Bis(2-ethylhexyl) terephthalate commonly abbreviated DEHT (Dioctyl terephthalate or DOTP), is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

C₆H₄(CO₂C₈H₁₇)₂. It is a non-

phthalate Phthalates ( ), or phthalate esters, are esters of phthalic acid. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility, transparency, durability, and longevity. They are used primarily to soften ...

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticizer ...

, being the

diester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinc ...

terephthalic acid 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 annuall ...

and the branched-chain

2-ethylhexanol 2-Ethylhexanol (abbreviated 2-EH) is an organic compound with the chemical formula . It is a branched, eight-carbon chiral alcohol. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is produced on a l ...

, which is often generically referred to as octyl. This colorless viscous liquid is used for softening

PVC Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons o ...

plastics and is known for chemical similarity to general purpose

s such as DEHP and DINP, but without any negative regulatory pressure. It possesses very good plasticizing properties and may be used as a direct replacement for DEHP and DINP in many applications.

Production

One method of manufacture entails the

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 ...

dimethyl terephthalate Dimethyl terephthalate (DMT) is an organic compound with the formula . It is the ester, diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colourless liquid. Production Dimethyl terephthalat ...

with

: :C₆H₄(CO)₂(OCH₃)₂ + 2 C₈H₁₇OH → C₆H₄(CO₂ C₈H₁₇)₂ + 2CH₃OH A second method of manufacture is a direct esterification of

with

: :C₆H₄(CO₂H)₂ + 2 C₈H₁₇OH → C₆H₄(CO₂ C₈H₁₇)₂ + 2H₂O

Use

DEHT is a general purpose

that is considered safer than ''ortho''-

s due to its reduced toxicity profile. The terephthalates exhibit none of the peroxisome proliferation of liver enzymes that some ''ortho''-

s have shown in several studies. It has uses in applications like extrusion, calendering, injection molding, rotational molding, dip molding, slush molding and coating.

Alternative plasticizers

Several plasticizers offer similar technical properties to DEHT. These alternatives include phthalates such as DINP, DOP,

DPHP Di(2-propylheptyl) phthalate (also known as bis(2-propylheptyl) benzene-1,2-dicarboxylate, di(propylheptyl) orthophthalate, or DPHP) is an organic compound with the formula C28H46O4. It is a phthalate and is the diester of phthalic acid and the 10 ...

, DIDP as well as non-phthalates such as DINCH and

citrate Citric acid is an organic compound with the formula . It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relati ...

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

Possible Health Effects

According to a panel appointed by the French Agency for the Safety of Health Products ( ANSM), there is very little clinical assessment data regarding the toxicity, migration from

Medical Devices A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

, and population exposure of alternative plasticizers (e.g. DEHT/DOTP) and their

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s. The French government report concludes: "The presently available information indicates that DEHTP is not expected to pose any health or environmental risks. DEHTP is not considered as toxic for reproduction and no alert was found on potential endocrine disruption properties of the substance." Researchers from Korea state that: "DEHT, a phthalate ester stoichiometrically eqivaluent to DEHP, has been shown to have potential reproductive and developmental toxicity."{{cite journal, last1=Kwon, first1=Bareum, last2=Ji, first2=Kyunghee, title=Estrogenic and Androgenic Potential of Phthalates and Their Alternatives, journal=Korean Journal of Environmental Health Sciences, date=2016, volume=42, issue=3, pages=169–188, doi=10.5668/JEHS.2016.42.3.169, doi-access=free The NOAELs quoted are actually quite high, indicating the potential for reproductive toxicity is low. The same paper further states: "The ability of DEHT to induce anti-androgenic effects in male offspring was assessed by giving pregnant rats 750 mg/kg/d DEHT; no changes were observed." And further: "Results of a uterotrophic assay in which immature females were given up to 2,000 mg/kg/d DEHT indicate that this compound does not possess estrogenic activity."

References

Ester solvents Plasticizers Terephthalate esters 2-Ethylhexyl esters