Acrylates (IUPAC: prop-2-enoates) are the salts, esters, and conjugate bases of acrylic acid. The acrylate ion is the anion CH2=CHCOO−. Often, acrylate refers to esters of acrylic acid, the most common member being methyl acrylate. These acrylates contain vinyl groups. These compounds are of interest because they are bifunctional: the vinyl group is susceptible to polymerization and the carboxylate group carries myriad functionalities. Modified acrylates are also numerous, some examples being methacrylates (CH2=C(CH3)CO2R) and cyanoacrylates (CH2=C(CN)CO2R). Acrylate can also refer to polyacrylates prepared through the polymerization of the vinyl groups of acrylate monomers.
Trimethylolpropane triacrylate (TMPTA), a trifunctional acrylate ester
Methyl acrylate, an acrylic ester
Ethyl cyanoacrylate, precursor to "super glue"
Acrylates and methacrylates (the salts and esters of methacrylic acid) are common monomers in polymer plastics, forming the acrylate polymers. Acrylates easily form polymers. A variety of acrylate-functionalized monomers are known.
Acrylate monomers, used to form acrylate polymers, are based on the structure of acrylic acid, which consists of a vinyl group and a carboxylic acid ester end or a nitrile. Other typical acrylate monomers are derivatives of acrylic acid, such as methyl methacrylate in which one vinyl hydrogen and the carboxylic acid hydrogen are both replaced by methyl groups, and acrylonitrile in which the carboxylic acid group is replaced by the related nitrile group.
Other examples of acrylate monomers are:
- Methyl acrylate
- Ethyl acrylate
- 2-Chloroethyl vinyl ether
- 2-Ethylhexyl acrylate
- Hydroxyethyl methacrylate
- Butyl acrylate
- Butyl methacrylate
Acrylates are industrially prepared by treating acrylic acid with the corresponding alcohol in presence of a catalyst. The reaction with lower alcohols (methanol, ethanol) takes place at 100–120 °C with acidic heterogeneous catalysts (cation exchanger). The reaction of higher alcohols (n-butanol, 2-ethylhexanol) is catalysed with sulfuric acid in homogeneous phase. Acrylates of even higher alcohols are obtainable by transesterification of lower esters catalysed by titanium alcoholates or organic tin compounds (e.g. dibutyltin dilaurate).
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