Calcium cyanamide

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Calcium cyanamide
CaCN2Xray.tif
Calcium cyanamide.png
Names
IUPAC name
Calcium cyanamide
Other names
Cyanamide calcium salt, Lime Nitrogen, UN 1403, Nitrolime
Identifiers
156-62-7 YesY
ChemSpider 10669887 YesY
21106503 N
EC number 205-861-8
Jmol-3D images Image
Image
PubChem 4685067
RTECS number GS6000000
UNII ZLR270912W YesY
UN number 1403
Properties
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 1,340 °C (2,440 °F; 1,610 K)[1]
Boiling point 1,150 to 1,200 °C (2,100 to 2,190 °F; 1,420 to 1,470 K) (sublimes)
Reacts
Hazards
Safety data sheet ICSC 1639
EU classification Harmful (Xn)
Irritant (Xi)
R-phrases R22 R37 R41
S-phrases (S2) S22 S26 S36/37/39
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond
Flash point Non-flammable
US health exposure limits (NIOSH):
none[2]
TWA 0.5 mg/m3
N.D.[2]
Related compounds
Related compounds
Cyanamide
Calcium carbide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N verify (what isYesY/N?)
Infobox references

Calcium cyanamide is the inorganic compound with the formula CaCN2. This calcium derivative of cyanamide (CN22-) is used as fertilizer,[3] first synthesized in 1898 by Adolph Frank and Nikodem Caro (Frank-Caro process).[4] It is commercially known as nitrolime.

Production[edit]

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.[5] 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)

The reaction is conducted in large steel chambers. An electric carbon element heats the reactants to red heat. Nitrogen gas 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).[6][7]

Uses[edit]

Transformation of calcium cyanamide.svg

The main use of calcium cyanamide is in agriculture as a fertilizer.[3] 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:

CaCN2 + Na2CO3 + 2C → 2 NaCN + CaO + 2CO

Sodium cyanide is used in cyanide process in gold mining. 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[edit]

References[edit]

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ a b "NIOSH Pocket Guide to Chemical Hazards #0091". National Institute for Occupational Safety and Health (NIOSH). 
  3. ^ 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. Retrieved 2008-07-18. 
  4. ^ "History of Degussa: Rich harvest, healthy environment". Retrieved 2008-07-18. 
  5. ^ a b Thomas Güthner; Bernd Mertschenk (2006). "Cyanamides". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_139.pub2. 
  6. ^ F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. Chemicke tabulky anorganickych sloucenin (Chemical tables of inorganic compounds). SNTL, 1986.
  7. ^ Vannerberg, N.G. "The crystal structure of calcium cyanamide" Acta Chemica Scandinavica (1-27,1973-42,1988) (1962) 16, p2263-p2266

External links[edit]