Oligomerization of -caprolactone and -valerolactone using heteropolyacid initiators and vanadium or molybdenum complexes

Y. Mahha (1, 2) , A. Atlamsani (2) , J.-C. Blais (3) , M. Tessier (4) , J.-M. Brégeault (1) , L. Salles (1)

1 SIEN - Systèmes interfaciaux à l'echelle nanometrique
2 Laboratoire de Chimie Physique Appliquee, Chimie des Surfaces, Interfaces et Catalyse, ,
3 SSFMB - Synthèse, Structure et Fonction de Molécules Bioactives
4 LCP - Chimie des polymères

Lactones are efficiently oligomerized by heteropolyacids H3[PM12O40]·aq with M=Mo or W, “H3+n[PMo12−nVnO40]·aq” (HPA-n) and molybdenum(VI) acetylacetonate, vanadium(V) sulfate initiators in the presence of dioxygen. The resulting linear oligomers display relatively low polydispersity (≤1.7) and high monomer conversion (≥99%), and are obtained with relatively short reaction times (1–24 h, 20–60 ◦C). The products were analysed by various physicochemical methods: size-exclusion chromatography (SEC) (to determine the molecular weight properties); IR; 1H and 13C NMR; matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOFMS). Lactone oligomerization is proposed to proceed by a coordination-insertion mechanism via cationic species (VO2 + and/or MO2 2+; M=Mo orW) with chain growth involving acyl-oxygen bond cleavage and an activated monomer. Br¨onsted acids catalyse the reaction. These reactions are the first examples of the ring-opening oligomerization of lactones catalysed by heteropolyacids and the inexpensive “VOSO4·xH2O/THF–H2O/O2” system.

Mots clés: Heteropolyacids; Lactones; Oligomers; Vanadyl sulfate; Acid catalysis; MALDI-TOF mass spectrometry

Domaines: Catalyse

Y. Mahha, A. Atlamsani, J.-C. Blais, M. Tessier, J.-M. Brégeault, et al.. Oligomerization of -caprolactone and -valerolactone using heteropolyacid initiators and vanadium or molybdenum complexes. Journal of Molecular Catalysis A: Chemical, 2005, 234, pp.63-73. ⟨hal-00162500⟩