methacrylic acid

Methacrylic acid
IUPAC name	2-methylpropenoic acid
Other names	MAA, 2-methyl-2-propenoic acid
Identifiers
CAS number	79-41-4 Y
SMILES	CC(C(O)=O)=C
Properties
Molecular formula	C4H6O2
Molar mass	86.06 g/mol
Density	1.015 g/cm3
Melting point	14 - 15 °C
Boiling point	161 °C
Hazards
NFPA 704	2 3 2
Y(what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Methacrylic acid, abbreviated MAA, is an organic compound. This colourless, 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). 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 billion kilograms of methyl methacrylate (MMA) are produced annually, and a significant fraction of the manufacturing processes proceed via the intermediacy of MAA (the dominant process, the "ACH route," does not). Isobutylene and tert-butanol, are oxidized sequentially to methacrolein and then to MAA, which is then largely esterified.^[1]

Methacrylic acid was first obtained in the form of its ethyl ester by treating phosphorus pentachloride with oxyisobutyric ester.^[2] 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 propionic acid. Sodium amalgam reduces it to isobutyric acid. A polymeric form of methacrylic acid was described in 1880.^[3]

References

1. ^ 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
2. ^ Edward Frankland Annalen, 1865, 136, p. 12
3. ^ F. Engelhorn et al. Ann., 1880, 200, p. 70.