Trimethyl orthoformate (TMOF) is the organic compound with the formula HC(OCH3)3. A colorless liquid, it is the simplest orthoester. It is a reagent used in organic synthesis for the formation of methyl ethers.[3] The product of reaction of an aldehyde with trimethyl orthoformate is an acetal. In general cases, these acetals can be deprotected back to the aldehyde by using hydrochloric acid.
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Preferred IUPAC name
Trimethoxymethane | |
Other names
2-Methoxyacetaldehyde dimethyl acetal; Methoxymethylal; Methyl orthoformate
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Identifiers | |
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3D model (JSmol)
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ECHA InfoCard | 100.005.224 |
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PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
C4H10O3 | |
Molar mass | 106.121 g·mol−1 |
Appearance | Colorless liquid |
Odor | pungent |
Density | 0.9676 g/cm3 |
Melting point | −53 °C (−63 °F; 220 K) |
Boiling point | 100.6 °C (213.1 °F; 373.8 K) |
Solubility | soluble in ethanol, diethyl ether |
Vapor pressure | 1 kPa at 7 °C[2] |
Refractive index (nD)
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1.3773 |
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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 | 13 °C (55 °F; 286 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Trimethyl orthoformate is prepared on an industrial scale by the methanolysis of hydrogen cyanide:[4]
Trimethyl orthoformate can also be prepared from the reaction between chloroform and sodium methoxide, an example of the Williamson ether synthesis.
Trimethyl orthoformate is a useful building block for creating methoxymethylene groups and heterocyclic ring systems. It introduces a formyl group to a nucleophilic substrate, e.g. RNH2 to form R-NH-CHO, which can undergo further reactions. It is used in the production of the fungicides, azoxystrobin, and picoxystrobin, as well as for some members of the floxacin family of antibacterial drugs.
A number of pharmaceutical intermediates are also made from trimethyl orthoformate.[4]
Trimethyl orthoformate is also an effective reagent for converting compatible carboxylic acids to their corresponding methyl esters.[5] Alternatively, acid-catalyzed esterifications with methanol can be driven closer to completion by employing trimethyl orthoformate to convert water byproduct to methanol and methyl formate.