General Description

Delta-Valerolactone possesses unique properties that make it suitable for various applications, including good thermal stability, excellent solvency power, low toxicity, biodegradability, and the ability to undergo chemical transformations. It has been explored in drug-carrier systems, showing promise as an effective carrier for oral administration of drugs. Additionally, Delta-Valerolactone has been utilized in the preparation of functional polyesters for various industrial applications. The cationic ring-opening polymerization mechanism was confirmed through kinetic study, chain end analysis, and density functional theory calculation, and the resulting polyesters possessed desirable mechanical and thermal properties. These findings highlight the potential of Delta-Valerolactone in diverse fields such as pharmaceuticals, materials science, and organic synthesis.

Figure 1. Delta-valerolactone

Properties

Delta-Valerolactone is a cyclic ester with unique properties that make it suitable for various applications. Firstly, Delta-Valerolactone possesses good thermal stability, with a high boiling point and low vapor pressure. This characteristic allows for its effective use in high-temperature processes without significant degradation. Additionally, Delta-Valerolactone exhibits excellent solvency power, making it a versatile solvent for a wide range of substances, including both polar and non-polar compounds. Moreover, Delta-Valerolactone is known for its low toxicity and favorable environmental profile. It is biodegradable under aerobic conditions, reducing its impact on the environment. Its biocompatibility makes it suitable for use in pharmaceutical and biomedical applications. Furthermore, δ-VL can undergo ring-opening polymerization to form polyesters, which possess desirable mechanical and thermal properties. These polyesters can be tailored for specific applications by adjusting the monomer ratio and polymerization conditions. Another notable property of Delta-Valerolactone is its ability to undergo chemical transformations, such as esterification and transesterification reactions. This versatility enables the synthesis of various derivatives and functionalized compounds, expanding its potential applications in fields such as materials science and organic synthesis. In summary, Delta-Valerolactone exhibits excellent thermal stability, solvency power, low toxicity, biodegradability, and the ability to undergo chemical transformations. ¹

Applications

Drug-carrier systems

Delta-Valerolactone has been recently explored for its application in drug-carrier systems. A study was conducted to investigate the release dynamics of aspirin (ASP) from a poly(ethylene-co-vinyl alcohol)/poly(Delta-Valerolactone) (PE-co-VAL/Delta-Valerolactone) hydrogel blend by modifying the degree of swelling through gradual loading of Delta-Valerolactone, which is hydrophobic in nature. Different ratios of PE-co-VAL/Delta-Valerolactone blends were prepared and characterized using various techniques such as Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electronic microscopy methods. The PE-co-VAL/Delta-Valerolactone50 blend was found to exhibit better performance in terms of cell viability, adhesion, and growth. Additionally, dynamic mechanical analysis revealed satisfactory intermediary mechanical properties between the two components. This blend was used as a carrier to study the control of ASP release dynamics when administered orally. The influences of ASP content and degree of swelling of the PE-co-VAL/Delta-Valerolactone blend were investigated. Based on the data obtained and the gastrointestinal transit time, it was possible to estimate the distribution of in vitro cumulative ASP released in different digestive system organs, regardless of the actions of any enzymes and microorganisms. The results indicate that the PE-co-VAL/Delta-Valerolactone blend shows promise as an effective drug-carrier system for oral administration of ASP. ²

Preparation of functional polyesters

Delta-Valerolactone has been utilized in the preparation of functional polyesters. A study was conducted to investigate the ring-opening polymerization (ROP) of Delta-Valerolactone with β-butyrolactone (BBL) as the comonomer, catalyzed by scandium triflate [Sc(OTf)3]. The resulting polyester containing active unsaturated bonds had a weight-average molecular weight (Mw) of 4.1 kg/mol, with the Delta-Valerolactone content at 38 mol% in accordance with the initial ratio of 40 mol%. The copolymers were characterized in detail, and the cationic ROP mechanism was confirmed through kinetic study, chain end analysis, and density functional theory (DFT) calculation. The unsaturated bonds in the Delta-Valerolactone repeating units were modified through thio-ene click reaction with mercapto-ended polysarcosine to yield amphiphilic grafting polymers. This approach allows for CO2 fixation toward the functional poly(Delta-Valerolactone-r-BBL), which could serve as a degradable polyester precursor for adhesive or surface-coating materials. The results demonstrate the potential of Delta-Valerolactone in the preparation of functional polyesters for various industrial applications. ³

Reference

1. PubChem. COMPOUND SUMMARY: delta-Valerolactone. National Library of Medicine, 2005, PubChem CID: 10953

2. Alghamdi AA, Saeed WS, Al-Odayni AB, Alharthi FA, Semlali A, Aouak T. Poly(ethylene-co-vinylalcohol)/Poly(δ-valerolactone)/Aspirin Composite: Model for a New Drug-Carrier System. Polymers (Basel). 2019 Mar 6;11(3):439.

3. Yue S, Bai T, Xu S, Shen T, Ling J, Ni X. Ring-Opening Polymerization of CO2-Based Disubstituted δ-Valerolactone toward Sustainable Functional Polyesters. ACS Macro Lett. 2021 Aug 17;10(8):1055-1060.