Pentaerythritol tetrakis(3,5-di-''tert''-butyl-4-hydroxyhydrocinnamate) is a chemical compound composed of four sterically hindered
phenol
Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire.
The molecule consists of a phenyl group () ...
s linked through a
pentaerythritol
Pentaerythritol is an organic compound with the formula C(CH2OH)4. The molecular structure can be described as a neopentane with one hydrogen atom in each methyl group replaced by a hydroxyl (–OH) group. It is therefore a polyol, specifically a ...
core. It is used as primary antioxidant for
stabilizing polymers, particularly
polyethylene
Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...
and
polypropylene
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene.
Polypropylene belongs to the group of polyolefin ...
.
Synthesis
Base catalysed
Michael addition
In organic chemistry, the Michael reaction or Michael 1,4 addition is a reaction between a Michael donor (an enolate or other nucleophile) and a Michael acceptor (usually an α,β-unsaturated carbonyl) to produce a Michael adduct by creating a c ...
of
methyl acrylate
Methyl acrylate is an organic compound, more accurately the methyl ester of acrylic acid. It is a colourless liquid with a characteristic acrid odor. It is mainly produced to make acrylate fiber, which is used to weave synthetic carpets. It is a ...
to
2,6-di-''tert''-butylphenol forms the intermediate dibutyl-
phloretic ester. High temperature
transesterification
Transesterification is the process of exchanging the organic functional group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. Strong acids catalyze the r ...
of this with
pentaerythritol
Pentaerythritol is an organic compound with the formula C(CH2OH)4. The molecular structure can be described as a neopentane with one hydrogen atom in each methyl group replaced by a hydroxyl (–OH) group. It is therefore a polyol, specifically a ...
gives the final product. Driving this reaction to completion can be difficult and commercial samples often contain low levels of the tri-ester.
Properties
The linking of phenols together with pentaerythritol maintains their activity with greatly reduced volatility. This is important during the processing and molding steps where the plastic is heated to molten, typically several hundred degrees.
See also
*
Octadecyl 3-(3,5-di-''tert''-butyl-4-hydroxyphenyl)propionate - an inexpensive and commonly used polymer stabiliser
*
Tris(3,5-di-''tert''-butyl-4-hydroxybenzyl) isocyanurate - a polymer stabiliser commonly used to protect against long term heat aging
*
Irganox 1098 - a polymer stabiliser with metal chelation properties
References
{{Reflist
Phenol antioxidants