Acrylic acid

Acrylic acid (IUPAC: propenoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a characteristic acrid or tart smell. It is miscible with water, alcohols, ethers, and chloroform. More than a million tons are produced annually.[6]

Acrylic acid[1]
Names
IUPAC name
Acrylic acid[2]
Systematic IUPAC name
Prop-2-enoic acid
Other names
Acrylic acid
Acroleic acid
Ethylenecarboxylic acid
Propenoic acid
Vinylformic acid
Identifiers
3D model (JSmol)
635743
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.001.071
EC Number
  • 201-177-9
1817
KEGG
RTECS number
  • AS4375000
UNII
Properties
C3H4O2
Molar mass 72.063 g·mol−1
Appearance clear, colorless liquid
Odor acrid[3]
Density 1.051 g/mL
Melting point 14 °C (57 °F; 287 K)
Boiling point 141 °C (286 °F; 414 K)
Miscible
log P 0.28[4]
Vapor pressure 3 mmHg[3]
Acidity (pKa) 4.25 (H2O)[5]
Viscosity 1.3 cP at 20 °C (68 °F)
Hazards
Safety data sheet MSDS
GHS pictograms
GHS Signal word Danger
GHS hazard statements
 H226, H302, H312, H314, H332, H400
P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P301+312, P301+330+331, P302+352, P303+361+353, P304+312, P304+340, P305+351+338, P310, P312, P321, P322, P330
NFPA 704 (fire diamond)
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
2
3
2
Flash point 68 °C (154 °F; 341 K)
429 °C (804 °F; 702 K)
Explosive limits 2.4%–8.02%[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 none[3]
REL (Recommended)
 TWA 2 ppm (6 mg/m3) [skin][3]
IDLH (Immediate danger)
 N.D.[3]
Related compounds
Other anions
 acrylate
acetic acid
propionic acid
lactic acid
3-hydroxypropionic acid
malonic acid
butyric acid
crotonic acid
Related compounds
 allyl alcohol
propionaldehyde
acrolein
methyl acrylate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Production

Acrylic acid is produced by oxidation of propylene, which is a byproduct of the production of ethylene and gasoline:

CH2=CHCH3 + ​3⁄2 O2 → CH2=CHCO2H + H2O

Historical methods

Because acrylic acid and its esters have long been valued commercially, many other methods have been developed. Most have been abandoned for economic or environmental reasons. An early method was the hydrocarboxylation of acetylene ("Reppe chemistry"):

This method requires nickel carbonyl, high pressures of carbon monoxide, and acetylene, which is relatively expensive compared to propylene.

Acrylic acid was once manufactured by the hydrolysis of acrylonitrile, a material derived from propene by ammoxidation, but this route was abandoned because it cogenerates ammonium side products, which must be disposed of. Other now abandoned precursors to acrylic acid include ethenone and ethylene cyanohydrin.[6]

Research

Propane is a significantly cheaper raw material than propylene, so one alternative route being explored is the one-step selective oxidation of propane.[7]

Carboxylating ethylene to acrylic acid under supercritical carbon dioxide condition is thermodynamically possible, but efficient catalysts have not been developed.[8] 3-Hydroxypropionic acid (3HP), an acrylic-acid precursor by dehydration, can be produced from sugars, but the process is not competitive.[9][10]

Reactions and uses

Acrylic acid undergoes the typical reactions of a carboxylic acid. When reacted with an alcohol, it forms the corresponding ester. The esters and salts of acrylic acid are collectively known as acrylates (or propenoates). The most common alkyl esters of acrylic acid are methyl, butyl, ethyl, and 2-ethylhexyl acrylate.

Acrylic acid and its esters readily combine with themselves (to form polyacrylic acid) or other monomers (e.g. acrylamides, acrylonitrile, vinyl compounds, styrene, and butadiene) by reacting at their double bond, forming homopolymers or copolymers, which are used in the manufacture of various plastics, coatings, adhesives, elastomers, as well as floor polishes and paints.

Acrylic acid is a compound, which is used in many industries like the diaper industry, the water treatment industry or the textiles industry. On a worldwide scale the consumption rate of acrylic acid is projected to reach more than an estimated 8,000 kilotons, by 2020. This increase is expected to occur as a result of using this product in new applications, including personal care products, detergents and products that are used for adult incontinence.[11]

Substituents

As a substituent acrylic acid can be found as an acyl group or a carboxyalkyl group, depending on the removal of the group from the molecule. More specifically, these are:

  1. The acryloyl group, with the removal of the −OH from carbon-1.
  2. The 2-carboxyethenyl group, with the removal of a −H from carbon-3. This substituent group is found in chlorophyll.

Safety

Acrylic acid is severely irritating and corrosive to the skin and the respiratory tract. Eye contact can result in severe and irreversible injury. Low exposure will cause minimal or no health effects, while high exposure could result in pulmonary edema. The LD50 is 340 mg/kg (rat, oral).

Acrylic acid is a constituent of tobacco smoke.[12]

See also

References
  1. Merck Index, 11th Edition, 124.
  2. ChemSpider lists 'acrylic acid' as a valid, expert-verified IUPAC name
  3. NIOSH Pocket Guide to Chemical Hazards. "#0013". National Institute for Occupational Safety and Health (NIOSH).
  4. "Acrylic acid_msds".
  5. Dippy, J. F. J.; Hughes, S. R. C.; Rozanski, A. (1959). "The dissociation constants of some symmetrically disubstituted succinic acids". Journal of the Chemical Society: 2492–2498. doi:10.1039/JR9590002492.
  6. Ohara, Takashi; Sato, Takahisa; Shimizu, Noboru; Prescher, Günter; Schwind, Helmut; Weiberg, Otto; Marten, Klaus; Greim, Helmut (2003). "Acrylic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_161.pub2.
  7. Naumann d'Alnoncourt, Raoul; Csepei, Lénárd-István; Hävecker, Michael; Girgsdies, Frank; Schuster, Manfred E.; Schlögl, Robert; Trunschke, Annette (2014). "The reaction network in propane oxidation over phase-pure MoVTeNb M1 oxide catalysts" (PDF). Journal of Catalysis. 311: 369–385. doi:10.1016/j.jcat.2013.12.008. hdl:11858/00-001M-0000-0014-F434-5. Archived from the original (PDF) on 2016-02-15. Retrieved 2017-07-15.
  8. Sakakura, Toshiyasu; Choi, Jun-Chul; Yasuda, Hiroyuki (13 June 2007). "Transformation of Carbon dioxide". Chemical Reviews. 107 (6): 2365–2387. doi:10.1021/cr068357u. PMID 17564481.
  9. Sweet Deal: Dow and Partner Cook up Sugar-to-Acrylic Plan. Durabilityanddesign.com. Retrieved on 2012-05-24.
  10. Better Bugs to Make Plastics, Technology Review, September 20, 2010, retrieved January 9, 2012. Technologyreview.com (2010-09-20). Retrieved on 2012-05-24.
  11. "Acrylic acid market". Retrieved 2018-05-30.
  12. Talhout, Reinskje; Schulz, Thomas; Florek, Ewa; Van Benthem, Jan; Wester, Piet; Opperhuizen, Antoon (2011). "Hazardous Compounds in Tobacco Smoke". International Journal of Environmental Research and Public Health. 8 (12): 613–628. doi:10.3390/ijerph8020613. ISSN 1660-4601. PMC 3084482. PMID 21556207.
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