Chemical Properties
Oxamide, H2NCOCONH2, mol wt 80.07, is sparingly soluble in water and insoluble in various organic solvents. It melts at about 350 °C, with accompanying decomposition. Because of the low solubility in water, the compound is granulated and used as a slow-release nitrogen fertilizer.
Chemical Properties
white fine crystalline powder
Uses
Oxamide is used as a stabilizer for nitrocellulose preparations. It also finds use in APCP rocket motors as a high performance burn rate suppressant.
Definition
ChEBI: A dicarboxylic acid diamide of oxalic acid.
Preparation
Oxamide can be prepared, for example, by pyrolyzing ammonium oxalate or by allowing hydrogen cyanide to react with hydrogen peroxide. It is also known to prepare oxamide by a reaction between dimethyl oxalate and ammonia, wherein methanol is produced in addition to oxamide. The preparation was carried out as a batch process in a liquid phase, with methanol acting as a solvent into which the dimethyl oxalate and ammonia are fed. The oxamide was separated from the solution by crystallization, and the remaining mother liquor was distilled to recover methanol and ammonia, which had been left over from the reaction.
Agricultural Uses
Oxamide (H2 NCOCONH2 ), a diamide of oxalic acid, is a
white crystalline and non-hygroscopic fertilizer
containing about 32% nitrogen, most of which is waterinsoluble
at 25°C. Oxamide is made from cyanogen
hydrolysis in an acid medium. It releases nitrogen slowly
and hence is used as a slow-release fertilizer. It is
decomposed by soil micro-organisms in the soil.
Synthesis
Oxalide is a simple dicarboxylic acid diamide, primarily synthesized from the corresponding acid or ester precursor. The most common industrial synthesis method is the ammonolysis of dimethyl oxalate . This process typically involves reacting dimethyl oxalate with ammonia in a solvent (usually methanol) under controlled temperature and pressure. This reaction is a simple nucleophilic acyl substitution reaction, where ammonia replaces the methoxy group, producing oxalamide and methanol as byproducts. Another important industrial synthesis method is the hydrolysis of dicyandiamide or the ammonolysis of oxalic acid ($HOOCCOOH) or its salts, but the dimethyl oxalate method is generally preferred due to its high yield and purity. In the laboratory, oxalamide can also be prepared by reacting oxalyl chloride (ClCOCOCl) with ammonia; this method is faster but more expensive. Due to its low solubility, oxalamide is widely used as a slow-release nitrogen fertilizer.
Purification Methods
Crystallise oxamide from water, grind it and dry it in an oven at 150o. [Beilstein 2 IV 1860.]
