Dimethyl terephthalate

Dimethyl terephthalate
Names
	Preferred IUPAC name Dimethyl benzene-1,4-dicarboxylate
	Other names Dimethyl terephthalate; 1,4-Benzenedicarboxylic acid dimethyl ester; Dimethyl 4-phthalate; Dimethyl p-phthalate; Di-Me terephthalate; Methyl 4-carbomethoxybenzoate; Methyl-p-(methoxycarbonyl)benzoate; Methyl terephthalate, di-; Terephthalic acid dimethyl ester (2:1);
Identifiers
CAS Number	120-61-6 ;
3D model (JSmol)	Interactive image; Interactive image;
Abbreviations	DMT
Beilstein Reference	1107185
ChEBI	CHEBI:156286;
ChemSpider	13863300 ;
ECHA InfoCard	100.004.011
EC Number	204-411-8;
MeSH	Dimethyl+4-phthalate
PubChem CID	8441; 12241382 (2H4);
RTECS number	WZ1225000;
UNII	IKZ2470UNV ;
CompTox Dashboard (EPA)	DTXSID0020498 ;
	InChI InChI=1S/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3 Key: WOZVHXUHUFLZGK-UHFFFAOYSA-N ; InChI=1/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3 Key: WOZVHXUHUFLZGK-UHFFFAOYSA-N;
	SMILES COC(=O)C1=CC=C(C=C1)C(=O)OC; O=C(OC)c1ccc(cc1)C(=O)OC;
Properties
Chemical formula	C10H10O4
Molar mass	194.186 g·mol−1
Appearance	white solid
Density	1.2 g/cm3
Melting point	142 °C (288 °F; 415 K)
Boiling point	288 °C (550 °F; 561 K)
Acidity (pKa)	−7.21
Basicity (pKb)	−6.60
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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.^[1]^[2] it is an intermediate in some schemes for the recycling of PET, e.g. from plastic bottles.^[3]

Production

Dimethyl terephthalate (DMT) can be prepared via a direct esterification of terephthalic acid with methanol:

C₈H₆O₄ + 2 CH₃OH → C₁₀H₁₀O₄ + 2 H₂O

On a commercial scale, this reaction is usually done at 250–300 °C (482–572 °F) using o-xylene as a solvent. The dimethyl terephthalate that is formed is then purified by distillation. Even terephthalic acid of low purity may be used in this method.

Alternatively, it can be prepared from para-xylene by alternating oxidation and methyl-esterification steps via methyl para-toluate (PT).^[1]

Uses

DMT is used in the production of polyesters, including polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polybutylene terephthalate (PBT). These polymers are produced by transesterification with a diol. In the production of PET, the transesterification initially produces 2-hydroxyethyl methyl terephthalate.

Hydrogenation of DMT affords the diol cyclohexanedimethanol, which is a useful monomer.^[4]

Hazards

DMT is not directly dangerous to humans, but it is harmful to aquatic organisms, so environmental releases are avoided. It is flammable and the dust may form explosive mixtures with air.^[5]

References

^ ^a ^b J. Sheehan, Richard. "Terephthalic Acid, Dimethyl Terephthalate, and Isophthalic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_193. ISBN 978-3-527-30673-2.
^ Elliott, John H.; Chris, Marjorie D. (1968-10-01). "Thermodynamic properties of high-purity dimethyl terephthalate". Journal of Chemical & Engineering Data. 13 (4): 475–479. doi:10.1021/je60039a005. ISSN 0021-9568.
^ Zhang, Hui; Xia, Qing; Yang, Ying; Zhang, Feng-Bao; Zhang, Guo-Liang (2013-04-10). "Solubility of Dimethyl Terephthalate and Monomethyl Terephthalate in the Methanol Aqueous Solution and Its Application To Recycle Monomethyl Terephthalate from Crude Dimethyl Terephthalate". Industrial & Engineering Chemistry Research. 52 (14): 5230–5234. doi:10.1021/ie400421e. ISSN 0888-5885.
^ Baikerikar, Kiran K.; Tulchinsky, Michael L.; Argyropoulos, John (March 2010). "UV curable, liquid diacrylate monomers based on (cis,trans)-1,3/1,4-cyclohexanedimethanol". Journal of Coatings Technology and Research. 7 (2): 175–188. doi:10.1007/s11998-009-9185-1. ISSN 1547-0091.
^ International Chemical Safety Card 0262

External links

http://www.inchem.org/documents/icsc/icsc/eics0262.htm

[Ullmann-1] J. Sheehan, Richard. "Terephthalic Acid, Dimethyl Terephthalate, and Isophthalic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_193. ISBN 978-3-527-30673-2.

[2] Elliott, John H.; Chris, Marjorie D. (1968-10-01). "Thermodynamic properties of high-purity dimethyl terephthalate". Journal of Chemical & Engineering Data. 13 (4): 475–479. doi:10.1021/je60039a005. ISSN 0021-9568.

[3] Zhang, Hui; Xia, Qing; Yang, Ying; Zhang, Feng-Bao; Zhang, Guo-Liang (2013-04-10). "Solubility of Dimethyl Terephthalate and Monomethyl Terephthalate in the Methanol Aqueous Solution and Its Application To Recycle Monomethyl Terephthalate from Crude Dimethyl Terephthalate". Industrial & Engineering Chemistry Research. 52 (14): 5230–5234. doi:10.1021/ie400421e. ISSN 0888-5885.

[4] Baikerikar, Kiran K.; Tulchinsky, Michael L.; Argyropoulos, John (March 2010). "UV curable, liquid diacrylate monomers based on (cis,trans)-1,3/1,4-cyclohexanedimethanol". Journal of Coatings Technology and Research. 7 (2): 175–188. doi:10.1007/s11998-009-9185-1. ISSN 1547-0091.

[5] International Chemical Safety Card 0262

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