Cyanamide

Physicochemical property

Cyanamide is also called hydrogen cyanamide，urine anhydride, its scientific name is amino nitrile. It is white orthogonal series crystals, in a diamond shaped, colorless, easy moisture. Melting point is 42℃, boiling point is 83℃ (50.66kPa), vapor pressure is (20℃) is 500MPa. Cyanamide is high solubility in water and weak acid, and completely miscible in water of 43℃. It is soluble in benzene and phenol, alcohols, amines, ethers, ketones, slightly soluble in benzene, halogenated hydrocarbons, but insoluble in epoxy ethane, cyclohexane. Solubility (20℃ ): water 4.59kg/L, methyl ethyl ketone 505g/kg, acetic acid ethyl ester 424g/kg, octanol 288g/kg, chloroform 2.4 g/kg. It can volatilize with water vapor, so it can dissolve in a series of solvents. In polar organic solvent, solubility is large, and in non-polar solvents is smaller. Crystal cyanamide is not stable, large polarity. Due to the cyanamide molecular structure containing the cyano and amino, both of which are active groups, it has the functional groups of the multiple reaction performance, prone to addition, substitution, condensation reaction. It is stable to light. It decomposites to dicyandiamide and polymers in alkali, and decomposites to urea in acid. It decompose when heated to 180℃. Product has four kinds of crystal of 25%, 40%, 50% and 90%. 25% of cyanamide solution is mainly used for creatine production, 50% and 90% of cyanamide solutions are mainly used for producing methylene urea pharmaceutical intermediates.

Figure 1 Three-dimensional structure of cyanamide

Main application

1. Important pharmaceutical raw material
Cyanamide is mainly used for the production of hydrochloric acid cytarabine, dye intermediate 3-amino-5-hydroxy-1,2,4-nitrogen azole, cyanide urea amine, melamine methyl carbamate, cyanide urine amide, thiourea, carbendazim. It is also raw material for preparation of organic guanidine, then the product pharmaceutical barbituric acid, sulfa drugs and guanidine salt, etc. It can also be used for production anticancer drugs of fluorouracil in medicine. Cyanamide calcium salt can be used for clinical treatment of alcoholism and anthelmintic action.
2. Raw materials for chemical pesticides
2.1 Cyanamide can be used as chemical raw materials of no residue, low toxicity, broad-spectrum pesticide, and can also be used for production of antibacterial agent such as carbendazim, benzene benomyl, methyl mepanipyrim and mepanipyrim, Pirimicarb, pyrimidinoxy phosphorus, herbicide Chlorsulfuron, Metsulfuron methyl, Metsulfuron methyl ethyl, long ether tribenuron methyl and bensulfuron methyl and pyrazole ethyl, hexazinone, etc. It has the significance of technological innovation for pesticide production, solves the environmental pollution while the general pesticide production enterprises can be difficult to solve the problem using calcium cyanamide in the production of pesticide. So using cyanamide can save equipment investment, reduce production costs.
2.2 In recent years, cyanamide is used as off leaf agents, herbicides and pesticides in abroad, but also can be used as pesticide, and cyanamide has a certain of nitrogen application effect. Cyanamide solution was used as a defoliant, non-toxic pesticides for fruit trees in abroad.
2.3 The cyanamide in agriculture can be used as plant growth regulators, with both pesticidal and bactericidal effects. Directly sprayed on crops, can effectively inhibit the activity of catalase in plants, accelerate plant oxidative pentose phosphate (PPP) circulation, thus speeding up the generation of basic substances in plants, play a role in the regulation of growth. The field efficacy trials showed that It can regulate the growth and increase production of cherries and grapes. Before 15 to 20 days in grape germination, it sprayed evenly on the branches, uniform of a drug on bud eye, can advance germination of 7 to 10 days. For early flowering, full flowering stage, coloring period and mature period, using it can aslo advance early. At the same time it is good dormancy terminating agent in the production of kiwi, cherries, grapes. it sprayed evenly on bud eye in the dormant period, it can break the dormancy period, can be early germination, early flowering, early mature and early on the market. It can significantly improve the yield, change fruit fleshy and improve the quality of varieties.

Excellent flame retardant materials

The cyanamide is mainly used for production of flame retardant agent such as o-methyl isourea, creatine, guanidine phosphate. At the same time, as a kind of flame retardant material with excellent performance, cyanamide polyols and polyether solution are used for production of polyurethane, can significantly improve the flame retardancy of polyurethane material, which is a new type of fine chemical new materials.

Fixing material

The materials from the two polymer fixing agent melamine dicyandiamide can be used in the production of fixing agent Y, fixing agent G, fixing agent M and fixing agent B. Reaction product of cyanamide, poly formaldehyde and acid copper is fixing agent B, which is gray powder, can be used for direct dyes and staining after treatment. 30.9 copies of diethylenetriamine and 24.8 dicyandiamide react under 100℃, then reaction again in 155 ℃, after 5h cooling, crushing to obtain colorless powder. It is a kind of formaldehyde-free fixing agent, low cost, having a development promising as green products.

Toxicity

1. It has the skin irritation and corrosive, can lead to severe dermatitis, the person suction can cause mucosal irritation, transient flushing, headache, dizziness, shortness of breath, tachycardia and hypertension and other symptoms.
2. Mutagenicity test: mild irritation to rabbit skin and eye severe stimulation, the drug of guinea pig skin allergic reaction test is attenuated sensitive drugs.
3.The effect maximum dose is 0.2mg/kg/d in rats with 90d sub chronic feeding experiment. Cyanamide drug and 50% aqueous solution are medium toxicity. Please use it to Caution!

Chemical property

Pure cyanamide is a transparent liquid, m.p.-115℃, b.p.-8.5℃, soluble in alcohols, phenols, amines, ethers, easily soluble in benzene, alkyl halides, 77.5% of it is soluble in water of 15℃. The high concentration of cyanamide is not stable, easy polymerization, often adding stabilizer. General merchandise for 50% of cyanamide solution, n20D 1.4050, the relative density is 1.082.

Uses

1.Cyanamide is an important intermediate of pesticide. It can also be used for production of antibacterial agent such as carbendazim, benzene benomyl, methyl mepanipyrim and mepanipyrim, Pirimicarb, pyrimidinoxy phosphorus, herbicide Chlorsulfuron, Metsulfuron methyl, Metsulfuron methyl ethyl, long ether tribenuron methyl and bensulfuron methyl and pyrazole ethyl, hexazinone, etc.
2. In the pharmaceutical industry, it is used as a raw material for the production of hydrochloric acid. It is also used for the production intermediates of 3-amino-5-hydroxyl-1,2,4-triazol in the dye industry. In addition, for organic synthesis and plastic raw materials, it can be used for production of cyanuric amide, dicyandiamide, cyanide methyl carbamate etc.
3.Cyanamide liquid is used for industrial raw materials, pharmaceutical intermediates, agricultural pesticides, fertilizer, plant growth regulator, food additives etc.
4. Used in the production of materials such as urine.

Methods of production

1.It is gotten by the reaction of lime nitrogen with sulphuric acid。
The preparation method is based on the lime nitrogen as raw material, reaction with sulfuric acid is made. In the reactor, the water is putted, with ice water cooling, lime nitrogen input, the temperature was kept between 0 to 15℃, dropping 5% of sulfuric acid solution, adjusting the pH = 6 and holding 20 min. Then filtration, washing, and then return to a reaction kettle, added lime nitrogen, repeat the above operation 2 times, the obtained filtrate is through membrane thickening, keeping a certain temperature, concentrated content reached 50%~55%, Cyanamide solution of 50% is obtained.
Reaction equation: CaCN2+H2O+H2SO4-> NH2CN+CaSO4
2. Urea process。

Description

Cyanamide and its salts are used on various occasions, such as in chemistry, in anti-rust solutions or in drugs for treating alcoholism (Come).

Chemical Properties

white crystalline solid

Chemical Properties

Cyanamide is a combustible crystalline solid, but it is usually found as a 25% liquid solution.

Uses

Fumigants, metal cleaners, production of synthetic rubber, chemical synthesis

Uses

Cyanamide is commonly used in liquid solution and is expected to be soluble in water, ether, benzene, acetone, phenols, amines, ketones, and alcohols. It is used mainly in agriculture as a restbreaking agent and in pharmaceutical industries in the production of antihistamines, antihelminthics, and many other drugs.

Uses

In Europe, cyanamide is used as a fertilizer, weed killer, and defoliant. In North America, these applications have been practically discontinued. It is also used to produce cationic starch and calcium cyanide, dicyandiamide, and melamine. New uses include intermediates for pesticides; detergents; medicines such as antihistamines, hypertension, sedatives, and contraceptives; photography industry; additive for fuels and lubricants; paper preservative; and cement additive. Dormex is a common rest-breaking agent applied in spring to stimulate uniform opening of buds.
Cyanamide has been tested as an effective and welltolerated pharmacological adjunct to treat alcohol-dependent patients. It is a potent aldehyde dehydrogenase inhibitor, and alters cholinergic function in the frontal cortex and hippocampus of rats exposed to ethanol.

Production Methods

The basic process for the manufacture of cyanamide comprises four steps. The first three steps produce calcium cyanamide: lime is made from high grade limestone; (2) calcium carbide is manufactured from lime and coal or coke; calcium cyanamide is produced by passing gaseous nitrogen through a bed of calcium carbide with 1% calcium fluorspar, which is heated to 1000–1100°C to start the reaction—the heat source is then removed and the reaction continues because of its strong exothermic character; and cyanamide is manufactured from calcium cyanamide by continuous carbonation in an aqueous medium.

Definition

cyanamide: 1. An inorganic saltcontaining the ion CN₂^{2-. See calciumcyanamide. 2. A colourless crystallinesolid, H₂NCN, made by the actionof carbon dioxide on hotsodamide. It is a weakly acidic compound(the parent acid of cyanamidesalts) that is soluble in water andethanol. It is hydrolysed to urea inacidic solutions.}

Reactions

Cyanamide reacts (1) as a base with strong acids forming salts, (2) as an acid forming metallic salts, such as calcium cyanamide CaCN2. Cyanamide is formed (1) by reaction of cyanogen chloride CN·Cl plus ammonia (ammonium chloride also formed), (2) by reaction of thiourea plus lead hydroxide (lead sulfide also formed).

General Description

Colorless deliquescent crystals. Mp: 45°C; bp: 260°C. Density: 1.282 g cm-3. Quite soluble in water (77 g / 100 g solution at 15°C). Soluble in butanol, methyl ethyl ketone, ethyl acetate, alcohols, phenols, amines, ethers. Note: The term "Cyanamide" is also used to refer to the important compound calcium Cyanamide, which is a different chemical.

Reactivity Profile

Cyanamide is the amide of cyanic acid. Non-flammable but combustible (flash point: 140°C). Decomposes on warming above 49°C. Emits toxic fumes of CN- and NOx when heated to decomposition or on contact with acids or acid fumes (Hazardous Chemicals Desk Reference, p. 353 (1987)). Contact with moisture, acids or bases may cause a violent reaction at temperatures above about 40°C. Dry solid may polymerize at temperatures above 122°C. Rapid or explosive polymerization may occur during the evaporation of aqueous solutions. Reacts explosively with strong oxidizing agents and strong reducing agents. Attacks various metals (International Chemical Safety Card).

Hazard

Strong irritant to skin and mucous membranes; avoid inhalation or ingestion.

Health Hazard

Cyanamide is an irritant of the eyes, mucous membranes, and skin; it is an inhibitor of aldehyde dehydrogenase and can cause an “antabuse” effect with ethanol ingestion.
Cyanamide is severely irritating and caustic to the eyes, skin, and respiratory tract.

Flammability and Explosibility

Not classified

Agricultural Uses

Herbicide, Plant growth regulator: A U.S. EPA restricted Use Pesticide (RUP). Not currently approved for use in EU countries (re-submitted). Used primarily as a plant growth regulator. Cyanamide may be melted to give a dimer, dicyandiamide or cyanoguanidine. At higher temperatures it gives the trimer, melamine, a raw material for melamine-formaldehyde resins.

Agricultural Uses

Cyanamide, the trade name for calcium cyanamide, contains calcium hydroxide and carbon in small quantities as impurities. It is used as a fertilizer, the powdered form of which contains about 22% nitrogen.

Trade name

DORMEX®; SKW 83010®

Contact allergens

Cyanamide and its salts are used in various occasions such as in chemistry, in antirust solutions, or in a drug (Come?) for treating alcoholism (inhibition of alcohol deshydrogenase).

Safety Profile

Poison by ingestion, inhalation, and intraperitoneal routes. Moderately toxic by skin contact. Experimental reproductive effects. Combustible when exposed to heat or flame. To fight fire, use CO2, dry chemical. Thermally unstable. Contact with moisture (water), acids, or alkalies may cause a violent reaction above 40'. Concentrated aqueous solutions may undergo explosive polymerization. Mixture with 1,2 phenylenediamine salts may cause explosive polymerization. When heated to decomposition or on contact with acid or acid fumes, it emits toxic fumes of CNand NOx. See also CYANIDE and AMIDES.

Potential Exposure

Cyanamide may be melted to give a dimer, dicyandiamide or cyanoguanidine. At higher tem- peratures it gives the trimer, melamine; a raw material for melamine-form aldehyde resins.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.

storage

(1) Color Code—Yellow: Reactive Hazard; Storein a location separate from other materials, especially flammables and combustibles. (2) Color Code—Blue: HealthHazard/Poison: Store in a secure poison location. Prior toworking with this chemical you should be trained on itsproper handling and storage. Store in tightly closed containers in a cool well-ventilated area away from acids or acidfumes. Cyanamide can be stored in glass containers if it isstabilized with phosphoric, acetic, sulfuric, or boric acid; itattacks iron and steel, copper, and brass.
Sources of ignition, such as smoking and open flames, areprohibited where cyanamide is used, handled, or stored in amanner that could create a potential fire or explosion hazard.Wherever cyanamide is used, handled, manufactured, orstored, use explosion-proof electrical equipment and fittings.

Shipping

UN3276 Nitriles, liquid, toxic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required, Potential Inhalation Hazard (Special Provision 5).

Purification Methods

Purify it by placing ca 15g in a Soxhlet thimble and extracting exhaustively (2-3hours) with two successive portions of Et2O (400mL, saturated with H2O by shaking before use) containing two drops of 1N acetic acid. Two successive portions of Et2O are used so that the NH2CN is not heated for too long. Each extract is dried over Na2SO4 (30g), then combined and evaporated under reduced pressure. The NH2CN may be stored unchanged at 0o in Et2O solution in the presence of a trace of AcOH. Extracts from several runs may be combined and evaporated together. The residue from evaporation of an Et2O solution is a colourless viscous oil which sets to a solid and can be recrystallised from a mixture of 2 parts of *C6H6 and 1 part of Et2O. Concentrating an aqueous solution of NH2CN at high temperatures causes EXPLOSIVE polymerisation. [Kurzer & Lawson Org Synth Coll Vol IV 645 1963, Pinck & Salissbury Inorg Synth III 39 1950, Soloway & Lipschitz J Org Chem 23 613 1958.] Hygroscopic.[Beilstein 3 IV 145.]

Toxicity evaluation

Adsorption–desorption studies in soil have estimated very low Koc values (0–6.81 ml g^-1 ) indicating low adsorption and high mobility potential of cyanamide in soil; however, soil column leaching studies indicate that cyanamide is only slightly mobile. Volatilization is not expected to be an important fate and transport process based on the Henry’s law constant and vapor pressure. When released into the air, vapor phase cyanamide is expected to have a half-life of less than 1 day. Aerobic biodegradation is expected to occur, with cyanamide serving as source of nitrogen and carbon. The estimated half-life of cyanamide from the water phase of the aquatic systems was 2.3 days for the river system and 4.3 days for the pond system, respectively. Bioconcentration and bioaccumulation potential is expected to be low, based on the estimated bioconcentration factor and experimental octanol–water partition coefficient.

Incompatibilities

Cyanamide may polymerize at tempera- tures above 122℃ , or on evaporation of aqueous solutions. Reacts with acids, strong oxidants, strong reducing agents such as hydrides and water, causing explosion and toxic hazard. Attacks various metals. Decomposes when heated above 49℃ C, on contact with acids, bases, 1,2-phenylene diamine salts; and moisture; producing toxic fumes includ- ing nitrogen oxides and cyanides. Nitriles may polymerize in the presence of metals and some metal compounds. They are incompatible with acids; mixing nitriles with strong oxidizing acids can lead to extremely violent reac- tions. Nitriles are generally incompatible with other oxi- dizing agents such as peroxides and epoxides. The combination of bases and nitriles can produce hydrogen cyanide. Nitriles are hydrolyzed in both aqueous acid and base to give carboxylic acids (or salts of carboxylic acids). These reactions generate heat. Peroxides convert nitriles to amides. Nitriles can react vigorously with reducing agents. Acetonitrile and propionitrile are soluble in water, but nitriles higher than propionitrile have low aqueous solubility. They are also insoluble in aqueous acids .

Waste Disposal

Add excess alkaline calcium hypochlorite with agitation. Flush to sewer after 24 hours. Cyanamide can also be destroyed in an incinerator equipped with afterburner and scrubber.