Polyurethanes and polycarbonates are widely used in a variety of applications including engineering, optical devices, and high-performance adhesives and coatings, etc., and are expected to find use also in the biomedical field owing to their biocompatibility and low toxicity. However, these polymers are currently produced using hazardous phosgene and isocyanates, which are derived from the reaction between an amine and phosgene. Extensive safety procedures are required to prevent exposure to phosgene and isocyanate because of its high toxicity. Therefore, the demand for the production of isocyanate-free polymers has now emerged. Among the alternative greener routes that have been proposed, a popular way is the ring-opening polymerization (ROP) of cyclic carbonate in bulk or solution, usually using metallic catalyst, metal-free initiator, or biocatalyst. This review presents the recent developments in the preparation and application of cyclic carbonates as monomers for ROP, with emphasis on phosgene- and isocyanate-free polymerization to produce aliphatic polycarbonates and polyurethanes and their copolymers.

The article contains sections titled: 1. General Aspects 2. Diols 2.1. 1,5‐Pentanediol 2.2. 1,4‐Butanediol 2.3. 1,3‐Propanediols 2.3.1. 2,2‐Dimethyl‐1,3‐propanediol (Neopentyl Glycol) 2.3.2. Hydroxypivalic Acid Neopentyl Glycol Ester 2.3.3. 2‐Methyl‐2‐propyl‐1,3‐propanediol and 2‐Butyl‐2‐ethyl‐1,3‐propanediol 2.3.3.1. 2‐Methyl‐2‐propyl‐1,3‐propanediol 2.3.3.2. 2‐Butyl‐2‐ethyl‐1,3‐propanediol 2.3.4. 2‐ sec ‐Butyl‐2‐methyl‐1,3‐propanediol 2.3.5. 1,3‐Propanediol 2.3.6. 2‐Methyl‐1,3‐propanediol 2.4. 1,6‐Hexanediol 2.5. Hexynediols 2.5.1. 3‐Hexyne‐2,5‐diol 2.5.2. 2,5‐Dimethyl‐3‐hexyne‐2,5‐diol 2.6. 1,10‐Decanediol 2.7. 1,12‐Dodecanediol 2.8. 2,2‐Bis(4‐hydroxycyclohexyl)propane 2.9. 1,4‐Bis(hydroxymethyl)cyclohexane 2.10. Tricyclodecanedimethanol 2.11. 2,2,4‐Trimethyl‐1,3‐pentanediol 2.12. Vicinal Diols by Hydroxylation of Olefins with Peracids 2.12.1. 1,2‐Pentanediol 2.12.2. Other 1,2‐Diols 2.12.2.1. 2‐Ethyl‐1,3‐hexanediol 2.12.2.2. 2,4‐Diethyl‐1,5‐pentanediol 3. Triols 3.1. Trimethylolpropane 3.2. Trimethylolethane 4. Tetrols 4.1. Ditrimethylolpropane 4.2. Pentaerythritol 5. Higher Polyols 5.1. Dipentaerythritol 5.2. Tripentaerythritol 6. Toxicology

Six-membered cyclic carbonates are potential monomers for phosgene and/or isocyanate free polycarbonates and polyurethanes via ring-opening polymerization. A two-step process for their synthesis comprising lipase-catalyzed transesterification of a polyol, trimethylolpropane (TMP) with dimethylcarbonate (DMC) in a solvent-free system followed by thermal cyclization was optimized to improve process efficiency and selectivity. Using full factorial designed experiments and partial least squares (PLS) modeling for the reaction catalyzed by Novozym®435 (N435; immobilized Candida antarctica lipase B), the optimum conditions for obtaining either high proportion of monocarbonated TMP and TMP-cyclic-carbonate (3 and 4), or dicarbonated TMP and monocarbonated TMP-cyclic-carbonate (5 and 6) were found. The PLS model predicted that the reactions using 15%-20% (w/w) N435 at DMC:TMP molar ratio of 10-30 can reach about 65% total yield of 3 and 4 within 10 h, and 65%-70% total yield of 5 and 6 within 32-37 h, respectively. High consistency between the predicted results and empirical data was shown with 66.1% yield of 3 and 4 at 7 h and 67.4% yield of 5 and 6 at 35 h, using 18% (w/w) biocatalyst and DMC:TMP molar ratio of 20. Thermal cyclization of the product from 7 h reaction, at 110°C in the presence of acetonitrile increased the overall yield of cyclic carbonate 4 from about 2% to more than 75% within 24 h. N435 was reused for five consecutive batches, 10 h each, to give 3+4 with a yield of about 65% in each run.

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