Furan Ketones Research Articles

Biobased furan-functionalized high-performance poly (aryl ether ketone) with low dielectric constant and low dielectric loss

Furandicarboxylic acid is considered one of the most representative biomass matrix platforms and has been widely used to synthesize various novel biomaterials. In this study, a series of copolymerized poly (aryl ether ketone) resins with excellent properties have been prepared by combining the nonlinear structure of furan ketone with the weakly polarized cyclohexane structure. And the relationship between the structure and properties of the resins has been systematically studied. The results showed that the synthesized resins had excellent thermal properties, and the 5% thermal decomposition temperature could reach up to 478 °C. In addition, the resin exhibits good solubility and can be dissolved in the most common solvents. Its water absorption is deficient, at only 0.71%. At 10 GHz, the lowest dielectric constant of the resin is 3.05. Most importantly, using bio-based monomers in this study provides an environmentally friendly strategy for material design and synthesis, providing a green way to develop high-performance low-dielectric materials.

Contributions of secondary alcohol-ketone O-H...O=C and furan-acetate Csp2-H...OOC synthons to the supramolecular packings of two bioactive molecules.

The crystal structures of rubescin D (1, C26H30O5) and monadelphin A (2, C30H36O11), bioactive molecules of the vilasinin and gedunin classes of limonoids, respectively, are reported for the first time and the synthons affecting their crystal packings are analyzed on the basis of their occurrences in molecules in the Cambridge Structural Database that share the same moieties. Rubescin D, 1, crystallizes in the space group P21 and its molecular structure consists of three six-membered rings A, C and D having, respectively, envelope, twist-boat and half-chair conformations, and three five-membered rings with half-chair (B and E) and planar conformations (F). Many synthons found in the crystal packing of 1 are in agreement with expectations derived from molecules displaying the same moieties. However, the secondary alcohol-ketone O-H...O=C synthon, which has a low occurrence (2.9%), contributes much to the layered packing, while the furan-ketone Csp2-H...O=C and secondary alcohol-epoxide O-H...OC2 synthons usually found in these compounds (occurrences of 20.6 and 17.6%, respectively) are missing. The packing of 1 is close to that of ceramicine B (3), but is completely different from that of TS3 (4), suggesting that the absence of the epoxide group in 3 would have favoured the furan-secondary alcohol Csp2-H...OH synthon and that the missing hydroxy group in 4, a strong hydrogen-bond donor, would have favoured the involvement of water molecules in the crystal packing. The molecular structure of monadelphin A, 2, consists of four six-membered fused rings (A, B, C and D) and one five-membered ring (E); they have twist-boat (A and C), chair (B), screw-boat (D) and planar (E) conformations. The molecule crystallizes in the space group P212121 with the contribution of many synthons usually found in compounds having the same moieties. However, the secondary alcohol-acetate O-H...OOC and secondary alcohol-ketone O-H...O=C synthons (occurrences of 16.7% each in these compounds) are missing. The furan-acetate Csp2-H...OOC synthon not observed in these compounds greatly contributes to the layered packing of 2. The layered packing is very close to those of 7-oxogedunin (5) and 6-dehydro-7-deacetoxy-7-oxogedunin (6), which both crystallize in the space group P21.

Kinetics of 2-Methylfuran Acylation with Fatty Acid Anhydrides for Biorenewable Surfactants

Friedel-Crafts acylation using long-chain fatty acid derivatives and biomass-derived furans is the key reaction to produce alkyl furan ketones, an important precursor for biorenewable oleo-furan surfactants. In this work, the steady-state acylation kinetics and reaction mechanism were investigated using a model system of 2-methylfuran and n-octanoic anhydride in a fixed-bed tubular reactor using Al-MCM-41, a mesoporous aluminosilicate. An apparent activation energy (15.5 +or- 1.4 kcal mol- 1) was obtained for the formation of the acylated product, 2-octanoyl-5-methylfuran (2O5MF), for a temperature range of 348-408 K. The apparent reaction rate orders were ~0.6 and ~0.5 in the 2-methylfuran and anhydride concentrations, respectively, while near-zero apparent rate orders were measured in the product concentrations, indicating negligible product inhibition. An Eley-Rideal catalytic acylation mechanism was proposed to explain the experimentally observed apparent rate orders.

Effect of Soy Sauce on Serum Uric Acid Levels in Hyperuricemic Rats and Identification of Flazin as a Potent Xanthine Oxidase Inhibitor.

This is the first report on the ability of soy sauce to effectively reduce the serum uric acid levels and xanthine oxidase (XOD) activities of hyperuricemic rats. Soy sauce was partitioned sequentially into ethyl acetate and water fractions. The ethyl acetate fraction with strong XOD inhibition effect was purified further. On the basis of xanthine oxidase inhibitory (XOI) activity-guided purification, nine compounds including 3,4-dihydroxy ethyl cinnamate, diisobutyl terephthalate, harman, daidzein, flazin, catechol, thymine, genistein, and uracil were obtained. It was the first time that 3,4-dihydroxy ethyl cinnamate and diisobutyl terephthalate had been identified from soy sauce. Flazin with hydroxymethyl furan ketone group at C-1 and carboxyl at C-3 exhibited the strongest XOI activity (IC50 = 0.51 ± 0.05 mM). According to fluorescence quenching and molecular docking experiments, flazin could enter into the catalytic center of XOD to interact with Lys1045, Gln1194, and Arg912 mainly by hydrophobic forces and hydrogen bonds. Flazin, catechol, and genistein not only were potent XOD inhibitors but also held certain antioxidant activities. According to ADME (absorption, distribution, metabolism, and excretion) simulation in silico, flazin had good oral bioavailability in vivo.

Synthesis and properties of 5-furyl(aryl)-?2-1,2,4-triazolines and -?2-1,3,4-thiadiazolines. Molecular and crystal structure of 2-acetylamino-5-phenyl-?2-1,3,4-thiadiazoline

We show that upon acylation of arylidene amidrazones of 5-nitro-2-furancarboxylic acid, 3-(5-nitro-2-furyl)-Δ2-1,2,4-triazolines or 5-(5-nitro-2-furyl)-1,2,4-triazole are formed (depending on the structure of the arylidene moiety). Δ2-1,3,4-thiadiazolines are obtained by reaction of thiosemicarbazones of aromatic and furaldehydes and furan ketones. We discuss schemes for closure of the triazolidine, triazole, and thiadiazoline rings. We describe the molecular structure of 2-acetylamino-4-acetyl-5-phenyl-Δ2-1,3,4-thiadiazoline.

Selective catalytic hydrogenation of double bonds in unsaturated furan ketones

In the hydrogenation of unsaturated furan ketones in solvents at atmospheric pressure and room temperature the Raney Pd−Al catalyst is highly active and selective towards the hydrogenation of double bonds. The only reaction products are the respective saturated ketones.

Role of metal salts in the synthesis of furan–ketone condensation macrocycles: an ‘apparent’ metal template effect

The acid-catalysed condensation of furan and acetone has been investigated by systematically varying the parameters of the reaction. The dramatic yield enhancement for macrocycles found on adding metal salts, and hitherto assumed to be due to a metal ion template effect, has now been demonstrated to result from pH effects. Optimisation of the condensation reaction conditions has enabled a number of tetrameric furan–ketone macrocycles to be synthesized with improved yields and a tetrameric furan–cyclohexanone macrocycle has been synthesized in a one-step reaction for the first time. Hexameric and octameric furan–acetone macrocycles have also been prepared. The tetrameric furan–ketone macrocycles show no binding interaction with any metal ion but the tetrameric tetrahydrofuran–acetone macrocycle binds strongly enough with LiClO4 to form an isolable 1:1 complex and gives very strongly perturbed 1H n.m.r. spectra in the cases of LiSCN and Ni(ClO4)2·6H2O. Increasing the number of donor sites, as in the hexameric furan–acetone and hexameric tetrahydrofuran–acetone macrocycle, did not lead to complexation of metal ions.

Basicity and structure of ?, ? -unsaturated heterocyclic ketones

The protolytic equilibrium constants of chalcone and its furan and thiophene analogs have been measured spectrophotometrically in sulfuric acid — glacial acetic acid solution. It is shown that the furan ketones are more basic than the thiophene ones, basicity depending on the position of the carbonyl group in the conjugated chain. In the systems studied, 2-furyl exhibits an appreciably greater positive dynamical conjugation effect than 2-thienyl, but as compared with the latter it gives rise to less steric hindrance to solvation of carbonium ions.