What Is Dicyandiamide?
Dicyandiamide is an organic compound with the chemical formula C2H4N4. It is known in IUPAC nomenclature as 2-cyanoguanidine. Other common names include dicyanodiamide and DCD, with a CAS registration number of 461-58-5.
Uses of Dicyandiamide
1. Main Applications
Dicyandiamide is primarily utilized as a curing agent for epoxy resins, an additive for starch paste, a raw material for both organic synthesis and dicyandiamide resin, a stabilizer for synthetic detergents, and in the production of dyes, fertilizers, and agricultural chemicals including insecticides and fungicides. As a curing agent, it requires the addition of a tertiary amine, such as an imidazole adduct, as a catalyst to manage the high curing temperature (180°C or higher) and the heat generated during curing.
2. Synthetic Applications
Upon heating above its melting point, dicyandiamide decomposes into melamine and ammonia, making it a valuable raw material for the organic synthesis of cyanamide derivatives such as guanidine, dicyandiamidine, diguanide, and melamine.
3. Use as Fertilizer
Dicyandiamide also serves as a component in slow-release fertilizers, applied as basal fertilizers at planting. Soluble in water, it inhibits soil microorganisms like nitrite bacteria, slowing the conversion of ammonia nitrogen to nitrate nitrogen, thereby retaining nutrients in the soil. Its effectiveness is influenced by the water temperature, affecting its solubility.
Properties of Dicyandiamide
Dicyandiamide, with a molecular weight of 84.08, melts at 210°C and appears as a white crystalline powder at room temperature. It forms orthorhombic or plate-like crystals in its crystalline state and is easily soluble in hot water, slightly soluble in cold water and ethanol, and insoluble in acetone. Aqueous solutions of dicyandiamide are nearly neutral.
Types of Dicyandiamide
Dicyandiamide is marketed both as a reagent for research and development and as an industrial chemical, available in various sizes including 25g, 500g, 1kg, and 3kg for R&D, and typically in 25 kg bags for industrial use. Its applications vary, so usage should be checked depending on whether it is intended as an epoxy resin hardener, starch glue additive, synthetic detergent stabilizer, or dye.
Other Information on Dicyandiamide
1. Synthesis of Dicyandiamide
The synthesis of dicyandiamide commonly involves reacting lime nitrogen with water and acid to form a cyanamide solution, which is then heated to induce polymerization. This method benefits from the tautomerism of cyanamide, with the process potentially yielding dicyandiamide through the reaction of cyanamide and carbodiimide in a basic solution.
2. Tautomerism of Dicyandiamide
Dicyandiamide exhibits tautomerism similar to cyanamide, with the nitrogen atom attached to the nitrile group being in equilibrium between bonding and protonation states, possibly existing as zwitterionic ions.