One-pot synthesis of 2,5-bis(hydroxymethyl)furan from biomass derived 5-(chloromethyl)furfural in high yield

5-(Chloromethyl)furfural(CMF),as a new platform molecular,has become a hot topic in the field of biorefinery.Herein,the one-pot conversion of CMF to 2,5-bis(hydroxymethyl)furan(BHMF)in the water phase was demonstrated for the first time.A 91%BHMF yield was obtained over Ru/Cu Oxcatalyst,and BHMF was mainly produced by the consecutive hydrolysis and hydrogenation of CMF with 5-hydroxymethylfurfural(HMF)as an intermediate.Kinetic studies revealed that the conversion of HMF to BHMF was the rate-determining step.Remarkably,the characterizations and density functional theory(DFT)calculations further revealed the lower electron density of Ru NPs in Ru/Cu Oxcatalyst,resulting in a larger adsorption energy and a smaller free energy difference for the formation of alcohols.The present findings offered a new pathway for biomass-derived diol production through CMF as a potential source.

DNA methylation mediated by RdDM pathway and demethylation affects furanone accumulation through regulation of QUINONE OXIDOREDUCTASE in strawberry

Recently,increasing evidence suggests that DNA methylation plays a crucial role in fruit ripening.However,the role of DNA methylation in regulating specific traits,such as flavor,remains unclear.Here,we report a role of DNA methylation in affecting furanone biosynthesis in strawberry.Strawberry quinone oxidoreductase(FaQR)is a key enzyme in furanone biosynthesis.There are four FaQR homologs in strawberry cultivar‘Yuexin’,and one of them,FaQR3,contributes∼50%of FaQR transcripts,indicating a major role of FaQR3 in furanone biosynthesis.Through characterization of levels of DNA methylation and FaQR3 transcript and furanone contents during fruit ripening and after the application of DNA methylation inhibitor,we found that the DNA methylation level of the FaQR3 promoter was negatively correlated with FaQR3 expression and furanone accumulation,suggesting that DNA methylation may be involved in furanone biosynthesis through adjusting FaQR3 expression,and responded to different temperatures consistently.In addition,transient expression of a gene in the RNA-directed DNA methylation(RdDM)pathway,FaAGO4,and enrichment analysis of the 24-nucleotide siRNAs suggested that DNA methylation in the FaQR3 promoter is mediated by the RdDM pathway.Transient RNA interference(RNAi)of FaDML indicated that the demethylation pathway may be involved in regulating furanone accumulation.These findings provide new insights into the role of DNA methylation and demethylation in affecting flavor quality in strawberry during fruit ripening.

Exposure to lead and dietary furan intake aggravates hypothalamus-pituitary-testicular axis toxicity in chronic experimental rats

Lead(Pb) and furan are toxic agents, and persistent exposure may impair human and animal reproductive function. We therefore explored the effects of Pb and furan on male rat hypothalamic-pituitary-gonadal reproductive status, oxidative stress, inflammation, and genomic integrity. We found that co-exposure to Pb and furan reduced the activities of testicular function enzymes, endogenous antioxidant levels, total sulfhydryl group,and glutathione. Sperm abnormality, biomarkers of oxidative stress, inflammation, and p53 expression were increased in a dose-dependent manner by treatment with furan and Pb. Typical rat gonad histoarchitecture features were also damaged. Conclusively, co-exposure to Pb and furan induced male reproductive function derangement by decreasing the antioxidant defences in rats, increasing abnormalities in spermatozoa morphology, and reducing reproductive hormone in circulation. These pathophysiological alterations, if persistent, might provide a permissive environment for potentiating reproductive dysfunction and infertility.

Food borne toxicants in coffee:Acrylamide and furan derivative content in Arabica and Robusta coffees with different roasting profiles and varying degrees of roast

To evaluate mitigation options for both acrylamide and furan and methylfurans a Vietnam Robusta grade 2 and a Brazil Arabica(unwashed)coffee were roasted by tangential,drum and hot air roasting.Three different roasting profiles were followed and three samples(light,medium and dark roast)were obtained per profile.Decaffeinated and steam treated batches of the two coffees were roasted.Special roasts,such as double roast(on 2 days with cooling down in between)or roasting with a sudden temperature change were studied.The contaminants were analyzed by GC-MS–in case of the furans headspace GC-MS–using deuterated standards.The acrylamide contents were highest in light roasts,and decreased after that with longer roasting time.This was true for both the Robusta and Arabica samples.The content of furan and 2-,3-and 2,5-methylfurans were low in light roasts and had a maximum in dark roasts.It is possible to minimize the content of either acrylamide and furans,however,a mitigation of both could not be established by changing the roasting parameters or using pretreatments.Among the furans determined,2-methylfuran was most abundant(average around 70%),followed by furan(average around 20%).The special roasts showed no options to minimize both contaminants as did the pretreatments.In Vietnam Robusta,furan related compounds were measured.5-hydroxymethylfurfural and 5-hydroxymethylfurfuryl-2-carboxylic acid decreased with the degree of roast and time,while furfuryl alcohol and 2-furoic acid content increased.

Preparation of 2,5-Bis(Aminomethyl)Furan by Direct Reductive Amination of 2,5-Diformylfuran over Nickel-Raney Catalysts

The direct reductive amination of 2,5-diformylfuran (DFF) with ammonia to 2,5-bis(aminomethyl)furan (BAF) was demonstrated, for the first time, over the commercial type Nickel-Raney and acid treated Nickel-Raney catalysts. The effects of reaction parameters such as reaction medium, temperature and hydrogen pressure were described. The acid treated Nickel-Raney catalyst exhibited the highest BAF yield in the THF-water mixed reaction medium. The relatively higher Ni0 species composition and larger surface area of the acid treated Nickel-Raney catalyst with specific reaction conditions contributed greatly to the BAF formation. The oligomeric species, such as furanic imine trimers and tetramers confirmed by MALDI-MS analysis were presented as the intermediates of DFF reductive amination.

Oxidation of 2,5‐bis(hydroxymethyl)furan to 2,5‐furandicarboxylic acid catalyzed by carbon nanotube‐supported Pd catalysts

The selective oxidation of 2,5‐bis(hydroxymethyl)furan(BHMF)in this work was proven as a promising route to produce 2,5‐furandicarboxylic acid(FDCA),an emerging bio‐based building‐block with wide application.Under ambient pressure,the modified carbon nanotube‐supported Pd‐based catalysts demonstrate the maximum FDCA yield of 93.0%with a full conversion of BHMF after 60 min at 60°C,much superior to that of the traditional route using 5‐hydroxymethylfurfural(HMF)as substrates(only a yield of 35.7%).The participation of PdH_(x) active species with metallic Pd can be responsible for the encouraging performance.Meanwhile,a possible reaction pathway proceeding through 2,5‐diformylfuran(DFF)and 5‐formyl‐2‐furancarboxylic acid(FFCA)as process intermediates is suggested for BHMF route.The present work may provide new opportunities to synthesize other high value‐added oxygenates by using BHMF as an alternative feedstock.

THE SYNTHESES OF BENZOFURAN DERIVATIVES

Two benzofuran derivatives were synthesized from 3,4-bis(trimethylsilyl) furan after a series of reactions. Their structures were identified by 1H NMR, 13C NMR, MS and EA.

Synthetic Studies of Naphtho[2,3-b]furan Moiety Present in Diverse Bioactive Natural Products

The preparation of several functionalized furan derivatives and attempts to transform them into a derivative containing 6H-furo[3,4-b]furanone skeleton towards the construction of naphtho[2,3-b] furan are described. Attempted Pummerer reaction of a furan sulfoxide derivative produced four interesting furan derivatives. Base promoted annulation between methyl 2-(phenylsulfinylmethyl)-3-furoate and 2-cyclohexenone proceeded to give dihydro naphtho[2,3-b]furanone derivative in a regiospecific manner.

How Baking Process Conditions Influence on Occurrence of Furan and Its Derivatives in Typical Polish Breads

Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile contaminants such as furan and its derivatives, and present a volatile profile of the most common furan derivatives in the described products. To measure concentration of chemical compounds such as furan and furan derivatives, fast and effective solid-phase micro-extraction/gas chromatography/mass spectrometry （SPME/GC/MS） methods were adapted. This study showed the differences in furan occurrence between Pytlowy and Staropolski, however, the greater differences were observed between different times and temperatures of baking rather than between the bread types. Clearly, the higher concentrations were found in products prepared during the longest baking time period of 50 min, and temperatures of 230 ℃ and 240 ℃. The highest furan level was detected in Staropolski 28.89 ± 1.16/μg/kg, baked for 50 min at 230 ℃ in bread crust. The volatile fraction of bread crust was composed of 5-9 furan derivatives while crumb layer contained only furan-2-pentyl. It was concluded that furan is present in almost each type of bread and percentage of furan derivatives in all volatile fractions ranged from 0.5 % to 60.6% in crust of examined bars.

Synthesis of benzoxazine-based phenolic resin containing furan groups

A novel benzoxazine-based phenolic resin containing furan groups（PFB） was synthesized via simple two-step reactions and the structure of PFB was confirmed by FTIR and ~1H NMR spectra.Differential scanning calorimetry（DSC） showed that the polybenzoxazine cured from PFB had good heat resistance and lower polymerization temperature compared with that of benzoxazine-based phenolic resins.

Effect of praseodymium on catalytic graphitization of furan resin carbon

We introduced a new catalyst,rare earth element praseodymium,for the catalytic graphitization of furan resin carbon.The extent of graphitization of the furan resin carbon was examined by X-ray diffraction and Raman spectroscopy.The morphology of furan resin carbon was characterized by scanning electron microscopy.The effects of the praseodymium content and the heat-treatment temperature on the catalytic graphitization of furan resin carbon were also investigated.The results indicated that the praseodymium c...

Synthesis and Biological Activities of α-Amino Acylamines Derivatives Containing Furan and Pyridine Ring

In order to find better herbicidal activity and fungicidal activity of a-amino acid derivatives, we introduced furan rings and pyridyl groups to seven different a-amino acids to form a series of 14 novel a-amino acylamines derivatives via dicyclohexylcarbodiimide/4-dimethylaminopyridine（DCC/DMAP） coupling method. The structures of all the compounds prepared were confirmed by IR, LC/MS, IH NMR, and elemental analysis. The herbicidal and fungicidal results show that some compounds containing glycine and valine substrate have good activities.

Optimization of tensile strength for new type acetone-urea-formaldehyde furan resin using uniform design

In this study,the 24 h tensile strength of new type acetone-urea-formaldehyde furan resin (nitrogen content 3%) was investigated by uniform design optimization.Four independent variables such as acetone:formaldehyde molar ratio (mol/mol),solution pH value,reaction temperature (℃) and reaction time (min) were considered in the experiments.U13(134) uniform design was employed and the equation of 24 h tensile strength model was obtained after 13 experimentations.The 24 h tensile strength was optimized by applying single factor experiments and stepwise non-linear regression analysis.Minitab (Minitab 15 trial version) and MATLAB (R2010a trial version) were used for data analysis.The t-value and p-value indicate that the major impact factors include the interaction effect of solution pH value and reaction temperature (X2X3),the linear terms of acetone:formaldehyde molar ratio (X1),reaction time (X4) followed by the square effects of acetone/formaldehyde molar ratio (X1X1).The optimized results were achieved with the acetone:formaldehyde molar ratio (mol/mol) at 3:1,solution pH value at 6.0,reaction temperature at 70℃,and reaction time at 140 min,respectively.This method can not only significantly reduce the number and cost of the tests,but also provide a good experimental design strategy for the development of furan resin.The investigation shows that the predicted results of 24 h tensile strength are consistent well with the experimental ones.

A new phenanthro [2,3-b] furan from Pleione bulbocodioides

A novel phenanthro [2,3-b] furan 1, named (3-hydroxy-9-(4′-hydroxy-3′-methoxyphenyl)-11-methoxy-5,6,9,10-tetrahydrophenanthro [2,3-b] furan-10-yl) methyl acetate, and two known phenolic compounds were isolated from the tubers of Pleione bulbocodioides (Franch.) Rolfe. Their structures were elucidated by spectroscopic methods.

A Novel Route of Furan Compounds Syntheses

A series of compounds that contained furan skeletons were synthesized using 3,4-bis(trimethylsilyl) furan as staring material.1H NMR,13C NMR, MS and EA had identified these new molecules. The important factors that influenced reactions were discussed, and the new furan intermediates could be used in various organic syntheses.

Effect of pH,temperature and heating time on the formation of furan in sugar–glycine model systems

Furan(C4H4O)has been classified as a possible animal and human carcinogen by many international agencies.The formation of furan in three sugar–glycine models using glucose,fructose,and sucrose was investigated using headspace gas chromatography mass spectrometry method(HSGC–MS)with various dual combinations of three important heat processing conditions,i.e.pH,temperature,and heating time.Results indicated that furan levels from sugar–glycine model systems during the thermal processing can be attributed to selective sugar types,pH,temperature,and heating time.In glucose–glycine and fructose–glycine system,the lowest furan level was detected in acid condition but in sucrose–glycine system furan formed significantly lower(P<0.05)in acidic conditions the lowest furan level was found in alkaline conditions.The furan levels were observed to increase with heating time in all three model systems.Furthermore,less furan was generated in non-reducing sugar system(sucrose)than in reducing sugar system(glucose and fructose).Therefore,they demonstrate the possibility of limiting the formation of furan in heat processed foods by both the careful selection of carbohydrates(i.e.non-reducing sugars and reducing sugars)ingredients and appropriate processing conditions.©2013 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

PHOTOINDUCED ADDITION REACTIONS OF CHLORANIL WITH FURAN DERIVATIVES

Photoinduoed reaction of chloranil (TCBQ) with 2-methylfuran la and 2,5-dimethylfuran 1b in benzene gave addition products 2a and 2b respecvely together with tetrachlorohydroquinone 3. A mechanism of sequential electron and proton transfer from la or 1b to ~3TCBQ followed by coupling of the furfuryl and semiquinone radical pairs was proposed and is evidenced by the photo-CIDNP studies of the TCBQ-1a and TCBQ-1b systems.

Reductive Conversion of Biomass-Derived Furancarboxylic Acids with Retention of Carboxylic Acid Moiety

Catalytic reduction systems of 2-furancarboxylic acid(FCA)and 2,5-furandicarboxylic acid(FDCA)with H 2 without reduction of the carboxyl groups are reviewed.FCA and FDCA are produced from furfural and 5-hydroxymethylfurfural which are important platform chemicals in biomass conversions.Furan ring hydrogenation to tetrahydrofuran-2-carboxylic acid(THFCA)and tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)easily proceeds over Pd catalysts.Hydrogenolysis of one C–O bond in the furan ring produces 5-hydroxyvaleric acid(5-HVA)and 2-hydroxyadipic acid.2-Hydroxyvaleric acid is not produced in the reported systems.5-HVA can be produced as the lactone form(δ-valerolactone;DVL)or as the esters depending on the solvent.These reactions proceed over Pt catalysts with good yields(~70%)at optimized conditions.Hydrogenolysis of two C–O bonds in the furan ring produces valeric acid and adipic acid,the latter of which is a very important chemical in industry and its production from biomass is of high importance.Adipic acid from FDCA can be produced directly over Pt-MoO_(x) catalyst,indirectly via hydrogenation and hydrodeoxygenation as one-pot reaction using the combination of Pt and acid catalysts such as Pt/niobium oxide,or indirectly via two-step reaction composed of hydrogenation catalyzed by Pd and hydrodeoxygenation catalyzed by iodide ion in acidic conditions.Only the two-step method can give good yield of adipic acid at present.

Emission of BTEX and PAHs from molding sands with furan cold setting resins containing different contents of free furfuryl alcohol during production of cast iron

At present, furan resin is the largest selling no-bake system of moulding sands. The most commonly used furan no-bake binders(FNB) are condensation products of furfuryl alcohol(FA) urea, formaldehyde and phenol. They are generally cured by exposure to organic sulfonic acids. FNB provide excellent mold and core strength, cure rapidly and allow the sand to be reclaimed at fairly high yields, generally 75%-80%, especially in applications where due allowance is made for the need to keep total sulfur content below 0.1%. However, due to probable carcinogenic properties of furfuryl alcohol, the EU Directive limits the content of this substance(in a monomer form in resin) to 25%. The classification of furfuryl alcohol and the resulting furan resin products has changed from "harmful" to "toxic by inhalation". The aim of this study was to determine the effect of free furfuryl alcohol content in the resin on the emission of harmful substances from the BTEX(Benzene Toluene Ethylbenzene & Xylene) and PAHs(polycyclic aromatic hydrocarbon) group exposed to high temperature and how it affects the emissions allowance of reclaimed sand in the matrix. Three resins from a leading manufacturer were examined, which contain a free furfuryl alcohol content of 71%-72%, about 50% and < 25%, respectively. The hardener for each resin was 65% aqueous solution of paratoluenesulfonic acid. Tests were carried out in semi-industrial conditions where liquid cast-iron was poured into sample sand mold at 1,350 °C. The matrix of the studied sands was reclaimed in the amount of 0, 50%, 100%, respectively.With the increase of free furfuryl alcohol content, the volume of evolved gases decreased. For all resins the main component from the BTEX group dominating in the emitted gases was benzene; however toluene also appeared in the amount of a few percentages. In contrast, ethylbenzene and xylenes occurred only in the gases emitted from resin-bonded sands with the largest furfuryl alcohol content. The increase in the share of reclaimed sands resulted in very significant increase in the volume of gas generated and participation of benzene in these gases. In terms of emission of compounds from the PAHs group virtually for all resins, the total content of these substances was comparable(within the limits of error). The main components were: fluoranthene, pyrene and benzo(a) anthracene.

Furans-Maleimides Diels-Alder Reactions in Protic Ionic Liquid

The authors have studied the Diels-Alder reactions between furan derivatives and maleimide derivatives in an ionic liquid and have found that higher reactivity can be obtained in a protic ionic liquid [Mim]Tf2N than in the conventional organic solvent. Furthermore, in the Diels-Alder reactions of 2- and 2,5-alkylfurans with N-alkylma- leimide, the reactivity increases by extending the alkyl chain length of N-alkylmaleimide. In addition, it was demon- strated that endo-selectivity increases when 2,5-disubstituted furans are used. These results will be explained by comparing the stability of the Diels-Alder adduct with that of the products obtained from the reactions of 2-substituted furans and 2,5-disubstituted furans.