Cyclohexanedimethanol (CHDM) is a mixture of

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s with formula C₆H₁₀(CH₂OH)₂. It is a colorless low-melting solid used in the production of

polyester Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...

resins. Commercial samples consist of a mixture of cis and trans isomers. It is a di-substituted derivative of

cyclohexane Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexan ...

and is classified as a

diol A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol may also be called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. They are used as protecting gro ...

, meaning that it has two OH

functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...

s. Commercial CHDM typically has a cis/trans ratio of 30:70.

Production

CHDM is produced by catalytic

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated ...

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. The cis/trans ratio of the CHDM is affected by the catalyst. Byproduct of this process are 4-methylcyclohexanemethanol (CH₃C₆H₁₀CH₂OH) and the monoester methyl 4-methyl-4-cyclohexanecarboxylate (CH₃C₆H₁₀CO₂CH₃, CAS registry number 51181-40-9).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. 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

comonomer In polymer chemistry, a comonomer refers to a polymerizable precursor to a copolymer aside from the principal monomer. In some cases, only small amounts of a comonomer are employed, in other cases substantial amounts of comonomers are used. Furt ...

s for production of

polyethylene terephthalate Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...

(PET), or polyethylene terephthalic ester (PETE), from which plastic bottles are made. In addition it maybe spun to form carpet fibers. : CHDMester

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 Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...

and CHDM. The properties of these polyesters also is affected by the cis/trans ratio of the CHDM monomer. CHDM reduces the degree of crystallinity of PET homopolymer, improving its processability. The copolymer tends to resist degradation, e.g. to

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...

. 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 Epoxy is the family of basic components or Curing (chemistry), cured end products of epoxy Resin, resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide fun ...

diluent. The key use for this diglycidyl ether is to reduce the viscosity of epoxy resins.

References

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External links

U.S. National Library of Medicine: Hazardous Substances Databank – 1,4-cyclohexanedimethanol
Monomers Diols