Furylated Flavonoids: Fully Biobased Building Blocks Produced by Condensed Tannins Depolymerization

Abstract

An original method has been set up to produce fully biobased phenolic building blocks from condensed tannins, largely available from agroindustrial residues or wood industry coproducts. The acid-catalyzed depolymerization of condensed tannins in the presence of furan or sylvan in mild conditions (30−40 °C, 0.1 M HCl) gives the corresponding furylated flavonoids with high yields. The reaction was more efficient with sylvan than with the less nucleophilic furan. A key feature of the products is the high stability of the flavanyl to furyl C−C linkage compared to the thioether bond obtained by the classical thiolysis, which makes them promising platform molecules for further functionalization, including in alkaline conditions. The simplicity of the process makes it easy to scale-up, and the reaction can be carried out on raw plant materials directly. In accordance with green chemistry concepts, solvents and excess reagents can readily be recovered by distillation and recycled.

From Tree to Tape: Direct Synthesis of Pressure Sensitive Adhesives from Depolymerized Raw Lignocellulosic Biomass

“… 4 , 10 − 14 Few studies have focused on the direct use of chemicals from raw biomass deconstruction. 15 , 16 Instead, lignin model compounds have been extensively explored toward the formulation of new products for applications, such as thermoplastics, thermoplastic elastomers, coatings, pressure sensitive adhesives (PSAs), composites, and resins. 17 − 26 However, a major unanswered question is “Can these biobased compounds be harvested from raw biomass to produce designer materials in a scalable and cost-effective manner?” Essentially, a huge gap exists between deriving well-defined chemicals from raw biomass and directly utilizing these chemicals for the formulation of specialized consumer products.…”

“…Lignin, a major component in lignocellulosic biomass, is the most abundant source of aromatic building blocks in nature, and the depolymerization of lignin is capable of producing value-added small aromatic molecules with great potential as fuel additives and platform chemicals. − Unfortunately, the aromatic moieties in lignin are linked by various kinds of robust C–C and C–O bonds, and deconstruction of lignin therefore generates a complex mixture of disparate compounds (monophenols, dimers, and oligomers). ,− Few studies have focused on the direct use of chemicals from raw biomass deconstruction. , Instead, lignin model compounds have been extensively explored toward the formulation of new products for applications, such as thermoplastics, thermoplastic elastomers, coatings, pressure sensitive adhesives (PSAs), composites, and resins. − However, a major unanswered question is “Can these biobased compounds be harvested from raw biomass to produce designer materials in a scalable and cost-effective manner?” Essentially, a huge gap exists between deriving well-defined chemicals from raw biomass and directly utilizing these chemicals for the formulation of specialized consumer products. Robust and scalable depolymerization, purification, functionalization, and polymerization steps, as well as potential recycle and reuse of catalyst and solvents in the process, are necessary to reduce the energy and cost associated with “green” materials fabrication and to encourage the sustained use of biomass-derived materials in mainstream applications.…”

Furanolysis with Menthofuran: A New Depolymerization Method for Analyzing Condensed Tannins

“…As the amount of extension units trapped by the nucleophile (i.e., EC-NU) and EC produced from the terminal units were expected to be equal, the ratio of the corresponding peak area was attributed to the ratio of respective molar responses of the products. 45,51 For ECG-PG, the molar response relative to EC of 3.7 given by Kennedy and Jones 30 was applied.…”

“…This especially concerns mercaptans frequently used in the analysis of proanthocyanidins, 40,41 while phloroglucinol seems to require higher doses to cause adverse effects. 42 Recently, the possibility to use metalloles (five-membered heterocyclic aromatic compounds) in the depolymerization of condensed tannins to produce biobased chiral ligands or fully biobased aromatic building blocks for applications in specialty chemicals and materials was evidenced by Fu et al 43 with pyrrole derivatives and by Rouméas et al 44,45 with furan derivatives. In the framework of our studies on the depolymerization of condensed tannins in the presence of substituted metalloles, preliminary experiments have led us to identify menthofuran (3,6-dimethyl-4,5,6,7-tetrahydro-1-benzofuran), a tri-substituted furan, as both an efficient and commercially available nucleophilic trapping reagent.…”

A novel thiolysis‐high‐performance liquid chromatography method for the determination of proanthocyanidins in grape seeds

“…First, the reaction conditions determine if the complex PC polymer is completely degraded to flavanol monomers and their derivatives [13,14]. Second, the preservation rate (stability) of the reaction products directly affects the quantitative result [15][16][17][18][19]. Limited availability of the pure reaction products of PC thiolysis has hindered detailed research of this factor.…”