Cyanamide

Cyanamide
Names
	IUPAC name Cyanamide
	Other names Amidocyanogen, carbamonitrile, carbimide, carbodiimide, cyanoamine, cyanoazane, N-cyanoamine, cyanogenamide, cyanogen amide, cyanogen nitride, diiminomethane, hydrogen cyanamide, methanediimine
Identifiers
CAS Number	420-04-2 ;
3D model (JSmol)	Interactive image; carbodiimide isomer: Interactive image;
3DMet	B00322;
ChEBI	CHEBI:16698 ;
ChEMBL	ChEMBL56279 ;
ChemSpider	9480 ;
DrugBank	DB02679 ;
ECHA InfoCard	100.006.358
EC Number	206-992-3;
Gmelin Reference	784
KEGG	D00123 ;
PubChem CID	9864;
RTECS number	GS5950000;
UNII	21CP7826LC ;
UN number	2811
CompTox Dashboard (EPA)	DTXSID9034490 ;
	InChI InChI=1S/CH2N2/c2-1-3/h2H2 Key: XZMCDFZZKTWFGF-UHFFFAOYSA-N ; InChI=1/CH2N2/c2-1-3/h2H2 Key: XZMCDFZZKTWFGF-UHFFFAOYAW;
	SMILES N#CN; carbodiimide isomer: N=C=N;
Properties
Chemical formula	CH2N2
Molar mass	42.040 g/mol
Appearance	Crystalline solid
Density	1.28 g/cm3
Melting point	44 °C (111 °F; 317 K)
Boiling point	260 °C (500 °F; 533 K) (decomposes); 83 °C at 6.7 Pa; 140 °C at 2.5 kPa
Solubility in water	85 g/100 ml (25 °C)
Solubility in organic solvents	soluble
log P	-0.82
Acidity (pKa)	10.3
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H314, H317, H351, H361, H373, H412
Precautionary statements	P201, P202, P260, P261, P264, P270, P272, P273, P280, P281, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P312, P314, P321, P322, P330, P333+P313, P361, P363, P405, P501
NFPA 704 (fire diamond)	2 1 2
Flash point	141 °C (286 °F; 414 K)
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	TWA 2 mg/m3
IDLH (Immediate danger)	N.D.
Safety data sheet (SDS)	ICSC 0424
Related compounds
Related compounds	Calcium cyanamide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Cyanamide is an organic compound with the formula C N₂H₂. 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. The molecule features a nitrile group attached to an amino group. Derivatives of this compound are also referred to as cyanamides, the most common being calcium cyanamide (CaCN₂).^[3]

Tautomers and self-condensations

Containing both a nucleophilic and electrophilic site within the same molecule, cyanamide undergoes various reactions with itself. Cyanamide exists as two tautomers, one with the connectivity N≡C–NH₂ and the other with the formula HN=C=NH ("carbodiimide" tautomer). The N≡C–NH₂ form dominates, but in a few reactions (e.g. silylation) the diimide form appears to be important.^[3]

Cyanamide dimerizes to give 2-cyanoguanidine (dicyandiamide). This dimerization is hindered or reversed by acids and is inhibited by low temperatures. The cyclic trimer is called melamine.^[3]

Production

Cyanamide is produced by hydrolysis of calcium cyanamide, which in turn is prepared from calcium carbide via the Frank-Caro process.^[4]

CaCN₂ + H₂O + CO₂ → CaCO₃ + H₂NCN

The conversion is conducted on slurries.

Reactions and uses

Cyanamide can be regarded as a functional single carbon fragment which can react as an electrophile or nucleophile. 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:

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, isothioureas, and guanidines. 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 and hexazinone. The hair-loss treatment minoxidil and the anthelmintics albendazole, flubendazole, and mebendazole feature 2-aminoimidazole substructures derived from cyanamide.^[3] Cyanamide is also used in the synthesis of other pharmaceutical drugs including tirapazamine, etravirine, revaprazan, and dasantafil.

The cyanamide anion has the character of a pseudo chalcogen, cyanamide can therefore be regarded as analogue to water or hydrogen sulfide.

A convenient method for the preparation of secondary amines which are not contaminated with primary or tertiary amines is the reaction of cyanamide with alkyl halides to N,N-dialkylcyanamides which can easily be hydrolyzed to dialkylamines and then decarboxylated.^[5] Cyanamide adds itself in the presence of N-bromosuccinimide to olefinic double bonds. The addition product is converted by bases to N-Cyanaziridine,^[6] cyclized in the presence of acids to imidazolines, which can be further reacted to vicinal diamines by alkaline cleavage.^[7]

Cyanamide is also a versatile synthetic building block for heterocycles: it forms 2-aminobenzimidazole with 1,2-diaminobenzene^[8] and it forms with the readily available cyclic enamine 4-(1-cyclohexenyl)morpholine^[9] and with elemental sulfur a 2-aminothiazole in good yields.^[10]

Sodium dicyanamide is available in good yield and high purity from cyanamid and cyanogen chloride,^[11]^[12] which is suitable as an intermediate for the synthesis of active pharmaceutical ingredients.^[13] A guanidino group is introduced by reaction of cyanamide with sarcosine In the industrial synthesis of creatine:.^[14]

This synthesis route mostly avoids problematic impurities like chloroacetic acid, iminodiacetic acid, or dihydrotriazine that occur in other routes. The physiological precursor guanidinoacetic is obtained analogously by reacting cyanamide with glycine.

Methods to stabilize cyanamide make it available on an industrial scale. Due to the strong affinity towards self-condensation in alkaline media (see above) solutions of cyanamide are stabilized by the addition of 0.5 wt% of monosodium phosphate as buffer. Solid cyanamide is produced by careful evaporation of the solvent and subsequent addition of a hydrolysis-labile ester of formic acid. The ester absorbs traces of moisture (suppression of urea formation), neutralizes alkalinity (ammonia) and continually releases small amounts of formic acid.^[15]

Agricultural use

Cyanamide, under the trade name Dormex, is a common agricultural rest-breaking agent applied in spring to stimulate uniform opening of buds, early foliation and bloom. Cyanamide can effectively compensate for the moderate lack of chilling units accumulated in the previous autumn and save the harvest that would otherwise be lost. It is particularly effective for woody plants such as blueberries, grapes, apples, peaches and kiwifruit. Most recently the product was approved for use on almonds and pistachios in the USA. Overdosage, high concentration and error in timing of application can damage the buds (especially of peach trees).^[16] Growers may avoid damage by applying 30 days prior to bud break according to the label.

A 50% aqueous solution of cyanamide is also used as a biocide (disinfectant) particularly in pig farming, because it effectively kills salmonella and shigella and fights flies in all stages of development.^[17]

Environmental aspects

Cyanamide degrades via hydrolysis to urea, an excellent fertilizer. Fungi, like Myrothecium verrucaria, accelerate this process utilizing the enzyme cyanamide hydratase.^[18]

Cyanamide functional group

Cyanamide is the name for a functional group with the formula R¹R²N−C≡N where R¹ and R² can be a variety of groups. These compounds are called cyanamides. One example is naphthylcyanamide, C₁₀H₇N(CH₃)CN, which has been produced by the von Braun reaction,^[19] a general method for the conversion of tertiary amines to cyanamides using cyanogen bromide as reagent.^[20] Some cyanamides where R¹ and R² are identical alkyl groups are prepared directly by alkylation of a salt of the parent cyanamide.^[11]

Cyanamide in space

Due to its high permanent dipole moment (i.e., 4.32 ± 0.08 D),^[21] cyanamide was detected in spectral emissions coming from the Sgr B2 molecular cloud (T < 100 K) through its microwave transitions as the first known interstellar molecule containing the NCN frame.^[22]

Safety

It is used as an alcohol-deterrent drug in Canada, Europe, and Japan.^[3]

Cyanamide has a modest toxicity in humans.^[23] Workplace exposure to hydrogen cyanamide sprays or exposure in people living in the vicinity of spraying have been reported as causing respiratory irritation, contact dermatitis, headache, and gastrointestinal symptoms of nausea, vomiting, or diarrhea.^[23]

References

^ "Cyanamide_msds".
^ ^a ^b NIOSH Pocket Guide to Chemical Hazards. "#0160". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b ^c ^d ^e Thomas Güthner; Bernd Mertschenk (2006). "Cyanamides". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_139.pub2. ISBN 3527306730.
^ Kurzer, Frederick; Lawson, Alexander (1954). "Methylisourea Hydrochloride". Organic Syntheses. 34: 67. doi:10.15227/orgsyn.034.0067.
^ Jonczyk A, Ochal Z, Makosza M (1978). "Reactions of Organic Anions; LXXXV1. Catalytic Two-Phase Alkylation of Cyanamide". Synthesis. 1978 (12): 882–883. doi:10.1055/s-1978-24922.
^ Ponsold K, Ihn W (1970). "Die Addition von cyanamid und Halogen an Olefine ein neues Verfahren zur Darstellung von vic.-Halogencyanaminen und Aziridinen". Tetrahedron Lett. 11 (13): 1125–1128. doi:10.1016/S0040-4039(01)97925-0. PMID 5439242.
^ Kohn, Harold; Jung, Sang Hun (1983). "New stereoselective method for the preparation of vicinal diamines from olefins and cyanamide". Journal of the American Chemical Society. 105 (12): 4106–4108. doi:10.1021/ja00350a068..
^ Weiss, Stefan; Michaud, Horst; Prietzel, Horst; Krommer, Helmut (1973). "A New, Simple Synthesis of 2-Aminobenzimidazole". Angewandte Chemie International Edition in English. 12 (10): 841. doi:10.1002/anie.197308411..
^ S. Hünig, E. Lücke, and W. Brenninger (1961). "1-Morpholino-1-Cyclohexene". Organic Syntheses: 65. doi:10.15227/orgsyn.041.0065{{cite journal}}: CS1 maint: multiple names: authors list (link).
^ Gewald, K.; Spies, H.; Mayer, R. (1970). "Zur Reaktion von Enaminen mit Schwefel und Cyanamid" [On the Reaction of Enamines with Sulfur and Cyanamide]. Journal für Praktische Chemie. 312 (5): 776–779. doi:10.1002/prac.19703120507..
^ ^a ^b E. B. Vliet (1925). "Diallylcyanamide". Organic Syntheses. 5: 45. doi:10.15227/orgsyn.005.0045.
^ Verfahren zur Herstellung von Natrium-Dicyanamid, veröffentlicht am 10. August 2000, Anmelder: SKW Trostberg AG.
^ "Sodium dicyanamide (Na-dicyanamide)". lonza.com. Archived from the original on 2013-05-23. Retrieved 2019-07-01.
^ Deutsche Offenlegungsschrift DE-OS 10 2006 016 227 A1, Offenlegungsdatum: 11. Oktober 2007, Anmelder: Degussa GmbH
^ Wehrstedt, Klaus-Dieter; Wildner, Werner; Güthner, Thomas; Holzrichter, Klaus; Mertschenk, Bernd; Ulrich, Armin (2009-10-30). "Safe transport of cyanamide". Journal of Hazardous Materials. 170 (2–3): 829–835. doi:10.1016/j.jhazmat.2009.05.043. ISSN 0304-3894. PMID 19505756.
^ Powell, A. (1999). "Action Program for Dormex Application on Peaches". Auburn University. Archived from the original on 2018-06-20.
^ "ALZOGUR®". AlzChem (in German). Retrieved 2019-07-01.
^ Stransky H, Amberger A (1973). "Isolierung und eigenschaften einer Cyanamid-hydratase (E.C.-Gruppe 4. 2.1.) aus Myrothecium verrucaria Alb. u. Schw" [Isolation and properties of a cyanamide hydratase (EC 4.2.1) from Myrothecium verrucaria]. Z. Pflanzenphysiol. 70: 74–87. doi:10.1016/S0044-328X(73)80049-2.
^ Homer W. J. Cressman (1947). "N-Methyl-1-Naphthylcyanamide". Organic Syntheses. 27: 56. doi:10.15227/orgsyn.027.0056.
^ March, Jerry (1992), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (4th ed.), New York: Wiley, p. 436–7, ISBN 0-471-60180-2
^ Tyler, J.K.; Sheridan, J.; Costain, C.C. (August 1972). "The microwave spectra of cyanamide". Journal of Molecular Spectroscopy. 43 (2): 248–261. doi:10.1016/0022-2852(72)90021-5.
^ Turner, B. E.; Liszt, H. S.; Kaifu, N.; Kisliakov, A. G. (November 1975). "Microwave detection of interstellar cyanamide". The Astrophysical Journal. 201: L149. Bibcode:1975ApJ...201L.149T. doi:10.1086/181963.
^ ^a ^b Schep L, Temple W, Beasley M (January 2009). "The adverse effects of hydrogen cyanamide on human health: an evaluation of inquiries to the New Zealand National Poisons Centre". Clinical Toxicology. 47 (1). Philadelphia, PA: 58–60. doi:10.1080/15563650802459254. PMID 18951270. S2CID 6961576.

External links

International Chemical Safety Card 0424
NIOSH Pocket Guide to Chemical Hazards. "#0160". National Institute for Occupational Safety and Health (NIOSH).
OSHA guideline for cyanamide

[chemsrc-1] "Cyanamide_msds".

[NIOSH-2] NIOSH Pocket Guide to Chemical Hazards. "#0160". National Institute for Occupational Safety and Health (NIOSH).

[Ullmann-3] Thomas Güthner; Bernd Mertschenk (2006). "Cyanamides". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_139.pub2. ISBN 3527306730.

[4] Kurzer, Frederick; Lawson, Alexander (1954). "Methylisourea Hydrochloride". Organic Syntheses. 34: 67. doi:10.15227/orgsyn.034.0067.

[5] Jonczyk A, Ochal Z, Makosza M (1978). "Reactions of Organic Anions; LXXXV1. Catalytic Two-Phase Alkylation of Cyanamide". Synthesis. 1978 (12): 882–883. doi:10.1055/s-1978-24922.

[6] Ponsold K, Ihn W (1970). "Die Addition von cyanamid und Halogen an Olefine ein neues Verfahren zur Darstellung von vic.-Halogencyanaminen und Aziridinen". Tetrahedron Lett. 11 (13): 1125–1128. doi:10.1016/S0040-4039(01)97925-0. PMID 5439242.

[7] Kohn, Harold; Jung, Sang Hun (1983). "New stereoselective method for the preparation of vicinal diamines from olefins and cyanamide". Journal of the American Chemical Society. 105 (12): 4106–4108. doi:10.1021/ja00350a068..

[8] Weiss, Stefan; Michaud, Horst; Prietzel, Horst; Krommer, Helmut (1973). "A New, Simple Synthesis of 2-Aminobenzimidazole". Angewandte Chemie International Edition in English. 12 (10): 841. doi:10.1002/anie.197308411..

[9] S. Hünig, E. Lücke, and W. Brenninger (1961). "1-Morpholino-1-Cyclohexene". Organic Syntheses: 65. doi:10.15227/orgsyn.041.0065{{cite journal}}: CS1 maint: multiple names: authors list (link).

[10] Gewald, K.; Spies, H.; Mayer, R. (1970). "Zur Reaktion von Enaminen mit Schwefel und Cyanamid" [On the Reaction of Enamines with Sulfur and Cyanamide]. Journal für Praktische Chemie. 312 (5): 776–779. doi:10.1002/prac.19703120507..

[allyl-11] E. B. Vliet (1925). "Diallylcyanamide". Organic Syntheses. 5: 45. doi:10.15227/orgsyn.005.0045.

[12] Verfahren zur Herstellung von Natrium-Dicyanamid, veröffentlicht am 10. August 2000, Anmelder: SKW Trostberg AG.

[13] "Sodium dicyanamide (Na-dicyanamide)". lonza.com. Archived from the original on 2013-05-23. Retrieved 2019-07-01.

[14] Deutsche Offenlegungsschrift DE-OS 10 2006 016 227 A1, Offenlegungsdatum: 11. Oktober 2007, Anmelder: Degussa GmbH

[Wehrstedt-15] Wehrstedt, Klaus-Dieter; Wildner, Werner; Güthner, Thomas; Holzrichter, Klaus; Mertschenk, Bernd; Ulrich, Armin (2009-10-30). "Safe transport of cyanamide". Journal of Hazardous Materials. 170 (2–3): 829–835. doi:10.1016/j.jhazmat.2009.05.043. ISSN 0304-3894. PMID 19505756.

[PO-16] Powell, A. (1999). "Action Program for Dormex Application on Peaches". Auburn University. Archived from the original on 2018-06-20.

[17] "ALZOGUR®". AlzChem (in German). Retrieved 2019-07-01.

[18] Stransky H, Amberger A (1973). "Isolierung und eigenschaften einer Cyanamid-hydratase (E.C.-Gruppe 4. 2.1.) aus Myrothecium verrucaria Alb. u. Schw" [Isolation and properties of a cyanamide hydratase (EC 4.2.1) from Myrothecium verrucaria]. Z. Pflanzenphysiol. 70: 74–87. doi:10.1016/S0044-328X(73)80049-2.

[19] Homer W. J. Cressman (1947). "N-Methyl-1-Naphthylcyanamide". Organic Syntheses. 27: 56. doi:10.15227/orgsyn.027.0056.

[20] March, Jerry (1992), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (4th ed.), New York: Wiley, p. 436–7, ISBN 0-471-60180-2

[21] Tyler, J.K.; Sheridan, J.; Costain, C.C. (August 1972). "The microwave spectra of cyanamide". Journal of Molecular Spectroscopy. 43 (2): 248–261. doi:10.1016/0022-2852(72)90021-5.

[22] Turner, B. E.; Liszt, H. S.; Kaifu, N.; Kisliakov, A. G. (November 1975). "Microwave detection of interstellar cyanamide". The Astrophysical Journal. 201: L149. Bibcode:1975ApJ...201L.149T. doi:10.1086/181963.

[Schep-23] Schep L, Temple W, Beasley M (January 2009). "The adverse effects of hydrogen cyanamide on human health: an evaluation of inquiries to the New Zealand National Poisons Centre". Clinical Toxicology. 47 (1). Philadelphia, PA: 58–60. doi:10.1080/15563650802459254. PMID 18951270. S2CID 6961576.

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Cyanamide

Tautomers and self-condensations

Production

Reactions and uses

Agricultural use

Environmental aspects

Cyanamide functional group

Cyanamide in space

Safety

References

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