Cyclohexanedimethanol
Chemical compound
From Wikipedia, the free encyclopedia
Cyclohexanedimethanol (CHDM) is a mixture of isomeric organic compounds with formula C6H10(CH2OH)2. It is a colorless low-melting solid used in the production of polyester resins. Commercial samples consist of a mixture of cis and trans isomers. It is a di-substituted derivative of cyclohexane and is classified as a diol, meaning that it has two OH functional groups. Commercial CHDM typically has a cis/trans ratio of 30:70.
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| Names | |
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| IUPAC name
[4-(hydroxymethyl)cyclohexyl]methanol | |
| Preferred IUPAC name
(cyclohexane-1,4-diyl)dimethanol | |
| Other names
1,4–Cyclohexanedimethanol; CHDM; 1,4-Bis(hydroxymethyl)cyclohexane | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.002.972 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C8H16O2 | |
| Molar mass | 144.21 g/mol |
| Appearance | White waxy solid |
| Density | 1.02 g/ml |
| Melting point | 41 to 61 °C (106 to 142 °F; 314 to 334 K) |
| Boiling point | 284 to 288 °C (543 to 550 °F; 557 to 561 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production
CHDM is produced by catalytic hydrogenation of dimethyl terephthalate (DMT). The reaction conducted in two steps beginning with the conversion of DMT to the diester dimethyl 1,4-cyclohexanedicarboxylate (DMCD):
- C6H4(CO2CH3)2 + 3 H2 → C6H10(CO2CH3)2
In the second step DMCD is further hydrogenated to CHDM:
- C6H10(CO2CH3)2 + 4 H2 → C6H10(CH2OH)2 + 2 CH3OH
A copper chromite catalyst is usually used industrially.[1] The cis/trans ratio of the CHDM is affected by the catalyst.[2]
Byproduct of this process are 4-methylcyclohexanemethanol (CH3C6H10CH2OH) and the monoester methyl 4-methyl-4-cyclohexanecarboxylate (CH3C6H10CO2CH3, CAS registry number 51181-40-9).[3] The leading producers in CHDM are Eastman Chemical in US and SK Chemicals in South Korea.
Applications
Via the process called polycondensation, CHDM is a precursor to polyesters. It is one of the most important comonomers for production of polyethylene terephthalate (PET), or polyethylene terephthalic ester (PETE), from which plastic bottles are made.[4][5] In addition it maybe spun to form carpet fibers.[6]
Thermoplastic polyesters containing CHDM exhibit enhanced strength, clarity, and solvent resistance. The properties of the polyesters vary from the high melting crystalline poly(1,4-cyclohexylenedimethylene terephthalate), PCT, to the non-crystalline copolyesters derived from both ethylene glycol and CHDM. The properties of these polyesters also is affected by the cis/trans ratio of the CHDM monomer.[7] CHDM reduces the degree of crystallinity of PET homopolymer, improving its processability. The copolymer tends to resist degradation, e.g. to acetaldehyde. The copolymer with PET is known as glycol-modified polyethylene terephthalate, PETG. PETG is used in many fields, including electronics, automobiles, barrier, and medical, etc.
CHDM is a raw material for the production of 1,4-cyclohexanedimethanol diglycidyl ether, an epoxy diluent.[8] The key use for this diglycidyl ether is to reduce the viscosity of epoxy resins.[9]