N-Methylacetamide

Chemical Properties

colourless liquid or solid. Soluble in water, ethanol, benzene, ether, chloroform, insoluble in petroleum ether.

Uses

N-Methylacetamide is used as a chemical intermediate in the production of life science, agrochemicals, electronic materials and construction materials. It is also used as a solvent, in electrochemistry.

Definition

ChEBI: N-methylacetamide is a monocarboxylic acid amide that is the N-methyl derivative of acetamide. It has a role as a metabolite. It is a member of acetamides and a monocarboxylic acid amide. It is functionally related to an acetamide.

Production Methods

Af-Methylacetamide has been prepared by reaction of methylamine with hot acetic acid (D'Alelio and Reid, 1937) and with acetic anhydride (Mauger and Soper, 1946). Other methods include heating iV,N-dimethylurea with acetic acid (US Patent, 1936) and reduction/hydrogenation of N-(hydroxymethyl)acetamide (US Patent, 1944).

Industrial uses

Even though N-methylacetamide shares many general physical and chemical properties with dimethylacetamide, it has not found the extensive industrial applications of the latter. N-methylacetamide dissolves many inorganic salts.

Safety Profile

Moderately toxic by intraperitoneal and subcutaneous routes. Mddly toxic by ingestion and intravenous routes. An experimental teratogen. Experimental reproductive effects. Mutation data reported. When heated to decomposition it emits toxic fumes of NOx.

Metabolism

In a recent comparative toxicity and metabolism study on four formamides and on N-methylacetamide, the sole metabolite of N-methylacetamide in the urine of mice was identified as N-(hydroxymethyl)acetamide (Kestell et al 1987). There was no evidence of induction of hepatic drug metabolizing enzymes in rats following treatment with N-methylacetamide (Ackerman and Leibman, 1977). N-Methylacetamide influenced neither the sleeping time induced by hexobarbital nor the metabolism of hexobarbital or aniline.

Purification Methods

Fractionally distil it under vacuum, then fractionally crystallise it twice from its melt. Likely impurities include acetic acid, methyl amine and H2O. For a detailed purification procedure, see Knecht and Kolthoff, Inorg Chem 1 195 1962. Although N-methylacetamide is commercially available it is often extensively contaminated with acetic acid, methylamine, water and an unidentified impurity. The recommended procedure is to synthesise it in the laboratory by direct reaction. The gaseous amine is passed into hot glacial acetic acid, to give a partially aqueous solution of methylammonium acetate which is heated to ca 130o to expel water. Chemical methods of purification such as extraction by pet ether, treatment with H2SO4, K2CO3 or CaO can be used but are more laborious. Tests for purity include the Karl Fischer titration for water; this can be applied directly. Acetic acid and methylamine can be detected polarographically. In addition to the above, purification of N-methylacetamide can be achieved by fractional freezing, including zone melting, repeated many times, or by vacuum distillation under reduced pressures. For details of zone melting techniques, see Knecht in Recommended Methods for Purification of Solvents and Tests for Impurities, Coetzee Ed. Pergamon Press 1982.[Beilstein 4 IV 176.]