Cyclohexanedimethanol synthesis

Glycols such as neopentyl glycol, 2,2,4-trimethyl-l,3-pentaiiediol, 1,4-cyclohexanedimethanol, and hydroxypivalyl hydroxypivalate are used in the synthesis of polyesters (qv) and urethane foams (see Foamed plastics). Their physical properties are shown in Table 1 (1 6). 

Chemical Properties. The chemistry of 1,4-cyclohexanedimethanol is characteristic of general glycol reactions however, its two primary hydroxyl groups give very rapid reaction rates, especially in polyester synthesis. 

Chemoenzymatic synthesis of alkyds (oil-based polyester resins) was demonstrated. PPL-catalyzed transesterification of triglycerides with an excess of 1,4-cyclohexanedimethanol mainly produced 2-monoglycerides, followed by thermal polymerization with phthalic anhydride to give the alkyd resins with molecular weight of several thousands. The reaction of the enzymatically obtained alcoholysis product with toluene diisocyanate produced the alkyd-urethane. 

Aliphatic and aromatic polyesters and copolyesters containing cyclohexanedimethanol units are reviewed covering from the synthesis of monomers up to their polymerization by the different known synthetic routes. Thermal and mechanical properties as well as thermal and chemical stability are discussed with reference to the polyester structure. Compounding, processing, recycling and applications of these polyesters and copolyesters are also reviewed. Finally, an account on the recent developments in blends and composites is provided. 

Since the discovery of 1,3- and 1,4-cyclohexanedimethanol, the interest in these monomers for the production of polyesters has gradually increased. Today they are frequently used for the synthesis of both aliphatic and aromatic polyesters and copolyesters, which distinguish by showing novel improved properties. 

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