Ring-Opening Reactions of beta-Lactones with Activated Anions.

Novel Synthesis of Poly(3-hydroxybutyrate)

“…The influence of various solvents on anion reactivity has been studied in many nucleophilic reactions. 13 In our investigations, the novel method of ring-opening polymerization of β-butyrolactone is based on the activation of anions of polymerization species by highly polar aprotic solvents, which are responsible for this particular polymerization. The polymerization has been performed in the solution of active highly polar aprotic solvent such as DMSO.…”

“…Then the polymer was precipitated in hexane, dried under vacuum for a Butyrolactone initial concentration was changed in the range from 1.0 to 2.0 mol/dm 3 ; conversion in each experiment was equal to 100%; initiator HBANa-(R,S)-3-hydroxybutyric acid sodium salt (initial concentration was changed in the range from 3.3 × 10 -1 to 4.4 × 10 -2 mol/dm 3 ). b Mn,th is the theoretical molecular weight calculated from the formula Mn,th ) 48 h, and analyzed by 1 H NMR and 13 C NMR spectroscopy, ESI-MS spectrometry, and the GPC technique.…”

“…The NMR spectra were recorded using a Varian VXR-300 multinuclear spectrometer. 1 H NMR and 13 C NMR spectra were run in CDCl 3 by using TMS as an internal standard. Gel permeation chromatography (GPC) was performed at 30 °C, using a Spectra Physics 8800 gel permeation chromatograph with two PL-gel packed columns (10 3 and 500 Å), THF was used as the eluent at a flow rate of 1 mL/min, and polystyrene standards with low polydispersity (PL-Lab.)…”

Influence of structural parameters on the ring-opening polymerization of new alkyl malolactonate monomers and on the biocompatibility of polymers therefrom

“…This finding is in agreement with the hyperconjugative effect of the methyl group and the lack of the electron‐withdrawing action by the carboxyl ester group. Not surprisingly, ring‐opening polymerization of BL can be performed only in presence of cryptands which increase the anionic character of the carboxyl terminus of the growing chain by complexation of the positive counter‐ion 44…”

Nucleophilic substitution and electron transfer in the ring‐opening reactions of β‐lactones: A short review

“…capable of complexing cations. The loose anion pairs, formed after cation complexation, usually become more reactive for two reasons: (1) complex formation of a cation leads to an increase in the rate of a given anionic reaction because an anion is activated due to its reduced interaction with the bulky complexed cation, and (2) increased anion concentration due to the better solubilization of the reagent (eq 1) [24].…”