Synthesis of Six-Membered Cyclic Carbonate Monomers by Disproportionation of 1,3-Bis(alkoxycarbonyloxy)propanes and Their Polymerization

Abstract

ABSTRACT:A new synthetic method of six-membered cyclic carbonates is presented. Different 1,3-bis(alkoxycarbonyloxy)propanes obtained from 1,3-diols and diethyl or dimethyl carbonate were subjected to disproportionation at 200 -350°C in the presence of colloidal silica or Sn(II) stearate leading to 1,3-dioxan-2-ones. The disproportionation was carried out in gaseous and liquid phases. The presented method was especially useful for preparation of six-membered mono-and biscyclic carbonates from polyfunctional alcohols such as trimethylolpropane, pentaerythritol and trimethylolpropane dimer. The structure of the polymers obtained from 5-methyl-1,3-dioxan-2-one and 5-ethyl-5-methoxycarbonyloxymethyl-1,3-dioxan-2-one in the presence of different catalysts were analyzed using MALDI-TOF mass spectrometry.KEY WORDS Six-Membered Cyclic Carbonates / Disproportionation of 1,3-Bis(alkoxycarbonyloxy)-propanes / Ring Opening Polymerization of Cyclic Carbonates/ In recent years a steadily growing interest can be observed for aliphatic cyclic carbonates used as monomers and reagents in polymer synthesis and modification. 1 -3 Especially attractive, seems to be cyclic carbonates application for oligocarbonate synthesis, taking into consideration that polyurethane elastomers obtained from oligocarbonate diols are resistant toward oxidation and hydrolysis. Poly(carbonate-urethane) elastomers are utilized in biomedical practice, where besides good mechanical properties, compatibility with blood is important, e.g., for the production of implanted medical devices.4-6 Carbonate copolymers with lactones and lactides exhibit biodegradability and can be easily recycled by thermal depolymerization. 7 Six-membered cyclic carbonates, similarly to their derivatives~spiroorthocarbon-ates, as was found by Endo et al.,8 polymerize with volume expansion. - 12Aliphatic cyclic carbonate monomers, similarly to cyclic bisphenol A oligocarbonates, 13 can be obtained in a reaction of diols with phosgene, diphosgene or triphosgene. The reaction is usually carried out in the presence of organic or inorganic bases. Instead of phosgene ethyl chloroformate can be used with good effect. 14 But in these methods toxic reagents and environmentally troublesome side-product (NaCl) produced in stoichiometric amounts are the main drawbacks.In contrast, transesterification of diols with diethyl or dimethyl carbonates is much more convenient for synthesis of aliphatic cyclic carbonate. Especially, dimethyl carbonate, because of cheap starting materials used for its production (methanol and CO), 15 is a useful source of carbonate linkages.As was shown by Sarel et al. •17 when a small excess (10%) of dialkyl carbonate was used in transesterification with 1,3-dioles the resulting post-reaction mixture contains mainly linear oligocarbonates, cyclic carbonate and some amount of monoester, In the next step sixtTo whom correspondence should be addressed.membered cyclic carbonates are produced as a result of thermal depolymerization of the oligocarbonates. Crude cyclic carb...

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“…The method used to prevent the accumulation of hydroxyl acids is the creation of membranes from nanofibers that are easily drained by biological fluids. A class of biopolymers, aliphatic polycarbonates, has been extensively researched by previous authors [36][37][38][39] and was found to be free of autocatalytic hydrolysis.…”

“…The method used to prevent the accumulation of hydroxyl acids is the creation of membranes from nanofibers that are easily drained by biological fluids. A class of biopolymers, aliphatic polycarbonates, has been extensively researched by previous authors [36][37][38][39] and was found to be free of autocatalytic hydrolysis.The new experimental isolating material assessed comprises electrospun membranes formed from micro-and nanometre-sized fibers. The degradation products of these membranes are drained by biological fluids, and thus no autocatalysis, accumulation or subsequent burst of hydroxyl acids occurs, minimizing inflammation.…”

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“…The nanofibrous mat is easily emptied by biological fluids and do not accumulate hydroxy acids. A class of biopolymers, aliphatic polycarbonates, which was widely studied by the authors before [26][27][28][29], creates a very weak carbonic acid during the hydrolytic degradation and therefore is free from the problem of autocatalytic hydrolysis.…”

Synthesis of Linear and Cyclic Carbonates

“…In this case, the high -purity (99%) alkylene carbonate was obtained via a short -path distillation at 323 -373 K at reduced pressure. Alkylene carbonates have also been obtained by the disproportionation of 1,3 -bis(alkoxycarbonyloxy)propanes, using colloidal silica or Sn(II) stearate [294] .…”