Dioctyl terephthalate commonly abbreviated DOTP or DEHT, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

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 betwee ...

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. Plasticiz ...

, being the

diester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are ...

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 tonnes are produced annua ...

and the branched-chain

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

, which is referred to as octyl. This colorless viscous liquid is used for softening PVC plastics and is known for chemical similarity to general purpose

s such as

DEHP Bis(2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate, diisooctyl phthalate, DEHP; incorrectly — dioctyl phthalate, DIOP) is an organic compound with the formula C6H4(CO2C8H17)2. DEHP is the most common member of the cl ...

and

DINP Diisononyl phthalate (DINP) is a phthalate used as a plasticizer. DINP is typically a mixture of chemical compounds consisting of various isononyl esters of phthalic acid, and is commonly used in a large variety of plastic items. Health Issues ...

, but without any negative regulatory pressure. It possesses very good plasticizing properties and may be used as a direct replacement for

and

in many applications.

Production

One method of manufacture entails the

transesterification In organic chemistry, transesterification is the process of exchanging the organic 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. The reaction can ...

dimethyl terephthalate 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.Richard J. Sheehan "Terepht ...

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

DOTP 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 DOTP. These alternatives include phthalates such as

, 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 Diisodecyl phthalate (DIDP) is a commonly used plasticizer used in the production of plastic and plastic coating to increase flexibility. It is a mixture of compounds derived from the esterification of phthalic acid and isomeric decyl alcohols. T ...

as well as non-phthalates such as

DINCH 1,2-Cyclohexane dicarboxylic acid diisononyl ester (DINCH) is a mixture of organic compounds with the formula C6H10(CO2C9H19)2. DINCH is colorless oil. It is used as a plasticizer for the manufacture of flexible plastic articles in sensitive appl ...

and

citrate Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

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. DOTP/DEHT) 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 (sic) ester stoichiometrically eqivaluent (sic) 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