Cyanamide salts

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. 

Other reactions of aminoguanidine with nitrous acid Cyanamide salts Silver cyanamide Nitrocyanamide salts Nitrophenol salts Lead picrate Lead styphenate Lead stypheratc manufacture... 

Reaction of 1,3-oxathiolium salts (264) with cyanamide in the presence of sodium ethoxide produces also substituted 4-aniinothiazolcs (265) (Scheme 136) (777). 

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. 

Plants can also be pests that need to be controlled, particulady noxious weeds infesting food crops. Prior to 1900, inorganic compounds such as sulfuric acid, copper nitrate, sodium nitrate, ammonium sulfate, and potassium salts were used to selectively control mustards and other broadleaved weeds in cereal grains. By the early 1900s, Kainite and calcium cyanamid were also used in monocotyledenous crops, as well as iron sulfate, copper sulfate, and sodium arsenate. Prom 1915 to 1925, acid arsenical sprays, carbon bisulfate, sodium chlorate, and others were introduced for weed control use. Total or nonselective herbicides kill all vegetation, whereas selective compounds control weeds without adversely affecting the growth of the crop (see Herbicides). 

The nitrogen of aHphatic and aromatic amines is alkylated rapidly by alkyl sulfates yielding the usual mixtures. Most tertiary amines and nitrogen heterocycles are converted to quaternary ammonium salts, unless the nitrogen is of very low basicity, eg, ia tn phenylamine. The position of dimethyl sulfate-produced methylation of several heterocycles with more than one heteroatom has been examined (22). Acyl cyanamides can be methylated (23). Metal cyanates are converted to methyl isocyanate or ethyl isocyanate ia high yields by heating the mixtures (24,25). 

Preparation. Hexagonal boron nitride can be prepared by heating boric oxide with ammonia, or by heating boric oxide, boric acid, or its salts with ammonium chloride, alkaU cyanides, or calcium cyanamide at atmospheric pressure. Elemental nitrogen does not react with boric oxide even in the presence of carbon, though it does react with elemental boron at high temperatures. Boron nitride obtained from the reaction of boron trichloride or boron trifluoride with ammonia is easily purified. 

Most of the reactions occurring at the amino group of the cyanamide molecule requite the anionic species, —N=C=N or HN C=N, sometimes in equivalent amount and occasionally as provided by base catalysis. Therefore, the process conditions for dimerization should be created to avoid the use of any metal salt, such as mono sodium phosphate (4). 

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. 

Numerous references for the preparation of aminoguanidine bicarbonate and other salts can be found in the excellent review article, The Chemistry of Aminoguanidine and Related Substances by Lieber and Smith. More recently, it has been prepared by treating a cyanamide solution at 20-50° with hydrazine and carbon dioxide, ... 

I-Cyano-3-phenylurea, first obtained by the alkaline hydrolysis of 5-anilino-3- -toluyl-l,2,4-oxadiazole, has been prepared by tlic condensation of phenyl isocyanate and the sodium salt of cyanamide. However, in these publications an incorrect structural assignment for the product was made. 1-Cyano-3-phenyl-urea is obtained also, together with other products, by warming gently l-cyano-3-phenylthiourea with caustic soda in the presence of ethylene chlorohydrin, or by gradually adding caustic )otash to a boiling solution of 1-phenyldithiobiuret and ethylene clilorohydrin in ethanol. ... 

Benzeneamine, N-hydroxy-N-nitroso,ammonium salt Nitrilotrlacetic acid 4,4 -Thiodianiline Ethyl acrylate Butyl acrylate Ethyleneimine (Aziridine) p-Nrtrosodiphenylamine Calcium cyanamide Hydrazine Aldrin... 

Sodium borohydride reduction of 4-substituted isoquinolinium salts led to vinylogous cyanamides, ureas, and urethanes, as well as the corresponding tetrahydroquinolines (640). Hydrogenation of /8-acylpyridinium salts (641) to vinylogous ureas was exploited in syntheses of alkaloids (642), leading, for instance, to lupinine, epilupinine, and corynantheidine (643, 644). Similarly, syntheses of dasycarpidone and epidasycarpidone were achieved (645) through isomerization of an a,/0-unsaturated 2-acylindole and cyclization of the resultant enamine. 

A convenient way of obtaining secondary amines without contamination by primary or tertiary amines involves treatment of alkyl halides with the sodium or calcium salt of cyanamide NH2—CN to give disubstituted cyanamides, which are then hydrolyzed and decarboxylated to secondary amines. Good yields are obtained when the reaction is carried out under phase-transfer conditions. The R group may be primary, secondary, allylic, or benzylic. 1, co-Dihalides give cyclic secondary amines. 

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... 

Besides companies specifically mentioned in the text, the authors are indebted for donations of materials to the American Cyanamid Company, the Geigy Company, and the Pennsylvania Salt Manufacturing Company. They also wish to express indebtedness to W. E. Baier, of the California Fruit Growers Exchange, for arranging to process the DDT-treated lemons and oranges, and to M. Elliot Miller and R. C. Blinn of these laboratories for most of the analytical work.. 

Cyanamid) Sodium salts (nitrate, sulfate thiocyanate) No retardation of thiocyanate ions... 

Materials. Monomers used in the preparation of the copolymers were as follows acrylamide as a 50% solution in water, stablized with cupric ion, supplied by American Cyanamid Company acrylic acid supplied by BASF and AMPS, 2-acrylamido-2-methylpropanesulfonic acid, (recrystallized grade) obtained from Lubrizol. The sodium salts of acrylic acid and AMPS were prepared by gradual neutralization of the monomers with sodium hydroxide solution, maintaining a temperature of 0 to 5°C, to give a final concentration of 50%. 

The title compound ( cyanamide dihydrochloride ) reacts with perchloric acid to form the perchlorate salt, and with ammonium nitrate, the nitrate salt, both being highly explosive, and the latter also an oxidant. 

Cyclization of a-cyanoalkyl cyanamides (74) with hydrogen bromide gave 4-aminoimidazoles (77) as their hydrobromide salts. These compounds (77) were found to be unstable as the free base but gave stable (V-acetyl derivatives (84 R2 = Br, R3 = COCH3) (33-82%) when treated with acetic anhydride in pyridine (64JOC153 66CA12211). 

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