| 英文名 | N-Methylacetamide |
|---|---|
| 类型 | 脂肪族化合物 |
| CAS号 | 79-16-3 |
| 物理性质 | M 73.1, m 30℃, b 70-71℃/2.5-3mm, pK125 -3.70, pK225 -0.42. |
| 提纯方法 | 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 130℃ 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.] |
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