Selective vapour phase dehydrogenation of biomass-derived 1,4-butanediol to gamma butyrolactone over Cu/ZrO2 catalysts: influence of La2O3 promotor

Air-Mediated Biomimetic Synthesis of Polyhydroxyalkanoate with C4 Diol

Poly(4-hydroxybutyrate) (P4HB) is a high-performance, well-recyclable, and biodegradable polyhydroxyalkanoate (PHA). However, conventional bioproduction of homopolymeric P4HB involves complex and costly processes with C4 feedstocks, particularly 1,4-butanediol (BDO), and enzyme-coenzyme systems in genetically engineered bacteria. An alternative extracellular chemical route utilizing aerial oxidation of BDO offers cost and energy benefits but struggle with conversion efficiency. Inspired by efficient intracellular oxidation of primary alcohols, we propose a ruthenium-phosphine synergistic catalytic system that mimics enzyme-coenzyme functionality. This system effectively catalyzed the air-mediated, solvent-free oxidation of BDO to produce γ-butyrolactone (γ-BL) and oligomeric P4HB, with a space-time yield (10.37 g [γ-BL unit] g-1 catalyst h-1) surpassing the values (<5.5) of previous approaches. The oligomer-containing products were reversibly converted to γ-BL and then to P4HB (28.9 kDa) via ring-opening polymerization, exceeding reported values (<16 kDa). This study provides the potential for large-scale synthesis of high-value PHAs from diverse non-grain-based diols, offering economic and environmental advantages.

One-pot redox cascade paired electrosynthesis of gamma-butyrolactone from furoic acid

The catalytic valorisation of biomass to afford synthetically useful small molecules is essential for sustainable biorefinery processes. Herein, we present a mild cascaded electrochemical protocol for converting furoic acid, a common biomass-derived feedstock, into a versatile platform chemical, gamma-butyrolactone. In the platinum(+)|nickel(-) electrode paired undivided cell, furoic acid is electrochemically oxidised with 84.2% selectivity to 2(5H)-furanone, the olefin of which is then hydrogenated to yield gamma-butyrolactone with 98.5% selectivity. The final gamma-butyrolactone yield is 69.1% with 38.3% Faradaic efficiency and 80.1% carbon balance when the reaction is performed with 100 mM furoic acid at 80 °C at +2.0 VAg/AgCl. Mechanistic investigation revealed the critical temperature and electrolyte pH conditions that maximise the production and protection of the key intermediate, furan radical, promoting its transition to 2(5H)-furanone rather than self-polymerising. The reaction is scalable, as 2.1 g of 98.1% pure gamma-butyrolactone is isolated through a simple solvent extraction.

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

Access to a wide range of plastic materials has been rationalized by the increased demand from growing populations and the development of high-throughput production systems. Plastic materials at low costs with reliable properties have been utilized in many everyday products. Multibillion-dollar companies are established around these plastic materials, and each polymer takes years to optimize, secure intellectual property, comply with the regulatory bodies such as the Registration, Evaluation, Authorisation and Restriction of Chemicals and the Environmental Protection Agency and develop consumer confidence. Therefore, developing a fully sustainable new plastic material with even a slightly different chemical structure is a costly and long process. Hence, the production of the common plastic materials with exactly the same chemical structures that does not require any new registration processes better reflects the reality of how to address the critical future of sustainable plastics. In this review, we have highlighted the very recent examples on the synthesis of common monomers using chemicals from sustainable feedstocks that can be used as a like-for-like substitute to prepare conventional petrochemical-free thermoplastics.

A Review of the Pharmacological Activities and Recent Synthetic Advances of γ-Butyrolactones

γ-Butyrolactone, a five-membered lactone moiety, is one of the privileged structures of diverse natural products and biologically active small molecules. Because of their broad spectrum of biological and pharmacological activities, synthetic methods for γ-butyrolactones have received significant attention from synthetic and medicinal chemists for decades. Recently, new developments and improvements in traditional methods have been reported by considering synthetic efficiency, feasibility, and green chemistry. In this review, the pharmacological activities of natural and synthetic γ-butyrolactones are described, including their structures and bioassay methods. Mainly, we summarize recent advances, occurring during the past decade, in the construction of γ-butyrolactone classified based on the bond formation in γ-butyrolactone between (i) C5-O1 bond, (ii) C4-C5 and C2-O1 bonds, (iii) C3-C4 and C2-O1 bonds, (iv) C3-C4 and C5-O1 bonds, (v) C2-C3 and C2-O1 bonds, (vi) C3-C4 bond, and (vii) C2-O1 bond. In addition, the application to the total synthesis of natural products bearing γ-butyrolactone scaffolds is described.

Direct ethanol condensation to diethyl acetal in the vapour phase at atmospheric pressure over CuNP/SBA-15 catalysts

Of the biomass valorization technologies, bioethanol production and its selective conversion to diethyl acetal is of utmost importance to meet the increasing demand for bio-fuel additives.