imported>Monkbot: Monkbot/task 21: Replace page(s) with article-number;

2025-10-01T01:06:02Z

Monkbot/task 21: Replace page(s) with article-number;

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{{chembox
|Watchedfields = changed
|verifiedrevid = 443496556
|ImageFile = Pytel na Caprolactam.jpg
|ImageFileL1 = Caprolactam-2D-skeletal.png
|ImageFileR1 = Caprolactam-from-xtal-3D-sf.png
|ImageSizeR1 = 130px
|PIN = Azepan-2-one
|OtherNames = {{ubl|1-Aza-2-cycloheptanone|2-Azacycloheptanone|ε-Caprolactam|Capron PK4|Cyclohexanone iso-oxime|Extrom 6N|Hexahydro-2-azepinone|Hexahydro-2H-azepin-2-one (9CI)|Hexanolactam|Hexano-6-lactam|Aminocaproic lactam}}
|Section1 = {{Chembox Identifiers
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 7480
|KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = C06593
|InChI = 1/C6H11NO/c8-6-4-2-1-3-5-7-6/h1-5H2,(H,7,8)
|InChIKey = JBKVHLHDHHXQEQ-UHFFFAOYAF
|ChEMBL_Ref = {{ebicite|correct|EBI}}
|ChEMBL = 276218
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C6H11NO/c8-6-4-2-1-3-5-7-6/h1-5H2,(H,7,8)
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = JBKVHLHDHHXQEQ-UHFFFAOYSA-N
|CASNo = 105-60-2
|CASNo_Ref = {{cascite|correct|CAS}}
|EINECS = 203-313-2
|PubChem = 7768
|Beilstein = 106934
|Gmelin = 101802
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = 6879X594Z8
|ChEBI_Ref = {{ebicite|correct|EBI}}
|ChEBI = 28579
|SMILES = O=C1NCCCCC1
}}
|Section2 = {{Chembox Properties
|C=6 | H=11 | N=1 | O=1
|Appearance = White solid
|Density = 1.01 g/cm3
|MeltingPtC = 69.2
|BoilingPtC = 270.8
|BoilingPt_notes = at 1013.25 hPa
|Solubility = 866.89 g/l (22 °C)
|VaporPressure = 8.10−8 mmHg (20°C)<ref name=NIOSH>{{PGCH|0097}}</ref>
}}
|Section3 = {{Chembox Hazards
|GHSPictograms = {{GHS07}}
|GHSSignalWord = Warning
|HPhrases = {{H-phrases|302|315|319|332|335}}
|PPhrases = {{P-phrases|261|264|270|271|280|301+312|302+352|304+312|304+340|305+351+338|312|321|330|332+313|337+313|362|403+233|405|501}}
|FlashPtC = 125
|PEL = none<ref name=NIOSH/>
|ExploLimits = 1.4%-8.0%<ref name=NIOSH/>
}}
}}

'''Caprolactam''' ('''CPL''') is an [[organic compound]] with the [[chemical formula|formula]] (CH2)5C(O)NH. This colourless solid is a [[lactam]] (a cyclic [[amide]]) of [[caproic acid]]. Global demand for this compound is approximately five million tons per year, and the vast majority is used to make [[nylon 6]] filament, fiber, and plastics.<ref name=Ullmann>{{Ullmann | author1 = Josef Ritz | author2 = Hugo Fuchs | author3 = Heinz Kieczka | author4 = William C. Moran | title = Caprolactam | doi = 10.1002/14356007.a05_031.pub2}}</ref>

==Synthesis and production==
Caprolactam was first described in the late 1800s when it was prepared by the cyclization of ε-[[aminocaproic acid]], the product of the hydrolysis of caprolactam. World demand for caprolactam was estimated to reach five million tons per year for 2015. 90% of caprolactam produced is used to make filament and fiber, 10% for plastics, and a small amount is used as a chemical intermediate.<ref name = Ullmann/> Due to its commercial significance, many methods have been developed for the production of caprolactam. It was estimated that 90% of all caprolactam is synthesised from [[cyclohexanone]] ('''1'''), which is first converted to its [[Cyclohexanone oxime|oxime]] ('''2'''). Treatment of this oxime with acid induces the [[Beckmann rearrangement]] to give caprolactam ('''3'''):<ref name=Ullmann/>

: [[File:Beckmann-rearangement (cropped).png|350px|The Beckmann Rearrangement]]

The immediate product of the acid-induced rearrangement is the bisulfate salt of caprolactam. This salt is neutralized with [[ammonia]] to release the free lactam and cogenerate [[ammonium sulfate]]. In optimizing the industrial practices, much attention is directed toward minimizing the production of ammonium salts.<ref name = Ullmann/>

The other major industrial route involves formation of the oxime from [[cyclohexane]] using [[nitrosyl chloride]], and this method accounts for 10% of world production.<ref name = Ullmann/> The advantage of this method is that cyclohexane is less expensive than [[cyclohexanone]].

A minor industrial route involves the treatment of [[cyclohexanecarboxylic acid]] with [[nitrosylsulfuric acid]] (the Snia Viscosa process). This is thought to proceed via a [[ketene]].

:[[File:Nitrosodecarboxylation_Caprolactam_Synthesis.svg|500px]]

Other paths to caprolactam include the depolymerization of waste nylon 6, and the reaction of [[caprolactone]] with ammonia.<ref name=Ullmann/> At bench scale, the reaction between cyclohexanone with [[hydrazoic acid]] to give caprolactam in the [[Schmidt reaction]] has been reported.<ref>{{cite journal | doi = 10.1016/S0040-4020(00)00218-0 | journal = Tetrahedron | title = Expansion to Seven-Membered Rings | author1 = Eric J. Kantorowski | author2 = Mark J. Kurth | volume = 56 | issue = 26 | pages = 4317–4353 | year = 2000}}</ref>

:[[File:Schmidt ring expansion.png|600px]]

==Uses==
Almost all caprolactam produced goes into the manufacture of nylon 6. The conversion entails a [[ring-opening polymerization]]:

:[[File:Caprolactam_polymerization.png|500px]]

Nylon 6 is widely used in [[fiber]]s and [[plastic]]s.

In situ anionic polymerization is employed for cast nylon production where conversion from ε-caprolactam to nylon 6 takes place inside a mold. In conjunction with endless fiber processing the term thermoplastic resin transfer molding (T-RTM) is often used.

Caprolactam is also used in the synthesis of several pharmaceutical drugs including [[pentylenetetrazol]], [[meptazinol]], and [[laurocapram]].

==Safety==
Caprolactam is an [[irritation|irritant]] and is mildly [[toxic]], with an {{LD50}} of 1.1 g/kg (rat, oral). In 1991, it was included on the list of hazardous air pollutants by the U.S. [[Clean Air Act (1990)|Clean Air Act of 1990]]. It was subsequently removed from the list in 1996 at the request of the manufacturers.<ref>[https://www3.epa.gov/ttn/atw/pollutants/atwsmod.html EPA - Modifications To The 112(b)1 Hazardous Air Pollutants]</ref> In water, caprolactam hydrolyzes to [[aminocaproic acid]], which is used medicinally.

As of 2016 caprolactam had the unusual status of being the only chemical in the [[International Agency for Research on Cancer]]'s lowest hazard category, Group 4: "probably not carcinogenic to humans".<ref>{{Cite journal |last=Smith |first=Carr J |last2=Perfetti |first2=Thomas A |date=2019-01-01 |title=An approximated one-quarter of IARC Group 3 (unclassifiable) chemicals fit more appropriately into IARC Group 4 (probably not carcinogenic) |journal=Toxicology Research and Application |language=EN |volume=3 |article-number=2397847319840645 |doi=10.1177/2397847319840645 |issn=2397-8473|doi-access=free }}</ref><ref>{{cite book | url=https://monographs.iarc.fr/ENG/Monographs/vol71/mono71-16.pdf | title=Agents Classified by the ''IARC Monographs'' |volume=71 |page=395 | access-date=21 October 2016| publisher=[[International Agency for Research on Cancer]]| date=February 22, 2016}}</ref>

Currently, there is no official [[permissible exposure limit]] set for workers handling caprolactam in the United States. The [[recommended exposure limit]] is set at 1 mg/m3 over an eight-hour work shift for caprolactam dusts and vapors. The [[short-term exposure limit]] is set at 3 mg/m3 for caprolactam dusts and vapors.<ref>{{Citation|access-date=November 8, 2013|title = NIOSH Pocket Guide to Chemical Hazards|publisher = CDC | url =https://www.cdc.gov/niosh/npg/npgd0097.html}}</ref>

==Climate impact==

The production of caprolactam can produce [[nitrous oxide]] as a by-product, a highly potent greenhouse gas. Emissions differ significantly due to different production processes and inconsistent use of emission abatement technology. A study commissioned by the German [[Federal Ministry for Economic Affairs and Climate Action]] estimates emissions between 9 kg of nitrous oxide per ton of caprolactam and almost zero.<ref>{{cite web | url=https://www.oeko.de/fileadmin/oekodoc/NACAG-N2O-mitigation-potentials.pdf|title=Mitigation potentials for emissions of nitrous oxide from chemical industry in industrialised countries world-wide|publisher=Öko-Institut|date=March 2023|access-date=2023-10-17}}</ref>

Nitrous oxide emissions from caprolactam production are unregulated in most countries. Unlike other chemical production processes, nitrous oxide emissions from caprolactam production are not included in the [[European Union Emissions Trading System]].<ref>{{cite news |last=Böck |first=Hanno |date=2023-09-28 |title=The avoidable Super-Greenhouse-Gas from Fertilizer, Nylon, and Vitamin B3 production |url=https://industrydecarbonization.com/news/the-avoidable-super-greenhouse-gas-from-fertilizer-nylon-and-vitamin-b3-production.html |work=Industry Decarbonization Newsletter |access-date=2023-10-17}}</ref>

==References==
{{Reflist}}

{{Carcinogen|state=collapsed}}

[[Category:Epsilon-lactams]]
[[Category:Monomers]]
[[Category:Commodity chemicals]]

Caprolactam - Revision history

imported>Monkbot: Monkbot/task 21: Replace page(s) with article-number;