Cyanamide
Encyclopedia
Cyanamide is an organic compound
with the formula
C
N
2H
2. This white solid is widely used in agriculture and the production of pharmaceuticals and other organic compounds. It is also used as an alcohol deterrent drug in Canada, Europe and Japan. The molecule features a nitrile
group attached to an amino group. Although it is similar in structure to hydrogen cyanide, it is not as toxic. Derivatives of this compound are also referred to as cyanamides, the most common being calcium cyanamide
(CaCN2).
s, one with the connectivity NCNH2 and the other with the formula HNCNH ("diimide" tautomer). The NCNH2 form dominates, but in a few reactions (e.g. silylation) the diimide form appears to be important.
Cyanamide dimerizes to give 2-cyanoguanidine
(dicyandiamide). This decomposition process is disfavored by acids and is inhibited by low temperatures. The trimer
is called melamine
.
via the Frank-Caro process
.
The conversion is conducted on slurries, consequently most commercial cyanamide is sold as an aqueous solution.
The main reaction exhibited by cyanamide involves additions of compounds containing an acidic proton. Water, hydrogen sulfide, and hydrogen selenide react with cyanamide to give urea
, thiourea
, and selenourea
, respectively:
In this way, cyanamide behaves as a dehydration agent and thus can induce condensation reactions. Alcohols, thiols, and amines react analogously to give alkylisoureas, "pseudothioureas," and guanidine
s. The anti-ulcer drug cimetidine
is generated using such reactivity. Related reactions exploit the bifunctionality of cyanamide to give heterocycles, and this latter reactivity is the basis of several pharmaceutical syntheses such as the aminopyrimidine imatinib
) and agrichemicals Amitrol (3-Amino-1,2,4-triazole) and Hexazinone. The hair-loss treatment Minoxidil
and the anthelmintic (worm-killing) drugs Albendazole
, Flubendazole
, and Mebendazole
feature 2-aminoimidazole substructures derived from cyanamide.
Cyanamide (U.S. trade name Dormex) is a common agricultural rest-breaking agent applied in spring to stimulate uniform opening of bud
s, early foliation and bloom. Dormex can effectively compensate for the moderate lack of chilling units accumulated in the previous autumn and save the harvest that would otherwise be lost. Overdosage, high concentration and error in timing of application can damage the buds (especially of peach
trees).
, headache
, and gastrointestinal symptoms of nausea, vomiting
, or diarrhea
.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
N
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
2H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
2. This white solid is widely used in agriculture and the production of pharmaceuticals and other organic compounds. It is also used as an alcohol deterrent drug in Canada, Europe and Japan. The molecule features a nitrile
Nitrile
A nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...
group attached to an amino group. Although it is similar in structure to hydrogen cyanide, it is not as toxic. Derivatives of this compound are also referred to as cyanamides, the most common being calcium cyanamide
Calcium cyanamide
Calcium cyanamide or CaCN2 is a calcium compound used as fertilizer, first synthesized in 1898 by Adolph Frank and Nikodem Caro . It is formed when calcium carbide reacts with nitrogen. It is commercially known as Nitrolime....
(CaCN2).
Tautomers and self-condenstations
Containing both a nucleophilic and electrophilic site within the same molecule, cyanamide undergoes various reactions with itself. Cyanamide exists as two tautomerTautomer
Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization. This reaction commonly results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond...
s, one with the connectivity NCNH2 and the other with the formula HNCNH ("diimide" tautomer). The NCNH2 form dominates, but in a few reactions (e.g. silylation) the diimide form appears to be important.
Cyanamide dimerizes to give 2-cyanoguanidine
2-Cyanoguanidine
2-Cyanoguanidine or commonly dicyandiamide is an nitrile derived from guanidine. It is a dimer of cyanamide, from which it can be prepared. 2-Cyanoguanidine is a colourless solid that is soluble in water, acetone, and alcohol, but not in diethyl ether or chloroform.-Production and...
(dicyandiamide). This decomposition process is disfavored by acids and is inhibited by low temperatures. The trimer
Trimer (chemistry)
In chemistry, a trimer is a product derived from three identical precursors. Trimers are typically cyclic. Chemical compounds that often trimerise are aliphatic isocyanates and cyanic acids. Often, trimerization competes with polymerization....
is called melamine
Melamine
Melamine is an organic base and a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass and, if mixed with resins, has fire retardant properties due to its release of nitrogen gas when burned or charred, and has several other industrial uses....
.
Production, reactions, uses
Cyanamide is produced by hydrolysis of calcium cyanamide, which in turn is prepared from calcium carbideCalcium carbide
thumb|right|Calcium carbide.Calcium carbide is a chemical compound with the chemical formula of CaC2. The pure material is colorless, however pieces of technical grade calcium carbide are grey or brown and consist of only 80-85% of CaC2 . Because of presence of PH3, NH3, and H2S it has a...
via the Frank-Caro process
Frank-Caro process
The Frank–Caro process, also called cyanamide process, is the nitrogen fixation reaction of calcium carbide and nitrogen gas in an electric furnace heated at about 1,000°C. The synthesis produces calcium cyanamide and carbon.-History:...
.
- CaCN2 + H2O + CO2 → CaCO3 + H2NCN
The conversion is conducted on slurries, consequently most commercial cyanamide is sold as an aqueous solution.
The main reaction exhibited by cyanamide involves additions of compounds containing an acidic proton. Water, hydrogen sulfide, and hydrogen selenide react with cyanamide to give urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
, thiourea
Thiourea
Thiourea is an organosulfur compound of with the formula SC2 . It is structurally similar to urea, except that the oxygen atom is replaced by a sulfur atom, but the properties of urea and thiourea differ significantly. Thiourea is a reagent in organic synthesis. "Thioureas" refers to a broad...
, and selenourea
Selenourea
Selenourea is the organoselenium compound with the formula SeC2. It is a white solid. This compound features a rare example of a stable, unhindered carbon-selenium double bond. The compound is used in the synthesis of selenium heterocycles...
, respectively:
- H2NCN + H2E → H2NC(E)NH2 (E = O, S, Se)
In this way, cyanamide behaves as a dehydration agent and thus can induce condensation reactions. Alcohols, thiols, and amines react analogously to give alkylisoureas, "pseudothioureas," and guanidine
Guanidine
Guanidine is a crystalline compound of strong alkalinity formed by the oxidation of guanine. It is used in the manufacture of plastics and explosives. It is found in urine as a normal product of protein metabolism. The molecule was first synthesized in 1861 by the oxidative degradation of an...
s. The anti-ulcer drug cimetidine
Cimetidine
Cimetidine INN is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers. It is marketed by GlaxoSmithKline under the trade name Tagamet...
is generated using such reactivity. Related reactions exploit the bifunctionality of cyanamide to give heterocycles, and this latter reactivity is the basis of several pharmaceutical syntheses such as the aminopyrimidine imatinib
Imatinib
Imatinib is a drug used to treat certain types of cancer. It is currently marketed by Novartis as Gleevec or Glivec as its mesylate salt, imatinib mesilate . It is used in treating chronic myelogenous leukemia , gastrointestinal stromal tumors and some other diseases...
) and agrichemicals Amitrol (3-Amino-1,2,4-triazole) and Hexazinone. The hair-loss treatment Minoxidil
Minoxidil
Minoxidil is an antihypertensive vasodilator medication which also slows or stops hair loss and promotes hair regrowth. Now off-patent, it is available over-the-counter for the treatment of androgenic alopecia. Minoxidil must be used indefinitely for continued support of existing hair follicles and...
and the anthelmintic (worm-killing) drugs Albendazole
Albendazole
Albendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
, Flubendazole
Flubendazole
Flubendazole is an anthelmintic. Its brand name is Flutelmium which is a paste manufactured by Janssen Pharmaceutica N.V. used by veterinarians for protection against internal parasites and worms in dogs and cats. Other brand names are Flubenol, Biovermin, and Flumoxal....
, and Mebendazole
Mebendazole
Mebendazole or MBZ is a benzimidazole drug developed by Janssen Pharmaceutica and marketed as Vermox, Ovex, Antiox, and Pripsen...
feature 2-aminoimidazole substructures derived from cyanamide.
Cyanamide (U.S. trade name Dormex) is a common agricultural rest-breaking agent applied in spring to stimulate uniform opening of bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s, early foliation and bloom. Dormex can effectively compensate for the moderate lack of chilling units accumulated in the previous autumn and save the harvest that would otherwise be lost. Overdosage, high concentration and error in timing of application can damage the buds (especially of peach
Peach
The peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...
trees).
Environmental aspects
Cyanamide degrades via hydrolysis to urea, an excellent fertilizer. Microorganisms, e.g. the bacterium Myrothecium verrucaria, accelerate this process utilizing the enzyme cyanamide hydratase.Safety
Cyanamide has a modest toxicity in humans. Workplace exposure to hydrogen cyanamide sprays or exposure in people living in the vicinity of spraying have been reported as causing respiratory irritation, contact dermatitisContact dermatitis
Contact dermatitis is a term for a skin reaction resulting from exposure to allergens or irritants . Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight....
, headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
, and gastrointestinal symptoms of nausea, vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, or diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
.