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{{Distinguish|text = the psychoactive chemical ], which is also commonly abbreviated as DMT}}

{{Chembox {{Chembox
| Watchedfields = changed |Watchedfields = changed
| verifiedrevid = 443690907 |verifiedrevid = 447275147
| ImageFile = Dimethylterephthalat.svg |ImageFile = Dimethylterephthalat.svg
| ImageName = Structural formula of dimethyl terephthalate |ImageName = Structural formula of dimethyl terephthalate
| PIN = Dimethyl terephthalate |PIN = Dimethyl benzene-1,4-dicarboxylate
|OtherNames = Dimethyl terephthalate<br />1,4-Benzenedicarboxylic acid dimethyl ester<br />Dimethyl 4-phthalate<br />Dimethyl ''p''-phthalate<br />Di-Me terephthalate<br />Methyl 4-carbomethoxybenzoate<br />Methyl-p-(methoxycarbonyl)benzoate<br />Methyl terephthalate, di-<br />Terephthalic acid dimethyl ester (2:1)
| SystematicName = 1,4-Dimethyl benzene-1,4-dicarboxylate
|Section1={{Chembox Identifiers
| OtherNames = 1,4-Benzenedicarboxylic acid dimethyl ester<br />
|Abbreviations = DMT
Dimethyl 4-phthalate<br />
|CASNo = 120-61-6
Dimethyl-p-phthalate<br />
|CASNo_Ref = {{cascite|correct|CAS}}
Di-Me terephthalate<br />
|UNII_Ref = {{fdacite|correct|FDA}}
Methyl 4-carbomethoxybenzoate<br />
|UNII = IKZ2470UNV
Methyl-p-(methoxycarbonyl)benzoate<br />
|PubChem = 8441
Methyl terephthalate<br />
|PubChem1 = 12241382
Terephthalic acid methyl ester<br />
|PubChem1_Comment = (<sup>2</sup>''H''<sub>4</sub>)
| Section1 = {{Chembox Identifiers
|ChEBI = 156286
| Abbreviations = DMT
|ChemSpiderID = 13863300
| CASNo = 120-61-6
| CASNo_Ref = {{Cascite|correct|CAS}} |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|EINECS = 204-411-8
| PubChem = 8441
|MeSHName = Dimethyl+4-phthalate
| PubChem_Ref = {{Pubchemcite|correct|PubChem}}
|RTECS = WZ1225000
| PubChem1 = 12241382
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| PubChem1_Comment = (<sup>2</sup>''H''<sub>4</sub>)
|StdInChI = 1S/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3
| PubChem1_Ref = {{Pubchemcite|correct|PubChem}}
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| ChemSpiderID = 13863300
|StdInChIKey = WOZVHXUHUFLZGK-UHFFFAOYSA-N
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|SMILES = COC(=O)C1=CC=C(C=C1)C(=O)OC
| EINECS = 204-411-8
|SMILES1 = O=C(OC)c1ccc(cc1)C(=O)OC
| MeSHName = Dimethyl+4-phthalate
|InChI = 1/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3
| RTECS = WZ1225000
|InChIKey = WOZVHXUHUFLZGK-UHFFFAOYSA-N
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|Beilstein = 1107185}}
| StdInChI = 1S/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3
|Section2={{Chembox Properties
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|C=10 | H=10 | O=4
| StdInChIKey = WOZVHXUHUFLZGK-UHFFFAOYSA-N
|Appearance = white solid
| SMILES = COC(=O)C1=CC=C(C=C1)C(=O)OC
|Density = 1.2 g/cm<sup>3</sup>, ?<!-- 1.2 g/cm<sup>3</sup>, solid / ? g/mL, liquid / ? g/L, gas -->
| SMILES1 = O=C(OC)c1ccc(cc1)C(=O)OC
|MeltingPtC = 142
| InChI = 1/C10H10O4/c1-13-9(11)7-3-5-8(6-4-7)10(12)14-2/h3-6H,1-2H3
|BoilingPtC = 288
| InChIKey = WOZVHXUHUFLZGK-UHFFFAOYSA-N
|pKa = -7.21
| Beilstein = 1107185}}
|pKb = -6.60}}
| Section2 = {{Chembox Properties
| C = 10
| H = 10
| O = 6
| ExactMass = 198.083015792 g mol<sup>-1</sup>
| Appearance = white solid
| Density = 1.2 g/cm³, ?<!-- 1.2 g/cm³, solid / ? g/ml, liquid / ? g/l, gas -->
| MeltingPtC = 142
| BoilingPtC = 288
| pKa = -7.21
| pKb = -6.60}}
| Section7 = {{Chembox Hazards
| ExternalMSDS =
| MainHazards =
}}
}} }}


'''Dimethyl terephthalate''' (DMT) is an ] with the formula C<sub>6</sub>H<sub>4</sub>(CO<sub>2</sub>CH<sub>3</sub>)<sub>2</sub>. It is the di] formed from ] and ]. It is a white solid that melts to give a distillable colourless liquid.<ref name=Ullmann>Richard J. Sheehan "Terephthalic Acid, Dimethyl Terephthalate, and Isophthalic Acid" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.{{DOI|10.1002/14356007.a26_193}}</ref> '''Dimethyl terephthalate''' ('''DMT''') is an ] with the formula C<sub>6</sub>H<sub>4</sub>(COOCH<sub>3</sub>)<sub>2</sub>. It is the ] formed from ] and ]. It is a white solid that melts to give a distillable colourless liquid.<ref name=Ullmann>Richard J. Sheehan "Terephthalic Acid, Dimethyl Terephthalate, and Isophthalic Acid" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.{{doi|10.1002/14356007.a26_193}}</ref>


==Production== ==Production==
DMT has been produced in a number of ways. Conventionally and still of commercial value is the direct esterification of terephthalic acid. Alternatively, it can be prepared by alternating oxidation and methyl-] steps from ] via methyl].<ref name=Ullmann/> Dimethyl terephthalate (DMT) has been produced in a number of ways. Conventionally, and still of commercial value, is the direct esterification of terephthalic acid. Alternatively, it can be prepared by alternating oxidation and methyl-] steps from ] via ] (PT).<ref name=Ullmann/>


===Dimethyl terephthalate by the Witten process===
==Use==
The method for the production of DMT from ''p''-xylene (PX) and methanol consists of a multistep process involving both oxidation and esterification. A mixture of p-xylene (PX) and methyl ''p''-toluate is oxidized with air in the presence of cobalt and manganese catalysts. The acid mixture resulting from the oxidation is esterified with methanol to produce a mixture of esters. The crude ester mixture is then distilled to remove all the heavy boilers and residue that are produced; lighter esters such as monomethyl terephthalate are recycled to the oxidation section. The raw DMT is then sent to the crystallization section to remove DMT isomers, residual acids and aromatic aldehydes.<ref>{{Cite web|url = http://www.gtctech.com/technology-licensing/polyester-technologies/dimethyl-terephthalate-technology/|title = Dimethyl Terephthalate (DMT)|date = 2013-05-02|access-date = 2015-03-05|archive-date = 2017-10-07|archive-url = https://web.archive.org/web/20171007020846/http://www.gtctech.com/technology-licensing/polyester-technologies/dimethyl-terephthalate-technology/|url-status = dead}}</ref>
DMT is used in the production of ]s, including ] (PET) and ]. It consists of ] substituted with carboxymethyl groups (CO<sub>2</sub>CH<sub>3</sub>) at the 1 and 4 positions. Because DMT is volatile, it is an intermediate is some schemes for the recyclic of PET, e.g. from ]s.
]
Oxidation of methyl p-toluate followed by esterification also yields dimethyl terephthalate (DMT) as shown in the below reaction:<ref name=Ullmann/>
:]

===Dimethyl terephthalate by direct esterification===
DMT can also be made by a different route, namely direct esterification of terephthalic acid with methanol. The dimethyl terephthalate that is formed is then purified by distillation. Even terephthalic acid of low purity may be used in this method.
:C<sub>8</sub>H<sub>6</sub>O<sub>4</sub> + 2CH<sub>3</sub>OH → C<sub>10</sub>H<sub>10</sub>O<sub>4</sub> + 2 H<sub>2</sub>O
in the presence of o-xylene at 250–300&nbsp;°C.

==Uses==
DMT is used in the production of ]s, including ] (PET), ] (PTT), and ] (PBT). Structurally, DMT consists of a ] ring substituted at the 1 and 4 positions with methyl carboxylate (-CO<sub>2</sub>CH<sub>3</sub>) groups. Because DMT is volatile, it is an intermediate in some schemes for the recycling of PET, e.g. from ]s.


Hydrogenation of DMT affords the diol ], which is a useful monomer. Hydrogenation of DMT affords the diol ], which is a useful monomer.
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==External links== ==External links==
* Supplier:Teijin Limited https://web.archive.org/web/20150503041344/http://www.teijin.com/products/chemicals/dmt/
* http://www.inchem.org/documents/icsc/icsc/eics0262.htm * http://www.inchem.org/documents/icsc/icsc/eics0262.htm
* {{ICSC|0262|02}} * {{ICSC|0262|02}}
*


{{Authority control}}
{{DEFAULTSORT:Dimethyl Terephthalate}}
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