Methacrylic acid

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
3D model (JSmol)
Abbreviations MAA
ChEBI
ChemSpider
ECHA InfoCard 100.001.096
EC Number 201-204-4
MeSH C008384
Properties
C4H6O2
Molar mass 86.06 g/mol
Appearance Colorless liquid or solid
Odor Acrid, repulsive[1]
Density 1.015 g/cm3
Melting point 14 to 15 °C (57 to 59 °F; 287 to 288 K)
Boiling point 161 °C (322 °F; 434 K)
9% (25 °C)[1]
Vapor pressure 0.7 mmHg (20 °C)[1]
Hazards
NFPA 704
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., phosphorusSpecial hazards (white): no codeNFPA 704 four-colored diamond
2
3
2
Flash point 77.2 °C (171.0 °F; 350.3 K)
US health exposure limits (NIOSH):
PEL (Permissible)
 none[1]
REL (Recommended)
 TWA 20 ppm (70 mg/m3) [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

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). The methacrylates have numerous uses, most notably in the manufacture of polymers with trade names such as Lucite and Plexiglas. MAA occurs naturally in small amounts in the oil of Roman chamomile.

Production

More than 3 million tons of methyl methacrylate (MMA) are produced annually, this high level of demand has lead to several methods for its production being commercialised.[2] In the most common route, acetone and cyanide react to form acetone cyanohydrin, which is converted to methacrylamide sulfate using sulfuric acid. This 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.[3]

It can be prepared by decarboxylation of itaconic acid, citraconic acid, and mesaconic acid by decarboxylation. Such green precursors are not of commercial value.

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] It is, however, more readily obtained by boiling citra- or meso-brompyrotartaric acids with alkalis. It crystallizes in prisms. 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. 1 2 3 4 5 6 "NIOSH Pocket Guide to Chemical Hazards #0386". National Institute for Occupational Safety and Health (NIOSH).
  2. ↑ Darabi Mahboub, Mohammad Jaber; Dubois, Jean-Luc; Cavani, Fabrizio; Rostamizadeh, Mohammad; Patience, Gregory S. (2018). "Catalysis for the synthesis of methacrylic acid and methyl methacrylate". Chemical Society Reviews. doi:10.1039/C8CS00117K.
  3. ↑ William Bauer, Jr. "Methacrylic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_441. Article Online Posting Date: June 15, 2000
  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.
  • Methacrylic Acid in Europe.
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