In situ monitoring of solid-state polymerization reactions in sodium chloroacetate and sodium bromoacetate by Na-23 and C-13 solid-state NMR spectroscopy.
1120 - 1126.
The thermally induced solid-state polymerization reactions in sodium chloroacetate and sodium bromoacetate, leading to poly(hydroxyacetic acid) (polyglycolide) and NaCl and NaBr, respectively, were studied by isothermal in situ solid-state NMR spectroscopy at 120, 130 and 140 degrees C with a time resolution of the order of 5 to 25 min. The nuclei probed were Na-23 and C-13, allowing the parent compounds (sodium halogenoacetates) and both reaction products (polymer and alkali halide) to be monitored, For sodium chloroacetate, there is no evidence for the involvement of intermediate phases during the reaction whereas this cannot be excluded for sodium bromoacetate. The crystal structure of sodium bromoacetate was determined directly from powder diffraction data by the Monte Carlo method, and was found to be isostructural with sodium chloroacetate. The topochemical reaction mechanism proposed previously for sodium chloroacetate is thus also applicable for the polymerization reaction in sodium bromoacetate, The mechanistic and kinetic information obtained from our in situ solid-stale NMR investigations is compared and contrasted with information obtained from other in situ probes of the polymerization reactions in these materials.
|Title:||In situ monitoring of solid-state polymerization reactions in sodium chloroacetate and sodium bromoacetate by Na-23 and C-13 solid-state NMR spectroscopy|
|Keywords:||NMR spectroscopy, polymerizations, solid-state chemistry, solid-state reactions, POWDER DIFFRACTION DATA, CRYSTAL-STRUCTURE DETERMINATION, X-RAY-DIFFRACTION, 2ND-ORDER QUADRUPOLAR, TEMPERATURE, SPECTRA, POLYGLYCOLIDE, CATALYSTS|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry|
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