Dimethoxymethane
| Names | |
|---|---|
| Preferred IUPAC name
Dimethoxymethane | |
| Other names
Formal
Formaldehyde dimethyl ether | |
| Identifiers | |
3D model (JSmol)
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| 1697025 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value). Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value).Lua error in Module:EditAtWikidata at line 29: attempt to index field 'wikibase' (a nil value). |
| EC Number |
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| E number | Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value). |
| 100776 | |
| MeSH | Dimethoxymethane |
PubChem CID
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| RTECS number |
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| UNII | |
| UN number | 1234 |
CompTox Dashboard (EPA)
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| Properties | |
| C3H8O2 | |
| Molar mass | 76.095 g·mol−1 |
| Appearance | Colorless liquid[1] |
| Odor | Chloroform-like[1] |
| Density | 0.8593 g cm−3 (at 20 °C)[1] |
| Melting point | −105 °C (−157 °F; 168 K)[1][3] |
| Boiling point | 42 °C (108 °F; 315 K)[1][3] |
| 33% (20 °C)[2][clarification needed] | |
| Vapor pressure | 330 mmHg (20 °C)[2] |
| −47.3·10−6 cm3/mol | |
| Hazards | |
| GHS labelling: | |
| GHS02: FlammableGHS07: Exclamation mark | |
| Danger | |
| H225, H315, H319, H335 | |
| P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501 | |
| Flash point | −18 °C (0 °F; 255 K) |
| Explosive limits | 2.2–13.8%[2] |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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5708 mg/kg (rabbit, oral)[4] |
LC50 (median concentration)
|
18000 ppm (mouse, 7 hr) 15000 ppm (rat) 18354 ppm (mouse, 7 hr)[4] |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
|
TWA 1000 ppm (3100 mg/m3)[2] |
REL (Recommended)
|
TWA 1000 ppm (3100 mg/m3)[2] |
IDLH (Immediate danger)
|
2200 ppm[2] |
| Related compounds | |
Related Ethers
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Dimethoxyethane |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dimethoxymethane, also called methylal, is a colorless flammable liquid with a low boiling point, low viscosity and excellent dissolving power. It has a chloroform-like odor and a pungent taste. It is the dimethyl acetal of formaldehyde. Dimethoxymethane is soluble in three parts water[clarification needed] and miscible with most common organic solvents.
Synthesis and structure
[edit | edit source]It can be manufactured by oxidation of methanol or by the reaction of formaldehyde with methanol. In aqueous acid, it is hydrolyzed back to formaldehyde and methanol.
Due to the anomeric effect, dimethoxymethane has a preference toward the gauche conformation with respect to each of the C–O bonds, instead of the anti conformation. Since there are two C–O bonds, the most stable conformation is gauche-gauche, which is around 7 kcal/mol more stable than the anti-anti conformation, while the gauche-anti and anti-gauche are intermediate in energy.[5] Since it is one of the smallest molecules exhibiting this effect, which has great interest in carbohydrate chemistry, dimethoxymethane is often used for theoretical studies of the anomeric effect.
Applications
[edit | edit source]Industrially, it is primarily used as a solvent and in the manufacture of perfumes, resins, adhesives, paint strippers and protective coatings. Another application is as a gasoline-additive for increasing octane number. Dimethoxymethane can also be used for blending with diesel. [6]
Reagent in organic synthesis
[edit | edit source]Another useful application of dimethoxymethane is to protect alcohols with a methoxymethyl (MOM) ether in organic synthesis. Dimethoxymethane can be activated with phosphorus pentoxide in dichloromethane or chloroform.[7] This method is preferred to the use of chloromethyl methyl ether (MOMCl). Phenols can also be MOM-protected using dimethoxymethane, p-toluenesulfonic acid.[8] Alternatively, MOMCl can be generated as a solution by treating dimethoxymethane with an acyl chloride in the presence of a Lewis acid catalyst like zinc bromide:
- MeOCH2OMe + RC(=O)Cl → MeOCH2Cl + RC(=O)(OMe)).
Unlike the classical procedure, which uses formaldehyde and hydrogen chloride as starting materials, the highly carcinogenic side product bis(chloromethyl) ether is not generated.[9]
References
[edit | edit source]- ^ a b c d e Merck Index, 11th Edition, 5936
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- ^ a b International Chemical Safety Card 1152
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External links
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