxygenated products and tars typically, selectivity was already less than 50% at benzene conversion as low as 5%. Even worse results were obtained using methanol, which was oxidized in competition with benzene to give formaldehyde dimethyl acetal. 

Acetone reacted with acetylene in methylal (formaldehyde dimethyl acetal) at 5°, in the presence of a 3 7 mixture of NaOH pellets and powdered KOH 2,5-dimethyl-3-hexyne-2,5-diol (startg. m. f. 159). Y 90-95%.—At lower temp., acetylene adds only 1 mole of acetone to give 3-methyl-l-butyn-3-ol. (H. Richet, A. ch. [12] 3, 317 (1948).)... 

Von Braun6 reported that no cyclization occurred when 3-phenyl-propylamine was treated with formaldehyde dimethyl acetal. However, the Bischler-Napieralski cyclization was later successfully used to prepare 2-benzazepines. Thus, the spirobenzazepine 80 (R1 = OMe R2 = H) was obtained by refluxing 81 with phosphorus pentoxide in benzene ... 

AI3-16096 Anesthenyi Bis(methoxy)methane Dimeth-oxymethane Dimethyl formal 2,4-Dioxapentane EINECS 203-714-2 Formal Formaldehyde dimethyl-acetal Formaldehyde methyl ketal HSDB 1820 Methane, dimethoxy- Methoxymethyl methyl ether Methylal Methylene dimethyl ether Metylal UN1234, Used as a solvent In organio synthesis perfumes, adhesives, protective coatings special fuel. Liquid mp = -104.8° bp = 42° d = 0.8593 soluble in H2O (30 g/100 ml), very soluble In EtOH, Et20, MezCO, CeHe LD50 (rbt orl) n5708mg/kg. 

Formaldehyde, the three nitrobenzaldehydes, isophthalaldehyde, and terephthaldehyde are converted into acetals by dimethyl sulfate and alkali, but 0-phthalaldehyde gives 1,3-dimethoxyphthalan under these conditions.908... 

Methylal (formaldehyde dimethyl acetal) was obtained by Fischer and Giebe910 as follows 1 % methanolic hydrochloric acid (2.5 parts) is poured over finely powdered paraformaldehyde (1 part), and the mixture is warmed at 100° for 12-15 h. All the solid dissolves and the smell of formaldehyde soon disappears. The mixture is neutralized with sodium hydroxide solution and fractionated through an efficient column. This gives methylal, b.p. 41-42°, in 80% yield. 

Weizmann, Bergmann, and Sulzbacher132 prepared this 2-(trichloromethyl)-2-propanol according to the following procedure Freshly molten and powdered potassium hydroxide (102 g) was added to anhydrous methylal (formaldehyde dimethyl acetal 500 ml) at —4° a mixture of chloroform (215 g) and acetone (116 g) was next run in at the same temperature during 2 h. The mixture was stirred for a further 2 h, after which it was poured into dilute sulfuric acid and ice. The upper layer was separated and the aqueous layer was shaken with methylal. The solvent was distilled off from the united organic layers, and the crystalline residue was distilled in steam, affording the product as needles, m.p. 91°. 

MANNICH REACTION Dimethyl-(methylene)ammonium trifluoro-acetate. Formaldehyde. 

Methylal [109-87-5] (formaldehyde dimethyl acetal, dimethoxymethane) is a pleasantly smelling, extremely volatile solvent. It dissolves polystyrene, polyfvinyl acetate), vinyl chloride copolymers, acrylates, methacrylates, and synthetic and natural resins. It is used in paints and lacquers, adhesives, and aerosols. Important extracting agent for natural substances, essences, and oils. It serves as a reaction medium in the chemical industry and as an intermediate for chemical syntheses. 

NFPA Health 1, Flammability 3, Reactivily 0 Uses Industrial solvent mfg. of formaldehyde, acetic acid, dimethyl tereph-thalate, methyl esters chemical synthesis antifreeze solvent for nitrocellulose, polyvinyl butyral, shellac, rosin, manila resin, dyes, paints, waterborne coatings plastics softener denaturanL solvent in cosmetics octane booster in gasoline as fuel for picnic stoves, soldering torches extractant for animal/veg. oils extraction solvent for hops extract, spice oleoresins (foods) pharmaceutical solvent, excipient in food-pkg. adhesives in paper/paperboard in contact with dry food defoamer in food-contact coatings and paper/paperboard solvent in food-contact PRO resins... 

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