Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is a hindered phenolic
antioxidant
Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...
commonly used as a
polymer stabiliser Polymer stabilizers (British English: polymer stabilisers) are chemical additives which may be added to polymeric materials to inhibit or retard their degradation. Mainly they protect plastic and rubber products against heat, oxidation, and UV light ...
.
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
2,6-Di-''tert''-butylphenol is an organic compound with the structural formula 2,6-((CH3)3C)2C6H3OH. This colorless solid alkylated phenol and its derivatives are used industrially as UV stabilizers and antioxidants for hydrocarbon-based produc ...
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
stearyl alcohol
Stearyl alcohol, or 1-octadecanol, is an organic compound classified as a saturated fatty alcohol with the formula CH3(CH2)16CH2OH. It takes the form of white granules or flakes, which are insoluble in water. It has a wide range of uses as an i ...
gives the final product.
Applications
Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is significantly less volatile than simpler phenolic antioxidants such as
butylhydroxytoluene (BHT). This makes it more suitable to stabilising plastics, as it is not driven out by the high temperatures experienced during
plastic extrusion
Plastics extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weatherstripping, fencing, deck railings, window frames, plastic ...
and moulding, when they are heated to 150-320 °C (300–600 °F). It is widely used in the
commodity plastics
Commodity plastics or commodity polymers are plastics produced in high volumes for applications such as packaging, food containers, and household products, including both disposable products and durable goods. In contrast to engineering plastics ...
, particularly in
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 ...
s 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 ...
. It has approval for use in
food contact materials
Food contact materials or food contacting substances (FCS) are materials that are intended to be in contact with food. These can be things that are quite obvious like a glass or a can for soft drinks as well as machinery in a food factory or a ...
, such as plastic food packaging in the EU and US, amongst others.
It is one of the most common polymer antioxidants, in part because of its comparatively low price. The stearyl tail reduces volatility and gives good chemical compatibility with plastics but contributes nothing to antioxidant performance. When higher performance is needed
a common alternative.
[{{cite journal , last1=Jipa , first1=S. , last2=Setnescu , first2=R. , last3=Setnescu , first3=T. , last4=Cazac , first4=C. , last5=Budrugeac , first5=P. , last6=Mihalcea , first6=I. , title=The comparative effectiveness of some commercial antioxidants as studied by lyoluminescence , journal=Polymer Degradation and Stability , date=January 1993 , volume=40 , issue=1 , pages=101–107 , doi=10.1016/0141-3910(93)90197-Q]
References
{{Reflist
Phenol antioxidants