Acrylonitrile

Acrylonitrile is an organic compound with the formula Template:Chem2 and the structure Template:Chem2. It is a colorless, volatile liquid. It has a pungent odor of garlic or onions.<ref name="atsdr">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Its molecular structure consists of a vinyl group (Template:Chem2) linked to a nitrile (Template:Chem2). It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses.<ref name = ullmann/>

Acrylonitrile is one of the components of ABS plastic (acrylonitrile butadiene styrene).<ref>Template:Citation</ref>

Structure and basic properties

Acrylonitrile is an organic compound with the formula Template:Chem2 and the structure Template:Chem2. It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions.<ref name="atsdr"/> Its molecular structure consists of a vinyl group (Template:Chem2) linked to a nitrile (Template:Chem2). It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses.<ref name = ullmann/>

Production

Acrylonitrile was first synthesized by the French chemist Charles Moureu in 1893.<ref>

• Template:Cite journal See especially pp. 187–189 ("Nitrile acrylique ou cyanure de vinyle (Propène-nitrile)").
• Template:Cite journal</ref> Acrylonitrile is produced by catalytic ammoxidation of propylene, also known as the SOHIO process. In 2002, world production capacity was estimated at 5 million tonnes per year,<ref name = ullmann>Template:Ullmann</ref><ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref> rising to about 6 million tonnes by 2017.<ref name=sweet>Template:Cite journal</ref> Acetonitrile and hydrogen cyanide are significant byproducts that are recovered for sale.<ref name = ullmann/> In fact, the 2008–2009 acetonitrile shortage was caused by a decrease in demand for acrylonitrile.<ref>Template:Cite journal</ref>

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In the SOHIO process, propylene, ammonia, and air (oxidizer) are passed through a fluidized bed reactor containing the catalyst at 400–510 °C and 50–200 kPa_g. The reactants pass through the reactor only once, before being quenched in aqueous sulfuric acid. Excess propylene, carbon monoxide, carbon dioxide, and dinitrogen that do not dissolve are vented directly to the atmosphere, or are incinerated. The aqueous solution consists of acrylonitrile, acetonitrile, hydrocyanic acid, and ammonium sulfate (from excess ammonia). A recovery column removes bulk water, and acrylonitrile and acetonitrile are separated by distillation. One of the first useful catalysts was bismuth phosphomolybdate (Template:Chem2) supported on silica.<ref>Template:Cite journal</ref> Further improvements have since been made.<ref name = ullmann/>

Alternative routes

Various green chemistry routes to acrylonitrile are being explored from renewable feedstocks, such as lignocellulosic biomass, glycerol (from biodiesel production), or glutamic acid (which can itself be produced from renewable feedstocks). The lignocellulosic route involves fermentation of the biomass to propionic acid and 3-hydroxypropionic acid, which are then converted to acrylonitrile by dehydration and ammoxidation.<ref name="GrasselliTrifirò2016">Template:Cite journal</ref><ref name=sweet /> The glycerol route begins with its dehydration to acrolein, which undergoes ammoxidation to give acrylonitrile.<ref name="Guerrero-PérezBañares2015">Template:Cite journal</ref> The glutamic acid route employs oxidative decarboxylation to 3-cyanopropanoic acid, followed by a decarbonylation-elimination to acrylonitrile.<ref name="Le NôtreScott2011">Template:Cite journal</ref> Of these, the glycerol route is broadly considered to be the most viable, although none of these green methods are commercially competitive.<ref name="GrasselliTrifirò2016" /><ref name="Guerrero-PérezBañares2015"/>

Uses

Acrylonitrile is used principally as a monomer to prepare polyacrylonitrile, a homopolymer, or several important copolymers, such as styrene-acrylonitrile (SAN), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), and other synthetic rubbers such as acrylonitrile butadiene (NBR). Hydrodimerization of acrylonitrile<ref>Template:Cite book</ref><ref>Template:Cite journal</ref> affords adiponitrile, used in the synthesis of certain nylons:

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Acrylonitrile is also a precursor in the manufacture of acrylamide and acrylic acid.<ref name = ullmann/>

Synthesis of chemicals

Hydrogenation of acrylonitrile is one route to propionitrile. Hydrolysis with sulfuric acid gives acrylamide sulfate, Template:Chem2. This salt can be converted to acrylamide with treatment with base or to methyl acrylate by treatment with methanol.<ref name = ullmann/>

The reaction of acrylonitrile with protic nucleophiles is a common route to a variety of specialty chemicals. The process is called cyanoethylation:

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Typical protic nucleophiles are alcohols, thiols, and especially amines.<ref name=UllmannAmine>Template:Ullmann</ref> When hydrogen cyanide is used the product is succinonitrile.<ref>Template:Cite encyclopedia</ref>

Acrylonitrile and derivatives, such as 2-chloroacrylonitrile, are dienophiles in Diels–Alder reactions.

Health effects

Acrylonitrile is toxic with LD50 = 81 mg/kg (rats). It undergoes explosive polymerization. The burning material releases fumes of hydrogen cyanide and oxides of nitrogen. It is classified as a Class 1 carcinogen (carcinogenic) by the International Agency for Research on Cancer (IARC),<ref name=":1">"Carcinogenicity of talc and acrylonitrile". The Lancet, Volume 25, Issue 8 (2024)</ref> and workers exposed to high levels of airborne acrylonitrile are diagnosed more frequently with lung cancer than the rest of the population.<ref>Acrylonitrile Fact Sheet (CAS No. 107-13-1). epa.gov</ref> Acrylonitrile is one of seven toxicants in cigarette smoke that are most associated with respiratory tract carcinogenesis.<ref>Cunningham FH, Fiebelkorn S, Johnson M, Meredith C. A novel application of the Margin of Exposure approach: segregation of tobacco smoke toxicants. Food Chem Toxicol. 2011 Nov;49(11):2921-33. doi: 10.1016/j.fct.2011.07.019. Epub 2011 Jul 23. Template:PMID</ref> The mechanism of action of acrylonitrile appears to involve oxidative stress and oxidative DNA damage.<ref>Pu X, Kamendulis LM, Klaunig JE. Acrylonitrile-induced oxidative stress and oxidative DNA damage in male Sprague-Dawley rats. Toxicol Sci. 2009;111(1):64-71. doi:10.1093/toxsci/kfp133</ref> Acrylonitrile increases cancer in high dose tests in male and female rats and mice<ref>"Acrylonitrile: Carcinogenic Potency Database".</ref> and induces apoptosis in human umbilical cord mesenchymal stem cells.<ref name="pmid = 24248151">Template:Cite journal</ref>

It evaporates quickly at room temperature (20 °C) to reach dangerous concentrations; skin irritation, respiratory irritation, and eye irritation are the immediate effects of this exposure.<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Pathways of exposure for humans include emissions, auto exhaust, and cigarette smoke that can expose the human subject directly if they inhale or smoke. Routes of exposure include inhalation, oral, and to a certain extent dermal uptake (tested with volunteer humans and in rat studies).<ref name="EPAfacts">Acrylonitrile Fact Sheet: Support Document (CAS No. 107-13-1). epa.gov</ref> Repeated exposure causes skin sensitization and may cause central nervous system and liver damage.<ref name=":0"/>

There are two main excretion processes of acrylonitrile. The primary method is excretion in urine when acrylonitrile is metabolized by being directly conjugated to glutathione. The other method is when acrylonitrile is enzymatically converted into 2-cyanoethylene oxide which will produce cyanide end products that ultimately form thiocyanate, which is excreted via urine.<ref name="EPAfacts" /> Exposure can thus be detected via blood draws and urine sampling.<ref name=":1"/>

In July 2024, the International Agency for Research on Cancer upgraded acrylonitrile's classification from 'possibly carcinogenic' to carcinogenic for humans. The Agency found sufficient evidence linking it to lung cancer.<ref>Template:Cite news</ref><ref>Template:Cite journal</ref>

Use in plastic bottles

In June 1974 Coca-Cola introduced the acrylonitrile/styrene 32oz Easy‐Goer plastic bottle, offering energy savings during manufacture, increased durability, and weight savings over glass.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In March 1977 after a suit filed by the Natural Resources Defense Council the FDA rescinded approval of acrylonitrile bottles citing adverse effects on test animals.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Monsanto, Coca-Cola's bottle manufacturer refuted the decision, stating “repeated tests have demonstrated that there is no detectable migration of acrylonitrile into the bottle's content.” After several appeals in court by September 1977 the FDA finalized their ban.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref>

Incidents

A large amount of acrylonitrile (approximately 6500 tons) leaked from an industrial polymer plant owned by Aksa Akrilik after the violent 17th August 1999 earthquake in Turkey. Over 5000 people were affected and the exposed animals had died.<ref name=ttb>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The leak was only noticed by the company 8 hours after the incident. Healthcare workers did not know about the health effects of acrylonitrile and tried to treat the victims with painkillers and IV fluids.<ref name=tabella>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> One lawyer, Ayşe Akdemir, sued the company with 44 families as the plaintiffs.<ref name=tabella/> Aksa Akrilik was sued by 200 residents who were affected by acrylonitrile.<ref name=bigpara>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> An increase in cancer cases in the area was confirmed by the Turkish Medical Association,<ref name=bigpara/> as the cancer rate in the affected area has increased by 80%, from 1999 to April 2002.<ref name=tabella/> In 2003, the owner of Aksa Akrilik died from lung cancer related to acrylonitrile exposure.<ref name=tabella/> As of 2001, this is the largest known acrylonitrile leak.<ref name=ttb/>

Occurrence

Acrylonitrile is not naturally formed on Earth. It has been detected at the sub-ppm level at industrial sites. It persists in the air for up to a week. It decomposes by reacting with oxygen and hydroxyl radical to form formyl cyanide and formaldehyde.<ref>Template:Cite journal</ref> Acrylonitrile is harmful to aquatic life.<ref name=":0"/> Acrylonitrile has been detected in the atmosphere of Titan, a moon of Saturn.<ref name="SP-20170728"/><ref name="SA-20170728"/><ref name="WP-20170808">Template:Cite news</ref> Computer simulations suggest that on Titan conditions exist such that the compound could form structures similar to cell membranes and vesicles on Earth, called azotosomes.<ref name="SP-20170728">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="SA-20170728">Template:Cite journal</ref>

External links

• National Pollutant Inventory – Acrylonitrile
• Comparing Possible Cancer Hazards from Human Exposures to Rodent Carcinogens Template:Webarchive
• Acrylonitrile – Integrated Risk Information System, U.S. Environmental Protection Agency
• CDC – NIOSH Pocket Guide to Chemical Hazards – Acrylonitrile
• OSHA Table Z-1 for Air Contaminants