Calcium cyanamide

Calcium cyanamide
IUPAC name Calcium cyanamide
Other names Cyanamide calcium salt, Lime Nitrogen, UN 1403, Nitrolime
Identifiers
CAS number	156-62-7 Y
PubChem	4685067
ChemSpider	10669887 Y
UNII	ZLR270912W Y
EC number	205-861-8
UN number	1403
RTECS number	GS6000000
Jmol-3D images	Image 1
SMILES [Ca+2].N#CN
InChI InChI=1S/CH2N2.Ca/c2-1-3;/h2H2;/q;+2 Y Key: STRTXDFFNXSZQB-UHFFFAOYSA-N Y InChI=1/CH2N2.Ca/c2-1-3;/h2H2;/q;+2 Key: STRTXDFFNXSZQB-UHFFFAOYAA
Properties
Molecular formula	CaCN2
Molar mass	80.102 g/mol
Appearance	White solid (Often gray or black from impurities)
Odor	odorless
Density	2.29 g/cm3
Melting point	1340 °C [1]
Boiling point	1150-1200 °C (sublim.)
Solubility in water	Reacts
Hazards
MSDS	ICSC 1639
EU Index	615-017-00-4
EU classification	Harmful (Xn) Irritant (Xi)
R-phrases	R22 R37 R41
S-phrases	(S2) S22 S26 S36/37/39
NFPA 704	0 3 1 W
Flash point	Non-flammable
Related compounds
Related compounds	Cyanamide Calcium carbide
Y cyanamide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Calcium cyanamide or CaCN₂ is a calcium compound used as fertilizer,^[2] first synthesized in 1898 by Adolph Frank and Nikodem Caro (Frank-Caro process).^[3] It is formed when calcium carbide reacts with nitrogen. It is commercially known as Nitrolime.

CaC₂ + N₂ → CaCN₂ + C

The reaction takes place in large steel chambers. An electric carbon element heats the reactants to red heat. Nitrogen is pressurised at 2 atmospheres.

It crystallizes in hexagonal crystal system with space group R3m and lattice constants a = 3.67, c = 14.85 (.10⁻¹ nm).^[4]

Preparation

Calcium cyanamide is prepared from calcium carbide. The carbide powder is heated at about 1,000°C in an electric furnace into which nitrogen is passed for several hours. The product is cooled to ambient temperatures and any unreacted carbide is leached out cautiously with water.

CaC₂ + N₂ → CaCN₂ + C (ΔHƒ°= –69.0 kcal/mol at 25°C)

Uses

The main use of calcium cyanamide is in agriculture as a fertilizer.^[2] In contact with water it decomposes and liberates ammonia:

CaCN₂ + 3 H₂O → 2 NH₃ + CaCO₃

It was used to produce sodium cyanide by fusing with sodium carbonate, which was used in cyanide process in gold mining:

CaCN₂ + Na₂CO₃ → 2 NaCN + CaO + O₂

It can also be used in the preparation of calcium cyanide and melamine.

Through hydrolysis, calcium cyanamide produces cyanamide.

CaCN₂ + H₂O + CO₂ → CaCO₃ + H₂NCN

The conversion is conducted on slurries, consequently most commercial cyanamide is sold as an aqueous solution.

Thiourea can be produced by the reaction of hydrogen sulfide with calcium cyanamide in the presence of carbon dioxide.^[5]

Calcium cyanamide is also used as a wire-fed alloy in steelmaking, in order to introduce nitrogen into the steel.

See also

• Cyanamide

References

1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
2. ^ ^{a b} Auchmoody, L.R.; Wendel, G.W. (1973). "Effect of calcium cyanamide on growth and nutrition of plan fed yellow-poplar seedlings". U.S. Department of Agriculture, Forest Service. http://www.treesearch.fs.fed.us/pubs/23629. Retrieved 2008-07-18. 
3. ^ "History of Degussa: Rich harvest, healthy environment". http://www.degussa-history.com/geschichte/en/inventions/calcium_cyanamide/. Retrieved 2008-07-18. 
4. ^ F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. Chemicke tabulky anorganickych sloucenin (Chemical tables of inorganic compounds). SNTL, 1986.
5. ^ Bernd Mertschenk, Ferdinand Beck, Wolfgang Bauer "Thiourea and Thiourea Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2002 by Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved. DOI: 10.1002/14356007.a26_803

External links

• NIOSH Pocket Guide to Chemical Hazards 0091
• History of calcium cyanamide
• Bioassay of Calcium Cyanamide for Possible Carcinogenicity (CAS No. 156-62-7)
• Entry at Classical Encyclopedia