Dimethyl terephthalate

Chemical compound From Wikipedia, the free encyclopedia

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]

Quick facts Names, Identifiers ...
Dimethyl terephthalate
Structural formula of dimethyl terephthalate
Structural formula of 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
3D model (JSmol)
Abbreviations DMT
1107185
ChEBI
ChemSpider
ECHA InfoCard 100.004.011 Edit this at Wikidata
EC Number
  • 204-411-8
MeSH Dimethyl+4-phthalate
  • 8441
  • 12241382 (2H4)
RTECS number
  • WZ1225000
UNII
  • InChI=1S/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3 checkY
    Key: WOZVHXUHUFLZGK-UHFFFAOYSA-N checkY
  • 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
  • COC(=O)C1=CC=C(C=C1)C(=O)OC
  • O=C(OC)c1ccc(cc1)C(=O)OC
Properties
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).
checkY verify (what is checkY☒N ?)
Close

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]

Structure of monomethyl terephthalate

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

External links

Related Articles

Wikiwand AI