Methacrylic acid

Methacrylic acid
Structural formula of methacrylic acid
Ball-and-stick model of the methacrylic acid molecule
Names
IUPAC name
2-methylpropenoic acid[1]
Other names
MAA, 2-methyl-2-propenoic acid, α-Methacrylic acid, 2-Methylacrylic acid, 2-Methylpropenoic acid
Identifiers
79-41-4 YesY
ChEBI CHEBI:25219 N
ChemSpider 3951 N
EC Number 201-204-4
Jmol interactive 3D Image
MeSH C008384
PubChem 4093
Properties
C4H6O2
Molar mass 86.06 g/mol
Appearance Colorless liquid or solid
Odor Acrid, repulsive[2]
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)[2]
Vapor pressure 0.7 mmHg (20 °C)[2]
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 fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special 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):
none[2]
TWA 20 ppm (70 mg/m3) [skin][2]
N.D.[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
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 and properties

More than 3 million tons of methyl methacrylate (MMA) are produced annually. In one route, acetone cyanohydrin is converted to methacrylamide sulfate using sulfuric acid. That compound is hydrolyzed to methacrylic acid, or it can be converted into 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]

Methacrylic acid was first obtained in the form of its ethyl ester by treating phosphorus pentachloride with oxyisobutyric ester.[4] 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.[5]

References

  1. ↑ CID 4093 from PubChem
  2. 1 2 3 4 5 6 "NIOSH Pocket Guide to Chemical Hazards #0386". National Institute for Occupational Safety and Health (NIOSH).
  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. ↑ Edward Frankland Annalen, 1865, 136, p. 12
  5. ↑ F. Engelhorn et al. Ann., 1880, 200, p. 70.

External links

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