Calcium cyanamide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Calcium cyanamide
Calcium cyanamide.png
Identifiers
CAS number 156-62-7 YesY
PubChem 4685067
ChemSpider 21106503 N
UNII ZLR270912W YesY
EC number 205-861-8
UN number 1403
RTECS number GS6000000
Jmol-3D images Image 1
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
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
Related compounds
Related compounds Cyanamide
Calcium carbide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
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[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. 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[edit]

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 + 2C → 2 NaCN + CaO + 2CO

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 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. 
  3. ^ "History of Degussa: Rich harvest, healthy environment". 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[edit]