Dimethyl Terephthalate — Scientific Chemical Chemical

1. Chemical Structure

Dimethyl terephthalate is the dimethyl ester of terephthalic acid. Its structure contains a benzene ring substituted at the 1,4 positions by two methyl ester groups.

The para-oriented arrangement of the two ester functionalities is an important structural feature and distinguishes dimethyl terephthalate from positional isomers such as dimethyl isophthalate and dimethyl phthalate.

2. Physical and Chemical Properties

PubChem reports a molecular weight of approximately 194.18 g/mol, an XlogP3 value of approximately 2.2, four hydrogen-bond acceptors, and no hydrogen-bond donors.

Reference chemical specifications commonly describe dimethyl terephthalate as a white solid. A commercial analytical reference lists a melting range of approximately 140–143 °C.

Other reported characteristics should be interpreted according to the particular grade and analytical specification of the material.

3. Chemical Classification

Dimethyl terephthalate can be classified as:

• Aromatic diester
• Terephthalic-acid derivative
• Benzene dicarboxylate ester
• Polyester-industry intermediate

It is not the same compound as dimethyl phthalate despite the similarity of the names. The two compounds have different substitution patterns on the aromatic ring.

4. Industrial and Materials-Science Applications

Dimethyl terephthalate is an important chemical intermediate used in polyester chemistry.

Documented applications include research and industrial processes involving:

• Polyester resin production
• Polyester fibres
• Polyester films
• Engineering polymers
• Production of polyethylene terephthalate (PET)
• Preparation of other ester-based materials

PubChem identifies dimethyl terephthalate as an industrial intermediate for polyester and related materials.

5. Chemical Research Applications

Potential research applications include:

Polymer Chemistry

Dimethyl terephthalate can serve as an aromatic diester building block in investigations of polyester formation and polymer properties.

Materials Research

Researchers can investigate how terephthalate-derived structures influence:

• Polymer morphology
• Thermal properties
• Mechanical characteristics
• Crystallinity
• Chemical resistance

Analytical Chemistry

Dimethyl terephthalate can also be used as a reference compound in analytical investigations involving aromatic esters and polyester-related materials.

Chemical Transformation Studies

Its ester functionality makes it relevant to research involving ester chemistry, hydrolysis, transesterification, and related transformations.

6. Analytical Characterization

Several complementary analytical techniques can be used to characterize dimethyl terephthalate.

HPLC / UHPLC
Useful for chromatographic separation and quantitative analysis.

GC-MS
Can provide chromatographic separation together with mass-spectral identification when the analytical conditions are appropriate.

NMR spectroscopy
¹H and ¹³C NMR can provide information about the aromatic and ester environments and support structural confirmation.

FTIR spectroscopy
Can provide characteristic information about ester carbonyl and other functional groups.

Melting-point analysis
Can provide a useful physical-property measurement and may contribute to assessment of material consistency.

Commercial analytical-grade material is available with documented infrared spectra and assay specifications, illustrating the types of characterization commonly associated with this compound.

7. Quality and Purity Documentation

For laboratory research, identity and purity should be established using appropriate analytical documentation.

Relevant documentation can include:

• Certificat d'analyse (COA)
• Batch or lot number
• HPLC or GC assay
• GC-MS or LC-MS data
• FTIR spectrum
• NMR spectrum
• Melting-point data
• Relevant impurity profile

A stated purity value should be treated as grade- or batch-specific unless supported by the corresponding analytical documentation.

8. Laboratory Handling

Dimethyl terephthalate should be handled according to the applicable Safety Data Sheet and institutional chemical-hygiene procedures.

General laboratory practices include:

• Appropriate laboratory PPE
• Avoidance of unnecessary exposure to chemical dust
• Appropriate ventilation
• Proper chemical labeling
• Controlled storage
• Suitable chemical-waste procedures

The exact precautions should be determined from the SDS for the specific grade and supplier.

9. Storage Considerations

Storage should follow the manufacturer’s or laboratory’s applicable chemical-storage requirements.

Relevant considerations include:

• Keeping the material in a properly closed container
• Protecting it from contamination
• Maintaining a dry storage environment
• Avoiding unnecessary heat exposure
• Following the supplier’s specified temperature requirements

Specific shelf-life claims should be supported by stability information for the relevant grade and packaging.

10. Environmental and Materials Research

Dimethyl terephthalate is relevant to research concerning the production and lifecycle of polyester materials.

Research areas may include:

• Polyester synthesis
• Polymer degradation
• Chemical recycling
• Monomer recovery
• Depolymerization studies
• Polymer-to-monomer conversion
• Sustainable materials development

Its relationship to PET chemistry makes it particularly relevant to research into alternative polyester manufacturing and recycling pathways.

11. Regulatory and Compliance Information

Dimethyl terephthalate has established industrial and laboratory uses, but applicable workplace, environmental, transportation, and chemical-management requirements can vary by jurisdiction.

Researchers should consult the current SDS, applicable institutional requirements, and relevant local regulations for the specific material and intended laboratory application.

12. Research Documentation

For a laboratory reference record, the following information is recommended:

• Nom chimique
• CAS number
• Molecular formula
• Molecular weight
• Supplier and grade
• Batch/lot number
• Certificate of Analysis
• Analytical results
• Conditions de stockage
• Date received
• Relevant SDS

13. FAQ

What is dimethyl terephthalate?

Dimethyl terephthalate is the dimethyl ester of terephthalic acid and has the molecular formula C₁₀H₁₀O₄.

What is the CAS number?

The CAS Registry Number is 120-61-6.

What is the molecular weight?

The molecular weight is approximately 194.18 g/mol.

Is dimethyl terephthalate the same as dimethyl phthalate?

No. Dimethyl terephthalate has its two ester groups in the para (1,4) arrangement, whereas dimethyl phthalate has a different substitution pattern.

What is dimethyl terephthalate used for?

It is primarily an industrial intermediate associated with polyester resins, fibres, films, engineering polymers, and PET-related chemistry.

Which techniques can be used to characterize it?

HPLC, GC-MS, NMR, FTIR, and physical-property measurements such as melting-point analysis can be used depending on the analytical objective.

14. Research-Only Scientific Disclaimer

This document is provided for scientific, educational, analytical, and materials-research reference purposes. It is not a substitute for the applicable SDS, laboratory procedures, regulatory requirements, or professional chemical-safety assessment.