Methacrylic acid, abbreviated MAA, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

. 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

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

s, especially

methyl methacrylate Methyl methacrylate (MMA) is an organic compound with the formula CH2=C(CH3)COOCH3. This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA ...

(MMA), and to poly(methyl methacrylate) (PMMA). MAA occurs naturally in small amounts in the oil of Roman chamomile.

Production

In the most common route, methacrylic acid is prepared from

acetone cyanohydrin Acetone cyanohydrin (ACH) is an organic compound used in the production of methyl methacrylate, the monomer of the transparent plastic polymethyl methacrylate (PMMA), also known as acrylic. It liberates hydrogen cyanide easily, so it is used as a ...

, 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. Another route to methacrylic acid starts with

isobutylene Isobutylene (or 2-methylpropene) is a hydrocarbon with the chemical formula . It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value. Producti ...

, which obtainable by dehydration of ''tert''-butanol. Isobutylene is oxidized sequentially to

methacrolein Methacrolein, or methacrylaldehyde, is an unsaturated aldehyde. It is a clear, colorless, flammable liquid. Methacrolein is one of two major products resulting from the reaction of isoprene with OH in the atmosphere, the other product being ...

and then methacrylic acid. Methacrolein for this purpose can also be obtained from

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

and

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

. Yet a third route involves the

dehydrogenation In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

Isobutyric acid Isobutyric acid, also known as 2-methylpropanoic acid or isobutanoic acid, is a carboxylic acid with structural formula ( CH3)2CH COOH. It is an isomer of ''n''-butyric acid. It is classified as a short-chain fatty acid. Deprotonation or esterif ...

. Various green routes have been explored but they have not been commercialized. Specifically, the decarboxylation of

itaconic acid Itaconic acid, or methylidenesuccinic acid, is an organic compound. This dicarboxylic acid is a white solid that is soluble in water, ethanol, and acetone. Historically, itaconic acid was obtained by the distillation of citric acid, but currentl ...

citraconic acid Citraconic acid is an organic compound with the formula CH3C2H(CO2H)2. It is a white solid. It is the ''cis''- isomer of mesaconic acid. It is one of the pyrocitric acids formed upon the heating of citric acid. Citraconic acid can be produced, ...

, and

mesaconic acid Mesaconic acid is one of several isomeric carboxylic acids obtained from citric acid. It is a colorless solid. Synthesis and reactions It is prepared from citric acid, which is first converted to itaconic anhydride by dehydration and decarboxy ...

s affords methacrylic acid. Salts of methacrylic acid have been obtained by boiling citra- or meso-brompyrotartaric acids with

alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

s. Pyrolysis of

ethyl methacrylate Ethyl methacrylate is the organic compound with the formula C2H5O2CC(CH3)=CH2. A colorless liquid, it is a common monomer for the preparation of acrylate polymers.. It is typically polymerized under free-radical conditions. Ethyl methacrylate ...

efficiently gives methacrylic acid.

Uses

Methacrylic acid is used in some nail primers to help

acrylic nails Artificial nails, also known as fake nails, false nails, acrylic nails, nail extensions or nail enhancements, are extensions placed over fingernails as fashion accessories. Many artificial nail designs attempt to mimic the appearance of real f ...

adhere to the nail plate.

Reactions

When fused with an alkali, it forms

propanoic acid Propionic acid (, from the Greek words πρῶτος : ''prōtos'', meaning "first", and πίων : ''píōn'', meaning "fat"; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula CH3CH2CO2H. It is a liqu ...

Sodium amalgam Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and sodium. The term amalgam is used for alloys, intermetallic compounds, and solutions (both solid solutions and liquid solutions) involving mercury as a major component. Sodium am ...

reduces it to

isobutyric acid Isobutyric acid, also known as 2-methylpropanoic acid or isobutanoic acid, is a carboxylic acid with structural formula ( CH3)2CH COOH. It is an isomer of ''n''-butyric acid. It is classified as a short-chain fatty acid. Deprotonation or esterif ...

. A

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

ic form of methacrylic acid was described in 1880.. 352px, left, Typical vinyl ester resin derived from bisphenol A diglycidyl ether and methacrylic acid.{{cite journal, last1=Pham, first1=Ha Q., last2=Marks, first2=Maurice J., title=Epoxy Resins, journal=Ullmann's Encyclopedia of Industrial Chemistry, year=2012, location=Weinheim, publisher=Wiley-VCH, doi=10.1002/14356007.a09_547.pub2, isbn=978-3527306732

References

External links

Methacrylic Acid in Europe. Monomers Enoic acids Foul-smelling chemicals