Cyanamide, crystalline

The largest production of acrylamide is in Japan the United States and Europe also have large production faciUties. Some production is carried out in the Eastern Bloc countries, but details concerning quantities or processes are difficult to obtain. The principal producers in North America are The Dow Chemical Company, American Cyanamid Company, and Nalco Chemical Company (internal use) Dow sells only aqueous product and American Cyanamid sells both Hquid and sohd monomer. In Europe, Chemische Eabrik Stockhausen Cie, Ahied CoUoids, The Dow Chemical Company, and Cyanamid BV are producers Dow and American Cyanamid are the only suppHers to the merchant market, and crystalline monomer is available from American Cyanamid. Eor Japan, producers are Mitsubishi Chemical Industries, Mitsui Toatsu, and Nitto Chemical Industries Company (captive market). Crystals and solutions are available from Mitsui Toatsu and Mitsubishi, whereas only solution monomer is available from Nitto. 

Melamine. Melamine (cyanurotriamide, 2,4,6-ttiainino-j -triazine) C H N, is a white crystalline soHd, melting at approximately 350°C with vaporization, only slightly soluble in water. The commercial product, recrystallized grade, is at least 99% pure. Melamine was synthesized eady in the development of organic chemistry, but it remained of theoretical interest until it was found to be a usehil constituent of amino resins. Melamine was first made commercially from dicyandiamide [461-58-5] (see Cyanamides), but is now made from urea, a much cheaper starting material (9—12) (see also... 

For production of commercial 50% solution and for recovery of crystalline cyanamide, this process is modified to improve purity and concentration. Calcium and iron may be removed by ion-exchange treatment. The commercial 50% solution is stabilized at pH 4.5—5.0 with 2% monosodium phosphate and contains less than 1.5% dicyandiamide and 0.2% urea. Such solutions are expected to show less than 1% change ia cyanamide content per month of storage below 10°C. It is advisable, however, to adjust the pH periodically duriag extended storage. Organic esters may be used iastead for improved stabihty (23). 

A mixture of 25 ml of 50% sodium hydroxide in 5 ml of water is added to a mixture of 15 g of cyanamide, 2.2 g of methylchloroformate, 3.5 ml of water and 3 ml of acetone over 45 minutes below 10°C, pH raised to 6.5. A moiar equivaient soiution of the diamine in 100 ml of ethanol isadded. The mixture is heated until the easily volatile solventsare expelled, to about 85°C, then maintained at this temperature with some water added for one-half hour. The product, methyl 5-propylthio-2-benzimidazolecarbamate, is separated, washed to give a colorless crystalline solid, MP 208°-210°C. 

Urea occurs as a colorless to white, prismatic, crystalline powder or as small, white pellets. It is commonly produced from C02 by ammonolysis or from cyanamide by hydrolysis. It is freely soluble in water and in boiling alcohol, but practi-... 

The von Braun degradation (85, 67) was reinvestigated and fully worked out by Boit (86). The reaction of strychnine with cyanogen bromide in hot benzene leads to the formation of two products, the amorphous bromocyanamide-I (LXXX) and the crystalline bromo-cyanamide-II (LXXXI). Dihydrostrychnine, on the other hand, gives only one product (LXXXII), which is identical with the product of catalytic hydrogenation (platinum in ethyl acetate) of bromocyan-amide-II. The corresponding brucine compounds behave analogously. 

Lithium carbide is a white or grey crystalline substance, its density at 18° C. being 1-65. At bright red heat it is decomposed, and Tucker and Moody found that at 925° C. and a pressure of fifty pounds to the square inch it absorbs nitrogen freely with formation of cyanamide, dicyanamide, and cyanide. It is a powerful reducer, decomposing water energetically at ordinary temperatures with formation of acetylene ... 

Cyanamide (H2NCN), a very irritating and caustic crystalline solid (mp 45°C), is prepared by hydrolysis of CaNCN ... 

Cyanamide, H2N =N , is a crystalline solid, mp 45 °C, prepared by hydrolysis of its calcium salt, CaNCN, under mild conditions (e.g. aqueous CO2) in order to avoid further hydrolysis of cyanamide. Calcium cyanamide is made on a large industrial scale by a high-temperature reaction of calcium carbide with molecular nitrogen (equation 18). The cyanamide... 

Cyanamide is a colorless, orthorhombic, hydrophilic, crystalline solid with a mild odor. It is commonly used in liquid solution, and is expected to be soluble in water, ether, benzene, acetone, phenols, amines, ketones, and alcohols. 

The dimer of cyanamide is formed when calcium cyanamide is boiled with water. This also is a colourless crystalline compound, the molecule of which has the structure ... 

The cyanogen halides polymerize on standing to the trimers, the cyanuric halides. Cyanamide is converted into the corresponding trimer, melamine, on heating to about 150°C. Isocyanic acid, however, polymerizes far more readily. If urea is distilled, isocyanic acid is formed but polymerizes to cyanuric acid, (NCOH)3, a crystalline solid, the vapour of which, on rapid cooling, yields isocyanic acid as a liquid which, above 0 C, polymerizes explosively to cyamelide, a white porcelain-like solid. This latter material is converted into salts of cyanuric acid by boiling with alkalis. These reactions are summarized in Chart 21.1. Cyanuric derivatives... 

Dicyandiamide is made in a crystalline form by extracting technical calcium cyanamide with hot water —... 

The product can be filtered off as a dark brown crystalline substance (Harvey, 19S9 Klopping, 1960 Littrell et al., 1967). They can also be synthesised by the reaction of calcium cyanamide with chloroformic acid alkyl ester and o-phenylene diamine (Adams and Schlatter, 1966 Toth et al., 1972 Burmakin et al., 1974), or by the reaction of alkyl cyano carbamates (25), produced by the treatment of cyanamide with chloroformic acid alkyl ester, with o-phenylene diamine (Adams and Schlatter, 1969), or by the reaction of cyanamide with alkyl mercaptan, chloroformic acid alkyl ester and o-phenylene diamine (Schlatter, 1970) ... 

Cyanamide, CN.NH2, is a crystalline, hygroscopic solid, which polymerizes readily. Like other compounds in which the amido group is in combination with a negative radical, metallic derivatives may be formed by the replacement of the hydrogen atoms. Silver cyanamide, CH.NAg2, is a yellow amorphous substance which, unlike most silver salts, is insoluble in ammonia. 

Alkali oxides are thermodynamically stable up to very high temperatures, and even hydrides have saline character and considerable stability. Lithium nitride is a compound which can be isolated from the solution in the metal in crystalline form. Dissolved oxides have the ability to react with transition metal oxides to form complex oxides, or with hydrogen to form hydroxides of the heavier alkali metals. Lithium cyanamide is formed by means of the reaction between nitrogen and carbon dissolved in the molten metal. The reaction product in liquid sodium is sodium cyanide. 

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