In chemistry, an ester is a compound derived from an acid in which at least one acidic hydrogen atom of that acid is replaced by an organyl group. An example of an ester formation is the substitution reaction of a carboxylic acid and an alcohol (R'OH), forming an ester, where R and R′ denote organyl groups, or H in the case of R. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Esters can be formed from oxoacids, but also from acids that do not contain oxygen.
Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.
Ethylene glycol is an organic compound with the formula (CH2OH)2. It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, colorless, flammable, viscous liquid. Ethylene glycol has a sweet taste, but it is toxic in high concentrations.
Polyethylene terephthalate, is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins.
Ethylene oxide is an organic compound with the formula C2H4O. It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of silver catalyst.
A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.
Although PET is used in several applications,, as of 2022 only bottles are collected at a substantial scale. The main motivations have been either cost reduction or recycle content of retail goods. An increasing amount is recycled back into bottles, the rest goes into fibres, film, thermoformed packaging and strapping. After sorting, cleaning and grinding, 'bottle flake' is obtained, which is then processed by either:
Terephthalic acid is an organic compound with formula C6H4(CO2H)2. This white solid is a commodity chemical, used principally as a precursor to the polyester PET, used to make clothing and plastic bottles. Several million tons are produced annually. The common name is derived from the turpentine-producing tree Pistacia terebinthus and phthalic acid.
In polymer chemistry, a structural unit is a building block of a polymer chain. It is the result of a monomer which has been polymerized into a long chain.
Dimethyl terephthalate (DMT) is an organic compound with the formula C6H4(COOCH3)2. It is the diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colourless liquid.
Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing.
Polytrimethylene terephthalate (PTT), is a polyester synthesized and patented in 1941. It is produced by a method called condensation polymerization or transesterification. The two monomer units used in producing this polymer are: 1,3-propanediol and terephthalic acid or dimethyl terephthalate. Similar to polyethylene terephthalate, the PTT is used to make carpet fibers.
In polymer chemistry, a repeat unit or repeating unit is a part of a polymer whose repetition would produce the complete polymer chain by linking the repeat units together successively along the chain, like the beads of a necklace.
The OMEGA process is a chemical process discovered by the Shell Global Solutions company that is used to produce ethylene glycol from ethylene. This process comprises two steps, the controlled oxidation of ethylene to ethylene oxide, and the net hydrolysis of ethylene oxide to monoethylene glycol (MEG). The first chemical plant using the OMEGA process was started in South Korea. Subsequent OMEGA plants have been started in Saudi Arabia and Singapore. Shell claims that this process, compared to conventional ones, does not produce higher glycols, uses less steam and water, and generates less waste.
Cyclohexanedimethanol (CHDM) is a mixture of isomeric organic compounds with formula C6H10(CH2OH)2. It is a colorless low-melting solid used in the production of polyester resins. Commercial samples consist of a mixture of cis and trans isomers. It is a di-substituted derivative of cyclohexane and is classified as a diol, meaning that it has two OH functional groups. Commercial CHDM typically has a cis/trans ratio of 30:70.
Bis(2-Hydroxyethyl) terephthalate is an organic compound; it is the ester of ethylene glycol and terephthalic acid. Together with 2-hydroxyethyl terephthalic acid, bis(2-Hydroxyethyl) terephthalate is an intermediate in the production of poly(ethylene terephthalate).
Ideonella sakaiensis is a bacterium from the genus Ideonella and family Comamonadaceae capable of breaking down and consuming the plastic polyethylene terephthalate (PET) using it as both a carbon and energy source. The bacterium was originally isolated from a sediment sample taken outside of a plastic bottle recycling facility in Sakai City, Japan.
Polyethylene 2,5-furandicarboxylate, also named poly(ethylene 2,5-furandicarboxylate), polyethylene furanoate and poly(ethylene furanoate) and generally abbreviated as PEF, is a polymer that can be produced by polycondensation or ring-opening polymerization of 2,5-furandicarboxylic acid (FDCA) and ethylene glycol. As an aromatic polyester from ethylene glycol it is a chemical analogue of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). PEF has been described in (patent) literature since 1951, but has gained renewed attention since the US department of energy proclaimed its building block, FDCA, as a potential bio-based replacement for purified terephthalic acid (PTA) in 2004.
PETases are an esterase class of enzymes that catalyze the hydrolysis of polyethylene terephthalate (PET) plastic to monomeric mono-2-hydroxyethyl terephthalate (MHET). The idealized chemical reaction is (where n is the number of monomers in the polymer chain):
The enzyme MHETase is a hydrolase, which was discovered in 2016. It cleaves 2-hydroxyethyl terephthalic acid, the PET degradation product by PETase, to ethylene glycol and terephthalic acid. This pair of enzymes, PETase and MHETase, enable the bacterium Ideonella sakaiensis to live on the plastic PET as sole carbon source.
