Editing Formaldehyde (section)

==Uses==

===Industrial applications===
Formaldehyde is a common precursor to more complex compounds and materials. In approximate order of decreasing consumption, products generated from formaldehyde include [[urea formaldehyde resin]], [[melamine resin]], [[phenol formaldehyde resin]], [[polyoxymethylene plastic]]s, [[1,4-butanediol]], and [[methylene diphenyl diisocyanate]].<ref name="Ullmann"/> The [[textile industry]] uses formaldehyde-based resins as [[Finishing (textiles)|finishers]] to make fabrics crease-resistant.<ref>{{cite web | title = Formaldehyde in Clothing and Textiles FactSheet | url = https://www.nicnas.gov.au/chemical-information/factsheets/chemical-name/formaldehyde-in-clothing-and-textiles | website = NICNAS | publisher = Australian National Industrial Chemicals Notification and Assessment Scheme | access-date = 2014-11-12 | date = 2013-05-01 | archive-url = https://web.archive.org/web/20190319234828/https://www.nicnas.gov.au/chemical-information/factsheets/chemical-name/formaldehyde-in-clothing-and-textiles | archive-date = 2019-03-19 | url-status = dead}}</ref>

[[File:UFresinSyn.svg|thumb|340px|Two steps in formation of urea-formaldehyde resin, which is widely used in the production of particle board]]

When condensed with [[phenol]], [[urea]], or [[melamine]], formaldehyde produces, respectively, hard thermoset phenol formaldehyde resin, urea formaldehyde resin, and melamine resin. These polymers are permanent adhesives used in [[plywood]] and [[carpet]]ing. They are also foamed to make [[Thermal insulation|insulation]], or [[casting|cast]] into moulded products. Production of formaldehyde resins accounts for more than half of formaldehyde consumption.

Formaldehyde is also a precursor to polyfunctional [[Alcohol (chemistry)|alcohol]]s such as [[pentaerythritol]], which is used to make [[paint]]s and [[explosive]]s. Other formaldehyde derivatives include methylene diphenyl diisocyanate, an important component in [[polyurethane]] paints and foams, and [[hexamine]], which is used in phenol-formaldehyde resins as well as the explosive [[RDX]].

Condensation with acetaldehyde affords [[pentaerythritol]], a chemical necessary in synthesizing [[PETN]], a high explosive:<ref>{{OrgSynth|first=H. B. J.|last=Schurink|title=Pentaerythritol|prep=cv1p0425|volume=4|pages=53|year= 1925|collvol=1|collvolpages=425}}</ref>
[[File:Pentaerythritol Synthesis.svg|600px|center]]

===Niche uses===
====Disinfectant and biocide====
An aqueous solution of formaldehyde can be useful as a disinfectant as it kills most [[bacteria]] and fungi (including their spores). It is used as an additive in vaccine manufacturing to inactivate toxins and pathogens.<ref>{{cite web | url = https://www.cdc.gov/vaccines/vac-gen/additives.htm | title = Ingredients of Vaccines - Fact Sheet | publisher = Center for Disease Control | access-date = 2018-08-04 | quote = Formaldehyde is used to inactivate bacterial products for toxoid vaccines, (these are vaccines that use an inactive bacterial toxin to produce immunity.) It is also used to kill unwanted viruses and bacteria that might contaminate the vaccine during production. Most formaldehyde is removed from the vaccine before it is packaged. | archive-url = https://web.archive.org/web/20190421020210/https://www.cdc.gov/vaccines/vac-gen/additives.htm | archive-date = 2019-04-21 | url-status = live}}</ref> [[Formaldehyde releaser]]s are used as biocides in personal care products such as cosmetics. Although present at levels not normally considered harmful, they are known to cause allergic [[contact dermatitis]] in certain sensitised individuals.<ref name="Formaldehyde Releasers" />

Aquarists use formaldehyde as a treatment for the parasites ''[[Ichthyophthirius multifiliis]]'' and ''[[Cryptocaryon irritans]]''.<ref>{{cite web|first=Ruth |last=Francis-Floyd |title=Use of Formalin to Control Fish Parasites |url=http://edis.ifas.ufl.edu/vm061 |publisher=Institute of Food and Agricultural Sciences, University of Florida |date=April 1996 |url-status=dead |archive-url=https://web.archive.org/web/20120527111132/http://edis.ifas.ufl.edu/vm061 |archive-date=May 27, 2012}}</ref> Formaldehyde is one of the main disinfectants recommended for destroying [[anthrax]].<ref>{{Citation |title=Disinfection, decontamination, fumigation, incineration |date=2008 |url=https://www.ncbi.nlm.nih.gov/books/NBK310477/ |work=Anthrax in Humans and Animals. 4th edition |access-date=2023-11-20 |publisher=World Health Organization |language=en |archive-date=2022-07-06 |archive-url=https://web.archive.org/web/20220706223226/https://www.ncbi.nlm.nih.gov/books/NBK310477/ |url-status=live}}</ref>

Formaldehyde is also approved for use in the manufacture of animal feeds in the US. It is an antimicrobial agent used to maintain complete animal feeds or feed ingredients ''Salmonella'' negative for up to 21 days.<ref>{{cite web | date = 2019-04-19 | title = §573.460 Formaldehyde | url = http://www.ecfr.gov/cgi-bin/text-idx?SID=373e2ce8edf3f674e80eb9270a461c7d&mc=true&node=se21.6.573_1460&rgn=div8 | url-status = dead | archive-url = https://web.archive.org/web/20170505205047/http://www.ecfr.gov/cgi-bin/text-idx?SID=373e2ce8edf3f674e80eb9270a461c7d&mc=true&node=se21.6.573_1460&rgn=div8 | archive-date = 2017-05-05 | publisher = U.S. Government Publishing Office | access-date = 2016-07-09}}</ref>

====Tissue fixative and embalming agent====
[[File:Steve O'Shea injecting formalin.jpg|thumb|Injecting a [[giant squid]] specimen with formalin for preservation]]
Formaldehyde preserves or [[Fixation (histology)|fixes]] tissue or cells. The process involves [[cross-link]]ing of primary [[amino group]]s. The European Union has banned the use of formaldehyde as a [[biocide]] (including [[embalming]]) under the [[Biocidal Products Directive]] (98/8/EC) due to its carcinogenic properties.<ref>[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31998L0008:EN:HTML Directive 98/8/EC of the European Parliament and of the Council of 16 February 1998 concerning the placing of biocidal products on the market] {{Webarchive|url=https://web.archive.org/web/20080219232906/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31998L0008:EN:HTML |date=19 February 2008}}. ''OJEU'' L123, 24.04.1998, pp.&nbsp;1–63. ([http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1998L0008:20080926:EN:PDF consolidated version to 2008-09-26 (PDF)] {{Webarchive|url=https://web.archive.org/web/20100127033519/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1998L0008:20080926:EN:PDF |date=2010-01-27}})</ref><ref>[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003R2032:EN:HTML Commission Regulation (EC) No 2032/2003 of 4 November 2003 on the second phase of the 10-year work programme referred to in Article&nbsp;16(2) of Directive&nbsp;98/8/EC of the European Parliament and of the Council concerning the placing of biocidal products on the market, and amending Regulation&nbsp;(EC) No&nbsp;1896/2000] {{Webarchive|url=https://web.archive.org/web/20110612142224/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003R2032:EN:HTML |date=12 June 2011}}. ''OJEU'' L307, 24.11.2003, p.&nbsp;1–96. ([http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:2003R2032:20070104:EN:PDF consolidated version to 2007-01-04 (PDF)] {{Webarchive|url=https://web.archive.org/web/20110614093404/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:2003R2032:20070104:EN:PDF |date=2011-06-14}})</ref> Countries with a strong tradition of embalming corpses, such as Ireland and other colder-weather countries, have raised concerns. Despite reports to the contrary,<ref>{{cite web | first = Alkesh | last = Patel | url = http://www.webwire.com/ViewPressRel.asp?aId=41468 | title = Formaldehyde Ban set for 22 September 2007 | publisher = WebWire | date = 2007-07-04 | access-date = 2012-05-19 | archive-url = https://web.archive.org/web/20181212180926/https://www.webwire.com/ViewPressRel.asp?aId=41468 | archive-date = 2018-12-12 | url-status = dead}}</ref> no decision on the inclusion of formaldehyde on Annex&nbsp;I of the Biocidal Products Directive for product-type&nbsp;22 (embalming and taxidermist fluids) had been made {{As of|2009|9|lc=on}}.<ref>{{cite web|url=http://esis.jrc.ec.europa.eu/ |title=European chemical Substances Information System (ESIS) entry for formaldehyde |access-date=2009-09-01 |url-status=dead |archive-url=https://web.archive.org/web/20140101220543/http://esis.jrc.ec.europa.eu/ |archive-date=2014-01-01}}</ref>

Formaldehyde-based crosslinking is exploited in [[ChIP-on-chip]] or [[ChIP-sequencing]] genomics experiments, where DNA-binding proteins are cross-linked to their cognate binding sites on the chromosome and analyzed to determine what genes are regulated by the proteins. Formaldehyde is also used as a denaturing agent in [[RNA]] gel [[electrophoresis]], preventing RNA from forming secondary structures. A solution of 4% formaldehyde fixes pathology tissue specimens at about one mm per hour at room temperature.

====Drug testing====
Formaldehyde and 18&nbsp;[[Concentration#Molality|M]] (concentrated) [[sulfuric acid]] makes [[Marquis reagent]]—which can identify [[alkaloid]]s and other compounds.

=== Photography ===
In photography, formaldehyde is used in low concentrations for the process [[C-41 process|C-41]] (color negative film) stabilizer in the final wash step,<ref>{{cite web | url = http://www.kodak.com/global/en/service/Zmanuals/z131.shtml | title = Process C-41 Using Kodak Flexicolor Chemicals - Publication Z-131 | publisher = Kodak | access-date = 2009-09-01 | archive-url = https://web.archive.org/web/20160615095319/http://www.kodak.com/global/en/business/retailPhoto/techInfo/zManuals/z131.jhtml | archive-date = 2016-06-15 | url-status = dead}}</ref> as well as in the [[E-6 process|process E-6]] pre-bleach step, to make it unnecessary in the final wash. Due to improvements in dye coupler chemistry, more modern (2006 or later) E-6 and C-41 films do not need formaldehyde, as their dyes are already stable.