Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Calcium cyanamide: Difference between pages

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 477000719

| ImageFile = calcium cyanamide.png

| ImageFile2 = Calcium-cyanamide-3D-vdW.png

| IUPACName = Calcium cyanamide

| OtherNames = Cyanamide calcium salt, Calcium carbondiamide, Lime Nitrogen, UN 1403, Nitrolime

| Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 21106503

| SMILES = [Ca+2].[N-2]C#N

| SMILES1 = [Ca+2].[N-]=C=[N-]

| InChI = 1/CN2.Ca/c2-1-3;/q-2;+2

| InChIKey = MYFXBBAEXORJNB-UHFFFAOYAU

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/CN2.Ca/c2-1-3;/q-2;+2

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = MYFXBBAEXORJNB-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| EINECS = 205-861-8

| PubChem = 45051688

| UNNumber = 1403

| RTECS = GS6000000

}}

|Section2={{Chembox Properties

| Formula = CaCN₂

| MolarMass = 80.102 g/mol

| Appearance = White solid (Often gray or black from impurities)

| Odor = odorless

| Density = 2.29 g/cm³

| MeltingPtC = 1340

| MeltingPt_ref =<ref>Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}</ref>

| BoilingPtC = 1150 to 1200

| BoilingPt_notes = (sublimes)

| Solubility = Reacts

}}

|Section7={{Chembox Hazards

| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics1639.htm ICSC 1639]

| NFPA-H = 3

| NFPA-F = 0

| NFPA-R = 1

| NFPA-S = W

| GHSPictograms = {{GHS corrosion}}{{GHS exclamation mark}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|302|318|335}}

| PPhrases = {{P-phrases|231+232|261|280|305+351+338}}

| FlashPt = Non-flammable

| PEL = none<ref name=PGCH>{{PGCH|0091}}</ref>

| IDLH = N.D.<ref name=PGCH/>

| REL = TWA 0.5 mg/m³

}}

|Section8={{Chembox Related

| OtherCompounds = [[Cyanamide]]<br/>[[Calcium carbide]]

}}

'''Calcium cyanamide''', also known as '''Calcium carbondiamide''', '''Calcium cyan-2°-amide''' or '''Calcium cyanonitride''' is the [[inorganic compound]] with the formula CaCN₂. It is the [[calcium]] salt of the [[cyanamide]] ({{chem|CN|2|2−}}) anion. This chemical is used as [[fertilizer]]<ref name="usforest">{{cite journal|url=https://www.fs.usda.gov/treesearch/pubs/23629|title=Effect of calcium cyanamide on growth and nutrition of plan fed yellow-poplar seedlings|author1=Auchmoody, L.R. |author2=Wendel, G.W. |journal=Res. Pap. Ne-265. Uppdr Darby, Pa: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 11 P|year=1973|volume=265|publisher=U.S. Department of Agriculture, Forest Service|accessdate=2008-07-18}}</ref> and is commercially known as '''nitrolime'''. It also has [[herbicide|herbicidal]] activity and in the 1950s was marketed as '''cyanamid'''.<ref>{{Cite thesis |last=Carr |first=Charles W. |title=The use of cyanamid for weed control in vegetable crops. |date=1953 |degree=MSc |publisher=University of Massachusetts Amherst |doi=10.7275/18863820 |doi-access=free}}</ref><ref name=scher/> It was first synthesized in 1898 by [[Adolph Frank]] and [[Nikodem Caro]] ([[Frank–Caro process]]).<ref>{{cite web |url= http://www.degussa-history.com/geschichte/en/inventions/calcium_cyanamide/ |title= History of Degussa: Rich harvest, healthy environment: Calcium cyanamide|accessdate=2008-07-18 |url-status=dead |archive-url=https://web.archive.org/web/20061019170614/http://www.degussa-history.com/geschichte/en/inventions/calcium_cyanamide/ |archive-date= 2006-10-19}}</ref>

== History ==

In their search for a new process for producing [[cyanide]]s for [[gold cyanidation|cyanide leaching of gold]], Frank and Caro discovered the ability of alkaline earth carbides to absorb atmospheric nitrogen at high temperatures.<ref>Deutsches Reichspatent DRP 88363, "Verfahren zur Darstellung von Cyanverbindungen aus Carbiden", Erfinder: A. Frank, N. Caro, erteilt am 31. März 1895.</ref> Fritz Rothe, a colleague of Frank and Caro, succeeded in 1898 in overcoming problems with the use of calcium carbide and clarified that at around 1,100&nbsp;°C not calcium cyanide but calcium cyanamide is formed in the reaction. In fact, the initial target product [[sodium cyanide]] can also be obtained from calcium cyanamide by melting it with sodium chloride in the presence of carbon:<ref>H.H. Franck, W. Burg, Zeitschrift für Elektrochemie und angewandte physikalische Chemie, '''40'''(10), 686-692 (Oktober 1934).</ref>

: CaCN₂ + 2&nbsp;NaCl + C → 2&nbsp;NaCN + CaCl₂

Frank and Caro developed this reaction for a large-scale, continuous production process. It was particularly challenging to implement because it requires precise control of high temperatures during the initial igniter step; the melting point of calcium cyanamide is only about 120°C lower than the boiling point of sodium chloride.

In 1901, Ferdinand Eduard Polzeniusz patented a process that converts calcium carbide to calcium cyanamide in the presence of 10% [[calcium chloride]] at 700&nbsp;°C. The advantage of this reaction temperature (lower by about 400&nbsp;°C), however, must be weighed against the large amount of calcium chloride required and the discontinuous process control. Nevertheless, both processes (the Rothe–Frank–Caro process and the Polzeniusz–Krauss process) played a role in the first half of the 20th century. In the record year 1945, a total of approximately 1.5 million tonnes was produced worldwide using both processes.<ref name="ACSLandmark">{{Cite web|url=https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/calciumcarbideacetylene.html|title=Commercialization of Calcium Carbide and Acetylene - Landmark|website=American Chemical Society|language=en|access-date=2019-01-31}}</ref> Frank and Caro also noted the formation of ammonia from calcium cyanamide.<ref>Angewandte Chemie, Band 29, Ausgabe 16, Seite R97, 25. Februar 1916</ref>

:CaCN₂ + 3&nbsp;H₂O → 2&nbsp;NH₃ + CaCO₃

Albert Frank recognized the fundamental importance of this reaction as a breakthrough in the provision of ammonia from atmospheric nitrogen and in 1901 recommended calcium cyanamide as a nitrogen fertilizer. Between 1908 and 1919, five calcium cyanamide plants with a total capacity of 500,000 tonnes per year were set up in Germany, and one in Switzerland.<ref>{{cite journal |last1=Eschenmooser |first1=Walter |title=100 Years of Progress with LONZA |journal=CHIMIA |date=June 1997 |volume=51 |issue=6 |page=259-269 |doi=10.2533/chimia.1997.259 |s2cid=100485418 |doi-access=free }}</ref> It was at the time the cheapest nitrogen fertilizer with additional efficacy against weeds and plant pests, and had great advantages over the nitrogen fertilizers that were conventional at the time. However, the large-scale implementation of ammonia synthesis via the [[Haber process]] became a serious competitor to the very energy-intensive Frank–Caro process. As urea (formed via the Haber–Bosch process) was significantly more nitrogen-rich (46% nitrogen compared to ca. 20%), cheaper, and faster acting, the role of calcium cyanamide was gradually reduced to a multifunctional nitrogen fertilizer for niche applications. Other reasons for its loss of popularity were its dirty-black color, dusty appearance and irritating properties, as well as its inhibition of an alcohol-degrading enzyme which causes temporary accumulation of [[acetaldehyde]] in the body leading to dizziness, nausea, and [[alcohol flush reaction]] when [[alcohol (drug)|alcohol]] is consumed around the time of bodily exposure.

==Production==

Calcium cyanamide is prepared from [[calcium carbide]]. The carbide powder is heated at about 1000&nbsp;°C in an electric furnace into which [[nitrogen]] is passed for several hours.<ref name=Ullmann>{{cite encyclopedia|author= Thomas Güthner |author2=Bernd Mertschenk |title= Cyanamides |encyclopedia= Ullmann's Encyclopedia of Industrial Chemistry |publisher= [[Wiley-VCH]] |location= Weinheim |year=2006|doi=10.1002/14356007.a08_139.pub2|isbn=3527306730 }}</ref> The product is cooled to ambient temperatures and any unreacted carbide is leached out cautiously with water.

:CaC₂ + N₂ → CaCN₂ + C (Δ''H''{{su|b=f|p=<s>o</s>}} = –69.0 kcal/mol at 25 °C)

It crystallizes in [[hexagonal crystal system]] with [[space group]] ''R3m'' and [[lattice constant]]s ''a'' = 3.67&nbsp;Å, ''c'' = 14.85&nbsp;Å.<ref name="chtas">F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. ''Chemicke tabulky anorganickych sloucenin'' (''Chemical tables of inorganic compounds''). SNTL, 1986.</ref><ref>Vannerberg, N.G. "The crystal structure of calcium cyanamide" Acta Chemica Scandinavica (1-27,1973-42,1988) (1962) 16, p2263-p2266</ref>

==Uses==

[[File:Transformation of calcium cyanamide.svg|thumb|left|400px]]

The main use of calcium cyanamide is in agriculture as a fertilizer.<ref name="usforest" /> In contact with water, it hydrolyses into [[hydrogen cyanamide]] which decomposes and liberates [[ammonia]]:<ref name=scher/>

: CaCN₂ + 3&nbsp;H₂O → 2&nbsp;NH₃ + CaCO₃

It was used to produce sodium cyanide by [[melting|fusing]] with [[sodium carbonate]]:

: CaCN₂ + Na₂CO₃ + 2&nbsp;C → 2&nbsp;NaCN + CaO + 2&nbsp;CO

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 in the presence of [[carbon dioxide]], calcium cyanamide produces cyanamide:{{clarify|reason=why doesn't this give ammonia as in earlier reaction?|date=February 2018}}

:CaCN₂ + H₂O + CO₂ → CaCO₃ + H₂NCN

The conversion is conducted in slurries. For this reason, most commercial calcium 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.<ref name="MertschenkBeck2000">{{Ullmann|last1= Mertschenk |first1= Bernd |last2= Beck |first2= Ferdinand |last3= Bauer |first3= Wolfgang |title= Thiourea and Thiourea Derivatives |year= 2000 |doi= 10.1002/14356007.a26_803.pub3}}</ref>

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

==Safety==

The substance can cause [[alcohol intolerance]], before or after the consumption of alcohol.<ref name=scher>[https://ec.europa.eu/health/scientific_committees/environmental_risks/docs/scher_o_169.pdf ''Potential risks to human health and the environment from the use of calcium cyanamide as fertiliser''], [[Scientific Committee on Health and Environmental Risks]], 1,534 kB, March 2016, Retrieved 22 July 2017</ref>

==References==

{{Reflist}}

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page 30, Fixation of Atmospheric Nitrogen, by Frank A. Ernst, Fixed Nitrogen Research Laboratory, U.S. Dept Agric; formerly with the Nitrate Division, Army Ordnance; American Cyanamid Company | Chapman & Hall, Ltd., 11 Henrietta Street, W.C.2, London; Copyright, 1928 by D. Van Nostrand, Inc. All rights reserved, including that of translation into the Scandinavian and other foreign languages.

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==External links==

*{{PGCH|0091}}

*[https://ntp.niehs.nih.gov/go/tr163abs Bioassay of Calcium Cyanamide for Possible Carcinogenicity (CAS No. 156-62-7)]

*{{Cite EB1911 |wstitle=Cyanamide |volume=7 |page=679 |short=1}}

{{Calcium compounds}}

{{Authority control}}

[[Category:Calcium compounds]]

[[Category:Cyanamides]]

[[Category:Inorganic fertilizers]]