Why δ-Valerolactone Polymerizes and γ-Butyrolactone Does Not

Abstract

gamma-Butyrolactone, unlike delta-valerolactone, does not polymerize despite a strain energy of approximately 8 kcal mol-1 which could be relieved by opening the s-cis lactone ester bond to an s-trans ester bond in the polymer. To explain this anomaly, we have applied quantum mechanical methods to study the thermochemistry involved in the ring-opening reactions of gamma-butyrolactone and delta-valerolactone, the conformational preferences of model molecules that mimic their corresponding homopolyesters, and the variation of enthalpy associated to the polymerizability of such two cyclic lactones. The overall results indicate that the lack of polymerizability of gamma-butyrolactone should be attributed to the low strain of the ring, which shows much less geometric distortion in the ester group than delta-valerolactone, and the notable stability of the coiled conformations found in model compounds of poly-4-hydroxybutyrate.

Towards Truly Sustainable Polymers: A Metal‐Free Recyclable Polyester from Biorenewable Non‐Strained γ‐Butyrolactone

“…[11] Cyclic esters (lactones and lactides) with relatively high strain energy are desired building blocks for the construction of high-molecular-weight (high MW) aliphatic polyesters through the ROPp rocess and ar apid chain-growth mechanism. [12] Thef ive-membered g-butyrolactone (g-BL) would also be ad esirable bio-derived monomer for the chemical synthesis of biopolyester,poly(g-butyrolactone) (PgBL), as g-BL is ak ey downstream chemical of succinic acid that was recently ranked first [13] in the DOEs top 12 biomass-derived compounds [14] best suited to replace petroleum-derived chemicals.H owever,i th as been ac hallenge to convert the non-strained g-BL, commonly referred as "non-polymerizable" in textbooks [15] and literature, [16] into high MW PgBL, even under ultra-high pressure (e.g., 20 000 atm) [17] or lipasecatalyzed conditions. [18] Then on-polymerization or low oligomerization observed in the ROPo fg-BL under ambient pressure [19] can be explained by its unfavorable thermodynamics because al arge negative DS p is not offset by as mall change of DH p of this ROP.…”

Organocatalyzed ring-opening copolymerization of α-bromo-γ-butyrolactone with ε-caprolactone for the synthesis of functional aliphatic polyesters – pre-polymers for graft copolymerization

“…discovered that unsubstituted γBL was unable to polymerize [24]. Subsequently, some theoretical calculations reconfirmed this result [25,26]. The same behavior was also observed for αBrγBL.…”

MonoMax Suture: A New Long-Term Absorbable Monofilament Suture Made from Poly-4-Hydroxybutyrate

“…Notably, the chemical synthesis of P4HB has been attempted, but it is generally considered impossible to produce the polymer with sufficiently high molecular weight necessary for thermoplastic applications [8]. Recent theoretical calculations have tried to elucidate the mechanistic reason for the difficulty in synthesizing P4HB [9]. Tepha, Inc. produces P4HB utilizing a genetically engineered Escherichia coli K12 microorganism that incorporates new biosynthetic pathways to produce the homopolymer.…”