Chlorinated paraffins
File:2,3,4,5,6,8-hexachlorodecane.svg
File:2,5,6,7,8,11,15-heptachloroheptadecane.svg
Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes (paraffin wax). The chlorination degree of CPs can vary between 30 and 70 wt%. CPs are subdivided according to their carbon chain length into short-chain CPs (SCCPs, C10–13), medium-chain CPs (MCCPs, C14–17) and long-chain CPs (LCCPs, C>17). Depending on chain length and chlorine content, CPs are colorless or yellowish liquids or solids.{{Ullmann | last1 = Rossberg | first1 = M. | last2 = Lendle | first2 = W. | last3 = Pfleiderer | first3 = G. | last4 = Tögel | first4 = A. | last5 = Dreher | first5 = E. L. | last6 = Langer | first6 = E. | last7 = Rassaerts | first7 = H. | last8 = Kleinschmidt | first8 = P. | last9 = Strack | first9 = H. | last10 = Cook | first10 = R. | last11 = Beck | first11 = U. | last12 = Lipper | first12 = K.-A. | last13 = Torkelson | first13 = T.R.| last14 = Löser | first14 = E. | last15 = Beutel | first15 = K.K. | last16 = Mann | first16 = T. | title= Chlorinated Hydrocarbons| year = 2006 | isbn = 3527306730 | doi=10.1002/14356007.a06_233.pub2 }}
Production
Chlorinated paraffins are synthesized by reaction of chlorine gas with unbranched paraffin fractions (<2 % isoparaffins, <100 ppm aromatics) at a temperature of 80–100 °C.{{sfn|Brooke|Crookes|Merckel|2009|pp=4, 23}} The radical substitution may be promoted by UV-light.{{sfn|Lassen|2014|p=50}}
: CxH(2x+2) + y Cl2 → CxH(2x−y+2)Cly + y HCl
When the desired degree of chlorination is achieved, residues of hydrochloric acid and chlorine are blown off with nitrogen. Epoxidized vegetable oil, glycidyl ether or organophosphorous compounds may be added to the final product for improved stability at high temperatures.{{sfn|Kellersohn|1998|p=}}{{sfn|Brooke|Crookes|Merckel|2009|p=5}}
Commercial products have been classified as substances of unknown or variable composition. CPs are complex mixtures of chlorinated n-alkanes containing thousands of homologues and isomers{{sfn|Tomy|1997|pp=2764–2765}} which are not completely separated by standard analytical methods.{{sfn|Lassen|2014|p=30}}
CPs are produced in Europe, North America, Australia, Brazil, South Africa and Asia.{{sfn|Lassen|2014|pp=50–51}} In China, where most of the world production capacity is located, 600,000 tons of chlorinated paraffins were produced in 2007.{{sfn|De Boer|El-Sayed|Fiedler|Legler|2010|p=8}} Production and use volumes of CPs exceeded 1,000,000 tons in 2013.{{cite journal| first1 = Juliane |last1=Glüge |first2=Lena |last2=Schinkel |first3= Konrad |last3=Hungerbühler |first4= Ronan |last4=Cariou |first5= Christian |last5=Bogdal| year = 2018| title = Environmental Risks of Medium-Chain Chlorinated Paraffins (MCCPs): A Review| journal = Environmental Science & Technology| volume = 52| issue = 12| pages = 6743–6760| doi = 10.1021/acs.est.7b06459|pmid=29791144 |bibcode=2018EnST...52.6743G | url = https://www.dora.lib4ri.ch/empa/islandora/object/empa%3A17512/datastream/PDF2/Gl%C3%BCge-2018-Environmental_risks_of_medium-chain_chlorinated-%28accepted_version%29.pdf}}
Industrial applications
Production of CPs for industrial use started in the 1930s,{{sfn|Kenne|Ahlborg|1996|p=}} with global production in 2000 being about 2 million tonnes.{{cite web |title=SETAC SciCon Session Summaries – SETAC Globe |url=https://globe.setac.org/setac-scicon-session-summaries/ |access-date=10 August 2021 |location=Chlorinated Paraffins – State of Science, Insights, Challenges and the Way Forward}} Currently, over 200 CP formulations are in use for a wide range of industrial applications, such as flame retardants and plasticisers, as additives in metal working fluids, in sealants, paints, adhesives, textiles, leather fat and coatings.{{sfn|De Boer|El-Sayed|Fiedler|Legler|2010|p=9}}
Safety
Short-chain CPs are classified as persistent and their physical properties (octanol-water partition coefficient (logKOW) 4.4–8, depending on the chlorination degree) imply a high potential for bioaccumulation. SCCPs are classified as toxic to aquatic organisms, and carcinogenic to rats and mice. Therefore, it was concluded that SCCPs have PBT and vPvB properties and they were added to the Candidate List of substances of very high concern for Authorisation under REACH Regulation.{{cite web |title=Candidate List of substances of very high concern for Authorisation: Alkanes, C10–13, chloro (Short Chain Chlorinated Paraffins) |url=https://echa.europa.eu/candidate-list-table/-/dislist/substance/external/100.079.496 |publisher=ECHA |access-date=2 January 2020}} SCCPs (average chain length of C12, chlorination degree 60 wt%) were categorised in group 2B as possibly carcinogenic to humans from the International Agency for Research on Cancer (IARC).{{cite journal |pmid=2197463 |year=1990 |title=Chlorinated paraffins |volume=48 |journal=IARC Monographs on the Evaluation of Carcinogenic Risks to Humans |url=http://monographs.iarc.fr/ENG/Monographs/vol48/mono48-7.pdf |isbn=978-92-832-1248-5|page=70|pmc=7681329 }} In 2017, it was agreed to globally ban SCCPs under the Stockholm Convention on Persistent Organic Pollutants, effective December 2018. However, also MCCPs are toxic to the aquatic environment and persistent; MCCPs in soil, biota, and most of the sediment cores show increasing time trends over the last years to decades; MCCP concentrations in sediment close to local sources exceed toxicity thresholds such as the PNEC. In July 2021 also MCCPs were added to the Candidate List of Substances of Very High Concern (SVHC) under the REACH Regulation.
Chlorinated paraffins have been detected in marine life such as cetaceans (whales) and bivalves (molluscs). Of particular concern is fetal accumulation in whales, with the chemicals beginning to build-up in the offspring before they are even born.{{cite journal |last1=Yuan |first1=Bo |last2=McLachlan |first2=Michael S. |last3=Roos |first3=Anna M. |last4=Simon |first4=Malene |last5=Strid |first5=Anna |last6=de Wit |first6=Cynthia A. |title=Long-Chain Chlorinated Paraffins Have Reached the Arctic |journal=Environmental Science & Technology Letters |date=9 August 2021 |volume=8 |issue=9 |pages=753–759 |doi=10.1021/acs.estlett.1c00470|bibcode=2021EnSTL...8..753Y |doi-access=free }}
References
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Sources
- {{cite book |last1=De Boer |first1=J. |last2= El-Sayed |first2=Ali T.|last3= Fiedler |first3=H. |last4= Legler |first4=J. |last5= Muir |first5= D. C. |last6= Nikiforov |first6=V. A. |last7= Tomy |first7=G. T. |last8= Tsunemi |first8=K. |year=2010 |title= The handbook of environmental chemistry 10: Chlorinated paraffins |location= Berlin |publisher= Springer-Verlag|isbn=978-3-642-10760-3}}
- {{cite book |last1=Brooke |first1= DM |last2=Crookes |first2= MJ |last3= Merckel |first3= MD |year=2009 |url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/290855/scho0109bpgr-e-e.pdf |title=Environmental risk assessment: long-chain chlorinated paraffins |location= Bristol, UK |publisher= Environment Agency}}
- {{cite encyclopedia |last=Kellersohn|first= Thomas |year=1998 |title=Chlorinated paraffins |encyclopedia=Ullmann’s encyclopedia of industrial chemistry, electronic release |edition= 6th |location= Weinheim |publisher= Wiley-VCH}}
- {{cite book |last1=Kenne |first1=Kerstin |last2= Ahlborg |first2= Ulf G |year=1996 |url=http://www.inchem.org/documents/ehc/ehc/ehc181.htm |title=Chlorinated paraffins |series= Environmental Health Criteria 181 |location= Geneva |publisher= World Health Organization |isbn=9241571810}}
- {{cite book |last=Lassen |first=Carsten |display-authors=etal |year=2014 |url=http://www2.mst.dk/Udgiv/publications/2014/11/978-87-93283-19-0.pdf |title=Survey of short-chain and medium-chain paraffins |location= Copenhagen |publisher= Danish Ministry of Environment, Environmental Protection Agency|archive-url=https://web.archive.org/web/20161016215522/http://www2.mst.dk/Udgiv/publications/2014/11/978-87-93283-19-0.pdf |archive-date=2016-10-16 }}
- {{cite journal |last=Tomy |first=Gregg T. |display-authors=etal |year=1997 |title=Quantifying C10–C13 polychloroalkanes in environmental samples by high-resolution gas chromatography/electron capture negative ion high-resolution mass spectrometry |journal=Analytical Chemistry |volume=69 |pages=2764–2765 |doi=10.1021/ac961244y}}
Further reading
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- {{cite journal |doi=10.1016/j.envint.2006.05.009 |title=Chlorinated paraffins: A review of analysis and environmental occurrence |year=2006 |last1=Bayen |first1=Stéphane |last2=Obbard |first2=Jeffrey Philip |last3=Thomas |first3=Gareth O. |journal=Environment International |volume=32 |issue=7 |pages=915–929 |pmid=16814386}}
- {{cite journal |doi=10.1093/annhyg/mep081|doi-access=free |title=Dermal Exposure to Metalworking Fluids and Medium-Chain Chlorinated Paraffin (MCCP) |year=2009 |last1=Cherrie |first1=J. W. |last2=Semple |first2=S. |journal=Annals of Occupational Hygiene |volume=54 |issue=2 |pages=228–35 |pmid=19959560}}
- European Chemicals Bureau (2000). [http://echa.europa.eu/documents/10162/f343cb93-2c44-4f19-91e8-4c0730edf604 European Union Risk assessment report Vol. 4: Alkanes, C10-13, chloro], Luxembourg: Office for Official Publications of the European Community.
- European Chemicals Bureau (2008). [http://echa.europa.eu/documents/10162/c157d3ab-0ba7-4915-8f30-96427de56f84 European Union Risk assessment report Vol. 81: Alkanes, C10-13, chloro (update)], Luxembourg: Office for Official Publications of the European Community.
- European Chemicals Bureau (2005). [http://echa.europa.eu/documents/10162/584faee8-d13a-41dd-8b33-959ad1a81171 European Union Risk assessment report Vol. 58: Alkanes, C14-17, chloro (MCCP), Part I-Environment], Luxembourg: Office for Official Publications of the European Community.
- European Commission (2011). [http://publications.jrc.ec.europa.eu/repository/bitstream/JRC63780/lbnb21640enn.pdf European Union Risk assessment report: Alkanes, C14-17, chloro; Addendum to the final report (2007) of the risk assessment – Environment part]. Luxembourg: Office for Official Publications of the European Community.
- European Commission (2011). [http://publications.jrc.ec.europa.eu/repository/bitstream/JRC66049/lbna25202enn.pdf European Union Risk assessment report: Alkanes, C14-17, chloro (MCCP), Part II-Human Health], Luxembourg: Office for Official Publications of the European Community.
- {{cite journal |doi=10.1039/b710053a |title=Analysis of short-chain chlorinated paraffins: A discussion paper |year=2007 |last1=Pellizzato |first1=Francesca |last2=Ricci |first2=Marina |last3=Held |first3=Andrea |last4=Emons |first4=Hendrik |journal=Journal of Environmental Monitoring |volume=9 |issue=9 |pages=924–30 |pmid=17726552}}
- {{cite journal |pmid=9498901 |year=1997 |last1=Tolbert |first1=Paige E. |title=Oils and Cancer |volume=8 |issue=3 |pages=386–405 |journal=Cancer Causes & Control |doi=10.1023/A:1018409422050 |jstor=3552699|s2cid=24166011 }}
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External links
- [http://echa.europa.eu/documents/10162/13640/svhc_axvrep_uk_pbt_sccp_20083006_en.pdf Short Chain Chlorinated Paraffins – Proposal for identification of a substance as a CMR, PBT, vPvB or a substance of an equivalent level of concern]
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