Cyclohexanedimethanol

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Cyclohexanedimethanol
CHDMisomers.png
Names
IUPAC name
[4-(hydroxymethyl)cyclohexyl]methanol
Other names
1,4–Cyclohexanedimethanol; CHDM; 1,4-Bis(hydroxymethyl)cyclohexane
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.002.972
UNII
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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Infobox references

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.

Applications[edit]

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.[1][2]

CHDMester.png

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.[3] 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.

Production[edit]

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.[4] The cis/trans ratio of the CHDM is affected by the catalyst.[5]

Byproduct of this process are 4-methylcyclohexanemethanol (CH3C6H10CH2OH) and the monoester methyl 4-methyl-4-cyclohexanecarboxylate (CH3C6H10CO2CH3, CAS registry number 51181-40-9).[6] The leading producers in CHDM are Eastman Chemical in US and SK Chemicals in South Korea.

References[edit]

  1. ^ 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.
  2. ^ S. Andjelic; D.D. Jamiolkowski; R. Bezwada (2007). "Mini-review The Polyoxaesters". Polymer International. 56: 1063–1077. doi:10.1002/pi.2257.
  3. ^ S. R. Turner, R.W. Seymour; T.W. Smith (2001). "Cyclohexanedimethanol Polyesters". Encyclopedia of Polymer Science and Technology. doi:10.1002/0471440264.pst257.CS1 maint: Multiple names: authors list (link)
  4. ^ 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.
  5. ^ J. M. Thomas; R. Raja (2002). "The materials Chemistry of Inorganic Catalyst". Australian Journal of Chemistry. 54: 551–560. doi:10.1071/CH01150.
  6. ^ Peter Werle, Marcus Morawietz, Stefan Lundmark, Kent Sörensen, Esko Karvinen and Juha Lehtonen "Alcohols, Polyhydric" Ullmann's Encyclopedia of Industrial Chemistry, 2008, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_305.pub2

External links[edit]