Methacrylic acid

Methacrylic acid, abbreviated MAA, is an organic compound. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Methacrylic acid is produced industrially on a large scale as a precursor to its esters, especially methyl methacrylate (MMA) and poly(methyl methacrylate) (PMMA). MAA occurs naturally in small amounts in the oil of Roman chamomile.

Methacrylic acid

Structural formula of methacrylic acid Ball-and-stick model of the methacrylic acid molecule
Names
Preferred IUPAC name 2-Methylprop-2-enoic acid
Other names Methacrylic acid 2-Methyl-2-propenoic acid α-Methacrylic acid 2-Methylacrylic acid 2-Methylpropenoic acid
Identifiers
CAS Number	79-41-4
3D model (JSmol)	Interactive image
Abbreviations	MAA
ChEBI	CHEBI:25219
ChemSpider	3951
ECHA InfoCard	100.001.096
EC Number	201-204-4
MeSH	C008384
PubChem CID	4093
UNII	1CS02G8656
CompTox Dashboard (EPA)	DTXSID3025542
InChI InChI=1S/C4H6O2/c1-3(2)4(5)6/h1H2,2H3,(H,5,6) Key: CERQOIWHTDAKMF-UHFFFAOYSA-N
SMILES CC(C(O)=O)=C
Properties
Chemical formula	C4H6O2
Molar mass	86.09 g/mol
Appearance	Colorless liquid or solid
Odor	Acrid, repulsive[1]
Density	1.015 g/cm^3
Melting point	14 to 15 °C (57 to 59 °F; 287 to 288 K)
Boiling point	161 °C (322 °F; 434 K)
Solubility in water	9% (25 °C)[1]
Vapor pressure	0.7 mmHg (20 °C)[1]
Hazards
NFPA 704 (fire diamond)	2 3 2
Flash point	77.2 °C (171.0 °F; 350.3 K)
NIOSH (US health exposure limits):
PEL (Permissible)	none[1]
REL (Recommended)	TWA 20 ppm (70 mg/m^3) [skin][1]
IDLH (Immediate danger)	N.D.[1]
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

In the most common route, methacrylic acid is prepared from acetone cyanohydrin, which is converted to methacrylamide sulfate using sulfuric acid. This derivative in turn is hydrolyzed to methacrylic acid, or esterified to methyl methacrylate in one step. In the second route, isobutylene or tert-butanol are oxidized to methacrolein, then methacrylic acid. Methacrolein for this purpose can also be obtained from formaldehyde and ethylene. Isobutyric acid can also be dehydrogenated to methacrylic acid.[2]

It can also be prepared by decarboxylation of itaconic acid, citraconic acid, and mesaconic acid. Such green precursors are not of commercial value. It is, however, obtained by boiling citra- or meso-brompyrotartaric acids with alkalis.

Uses

Methacrylic acid is used in some nail primers to help acrylic nails adhere to the nail plate.[3]

Reactions

Methacrylic acid was first obtained in the form of its ethyl ester by treating phosphorus pentachloride with oxyisobutyric ester (A synonym for beta-hydroxy-butyric acid or 3-hydroxybutyric acid[4]) .[5] When fused with an alkali, it forms propanoic acid. Sodium amalgam reduces it to isobutyric acid. A polymeric form of methacrylic acid was described in 1880.[6]

Typical vinyl ester resin derived from bisphenol A diglycidyl ether and methacrylic acid.[7]

References

1. NIOSH Pocket Guide to Chemical Hazards. "#0386". National Institute for Occupational Safety and Health (NIOSH).
2. William Bauer, Jr. (2002). "Methacrylic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a16_441.CS1 maint: uses authors parameter (link)
3. "Products - Nail Care Products". www.fda.gov. U.S. Food and Drug Administration. 2018-03-06. Retrieved 2019-04-03.
4. https://www.vocabulary.com/dictionary/oxybutyric%20acid
5. Edward Frankland Annalen, 1865, 136, p. 12
6. F. Engelhorn et al. Ann., 1880, 200, p. 70.
7. Pham, Ha Q.; Marks, Maurice J. (2012). "Epoxy Resins". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a09_547.pub2.

External links

• Methacrylic Acid in Europe.