Cyclohexanedimethanol

Cyclohexanedimethanol
IUPAC name [4-(hydroxymethyl)cyclohexyl]methanol
Other names 1,4–Cyclohexanedimethanol; CHDM; 1,4-Bis(hydroxymethyl)cyclohexane
Identifiers
CAS number	105-08-8 Y
PubChem	7735
Jmol-3D images	Image 1
SMILES OCC1CCC(CO)CC1
Properties
Molecular formula	C8H16O2
Molar mass	144.21 g/mol
Appearance	White waxy solid
Density	1.02 g/ml
Melting point	41-61 °C, 314-334 K, 106-142 °F
Boiling point	284-288 °C, 557-561 K, 543-550 °F
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Cyclohexanedimethanol (CHDM) is an organic compound 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, as seen for other disubstituted derivatives of cyclohexane.

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). In the second step DMCD is further hydrogenated to CHDM. The cis/trans ratio of CHDM is differ according to the catalyst, 80:20 for Cu₄Ru₁₂ catalyst, 65:35 in case of the RuPt catalyst, 88:12 for the Ru-Sn catalyst ^[1], 30:70 in case of the copper chromite catalyst usually used in industrial processing.^[2]

C₆H₄(CO₂CH₃)₂ + 3 H₂ → C₆H₁₀(CO₂CH₃)₂

C₆H₁₀(CO₂CH₃)₂ + 4 H₂ → C₆H₁₀(CH₂OH)₂ + 2 CH₃OH

Most of the commercial CHDM has cis/trans ratio of 30:70. The leading producers in CHDM are Eastman Chemicals and SK Chemicals.

Applications

Via the process called polycondensation, CHDM is a precursor to polyesters. It is one of the most important co-monomers for production of polyethylene terephthalate (PET), or polyethylene terephalic ester (PETE), from which plastic bottles are made.^[3][4] Thermoplastic polyesters containing CHDM exhibit enhanced strength, clarity, and solvent resistance. The exact properties of the polyesters vary from the high melting crystalline poly(1,4-cyclohexylenedimethylene terephthalate), PCT, to the non-crystalline copolyesters with the combination of ethylene glycol and CHDM in the backbone. The properties of these polyesters is also dependent on the cis/trans ratio of the CHDM monomer.^[5] CHDM has low melting point and reduce the degree of crystallinity of PET homopolymer. These PET is known as glycol modified polyethylene terephthalate, PETG. PETG is used in many fields, electronics, automobiles, barrier, and medicals etc. So the resin can be plastically formed with lower force and /or with low heat requirement. These reasons stabilize the polymer from degradation and reduce final products acetaldehyde level to acceptable level.

Reference

1. ^ J. M. Thomas; R. Raja (2002). "The materials Chemistry of Inorganic Catalyst". Australian journal of Chemistry 54: 551–560. doi:10.1071/CH01150. 
2. ^ S.R. Turner; Y. Li (2010). "Synthesis and Properties of Cyclic Diester Based Aliphatic Copolyesters". Journal of Polymer Science Part A: Polymer Chemistry 48: 2162–2169. doi:10.1002/pola.23985. 
3. ^ S.R. Turner (2004). "Development of amorphous copolyesters based on 1,4- cyclohexane-dimethanol". Journal of Polymer Science Part A: Polymer Chemistry, 42: 5847–5852. doi:10.1002/pola.20460. 
4. ^ S. Andjelic; D.D. Jamiolkowski; R. Bezwada (2007). "Mini-review The Polyoxaesters". Polymer International 56: 1063–1077. doi:10.1002/pi.2257. 
5. ^ S. R. Turner, R.W. Seymour; T.W. Smith (2001). "Cyclohexanedimethanol Polyesters". Encyclopedia of Polymer Science and Technology. doi:10.1002/0471440264.pst257.