Formation Of Phenol Research Articles

Gas-Liquid Interface of Aqueous Solutions of Surface Active Aromatic Molecules Studied Using Extreme Ultraviolet Laser Photoelectron Spectroscopy and Molecular Dynamics Simulation.

We investigated the gas-liquid interface of aqueous solutions containing phenol and related aromatic compounds using extreme ultraviolet laser photoelectron spectroscopy and molecular dynamics simulations. The interfacial densities of protonated and deprotonated forms of phenol, aniline, and 4-nitrophenol were found to be primarily determined by their surface affinities and exhibit similar concentration dependences to their respective bulk densities. Despite the distinct interfacial orientations of their permanent dipole moments, these compounds monotonically decreased the surface potential at higher concentrations. The exception was sodium phenolate, whose surface potential first increased and then decreased with increasing concentration. This behavior is attributed to the opposing effects of the electric double layer formed by Na+ and phenolate ions at the gas-liquid interface and the induced electronic polarization of phenolate.

PENETAPAN KADAR FENOL TOTAL EKSTRAK ETANOL RIMPANG TEMU PUTIH (Curcuma zedoaria (Christm.) Roscoe) DENGAN PERBEDAAN KONSENTRASI PELARUT

White Temu (Curcuma zedoaria (Berg.) Roscoe) has an actoxidant activity because it contains phenolic compounds. Phenolic compounds are aromatic compounds with a structure derived from benzene so that they have aromatic rings and the presence of one or more hydroxyl (OH) groups. This study aims to determine the total phenol content of white rhizome ethanol extract with the difference in solvent concentration using UV-Vis spectrophotometry. The research conducted is an experimental research. The results showed that the rhizome of white temu contained secondary metabolite compounds in the form of phenolics, alkaloids, flavonoids, saponins, and terpenoids. Based on the results of determining the total phenol content of white temu extract with a difference in ethanol solvent concentrations of 30%, 50%, and 70%, the levels were 23.4477±0.9827 mg GAE/g, 32.2464±1.3022 mg GAE/g, and 51.6880±0.4948 mg GAE/g. The results of statistical analysis obtained normal and homogeneous data so that a one-way anova test with p value results was used(0.00) < (0.05) so it can be concluded that there is a significant difference in the total phenol levels of the three samples.

Scalable and Practical Approach of Phenol Formation from Hydroxylation of Arylboronic Acids under Metal-, Photocatalyst-, and Light-Free Conditions

Scalable and Practical Approach of Phenol Formation from Hydroxylation of Arylboronic Acids under Metal-, Photocatalyst-, and Light-Free Conditions

Identification of phenols and their formation network during the brewing process of Shanxi aged vinegar.

Phenols are important functional compounds present in vineagr, however, their composition and formation pathways remain uncertain. Herein, non-targeted metabolomics and macrotranscriptomics methods were applied to identify phenols and analyze their formation network during the brewing process of Shanxi aged vinegar. A total of 82 phenols were detected from the raw material and the brewing process. Results indicated that phenolic acids were the major phenols and were mainly formed during acetic acid fermentation stages. Water, reducing sugars, lactic acid, and 7 amino acids influenced the formation and transformation of phenols, as shown through Spearman analysis. Furthermore, 16 genera and 38 enzymes were involved in substrates decomposition and phenols formation according to the metabolic pathway analysis, with Xenobiotics biodegradation and metabolism identified as the main pathway for phenols formation. Lactobacillus and Acetobacter were the key genera responsible for the phenols transformation. This study provides new insights into the phenols formation mechanisms in cereal vinegars and it is helpful for isolating the functional strains to reinforce the phenols formation.

Nondirected Ortho C-H Arylation for One-Pot Synthesis of Biaryl Scaffolds via In Situ Generated Mixed Acetal.

Herein, we introduce a mild and efficient method for synthesizing aniline biaryls and unsymmetrical phenol biaryls through iodine-catalyzed coupling of quinone imine ketals (QIKs)/quinonemonoacetals (QMAs) and β-naphthols. This approach allows for the unusual formation of ortho-substituted anilines and phenols, valuable in pharmaceuticals and advanced materials but typically difficult to produce. Our method achieves high ortho-selectivity without needing transition metals or external/internal templates. The process involves a [3,3] sigmatropic rearrangement of the in situ generated mixed acetal, which is the key intermediate. Notable features include scalability, broad functional group tolerance, and late-stage derivatization of natural products using a cost-effective, air-tolerant catalytic system, eliminating the need for hazardous catalysts.

PERBANDINGAN PROFIL FITOKIMIA DAN GCMS MENGGUNAKAN EKSTRAKSI MASERASI DAN SOKHLETASI SERTA PROFIL HISTOKIMIA DAUN SUNGKAI (P. canescens Jack.)

Sungkai leaf (P. canescens Jack.) is a native plant of Indonesia that has long been used in traditional medicine as a mouthwash and minor wounds. Sungkai leaves P. canescens Jack. are believed by the community to have many health benefits. Several studies have shown that sungkai leaves (P. canescens Jack.) contain active compounds. As for the extraction process, it is known that the content of active compounds obtained in the sungkai leaf extract is strongly influenced by the selection of solvents used and the extraction method carried out. In previous studies, total flavonoid content has been obtained using maceration and soxhletation methods in sungkai leaf extracts, where flavonoids are one of the profiles of secondary metabolite compounds possessed by sungkai leaves. In the next research, the profile of sungkai leaves will be determined more thoroughly through phytochemical screening and GCMS analysis of the extraction results using maceration and soxhletation methods. The histochemical profile of sungkai leaves will also be determined. Histochemical test results show that flavonoid compounds are evenly distributed in all tissues of sungkai leaves, besides that some tissues in sungkai leaves show positive results for the presence of alkaloid, steroid, terpenoid, tannin, phenol and saponin compounds.The results of phytochemical screening showed that sungkai leaves positively contained secondary metabolite compounds in the form of alkaloids, flavanoids, steroids, terpenoids, tannins, phenolics, saponins while the results of GCMS analysis for the maceration process obtained metabolite compounds in the form of terpenoids, alkaloids, and phenolics, while for the sokletation process obtained metabolite compounds in the form of flavonoids, terpenoids, and phenolics.

LC-MS Based Metabolite Profiling of Ethanol Extract From the Sungkai (Peronema canescens Jack) and In Silico Prediction of Antidiabetic Activity With α-Glucosidase

Sungkai (Peronema canescens Jack) is a medicinal plant in the Verbenaceae family that is known to have antidiabetic activity. The secondary metabolite content found in sungkai leaves is in the form of alkaloids, flavonoids, triterpenoids, steroids, phenolics, and saponins. This research aimed to identify the biological activity of compounds in sungkai plants as antidiabetic agents using α-glucosidase inhibitors in silico. Sungkai leaf extract with ethanol solvent was identified using a Liquid Chromatography Mass Spectrometer (LC-MS/MS). There are 15 compounds resulting from LC-MS/MS analysis which will then predict antidiabetic activity using molecular docking. Molecular docking was carried out using AutoDock Tools software and visualized with Discovery Studio. The highest scoring result obtained from the molecular docking test was the compound C13H23N6S with a free bond energy result of -7.31 and an inhibition constant value of 4.41 μM, which binds three hydrogen bonds in GLU 78, ALA 75, and GLU 198. Keywords: In sillico, metabolite profilling, Peronema canescens

(Invited) Surface Local Structure Dependence of Photoinduced Reaction Process on TiO2 Single Crystal Electrode in Aqueous Solution

Metal oxides such as TiO2 are widely used as electrocatalysts and photo-responsive electrodes in various electrochemical devices, and many researchers have studied them. However, the reaction processes at their interfaces are generally complex, and there are many aspects that remain to be elucidated. Even for TiO2 electrodes, which have been the most widely studied, the mechanism of interfacial reactions still remains unclear, especially the effects of crystal faces and atomic- to nano-level surface structures on electrode reactions. Our group has been investigated how the atomic- to nano-level structure of the TiO2 electrode surface affects the reaction at the TiO2 electrode interface.In our previous study, we revealed that the water photooxidation reaction (i.e. oxygen evolution reaction) on TiO2 surface accompanies with other three kinds of side reactions (photoluminescence (PL), surface roughening and non-radiative recombination) [1]. These reactions are competitive with each other and the ratio of their quantum efficiencies strongly depends on the atomic-scale surface local structure. Thus, we investigated the surface local structure dependence of those competitive reactions on TiO2 surface using atomically flat TiO2 (rutile) single crystal electrode those step-terrace structure was strictly controlled. It was revealed that the ratio of the quantum efficiency of four kinds of reactions strongly depends on the surface local structure such as step-terrace structure. On the other hand, the surface roughening process, which is one of the four competitive reactions, induced the drastic change of the surface local structure and also induced the change in the ratio of quantum efficiency of four kinds of competitive reactions, leading to the increase of the photocatalytic activity for oxygen photoevolution [2]. Such an investigation would be very important because some recent studies indicate that the surface local structure changes during the photooxidation process even in the case of practical catalyst. We also investigated the influence of nanostructure formed on the TiO2 electrode on the branch ratio of 4 competitive photooxidation reactions. We found that the overvoltage for O2 evolution on nanostructured electrode was decreased comparing with that on atomically flat (100) surface. We can explain these results by the spatial configuration of edge and facet sites which depends on the surface nanostructure.The organic synthesis by using of photooxidation reaction on photocatalysis has been investigated by many researchers. Although the formation of phenol from benzene on TiO2 surface by photo-induced oxidation reaction is one of the representative reactions, its molecular mechanism is still unclear. We can assumed that the quantum efficiencies of phenol generation depends on the atomic-scale surface local structure. We investigated the atomic leveled surface local structure dependence of the efficiency of photooxidation reaction of benzene (in HClO4aq solution) on Nb-doped rutile TiO2(110) single crystal electrode. It was found that the efficiency of the photooxidation reaction of benzene is largely affected by the step structure on the TiO2 surface [3]. Detailed analysis of the dependence on surface structure revealed that the photooxidation reaction of benzene and the photoinduced decomposition of water (Oxygen evolution reaction) proceed competitively via the same intermediate, and that the ratio of their efficiencies is strongly affected by the step direction and step density.[1] A. Imanishi, T. Okamura, N. Ohashi, R. Nakamura, Y. Nakato, J. Am. Chem. Soc., 129, 11569(2007)., A. Imanishi, K. Fukui, J. Phys. Chem. Lett. 5, 2108(2014) [2] E. Tsuji, K. Fukui, A. Imanishi, J. Phys. Chem. C, 118, 5406(2014). [3] S. Nagaoka, S. Kadono, K. Fukui, A. Imanishi, of the 87th ECSJ Spring Meeting (2020).

Visible-Light Induced C-H Oxygenation of Hydrocarbons Using Chlorine Dioxide as a Photoredox Catalyst

Photocatalytic oxygenation of benzene occurs in an oxygen-saturated acetonitrile solution containing acridnium ion or quinolinium ion derivatives as a photoredox catalyst, benzene and water under light irradiation to yield phenol and hydrogen peroxide selectively. The benzene radical cation, which is formed by photoinduced one-electron oxidation of benzene with the excited state of catalyst, reacts with H2O to yield phenol.Photocatalytic oxygenation of benzene with oxygen occurs under photoirradiation of an acetonitrile solution of 3-cyano-1-methylquinolinium perchlorate (QuCN+ClO4 –) in an oxygen-saturated acetonitrile (MeCN) containing benzene and H2O with a xenon lamp (500 W) attached with a color-cut glass filter. The selectivity of formation of phenol was 98% with 16% quantum yield after 1 h irradiation, and then 51% of phenol yield after 5 h irradiation. The photocatalytic turnover number (TON) was 7.5. This is the first example of photocatalytic oxygenation of benzene to phenol in a homogeneous system. A preparative gram-scale photocatalytic reaction with benzene (2.3 g, 29 mmol) and QuCN+ (210 mg, 0.8 mmol) in MeCN (200 mL) for 48 h was also examined to afford phenol (1.1 g, 12 mmol) as 41% yield.

Metagenomic analysis of Lactobacillus plantarum DACN768 inoculation effects on volatile flavor compounds, microbial succession, and flavor metabolic network in suansun

This study analyzed volatile flavor compounds and microbial communities in Lactobacillus plantarum-fermented suansun (LPS), emphasizing the underlying metabolic pathways. A comparison with naturally fermented suansun (NFS) identified 56 volatile flavor compounds in LPS, detected via GC–MS, with levels peaking at 14 days. Alcohols, aldehydes, and esters were the primary components in both NFS and LPS. However, LPS contained significantly more and diverse aldehydes, likely due to L. plantarum’s ability to convert free amino acids into aldehydes through the Ehrlich pathway, while keeping phenol levels consistently low. The analysis focused on the ten most abundant bacterial genera in LPS, with Weissella being the most dominant, followed by Lactobacillus, Lactococcus, and Enterococcus. Lactobacillus plantarum exhibited higher metabolic activity and stronger strain interactions compared to NFS. Metagenomic data revealed enhanced carbohydrate and amino acid metabolism in LPS, identifying key pathways contributing to flavor development. Glycolysis and gluconeogenesis, essential for lactic acid bacteria, were active in both LPS and NFS. Pyruvate and propionic acid were major intermediates, while tyrosine was the primary amino acid metabolized in NFS, serving as a main source of aldehydes, alcohols, phenols, and esters. Pyruvate kinase and hexokinase were critical enzymes for the synthesis of alcohols and phenols, primarily mediated by Lactobacillus and Lactococcus. Tyrosine metabolism, specifically through the 4-hydroxyphenylpyruvate and 4-hydroxyphenylacetic acid pathways, was crucial for the formation of phenol and p-cresol. These results offer new insights into the biochemical mechanisms driving flavor formation in suansun.

Hydrothermal liquefaction of diverse plastics using water and seawater

In this study, a variety of plastics are converted to their monomers, fuel range hydrocarbons and other platform chemicals using hydrothermal liquefaction (HTL) at sub-critical (350 °C), near-critical (400 °C) and super-critical (450 °C) temperatures. The effect of seawater as a medium on the HTL of plastics is also studied. Polymers like polycarbonate (PC), acrylonitrile–butadiene–styrene (ABS), polyamides (PA-6, PA-66), and polyoxymethylene (POM) liquefied effectively at 350 °C, while polyolefins like polyethylene (PE) and polypropylene (PP) required ≥ 400 °C. HTL of polystyrene (PS) resulted in the highest oil yield (93 wt%) and energy recovery from oil (93.5 %) at 450 °C. HTL of PC, PS and ABS led to the formation of phenols and benzene derivatives, while polyethylene terephthalate (PET) and PA-6 formed their monomers terephthalic acid and caprolactam, respectively. Crude oils from PP and PE contained fuel grade aliphatic hydrocarbons with carbon chain length ranging between C7 and C36. Highest calorific value was recorded for the oil from PP (46.3 MJ kg−1) at 400 °C. The use of seawater generally reduced the oil yields from all the plastics, except ABS, PET and PP. The production of benzoic acid from PET was enhanced, while the selectivity to caprolactam from PA-6 decreased when seawater was used, possibly due to the enhanced decarboxylation and aromatization reactions induced by the ions in the aqueous phase. In general, the crude oil from HTL of PC, PS, ABS and polyamides are suitable for sustainable production of specialty chemicals and monomers, while that from PE and PP are good candidates for sustainable transportation fuels.

Phenolic compounds and spare carbohydrates content dynamics in seeds of the invasive species Acer negundo and the native species Acer tataricum in connection with their competitiveness in biocenoses

Changes in the content of various phenolic carboxylic acids (FCC) – chlorogenic (HC), caffeic (CC), ferulic (FC), as well as the amounts of flavonoids and spare carbohydrates (monosaccharides, polysaccharides and starch) in the tissues of Acer tataricum and Acer negundo seed embryos (indigenous and invasive species, respectively) during their storage were studied from October to March (cold chamber, t° = +5°C, humidity 80%). There was a significant increase in the content of HC and the absence of CC in December-January in an aboriginal species with a long dormant period. In the invasive species A. negundo, which does not have a rest period, the level of HC also increased, but was ten times lower than in A. tataricum, while a high level of CC was identified. In terms of flavonoid content, the native species A. tataricum is ten times superior to the invasive A. negundo. The carbohydrate content in A. tataricum was about 40%, and in the tissues of A. negundo seed embryos about 15% and did not change during the entire storage period. The dynamics of the content of phenolic compounds and forms of spare carbohydrates, their relationship with the activation of metabolic processes and protective anti-stress mechanisms during the cold storage of seeds and competitiveness in biocenoses are discussed.

Mitochondria-Targeted NIR Ratiometric and Colorimetric Fluorescent Probe for Biothiols Based on a Thiol-Chromene Click Reaction.

In this work, a mitochondria-targeted NIR ratiometric and colorimetric fluorescent probe 1 was tactfully designed and synthesized by a novel design strategy of modifying chromene to pyridine for the first time. 1 exhibited a maximum absorption peak at 508 nm and a maximum fluorescence emission peak at 650 nm. Under the stimulus of biothiols (cysteine (Cys), homocysteine (Hcy), and glutathione (GSH)), the maximum absorption and fluorescence emission peaks of 1 blue-shifted to 448 and 541 nm, respectively, along with color changes from red to yellow under visible light and from red to green under a 365 nm ultraviolet (UV) lamp, which can be ascribed to the click reaction of biothiols with the α,β-unsaturated ketone of the chromene moiety with pyran ring-opening, phenol formation, and 1,6-elimination of the p-hydroxybenzyl moiety. 1 detected biothiols (Cys, GSH, and Hcy) with high sensitivity (LODs of 29, 23, and 16 nM for Cys, GSH, and Hcy, respectively), excellent selectivity, and fast response. Moreover, 1 can target mitochondria and image the fluctuation of intracellular biothiols by dual-emission channels.

Efficient Electrocatalytic Hydrodechlorination and Detoxification of Chlorophenols by Palladium-Palladium Oxide Heterostructure.

Electrocatalytic hydrodechlorination is a promising approach for simultaneous pollutant purification and valorization. However, the lack of electrocatalysts with high catalytic activity and selectivity limits its application. Here, we propose a palladium-palladium oxide (Pd-PdO) heterostructure for efficient electrocatalytic hydrodechlorination of recalcitrant chlorophenols and selective formation of phenol with superior Pd-mass activity (1.35 min-1 mgPd-1), which is 4.4 times of commercial Pd/C and about 10-100 times of reported Pd-based catalysts. The Pd-PdO heterostructure is stable in real water matrices and achieves selective phenol recovery (>99%) from the chlorophenol mixture and efficient detoxification along chlorophenol removal. Experimental results and computational modeling reveal that the adsorption/desorption behaviors of zerovalent Pd and PdO sites in the Pd-PdO heterostructure are optimized and a synergy is realized to promote atomic hydrogen (H*) generation, transfer, and utilization: H* is efficiently generated at zerovalent Pd sites, transferred to PdO sites, and eventually consumed in the dechlorination reaction at PdO sites. This work provides a promising strategy to realize the synergy of Pd with different valence states in the metal-metal oxide heterostructure for simultaneous decontamination, detoxification, and resource recovery from halogenated organic pollutants.

Spectroscopic and Computational Study of Vanillin-Dipyrrin Ligand that Capable of Colorimetric Sensor for Zinc and Copper Ions

Phenolic-dipyrrin is a promising colorimetric chemosensor due to its tautomeric formation (phenolic-hemiquinone forms). In methanol solution, the vanillin-dipyrrin compound exists as a hemiquinone species, whereas the complexes exist in a phenolic form. This molecule showed a red-magenta color in methanol, in contrast to yellowish allyl-protected-dipyrrin. In the presence of zinc or copper ions, the vanillin-dipyrrin solution turned into a pale-yellow complex, similar to that of protected-dipyrrin. A computational study of the ligands and complexes showed a close relevance, where the energy transition between the highest molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the ligand in the hemiquinone form had a lower energy transition, and the two complexes showed slightly different transition energies. Apart from naked-eye color changes, vanillin-dipyrrin showed limits of detection of 9.2 × 10–7 M and 4.8×10−7 M for zinc and copper ions, respectively.

Synthesis and characterizations of a novel trans-Pd(O,N)2 complex with an AZO-dye ligand: Crystal structure, theoretical studies and DNA binding interactions

The transition metal-azo dye complexes have attracted attention in both fundamental and applied research due to their electronic and structural properties, particularly due to their potential to yield new compounds with diverse biological activities and anticancer agents. A novel square planar-trans-Pd(O,N)2 was synthesized with a high yield utilizing a one-pot approach employing (E)-methyl 2-((2-hydroxynaphthalen-1-yl)diazenyl)benzoate as the AZO-dye ligand. In order to analyze their structure and understand their properties. The desired complex was characterized using FT-IR, UV–Vis, NMR, and CHN-EA techniques. Subsequently, theoretical modeling of the complex was performed using MEP/MAC/NPA methodologies. Two methodologies were employed to monitor the coordination process of AZO-ligand with Pd(II): UV–Vis absorption and FT-IR spectrum analysis. The TD-DFT and DFT/IR behaviors were simultaneously assessed to compare the experimental results with theoretical predictions. Furthermore, both SC-XRD and DFT analysis demonstrated that the deprotonated phenolic diazene form of the AZO-ligand attached to the Pd(II) center by utilizing one nitrogen atom of the AZO-ligand and the ionic oxygen of the phenol. The SC-XRD analysis verified the presence of a slightly distorted square-planar geometry around the PdII center in the neutral trans-Pd(O,N)2 complex. All of the oxygen atoms in the complex participated in non-classical C-H….O hydrogen bonding, leading to the formation of novel edge-fused rings R22(24) and R22(12) synthons. These synthons create a 3D-network with a linked parallel matrix. Interestingly, Hirshfeld surface analysis (HSA) stimulation revealed many hot sites on the complex surface, confirming the formation of strong non-classical [C-H....O] interactions. From the observed docking behavior with the DNA, it can be concluded that the trans-Pd(O,N)2 showed superior binding compared to the free AZO-ligand. The results of this work are a contribution to the study of this class of metal complexes and their physicochemical properties and offer promising perspectives for the realization of new works.

Comparison of the pyrolysis behavior of PC, ABS and PC/ABS

Three types of plastics—polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), and PC/ABS blend—were studied in this work. Kinetic analyses were performed using the Flynn-Wall-Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. The evolved volatiles during the pyrolysis of each material were analyzed, and the pyrolysis behavior was proposed using in-situ tools such as thermogravimetric analyzer-Fourier transform infrared spectroscopic (TG-FTIR) and gas chromatographic separation and mass spectrometry detection (Py-GC/MS). The three samples were also pyrolysed in a fixed bed reactor to elucidate the impact of secondary reaction. For PC, the activation energy increases as the reaction progresses. PC primarily generated CO2 and oxygenated compounds. For ABS, the activation energy experienced a slight decrease once the depolymerization reaction initiates, while a reversed trend can be observed at higher conversion rates. ABS pyrolysis mainly produced nitrogen-containing compounds and mono-aromatics. In the case of PC/ABS blend, a distinctive two-stage decomposition mechanism was observed. The interaction between PC and ABS in the blend promoted the formation of N/O-containing compounds. Additionally, this interaction enhanced the production of lighter phenols at the expense of bisphenol A, while ABS was not affected markedly. Stronger re-condensation and cracking reactions in the fixed bed system, facilitated the formation of poly-aromatics and lighter phenols (p-cresol and 4-ethylphenol) at the expense of bisphenol A during the pyrolysis of PC. In contrast, styrene from ABS decomposition was weakly affected by the secondary reaction. The intensified secondary reactions occurring the sample bed of the fixed bed experiments can also enhance the interaction between volatiles from ABS and PC, forming more heterocyclic N-compounds.

Catalytic pyrolysis mechanism of lignin moieties driven by aldehyde, hydroxyl, methoxy, and allyl functionalization: the role of reactive quinone methide and ketene intermediates.

The catalytic pyrolysis of guaiacol-based lignin monomers, vanillin, syringol, and eugenol over commercial HZSM-5 has been investigated using operando Photoelectron Photoion Coincidence (PEPICO) spectroscopy to unveil the reaction mechanism by detecting reactive intermediates, such as quinone methides and ketenes, and products. Vanillin shares the decomposition mechanism with guaiacol due to prompt and efficient decarbonylation, which allows us to control this reaction leading to a phenol selectivity increase by switching to a faujasite catalyst and decreasing the Si/Al ratio. Syringol first demethylates to 3-methoxycatechol, which mainly dehydroxylates to o- and m-guaiacol. Ketene formation channels over HZSM-5 are less important here than for guaiacol or vanillin, but product distributionremains similar. C3 addition to guaiacol yields eugenol, which shows a more complex product distribution upon catalytic pyrolysis. By analogies to monomers with simplified functionalization, namely allylbenzene, 4-allylcatechol, and 4-methylcatechol, the eugenol chemistry could be fully resolved. Previously postulated reactive semi-quinone intermediates are detected spectroscopically, and their involvement opens alternative pathways to condensation and phenol formation. Allyl groups, produced by dehydroxylation of the β-O-4 bond, may not only decompose via C1/C2/C3 loss, but also cyclize to indene and its derivatives over HZSM-5. This comparably high reactivity leads to an unselective branching of the chemistry and to a complex product distribution, which is difficult to control. Indenes and naphthalenes are also prototypical coke precursors efficiently deactivating the catalyst. We rely on these mechanistic insights to discuss strategies to fine-tune process conditions to increase the selectivities of desired products by enhancing either vanillin and guaiacol or supressing eugenol yields from native lignin.

Catalytic conversion of biomass pyrolysis volatiles over composite catalysts of activated carbon and HY zeolite

Bio-oil has complex compositions and high oxygen content, which restricts its high-value utilization. Commercial activated carbon (AC) and HY zeolite were used as composite catalysts to study their effect on pyrolysis volatiles from rice straw and poplar sawdust by changing the mixing modes of two catalysts. The results showed that the loading modes of AC and HY zeolite obviously affected the products distribution and bio-oil components. The lowest yield of bio-oil was obtained when HY zeolite and AC were mechanically mixed at a mass ratio of 1:1 (YACM). But the loading mode of YACM was beneficial to the deoxidation and aromatic hydrocarbon generation. Under the mode of YACM, the aromatics content in rice straw and poplar sawdust bio-oil can be increased from 13.8% and 8.0% without catalyst to 56.4% and 53.1%, respectively. However, the layered loading with upper HY zeolite and lower AC (YTACL) was favorable for formation of phenolic compounds. The selectivity to monocyclic and bicyclic aromatic hydrocarbons followed the order of YTACL > ACTYL > YACM, and YACM > ACTYL > YTACL, respectively. Compared with HY zeolite, AC catalyst possessed smaller pore size and fewer acidity, and the active sites of AC were conducive to rearrangement of furan compounds to generate cyclopentanone, 2-cyclopentenone and methyl-cyclopentenone, and further rearrangement to form phenol. Therefore, the loading mode of YTACL exhibited a promotion effect on the formation of phenol, cresol, toluene, ethylbenzene and p-xylene. The strong acidic sites of HY zeolite were favorable for the aromatization, so the loading mode of ACTYL had good selectivity to the formation of naphthalene, methylnaphthalene, anthracene and pyrene. This work will provide a guide for products regulation from biomass pyrolysis and enrich aromatics and phenols in bio-oil.

Lactiplantibacillus plantarum inoculation enhanced the color stabilization and aroma quality of blueberry wine

Inoculation of Lactiplantibacillus plantarum before yeast has the potential to affect the blueberry wine quality. The effects of four L. plantarum strains on the anthocyanins and volatile profile of blueberry wine were studied. Different L. plantarum inoculated wines presented a great color variation, and B3 strain was able to retain more bluish hue of blueberry wine. Compared with RF wine fermented by only Saccharomyces cerevisiae yeast, L. plantarum inoculated wines exhibited a better preservation of monomeric and acylated anthocyanins. More importantly, inoculation of L. plantarum, especially for B3 and B4 strains, enhanced the accumulation of pyranoanthocyanins, which may improve the color stability of blueberry wine. In addition, inoculation with L. plantarum favored the formation of lactate-related esters, acetoin, C6 alcohols, terpenes, aldehydes, and volatile phenols. Flash-Profile analysis indicated that B3, B4 and SS6 strains conferred wines more sour and astringent tastes, along with more ‘fruity’ and ‘chemical’ aromas.