Acrylic acid is produced by oxidation of propylene, which is a byproduct of the production of ethylene and gasoline:
Historical methods
Because acrylic acid and its esters have long been valued commercially, many other methods have been developed. Most have been abandoned for economic or environmental reasons. An early method was the hydrocarboxylation of acetylene : This method requires nickel carbonyl, high pressures of carbon monoxide, and acetylene, which is relatively expensive compared to propylene. Acrylic acid was once manufactured by the hydrolysis of acrylonitrile, a material derived from propene by ammoxidation, but this route was abandoned because it cogenerates ammonium side products, which must be disposed of. Other now abandoned precursors to acrylic acid include ethenone and ethylene cyanohydrin.
Research
is a significantly cheaper raw material than propylene, so one alternative route being explored is the one-step selective oxidation of propane. Carboxylating ethylene to acrylic acid under supercritical carbon dioxide condition is thermodynamically possible, but efficient catalysts have not been developed. 3-Hydroxypropionic acid, an acrylic-acid precursor by dehydration, can be produced from sugars, but the process is not competitive.
Reactions and uses
Acrylic acid undergoes the typical reactions of a carboxylic acid. When reacted with an alcohol, it forms the corresponding ester. The esters and salts of acrylic acid are collectively known as acrylates. The most common alkyl esters of acrylic acid are methyl, butyl, ethyl, and 2-ethylhexyl acrylate. Acrylic acid and its esters readily combine with themselves or other monomers by reacting at their double bond, forming homopolymers or copolymers, which are used in the manufacture of various plastics, coatings, adhesives, elastomers, as well as floor polishes and paints. Acrylic acid is a compound, which is used in many industries like the diaper industry, the water treatment industry or the textiles industry. On a worldwide scale the consumption rate of acrylic acid is projected to reach more than an estimated 8,000 kilotons, by 2020. This increase is expected to occur as a result of using this product in new applications, including personal care products, detergents and products that are used for adult incontinence.
Substituents
As a substituent acrylic acid can be found as an acyl group or a carboxyalkyl group, depending on the removal of the group from the molecule. More specifically, these are:
The acryloyl group, with the removal of the −OH from carbon-1.
The 2-carboxyethenyl group, with the removal of a −H from carbon-3. This substituent group is found in chlorophyll.
Safety
Acrylic acid is severely irritating and corrosive to the skin and the respiratory tract. Eye contact can result in severe and irreversible injury. Low exposure will cause minimal or no health effects, while high exposure could result in pulmonary edema. The is 340 mg/kg. Acrylic acid is a constituent of tobacco smoke.
