Cyanamides, addition

In the United States, Du Pont and PPG had a long-established reputation in industrial and consumer paints. W. R. Grace since buying Dewey Almy, and Rohm Haas because of its age-old tradition in acrylics, drew substantial profits from their specialties. This was also true of American Cyanamid (additives for plastics, cosmetics) and of Monsanto (products for rubber, special polymers). Since its withdrawal from the tire business, BF Goodrich, aside from its PVC lines, is concentrating now on specialties. 

FM-35 American Cyanamid Addition-type polyimide film on glass cloth with metal fillers. 

The selenoureas needed for condensation can usually be prepared by addition of hydrogen selenide to a solution of the corresponding cyanamides or carbodiimides. They can be less dangerously and quite... 

Aminothiazole derivatives (243) can be prepared by treatment of enamines of type 240 with sulfur and cyanamide at room temperature in ethanol (701) yields range from 30 to 70%, and no catalyst is required. Initial formation of the thiolated intermediate (241) is probably followed by addition of cyanamide, yielding 242 (Scheme 124). 

Urea is also used as feed supplement for mminants, where it assists in the utilization of protein. Urea is one of the raw materials for urea—formaldehyde resins. Urea (with ammonia) pyrolyzes at high temperature and pressure to form melamine plastics (see also Cyanamides). Urea is used in the preparation of lysine, an amino acid widely used in poultry feed (see Amino acids Feeds and feed additives, petfoods). It also is used in some pesticides. 

Processes rendered obsolete by the propylene ammoxidation process (51) include the ethylene cyanohydrin process (52—54) practiced commercially by American Cyanamid and Union Carbide in the United States and by I. G. Farben in Germany. The process involved the production of ethylene cyanohydrin by the base-cataly2ed addition of HCN to ethylene oxide in the liquid phase at about 60°C. A typical base catalyst used in this step was diethylamine. This was followed by liquid-phase or vapor-phase dehydration of the cyanohydrin. The Hquid-phase dehydration was performed at about 200°C using alkah metal or alkaline earth metal salts of organic acids, primarily formates and magnesium carbonate. Vapor-phase dehydration was accomphshed over alumina at about 250°C. 

A second commeicial route to aciylonitiile used by Du Pont, Ameiican Cyanamid, and Monsanto was the catalytic addition of HCN to acetylene... 

Calcium. Calcium is the fifth most abundant element in the earth s cmst. There is no foreseeable lack of this resource as it is virtually unlimited. Primary sources of calcium are lime materials and gypsum, generally classified as soil amendments (see Calcium compounds). Among the more important calcium amendments are blast furnace slag, calcitic limestone, gypsum, hydrated lime, and precipitated lime. Fertilizers that carry calcium are calcium cyanamide, calcium nitrate, phosphate rock, and superphosphates. In addition, there are several organic carriers of calcium. Calcium is widely distributed in nature as calcium carbonate, chalk, marble, gypsum, fluorspar, phosphate rock, and other rocks and minerals. 

U.S.A., in lactating dairy cattie to increase milk production. EH Lilly and Company, The Upjohn Company, and American Cyanamid Company also have interests in the commercial appHcation of recombinant bovine GH. Recombinant porcine GH [9061-23-8] preparations from several companies, eg. The Upjohn Company, Smith Kline Beecham Animal Health, Pitman-Moore, Inc., Monsanto Company, and American Cyanamid Company, are being evaluated for commercial use. Recombinant human GH for clinical use is marketed under such names as Protropin (Genentech), Umatrope (EH Lilly), Genotropin (Sumitomo), and Somatonorm (Kabi-Vitmm) by a variety of pharmaceutical companies. A listing of additional suppHers is available (2). 

The chemical industry manufactures a large number of antioxidants (qv) as well as uv stabilizers and their mixtures with other additives used to facilitate resin processing. These companies include American Cyanamid, BASE, Ciba—Geigy, Eastman Chemical, Elf Atochem, Enichem, General Electric, Hoechst—Celanese, Sandoz, and Uniroyal, among others. The combined market for these products in the United States exceeded 900 million in 1994 and will reach 1 billion in the year 2000. 

Hydrogen sulfide reacts with nitriles in the presence of a basic catalyst forming thioamides. A commercial example is its addition to cyanamide with the formation of thiourea [62-56-6]. ... 

Reactions. Reactions of cyanamide are either additions to the nitrile group or substitutions at the amino group. Both are involved in the dimerization to dicyandiamide. 

Dimerization involves addition of the cyanamide anion to the nitnle group of an undissociated molecule to give the anion of cyanoguanidine, or dicyandiamide. This reaction takes place most readily at pH 8—10 where the reactants are present in favorable proportion. The product is a weaker acid than cyanamide and is protonated at once with generation of a new cyanamide anion. 

Sinulatly, nucleophilic reagents are suitable for addition reactions only if they are not so strongly basic as to produce the cyanamide anion in large amounts. In such cases, dicyandiamide is produced or a cyanamide salt is obtained. Ai,Ai-Disubstituted cyanamides do not ionize, of course, and react easily with strongly basic nucleophiles. 

Substitutions. The cyanamide anion is strongly nucleophilic and reacts with most alkylating or acylating reagents (4) addition to a variety of unsaturated systems occurs readily (4). In some cases, a cyanamide salt is used in others, base catalysis suffices. Ethyl iodide reacts with sodium hydrogen cyanamide [17292-62-5] to form a trisubstituted isomelamine. 

Additions. The addition reactions of ammonia and amines to the cyanamide nitrile group have been thoroughly studied (15). For optimum conditions, the reaction should be carried out ia an aqueous medium at about 140°C. Gradual addition of the cyanamide to the amine salt minimises dimerization. 

Specifications and Analysis. Cyanamide is sold as anhydrous, aqueous 50%, and calcium cyanamide. Aqueous 50% cyanamide solutions contain a buffer additive, usually 2% NaH2P04, to stabilize the pH and prevent formation of dicyandiamide and urea. Calcium cyanamide is stable under dry conditions. Table 2 gives a typical analysis of the three commercial forms. 

Industrial uses make up most of the market for cyanamide. Calcium cyanamide is used directly for steel nitridation (34) and to some extent for desulfurization (36) (see Steel). Cyanamide is used to produce cationic starch (36) and calcium cyanide. Cyanamide is, of course, the raw material for dicyandiamide and melamine. New uses include intermediates for pesticides, detergents (37), medicines such as antihistamines, hypertension, sedatives, contraceptives, etc (38), the photography industry (39), as an additive for fuels and lubricants, as a paper preservative, and as a cement additive. 

The acylation of enamines derived from cyclic ketones, which can lead to the acyl ketone or ring expansion (692-694), was studied by NMR and mass spectroscopic analysis of the products (695,696). In a comparative study of the rates of diphenylketene addition to olefins, a pronounced activation was observed in enamines (697). Enamine N- and C-acylation products were obtained from reactions of Schiff s bases (698), vinylogous urethanes (699), cyanamides (699), amides (670,700), and 2-benzylidene-3-methylbenzothiazoline (672) with acid chlorides, anhydrides, and dithio-esters (699). 

Addition of alcohols or other carbocation sources to cyanamides (Ritter)... 

Another important click reaction is the cycloaddition of azides. The addition of sodium azide to nitriles to give l//-tetrazoles is shown to proceed readily in water with zinc salts as catalysts (Eq. 11.71).122 The scope of the reaction is quite broad a variety of aromatic nitriles, activated and nonactivated alkyl nitriles, substituted vinyl nitriles, thiocyanates, and cyanamides have all been shown to be viable substrates for this reaction. The reaction of an arylacetylene with an azide in hot water gave 1,4-disubstituted 1,2,3-triazoles in high yields,123 while a similar reaction between a terminal aliphatic alkyne and an azide (except 111 - nitroazidobenzcnc) afforded a mixture of regioisomers with... 

This work and any practicable results derived therefrom have been encouraged and expedited throughout by the American Cyanamid Company. Additionally, the authors wish to express appreciation for aid in various phases of the work to Mrs. M. Elliot Miller, Charlotte McHale, Jacquelyn Sellers, L. D. Anderson, M. M. Barnes, G. E. Carman, J. H. Barkley, J. C. Ortega, C. R. Shafer, and H. U. Meyer of these laboratories, and to W. E. Baier and C. W. Wilson of the California Fruit Growers Exchange, Ontario. 

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