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The Pinnick oxidation, due to its tolerance for sensitive functional groups, is widely used in the process of oxidizing α,β-unsaturated aldehydes to corresponding carboxylic acids. The reaction reagents typically include sodium chlorite, buffer salts, and a scavenger. However, the controllability of Pinnick oxidation in the batch reaction process is poor due to the inherent limitations of the reactor's performance. This leads to potential safety risks and necessitates the reaction to proceed slowly under conditions of low temperature and low concentration. In this work, we introduced a new continuous micro-reaction process to intensify the Pinnick oxidation. The water-soluble crotonic acid was selected as a typical object of study. Through the study of reaction parameters and the construction of a micro-reaction system, efficient continuous process was achieved under high-temperature and high-pressure conditions for the first time. Compared to the batch process, the reaction benefited from the superheated condition resulting in a significant acceleration of the reaction rate, efficient gas–liquid interphase mass transfer allowing for effective utilization of the generated chlorine dioxide, and the inherent safety of the microreactor enabling an increase in reaction concentration. In addition, the buffer salts used in the Pinnick oxidation has been successfully replaced by hydrochloric acid and applied to the continuous flow. This work shows the tremendous potential of microreactors in utilizing harsh reaction conditions to achieve process intensification. Article Highlights: A superheated micro-reaction process was introduced into the Pinnick oxidation to achieve efficient and safe preparation of crotonic acid. Efficient gas–liquid interphase mass transfer in microreactor realized effective utilization of the by-product chlorine dioxide. The great replacement of phosphate buffer salts with hydrochloric acid was achieved in continuous flow. [ABSTRACT FROM AUTHOR]

Current innovations in microalgae technology include the use of wastewater as a cultivation medium for renewable energy generation and wastewater treatment. In this study, thermal pyrolysis was performed on a co-culture of Chlorella vulgaris and Arthrospira platensis grown in winery wastewater fed continuously into a membrane photobioreactor. The yield and composition of the reaction gases, reaction liquids, and solid residues collected at different reaction times and pyrolysis temperatures were compared with those of the same co-culture grown in its conventional medium. In general, the gaseous fraction resulted rich in combustible compounds. The highest yield in liquid products (55 %) was obtained by thermal pyrolysis of the co-culture grown in winery wastewater at 500 °C. Liquid fraction was made up of a mixture of oxygenated and nitrogenated compounds that are suitable as chemical intermediates and can therefore contribute to making the pyrolysis treatment economically feasible. For example, this fraction resulted particularly rich in crotonic acid, useful for the synthesis of copolymers (crotonic acid-vinyl acetate) and probably derived from the thermal cracking of polyhydroxy alkenoate. The results of this study suggest that thermal pyrolysis may be a good strategy to recover the energy potential of microalgae co-cultures used to treat wastewater. [ABSTRACT FROM AUTHOR]

The temperature and pH responsive hydrogels of the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate) and polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl methacrylate) were prepared by free radical polymerization using N-vinylcaprolactam, crotonic acid, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate as raw materials. In the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate) hydrogels, N-vinylcaprolactam is the temperature sensitive component, and crotonic acid is pH sensitive component. Six the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate) hydrogels with different 2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate contents were prepared. The chemical structure and morphology of the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate) hydrogels were characterized by fourier transform infrared spectrum and scanning electron microscopy, respectively. The swelling kinetic curves and equilibrium swelling ratios under different temperature and pH of the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate) hydrogels were tested. Mechanical properties of the two hydrogels were determined by compressive testing. Results show that the 2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate content in the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate/2-hydroxyethyl methacrylate) hydrogels affects the pore size, swelling ratio and mechanical properties. Compared with the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl methacrylate) hydrogel, the polymer(N-vinylcaprolactam-crotonic acid-2-hydroxyethyl acrylate) hydrogel has higher swelling properties and mechanical properties due to its uniform network structure. [ABSTRACT FROM AUTHOR]

Controlled thermal degradation of high-molecular-weight poly-3-hydroxybutyrate (PHB) was studied in dimethylformamide (DMF), bromoform, tetrabromoethane, and trichloropropane. Samples with molecular weights of 1.6 kDa and higher were obtained. PHB degradation in pure DMF and in trichloropropane resulted in the formation of C-terminal crotonic acid residues at the sites of polymer chain scission. In the case of bromoform and tetrabromoethane, 3-bromobutyric acid residues were formed (61–68% at 100 °C and 29–54% at 145 °C), along with crotonic acid residues. This indicates the possibility of halogen capture from solvent molecules at the moment of chain scission. Presumably, the reaction follows the E1 mechanism involving the formation of an intermediate carbocation. The results show the possibility of using thermochemical degradation of biodegradable polyesters in solutions for obtaining their oligomeric bromo-substituted derivatives. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoate (PHA) is a biodegradable polymer that microorganisms can synthesize amidst non-optimal growth conditions with excess carbon sources. Palm oil, rich in fatty acids, serves as a carbon source for PHA synthesis. The bacterial PHA production can be influenced by carbon concentration in the growth medium. Therefore, determining the optimal concentration of palm oil as a carbon source is crucial for PHA production. Additionally, it is possible to determine the type of PHA generated by bacteria, which can then be utilized as information when processing utilizing the PHA. The experiment employed palm oil concentrations of 0.5%, 1%, and 2% and was carried out for periods of 48, 72, 96 hours. It was discovered that Bacillus sp. strain CL33 and Bacillus flexus strain S5a produced the most effective PHA at a concentration of 25 with an incubation period of 96 hours. The PHA generated by these bacteria was quantitatively analyzed through measurements of total bacterial growth, cell dry weight, and the levels of crotonic acid. PHA types were also analyzed using GC-MS, with monomers including 2-hydroxybutyrate(-2HB), 2-hydroxy-3-phenylpropionate (2H3PhP), 3-Hydroxyhexanoate (3HHx), 3-hydroxyoctanoate (3H2O), and 3-hydroxydecanoate (3HD). The Bacillus sp. strain CL33 yielded a PHA level of 92.23%. Meanwhile, Bacillus flexus strain S5a synthesized a polyhydroxyalkanoate comprising mostly 3-hydroxyhexanoate (3HHx) and polydimethylsiloxane (PDMS). The monomers used were decamethyltetrasiloxane, dodecamethylpentasiloxane, hexamethylcyclotrisiloxane, octamethylpentasiloxane, and dodecamethylcyclohexasiloxane. The type of PHA produced accounted for 85.93% of the total. [ABSTRACT FROM AUTHOR]

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Copyright of Progress in Plant Protection is the property of Institute of Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bisphenol-C epoxy crotonate resin was synthesized by reacting 8.09g epoxy resin of bisphenol-C, and 2.15g crotonic acid using 25 mL 1,4-dioxane as a solvent, and 1 mL triethylamine as a catalyst at reflux temperature for 1-6 h. Solid epoxy crotonate (ECCR) is highly soluble in common organic solvents. ECCR was characterized by its acid (24.5-1.5 mg KOH/g) and hydroxyl (504.5-678.4 mg KOH/g) values. The structure of ECCR is supported by FTIR and 1HNMR spectroscopic methods. A DSC endothermic transition at 229oC indicated melting followed by thermal polymerization of ECCR. ECCR is thermally stable up to 320oC and follows three-step degradation kinetics. The first step followed first-order degradation kinetics, while the second and third steps followed one-half-order degradation kinetics. High values of kinetic parameters suggested the rigid nature of the crosslinked resin. Jute-, Glass- and Jute-natural fiber-ECCR composites showed moderate tensile strength, flexural strength, electric strength, and volume resistivity due to the rigid nature and poor interfacial adhesion of the composites. J-ECCR and G-ECCR composites showed high water absorption tendency and excellent hydrolytic stability against water, 10% aq. HCl and 10% aq. NaCl and even in boiling water. Mechanical and electrical properties and water absorption tendency of the composites indicated their usefulness as low load-bearing housing and insulating materials. They can also be utilized in harsh environmental conditions. [ABSTRACT FROM AUTHOR]

Copolymers of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride with acrylic, methacrylic, crotonic and vinylacetic acids were synthesized by radical copolymerization in the presence of a radical initiator azobiisobutyronitrile. Composite materials containing silver nanoparticles ranging in size from 7 to 43.5 nm, depending on the nature of the polymer matrix, were fabricated according to the borohydride method. The structure of the nanocomposites was analyzed by UV, IR, NMR spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. The synthesized nanocomposites have antimicrobial activity and are promising for the creation of new drugs. [ABSTRACT FROM AUTHOR]

With the growing interest in bioplastics, there is an urgent need to develop rapid analysis methods linked to production technology development. This study focused on the production of a commercially non-available homopolymer, poly(3-hydroxyvalerate) (P(3HV)), and a commercially available copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), through fermentation using two different bacterial strains. The bacteria Chromobacterium violaceum and Bacillus sp. CYR1 were used to produce P(3HV) and P(3HB-co-3HV), respectively. The bacterium Bacillus sp. CYR1 produced 415 mg/L of P(3HB-co-3HV) when incubated with acetic acid and valeric acid as the carbon sources, whereas the bacterium C. violaceum produced 0.198 g of P(3HV)/g dry biomass when incubated with sodium valerate as the carbon source. Additionally, we developed a fast, simple, and inexpensive method to quantify P(3HV) and P(3HB-co-3HV) using high-performance liquid chromatography (HPLC). As the alkaline decomposition of P(3HB-co-3HV) releases 2-butenoic acid (2BE) and 2-pentenoic acid (2PE), we were able to determine the concentration using HPLC. Moreover, calibration curves were prepared using standard 2BE and 2PE, along with sample 2BE and 2PE produced by the alkaline decomposition of poly(3-hydroxybutyrate) and P(3HV), respectively. Finally, the HPLC results obtained by our new method were compared using gas chromatography (GC) analysis. [ABSTRACT FROM AUTHOR]

A europium complex with double bonds was synthesized with crotonic acid as the ligand and a europium ion as the center ion. Then, the obtained europium complex was added to synthesized poly(urethane-acrylate) macromonomers to prepare the bonded polyurethane-europium materials by the polymerization of the double bonds in the complex and the poly(urethane-acrylate) macromonomers. The prepared polyurethane-europium materials had high transparency, good thermal stability and good fluorescence. The storage moduli of polyurethane-europium materials are obviously higher than those of pure polyurethane. Polyurethane-europium materials exhibit bright red light with good monochromaticity. The light transmittance of the material decreases slightly with increases in the europium complex content, but the luminescence intensity gradually increases. In particular, polyurethane-europium materials possess a long luminescence lifetime, which has potential applications for optical display instruments. [ABSTRACT FROM AUTHOR]

This study examines the opportunity of using recycled poly(hydroxybutyrate-co-valerate) (PHBV) as food packaging. The recyclability was evaluated by assessing the effect of repeated polymer processing (up to four extrusion cycles) on the structural and barrier properties of the material, as well as its ability to produce neo-formed chemicals susceptible to migrate into food. It was shown that increasing the number of processing cycles results in a decrease of the polymer molecular weight, leading to a decrease of mechanical properties, balanced by a maintenance of the crystalline structure and of the thermal stability. The oxygen and water vapour transfer properties were also maintained after four cycles suggesting that r-PHBV-based packaging can retain its property and use panel. The specific migration of crotonic acid, one of the main products of the thermomechanical degradation of the PHBV was measured in three different food simulants. In all cases, it did not exceed the specific migration limit (SML) set at 0.05 mg/Kg food, revealing the food contact suitability of non-contaminated recycled PHBV under test conditions. [ABSTRACT FROM AUTHOR]

This study was designed to investigate, at a laboratory scale, the possibility of valorizing the leftover carob fruits to produce the eco-friendly biopolymer polyhydroxybutyrate (PHB) by using the bacterial strain Bacillus paramycoides, which has been isolated from the botanical garden of Skikda University in Algeria. The PHB production was tested under various conditions: a pH of 3–8, temperature range of 30–44 °C, carob extracted molasses concentration of 2–8% v/v, an incubation time of 24–96 h and an agitation speed of 150–300 rpm. The effects of different nitrogen sources and carob extracted molasses treatment types were also investigated. The PHB concentration was determined quantitatively as crotonic acid by measuring the absorbance at 300 nm. Cell growth was quantified by measuring the density of the culture at 600 nm. The presence of PHB was confirmed by applying high-performance liquid chromatography (HPLC) using an Aminex HPX-87H and implementing gas chromatography analysis. The best yield of PHB synthesis was obtained by using 6% v/v of 5 M H2SO4 treated with carob molasses as a carbon source, with peptone as a nitrogen source; incubation was conducted at 37 °C for 96 h at an agitation speed of 300 rpm (114.95 mg/L). The HPLC analysis confirmed the synthesis of PHB by B. paramycoides to have a chromatogram retention time of 22.5 min. Carob waste was successfully valorized to PHB.

Background: Biopolymers like polyhydroxyalkanoates (PHA) are the best natural macromolecules to use as alternative to the synthetic polymers. Many prokaryotes accumulate PHA as cytoplasmic intracellular granules and their accumulation is triggered by starving conditions. The PHAs are ecofriendly and used to create biodegradable plastics. The microbial synthesized PHA had acquired global importance in industrial and biomedical sectors. Results: Ten different bacterial strains were isolated for the screening of PHA producers from the estuarine region of the Bay of Bengal, Suryalanka in Bapatla. A yellowish slimy circular colony known as M4 is actively growing on selective minimal media and was screened for polymeric granules in its cytoplasm using Sudan Black B and confirmed with the fluorescent dye Nile blue A. All of the isolates were biochemically tested and isolate M4 is the most capable of growing at high NaCl concentrations (3.2 percent) and tests positive for catalase, methyl red. The M4 strain revealed clear hydrolysis of gelatin, starch, and casein. The 16S rRNA sequencing revealed that M4 is 99.72% of identity to Brachybacterium paraconglomeratum LMG 19861(T) in BLAST and the obtained strain was assigned with accession no. MTCC 13074 and deposited in NCBI with accession no. MW899045. The chief cellular fatty acids found in M4 were C14:0, C15:0, C16:0, C18:1cis-9, C18:0, iso-C15: 0, iso-C14: 0, anteiso-C17: 0 and C18:1-7. Crotonic acid formation from M4-PHB extract was detected at 235nm in a UV spectrophotometer. Methanolysis was done, and derivatives of polyhydroxybutyric acid (PHB) in the extract were analyzed using GC-MS. Increasing viscosity was seen in the extracts which confirms the presence of polymer in the extracts. Thermogravimetric analysis was studied to determine the thermal profile of the PHB in the extract of M4. Conclusion: In the study, the selective screening and extraction of ecofriendly PHB from M4 strain was highlighted. Brachybacterium paraconglomeratum is a novel strain showed its uniqueness by producing few monomeric derivatives of PHB. The strain was reporting for the first time as PHA producer. B. paraconglomeratum has promising characteristics according to its metabolic profile. In addition, this study also helps to understand the diversity of bacteria isolated from marine sources. [ABSTRACT FROM AUTHOR]

A new ammonolysis technology is developed for producing targeted functional C4 acids from a renewable feedstock, i.e., poly(3-hydroxybutyrate) (PHB). β-Aminobutyric acid (BABA) and β-hydroxybutyric acid (BHBA) are produced from PHB with an aggregate selectivity of 99% under a one-pot catalyst-free reaction at 140 °C. The product distribution can be controlled by ammonia concentration, and the reaction mechanism is investigated based on quantum chemical calculation. This work establishes a promising route for the production of β-substituted C4 acids via a green and sustainable pathway. [ABSTRACT FROM AUTHOR]

Synthesis of the originally assigned structure of the styryl tetrahydropyranol-dihydropyranone natural product cryptoconcatone H from C 2-symmetric (±)-1,8-nonadiene-4,6-diol is reported. Desymmetrization by Mitsunobu reaction with crotonic acid established the requisite inter-ring stereochemical relationship and was followed by a highly diastereoselective Re2 O7-catalyzed Prins cyclization with cinnamaldehyde to construct the 2,4,6- cis -tetrahydropyranol ring. Ring-closing metathesis resulted in formation of the dihydropyranone ring and completed the synthesis in three steps and 32% overall yield. The brevity of the synthesis is the result of the recognition of hidden, inter-ring symmetry in the target and the ensuing choice of an appropriately symmetric diol as our starting material. [ABSTRACT FROM AUTHOR]

Background: Microorganisms are an important factor in solubility of nutrition minerals; phosphate solubilizing fungi (PSF) considered one of the main sources of sustainability of agriculture production systems. Some fungi are well known for their natural capability to produce various organic acids, due to the lowering pH in the soil. The study amid to isolate PSF from rhizosphere soil and some plant residue and identify its secrenning compound using GC-MS analysis. Methods: in laboratory investigation during 2016, isolates of PSF and check their solubilizing activities using selective artificial media PVK and NBRIP in soild and broth form. The secrening of secondary organic compound in broth culture extracted and identify using GC-MS analysis. Result: the results inventory six isolates, among these isolates Aspergillus niger AD-A2 and AG-B1 were Distinguished by formed halo-clear zones around their colonies as a result of their phosphate-solubilizing ability in soild PVK and NBRIP media. pH decrese of the final product of PSF isolate in broth medium. Various compounds formed by submerged fermentation of A. niger isolates were 1,3-dioxan-5-ol (96.47%); octanoic acid, 4-chlorobenzyl ester (0.14%); 1,3,5-cycloheptatriene (0.58%); Crotonic acid (2.64%); 2-Propanone, 1,1-diethoxy (0.18%); 2-Butanone, 4-hydroxy (13.11%); 1-Tetrazol-2-ylethanone (86.4%); Propanethioamide (0.49%); Acetic acid, ethyl ester; Acetidin (100%); Methylolacetone (100%) and Trichoderma hamatum (T-113) were identified: Ethane, 1,1-diethoxy (100%) and 2-Butanone, 4-hydroxy-(100%). [ABSTRACT FROM AUTHOR]

With the threat of 'white pollution', the large‐scale production and application of biodegradable plastics have become crucial. Poly‐3‐hydroxybutyrate (PHB) is the simplest and most used member of the polyhydroxyalkanoate family, with a uniform C4 structural unit (C4H6O2). To reduce the impact of PHB on waste treatment, various recycling strategies have been developed for the tailored conversion of PHB to targeted chemicals and fuels. Given the special structural unit, PHB and its plastic forms have the potential to serve as a sustainable feedstock for producing a series of value‐added chemicals and fuels, including (i) crotonic acid via pyrolysis, (ii) (R)‐β‐hydroxybutyric acid via hydrolysis, (iii) propylene via depolymerization and decarboxylation, (iv) liquid fuels via deoxygenation and oligomerization, (v) n‐biobutanol via catalytic hydrogenolysis, (vi) methyl crotonate via thermolysis and esterification, (vii) (R)‐3‐hydroxybutyrate methyl ester via catalytic methanolysis, and (viii) β‐aminobutyric acid via ammonolysis. This review article provides a systematic review focusing on the reaction pathways, primary applications and market potential of the target products, and the pros and cons of current bio‐refineries in comparison with conventional petroleum refineries. The thermochemical processes developed for PHB degradation and polypropylene (a typical petroleum‐derived plastic to be replaced by PHB) are also comprehensively evaluated to reveal the future opportunities and challenges of PHB's broad‐scale production and utilization. PHB‐derived chemicals and fuels have a mature market already, and it is confirmed that the tailored valorization of PHB is a promising pathway to expand the market and gain more environmental and energy benefits. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the valorization of the date fruit by-product by conversion of date syrup into biopolymer polyhydroxybutyrate (PHB), based on the metabolic capacity of the bacterial strain Bacillus paramycoides to accumulate PHB from date syrup. Total reducing sugars in date syrup was essayed using 3',5-dinitrosalicylic acid (DNS) and HPLC methods. Bacillus paramycoides was isolated from soil of the botanic garden of Skikda university, Algeria. The accumulated PHB was extracted using chloroform. It was quantified as crotonic acid in concentrated sulfuric acid (H2SO4) by spectrophotometry at 300nm. Date syrup is characterized by high levels of total sugars (79.66 g/L) with 31.86 g/L of total reducing sugars. PHB accumulation reached its maximum (104.3 ug/mL) after 96 h of incubation at pH 7 and temperature 37°C using Tryptophane as the nitrogen source and acid pretreated syrup at a concentration of 8%. HPLC analysis on Aminex HPX-87H showed that the produced PHB from date syrup is characterized by a chromatogram peak with a retention time at 22.5 min. [ABSTRACT FROM AUTHOR]

This study was designed to investigate, at a laboratory scale, the possibility of valorizing the leftover carob fruits to produce the eco-friendly biopolymer polyhydroxybutyrate (PHB) by using the bacterial strain Bacillus paramycoides, which has been isolated from the botanical garden of Skikda University in Algeria. The PHB production was tested under various conditions: a pH of 3-8, temperature range of 30-44 °, carob extracted molasses concentration of 2-8% v/v, an incubation time of 24-96 hand an agitation speed of 150-300 rpm. The effects of different nitrogen sources and carob extracted molasses treatment types were also investigated. The PHB concentration was determined quantitatively as crotonic acid by measuring the absorbance at 300 nm. Cell growth was quantified by measuring the density of the culture at 600 nm. The presence of PHB was confirmed by applying high-performance liquid chromatography (HPLC) using an Aminex HPX-87H and implementing gas chromatography analysis. The best yield of PHB synthesis was obtained by using 6% v/v of 5 M H2SO4 treated with carob molasses as a carbon source, with peptone as a nitrogen source; incubation was conducted at 37 °C for 96 h at an agitation speed of 300 rpm (114.95 mg/L). The HPLC analysis confirmed the synthesis of PHB by B. paramycoides to have a chromatogram retention time of 22.5 min. Carob waste was successfully valorized to PHB. [ABSTRACT FROM AUTHOR]

With the growing interest in bioplastics, there is an urgent need to develop rapid analysis methods linked to production technology development. This study focused on the production of a commercially non-available homopolymer, poly(3-hydroxyvalerate) (P(3HV)), and a commercially available copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), through fermentation using two different bacterial strains. The bacteria Chromobacterium violaceum and Bacillus sp. CYR1 were used to produce P(3HV) and P(3HB-co-3HV), respectively. The bacterium Bacillus sp. CYR1 produced 415 mg/L of P(3HB-co-3HV) when incubated with acetic acid and valeric acid as the carbon sources, whereas the bacterium C. violaceum produced 0.198 g of P(3HV)/g dry biomass when incubated with sodium valerate as the carbon source. Additionally, we developed a fast, simple, and inexpensive method to quantify P(3HV) and P(3HB-co-3HV) using high-performance liquid chromatography (HPLC). As the alkaline decomposition of P(3HB-co-3HV) releases 2-butenoic acid (2BE) and 2-pentenoic acid (2PE), we were able to determine the concentration using HPLC. Moreover, calibration curves were prepared using standard 2BE and 2PE, along with sample 2BE and 2PE produced by the alkaline decomposition of poly(3-hydroxybutyrate) and P(3HV), respectively. Finally, the HPLC results obtained by our new method were compared using gas chromatography (GC) analysis.

Valorization of renewable and biodegradable biopolymers to value added chemicals and green fuels is currently considered as an important research topic aiming at reducing the dependency on fossil derived feedstocks as well as their negative consequences on the environment. In this report, we are introducing an ionic liquid (IL) mediated, sustainable, and green synthesis of crotonic acid (CA) from poly-(3-hydroxybutyrate, PHB), a biopolymer derived from microbial fermentation. In this actual case, imidazolium cation comprising ILs have been used in the synthesis, where the influence of various reaction parameters such as reaction temperature and types of ILs as well as the amount of polymer, water, and IL in the reaction mixture were examined. The conversion of PHB to CA in IL took place by a base catalyzed depolymerization with formation of crotonyl terminated polymeric entities as intermediates, a mechanism that was confirmed by NMR analysis of the reaction mixtures sampled when the reactions were carried out at various temperatures. The rate of CA formation via the IL mediated base catalyzed depolymerization increased with increasing temperature in the tested interval, and 97% yield of CA was obtained after 90 min at 140 °C. The [EMIM][AcO] IL applied as solvent and catalyst is capable of completely depolymerizing PHB to CA in 5 h at 120 °C up to a polymer loading of 40 wt%. At higher loadings the depolymerization became incomplete, which is attributed to a deactivation of the IL due to hydrogen bonding interactions with the in situ formed CA, confirmed by NMR and DSC techniques. Since the depolymerization is base catalyzed, the only tested ILs that were able to form CA were based on acetate anions, whereas the less basic or neutral [EMIM][Cl] IL was found to be inactive. Finally, more than 90% of CA as well as [EMIM][AcO] IL were recovered in high purity by solvent extraction with brine (saturated aqueous NaCl) and 2-methyl tetrahydrofuran (2-Me-THF). Most importantly, here we introduce a sustainable, metal free, and single solvent based reaction approach for selective depolymerization of PHB to industrially valuable CA in basic and recoverable ILs. [ABSTRACT FROM AUTHOR]

The ortho -tyrosinol derivative, as a key synthetic intermediate for alkaloidal metabolites of Cordyceps, was synthesized from L-phenylalanine methyl ester via condensation with crotonic acid and oxidative intramolecular lactone formation by using phenyliodine(III) bis(trifluoroacetate). Subsequent elongation of the side chain involving a cross-metathesis reaction and deprotection yielded cordytakaoamide B and cordycepamide C in notably few synthetic steps. Furthermore, the S- configurations at the C-2 position of both cordytakaoamide B and cordycepamide C were confirmed by comparison with the sign of the optical rotation of the synthetic sample. [ABSTRACT FROM AUTHOR]

An efficient Et3N/DMAP-assisted approach has been reported for the synthesis of indenopyrimidine sulfonamides from indenopyrimidine-2-amines via S-N bond formation. The various indenopyrimidine-2-amines were synthesized from crotonic acid, corresponding aldehydes and guanidinium hydrochloride using one-pot three-component strategy. The treatment of indenopyrimidine-2-amines with various sulfonyl chlorides in the presence of Et3N/DMAP in N-methylpyrrolidinone afforded the corresponding sulfonamides in good to excellent yields. All newly synthesized compounds were characterized by 1H NMR, 13C NMR and mass spectral studies. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate) (PHB) is a natural and biodegradable polyester which represents an alternative to replace conventional plastics in the packaging field. PHB production is currently limited owing to the high production costs. Early reports point to halotolerant and halophilic bacteria as feasible candidates for cost-effective production of PHB. Therefore, this work aimed at the synthesis of PHB using the extremely halotolerant Halomonas elongata DSM 2581T in nonsterile conditions and further mechanical evaluation of generated PHB films. H. elongata produced 2.96 g/L PHB after 72 h of incubation in a nonsterile medium supplemented with 1% w/v D-glucose and 0.1% w/v yeast extract at high salinity (8% w/v NaCl). The crotonic acid assay and 1H-NMR confirmed that the extracted polyester was PHB. The 2.7-µm thick 1% w/v PHB films generated using the polyester extracted from H. elongata indicated a higher hardness (43.78 MPa), Young's Modulus (1.28 GPa), tensile stress (9.99 MPa) and tensile strain 1.39% than those measured for the films fabricated from commercially available PHB and poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Overall, this study is the first report on the mechanical evaluation of a PHB film generated from the polyester recovered from H. elongata cultured at high salinity combined with nonsterile settings. In perspective, by producing PHB films from polyesters synthesized by H. elongata under nonsterile conditions it is possible to achieve mechanical properties required for the development of eco-friendly packaging products. [ABSTRACT FROM AUTHOR]

E-crotonic acid was isolated in cryogenic solid N2 and xenon matrices, and subjected to Laser ultraviolet (UV) and near-infrared (NIR) irradiations. In the deposited matrices, the two low-energy cis C-O E-cc and E-ct conformers, which are the only forms significantly populated in the gas phase, were observed. UV irradiation (λ= 250 nm) of the compound in N2 matrix allows for experimental detection, not just of the two low-energy cis C-O isomers of Z-crotonic acid previously observed in the experiments carried out in argon matrix [Z-cc and Z-ct; R. Fausto, A. Kulbida, and O. Schrems, J. Chem. Soc., Faraday Trans. 91, 3755-3770 (1995)] but also of the never observed before high-energy forms of both E- and Z-crotonic acids bearing the carboxylic acid group in the trans arrangement (Etc and Z-tc conformers). In turn, NIR irradiation experiments in the N2 matrix allow to produce the high-energy E-tc trans C-O conformer in a selective way, from the initially deposited E-cc form. The vibrational signatures of all the 6 rotameric structures of the crotonic acids experimentally observed, including those of the new trans C-O forms, were determined and the individual spectra fully assigned, also with support of theoretically obtained data. On the other hand, as found before for the compound isolated in argon matrix, the experiments performed in xenon matrix failed to experimental detection of the trans C-O forms. This demonstrates that in noble gas matrices these forms are not stable long enough to allow for their observation by steady state spectroscopy techniques. In these matrices, the trans C-O forms convert spontaneously into their cis C-O counterparts, by tunnelling. Some mechanistic details of the studied processes were extracted and discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A green strategy for highly efficient biodegradable oligomeric lactate flame-retardant plasticizers (PBCL) was developed. • The PBCL could be used to prepare ultra-flexible and flame-retardant poly (lactic acid) composites. • The PBCL could improve crystallinity and crystallization rate of PLA resin. • The PBCL were degradable with active soil and tenebrio molitors. Biobased multifunctional plastic additives not only overcome the toxicity and non-degradability of phthalates but also provide multiple functions to polymers. In this study, novel biodegradable oligomeric lactate flame-retardant plasticizers (PBCL) integrated from l-lactic acid and crotonic acid with excellent fire-retardant and plasticizing functions were synthesized to overcome the inflammability and fragileness of poly(lactic acid) (PLA). The results revealed that PBCL-plasticized PLA composites achieved a good balance between flexibility and fire retardancy. Even with a ratio of 0.2:1 of 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to 2-(2-n-butoxyethoxy) ethanol of crotonic acid lactate ester (BCL), the plasticized PLA blends showed the highest elongation at break (433.72 %), accompanied by a high limiting oxygen index (27.1 %). Remarkably, the vertical burning tests (UL-94) indicated that all blends passed UL-94 V-0 grade, signifying their superior fire resistance. Interestingly, the addition of PBCL had minimal impact on the transparency of PLA, with the transmittances of all composites still remained at above 87 % at 800 nm. Furthermore, the PBCL-plasticized PLA composites exhibited better migration resistance and volatility resistance than commercial plasticizer acetyl tributyl citrate (ATBC). Additionally, the biodegradability of PBCL was studied through the degradation experiments using active soil and tenebrio molitors, with characterization of the degradation products. The results of the biodegradation experiments showed that PBCL decomposed into non-toxic and harmless small molecules. This study presents an eco-benign method for developing biodegradable additives with flame-retardant and plasticizing functions, holding excellent prospects for industrial applications. [ABSTRACT FROM AUTHOR]

The results described in the literature and our previous research confirms the efficiency of the reduction reactions of α, β-unsaturated compounds and carbonyl compounds mediated by the Ni-Al alloy in alkaline (NaOH) aqueous solution. Some particularly experiments for reduction of crotonic and cinnamic acid, was designed to bring information on the mechanism of reduction reaction with Ni-Al alloys in alkaline aqueous media. Also it was developed several deuteriation reaction of this α, β-unsaturated acids. The analysis of the isotopic distribution shows a significant and reproducible difference between Cα and Cβ that help us to draw some conclusions. In addition, recent researches give us additional arguments concerning the existence of anionic aluminum clusters with water. All this information contributes to propose a mechanism of reduction reaction and could provide new possibilities for development of this reaction: improving yield and selectivity, promoting a new synthesis etc.

A novel thermolytic distillation process was developed to depolymerize polyhydroxybutyrate (PHB) for the selective production of crotonic acid. The conditions adopted (170 °C, 150 mbar) were applied to pure PHB and PHB-enriched bacteria containing 60 and 30% of PHB, giving a recovery of crotonic acid of 92, 78 and 58%, respectively. The high efficiency of the developed process poses the basis for a drop-in production of bio-based crotonic acid, whose versatility as a platform chemical has been investigated through a photochemical approach. The photocatalytic addition (promoted by tetrabutylammonium decatungstate – TBADT) of aliphatic and aromatic aldehydes to crotonic acid took place under solar-simulated light irradiation. TBADT triggered the in situ formation of valuable acyl radicals from the corresponding aldehydes, thus inducing the desired hydroacylation via radical conjugate addition. Notably, the functionalization took place in a satisfactory yield quite independently of the adopted sample of crotonic acid (whether commercial or bio-based). [ABSTRACT FROM AUTHOR]

To prepare biobased polymers, particular attention must be paid to the obtention of the monomers from which they are derived. (Meth)acrylates and their analogs constitute such a class of monomers that have been extensively studied due to the wide range of polymers accessible from them. This review therefore aims to highlight the progresses made in the production and polymerization of (meth)acrylates and their analogs. Acrylic acid production from biomass is close to commercialization, as three different high‐potential intermediates are identified: glycerol, lactic acid, and 3‐hydroxypropionic acid. Biobased methacrylic acid is less common, but several promising options are available, such as the decarboxylation of itaconic acid or the dehydration of 2‐hydroxyisobutyric acid. Itaconic acid is also a vinylic monomer of great interest, and polymers derived from it have already found commercial applications. Methylene butyrolactones are promising monomers, obtained from bioresources via three different intermediates: levulinic, succinic, or itaconic acid. Although expensive, methylene butyrolactones have a strong potential for the production of high‐performance polymers. Finally, β‐substituted acrylic monomers, such as cinnamic, fumaric, muconic, or crotonic acid, are also examined, as they provide an original access to biobased materials from various renewable raw materials, such as protein waste, lignin, or wastewater. [ABSTRACT FROM AUTHOR]

Introduction: Poly(3-hydroxybutyrate) (PHB) is a well-known biodegradable polymer produced by some microorganisms and can be a suitable alternative for petrochemical plastics. PHB synthase encoded by phbC gene is the main enzyme in PHB biosynthesis pathway in Ralstonia eutropha. The aim of current study was the transformation of R. eutropha PTCC 1615 with its own phbC gene and evaluation of the overexpression effect on PHB accumulation. Methods: DNA fragment including phbC gene and its promoter and terminator regions, was isolated from R. eutropha PTCC 1615, inserted into pET28a(+) vector, and transferred to the competent bacteria using calcium chloride and heat shock method. The effect of the cloned gene expression on PHB production was investigated with absorption of crotonic acid produced through PHB dehydration. Statistical analyses were carried out by SPSS software. Results: PHB content of cells of the engineered strain was 1.4 times more than that of the native bacteria. This significant difference can be an important finding for improvement of biopolymer production. Conclusion: Overexpression of phbC, the critical gene in PHB biosynthesis pathway, in R. eutropha PTCC 1615 had considerable effect on PHB accumulation. [ABSTRACT FROM AUTHOR]

β-Aminobutyric acid (BABA) can be widely used in the preparation of anti-tumor drugs, AIDS drugs, penicillin antibiotics, and plant initiators. However, the efficient, economical, and environmentally friendly production of BABA still faces challenges. Its important production enzyme, aspartase, catalyzes the substrate crotonic acid, and depends on harsh conditions, such as high temperatures and the presence of strong alkali. Here, we modified the surface charge of the enzyme to enable it to become more negatively charged (K19E, N87E, N125D, S133D, Q262E, and N451E; from −60 to −80), reducing its optimal pH from 9.0 to 8.0. The M20 enzyme showed improved specific activity (400.21 mU/mg at pH 8.0; 2.47-fold that of aspartase), and at pH 7.0, its activity increased 3-fold. The thermal stability of the enzyme was also improved. For the production of BABA, a 500 g/L whole-cell transformation was obtained with a 1.41-fold increase in yield, and the final production of BABA reached 556.1 g/L within 12 h. Our method provides a new strategy for modifying the characteristics of the enzyme through the modification of its surface charge, which also represents the first modification of the optimal pH for aspartase. [ABSTRACT FROM AUTHOR]

Aspartate ammonia-lyase gene of Bacillus sp.YM55-1 was cloned into the expression vector pET-28a(+). By site-directed mutagenesis of aspartate ammonia-lyase gene, the heterologous expression was obtained in E. coli BL21 (DE3) cells. Conversion of crotonic acid to (R)-3-aminobutyric acid was performed by the recombinant aspartate ammonia-lyase in the presence of ammonia and ammonium sulfate. The aspartate ammonia-lyase engineering bacteria were prepared into immobilized cells, and then enzymatic reaction conditions were optimized to achieve higher production of (R)-3-aminobutyric acid. The optimum pH and reaction temperature was 9.0 and 40 °C, respectively. Under these conditions, immobilized cells of 30 g/L were added and incubated for 22 h. Finally, the production of (R)-3-aminobutyric acid was 220 g/L, enantiomeric excess was more than 99.95%, conversion up to 98% and immobilized cells could be reused no less than 24 times. [ABSTRACT FROM AUTHOR]

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We report a reaction platform for the synthesis of three different high‐value specialty chemical building blocks starting from bio‐ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative dehydrogenation of ethanol to acetaldehyde generates an aldehyde‐containing stream active for the production of C4 aldehydes via base‐catalyzed aldol‐condensation. Then, the resulting C4 adduct is selectively converted into crotonic acid via catalytic aerobic oxidation (62 % yield). Using a sequential epoxidation and hydrogenation of crotonic acid leads to 29 % yield of β‐hydroxy acid (3‐hydroxybutanoic acid). By controlling the pH of the reaction media, it is possible to hydrolyze the oxirane moiety leading to 21 % yield of α,β‐dihydroxy acid (2,3‐dihydroxybutanoic acid). Crotonic acid, 3‐hydroxybutanoic acid, and 2,3‐dihydroxybutanoic acid are archetypal specialty chemicals used in the synthesis of polyvinyl‐co‐unsaturated acids resins, pharmaceutics, and bio‐degradable/ ‐compatible polymers, respectively. [ABSTRACT FROM AUTHOR]

Post-translational modifications (PTMs) play pivotal roles in controlling the stability and activity of the tumor suppressor p53 in response to distinct stressors. Here we report an unexpected finding of a short chain fatty acid modification of p53 in human cells. Crotonic acid (CA) treatment induces p53 crotonylation, but surprisingly reduces its protein, but not mRNA level, leading to inhibition of p53 activity in a dose dependent fashion. Surprisingly this crotonylation targets serine 46, instead of any predicted lysine residues, of p53, as detected in TCEP-probe labeled crotonylation and anti-crotonylated peptide antibody reaction assays. This is further confirmed by substitution of serine 46 with alanine, which abolishes p53 crotonylation in vitro and in cells. CA increases p53-dependent glycolytic activity, and augments cancer cell proliferation in response to metabolic or DNA damage stress. Since serine 46 is only found in human p53, our studies unveil an unconventional PTM unique for human p53, impairing its activity in response to CA. Because CA is likely produced by the gut microbiome, our results also predict that this type of PTM might play a role in early human colorectal neoplasia development by negating p53 activity without mutation of this tumor suppressor gene. • p53 in human cells is crotonylated in response to crotonic acid. • This crotonylation is detected independently by a Pan anti-crotonylated peptide antibody and a TCEP probe. • This crotonylation surprisingly occurs at the serine 46 residue of p53. • Substitution of serine 46, but not any of predicted lysines, by alanine abolishes this p53 crotonylation. • Crotonic acid increases glycolytic activity and cancer cell proliferation by impairing p53 activity in human cancer cells. [ABSTRACT FROM AUTHOR]

Poly(N,N-dimethymethylacrylamide -co-crotonic acid) (P(DMA-CAx)) hydrogels were prepared by free radical polymerization, using N,N- methylenebisacrylamide (NMBA) as cross-linking agent. The synthesized hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The effects of comonomer composition and pH of the medium on the swelling behavior of hydrogels were investigated. The obtained results showed that the swelling capabilities of hydrogels increased as crotonic acid content and pH increased. In order to evaluate the controlled release potential of the polymeric matrix, it was loaded with potassium nitrate and ammonium nitrate as fertilizers and the release kinetics was studied as a function of the chemical composition of the hydrogel and the content of the fertilizer. Various kinetic parameters such as the diffusion exponent and diffusion coefficient were also determined. These pH sensitive copolymer hydrogels present a promising approach for controlled release of fertilizers. [ABSTRACT FROM AUTHOR]

We herein designed two new PtIV prodrugs of oxoplatin (cis,cis,cis-[PtCl2(NH3)2(OH)2]), [PtIVCl2(NH3)2(O2C-FA)2] (Pt-2) and [PtIVCl2(NH3)2(O2C-RH)2] (Pt-3), by conjugating with ferulic acid (FA-COOH) and rhein (RH-COOH) which have well-known biological activities. Three other Pt(IV) complexes of [PtIVCl2(NH3)2(O2C-BA)2] (Pt-1), [PtIVCl2(NH3)2(O2C-CA)2] (Pt-4) and [PtIVCl2(NH3)2(O2C-TCA)2] (Pt-5) (where BA-COOH = benzoic acid, CA-COOH = crotonic acid and TCA-COOH = trans-cinnamic acid) were also prepared for the comparative study. Like most PtIV prodrug complexes, the cytotoxicity of Pt-3 containing the biologically active rhein (RH-COOH) ligand against lung carcinoma (A549 and A549/DDP) cells was higher than those of Pt-1, Pt-2, Pt-4, cisplatin and Pt-5. Moreover, the cytotoxicity of Pt-3 in HL-7702 normal cells was lower than those of PtIV derivatives bearing BA-COOH, FA-COOH, TCA-COOH and CA-COOH ligands. The highly efficacious Pt-2 and Pt-3 were found to accumulate strongly in the A549/DDP cells, with the prodrug Pt-3 showing highest levels of penetration into the mitochondria. The prodrug Pt-3 effectively entered the A549/DDP cells and caused mitochondrial damage, significantly greater than Pt-2. In addition, the prodrug Pt-3 exhibited higher antitumor efficacy (inhibition rates (IR) = 67.45%) than Pt-2 (28.12%) and cisplatin (33.05%) in the A549/DDP xenograft mouse model. Thus, the prodrug Pt-3 containing the rhein (RH-COOH) ligand is a promising candidate drug targeting the mitochondria. [ABSTRACT FROM AUTHOR]

FK520 (ascomycin), a 23-membered macrolide with immunosuppressive activity, is produced by Streptomyces hygroscopicus. The problem of low yield and high impurities (mainly FK523) limits the industrialized production of FK520. In this study, the FK520 yield was significantly improved by strain mutagenesis and genetic engineering. First, a FK520 high-producing strain SFK-6-33 (2432.2 mg/L) was obtained from SFK-36 (1588.4 mg/L) through ultraviolet radiation mutation coupled with streptomycin resistance screening. The endogenous crotonyl-CoA carboxylase/reductase (FkbS) was found to play an important role in FK520 biosynthesis, identified with CRISPR/dCas9 inhibition system. FkbS was overexpressed in SFK-6-33 to obtain the engineered strain SFK-OfkbS, which produced 2817.0 mg/L of FK520 resulting from an increase in intracellular ethylmalonyl-CoA levels. In addition, the FK520 levels could be further increased with supplementation of crotonic acid in SFK-OfkbS. Overexpression of acetyl-CoA carboxylase (ACCase), used for the synthesis of malonyl-CoA, was also investigated in SFK-6-33, which improved the FK520 yield to 3320.1 mg/L but showed no significant inhibition in FK523 production. To further enhance FK520 production, FkbS and ACCase combinatorial overexpression strain SFK-OASN was constructed; the FK520 production increased by 44.4% to 3511.4 mg/L, and the FK523/FK520 ratio was reduced from 9.6 to 5.6% compared with that in SFK-6-33. Finally, a fed-batch culture was carried out in a 5-L fermenter, and the FK520 yield reached 3913.9 mg/L at 168 h by feeding glycerol, representing the highest FK520 yield reported thus far. These results demonstrated that traditional mutagenesis combined with metabolic engineering was an effective strategy to improve FK520 production. [ABSTRACT FROM AUTHOR]

• This is the first application of organic phosphazene bases to PHB pyrolysis. • PHB pyrolysis proceeded smoothly at 110 °C as the mildest condition demonstrated to date. • The effects of types and content of catalyst, solvent polarity, and temperature were explored. • The mechanism involves a random chain scission process caused by β -elimination reaction. Utilizing end-of-life poly(3-hydroxybutyrate) (PHB) as a carbon source for the production of value-added chemicals has attracted increasing interest in recent years. In this report, an organocatalytic pyrolysis method was explored for chemical recycling of PHB into trans -crotonic acid (CA). Under relatively mild conditions and through the promotion of organic base catalysts, the CA was recovered with high efficiency and yield. The effect of reaction conditions on the depolymerization process, such as types of catalysts, solvent polarity, temperature, and molar equivalents of PHB to catalyst, was investigated in detail. This work is the first to achieve the pyrolysis of PHB using organic base catalysts, which provides a green and efficient option for plastic degradation and promotes the development of circular plastic economy. [ABSTRACT FROM AUTHOR]

Conventional wastewater treatment processes can be tailored to recover organic carbon from wastewater as intracellular polyhydroxybutyrate (PHB) polymer granules while simultaneously meeting effluent discharge standards. Traditional applications of PHB as a bioplastic are hampered by its suboptimal properties (e.g., brittle), lack of efficient and sustainable approaches for recovering PHB from cells, and concerns about wastewater-derived impurities. In this study, we report on the conversion of PHB and its monomer acids – 3-hydroxybutyric acid (3HBA) and crotonic acid (CA) – under hydrothermal conditions (in condensed water at elevated temperature and pressure) to form propylene, a valuable chemical intermediate that self-separates from water. PHB depolymerization results in a mixture of 3HBA and CA, which can interconvert via (de)hydration reactions that vary with prevailing reaction conditions. Further hydrothermal conversion of the monomer acids yields propylene and CO2. Conversion of 3HBA occurs at lower temperatures than CA, and a new concerted dehydration-decarboxylation pathway is proposed, which differs from the sequential dehydration (3HBA to CA) and decarboxylation (CA to propylene and CO2) pathway reported for dry thermal conversion. A kinetics network model informed by experimental results reveals that CA conversion to propylene and CO2 proceeds predominantly via hydration to 3HBA followed by the concerted dehydration-decarboxylation pathway rather than by direct decarboxylation of CA. Demonstrative experiments using PHB-containing methanotrophic biomass show results consistent with the model, producing propylene at near-theoretical yields at lower temperatures than reported previously. [ABSTRACT FROM AUTHOR]

Commercial metallocene ethylene–octene random copolymer, Resinex PE RXP 1502 (RXP), was grafted with acrylic or crotonic acid in the solution and in the melt to increase the RXP's polarity and adhesion to cellulose-based substrates. Acrylic or crotonic acids were grafted on the RXP macromolecules which were activated with an oxygen–ozone mixture. The formed graft copolymer was tested as additive to a hot melt adhesive (HMA) improving adhesive properties. The most effective procedure was to graft RXP with acrylic acid in the melt, while grafting activated RXP in a toluene solution was less efficient. The melt grafting efficiency is high and varies between 0.77 and 0.97. The RXP polarity after grafting increases significantly, as there is a 15% decrease in the water contact angle and an increase in the surface energy and its polar component by 1.1–1.7 times as compared to the virgin RXP. The heat-fail temperature resistance in peel of RXP grafted with acrylic and/or crotonic acid increased by more than 10°C, while the heat-fail temperatures of adhesive joints in shear tests were similar. The adhesive joint peel strength increased 1.2 times. The cardboard–HMAs based on virgin RXP adhesive joint peel tests exhibit adhesive failure, whereas the cardboard–HMAs containing grafted RXP joints show cohesive failure. [ABSTRACT FROM AUTHOR]

Oxidation of crotonaldehyde to crotonic acid is an important chemical reaction process because crotonic acid, its derivative and copolymer are ubiquitous in the productions of chemical, cosmetic, and medicines. However, the reactor safety and process efficiency are still not satisfactory. In order to solve such problems, a novel reactor of gas-liquid-solid mini-fluidized bed with bed inner diameter of 3 mm was developed to carry out the selective catalytic oxidation reaction. The effects of operation conditions and solid particle properties on the conversion rate of reactant crotonaldehyde and the selectivity of product crotonic acid were investigated. The causes of these effects are explained from the standpoint of residence time and gas-liquid mass transfer flux. Moreover, the comparison of reactor performance between the three-phase mini-fluidized bed and the batch stirred tank reactor as a traditional one was made to evaluate the performance of such a reactor. Experimental results show that the average reaction or conversion rate of the mini-fluidized bed is about 30 times much higher than that of batch stirred tank reactor to evaluate the improved performance. But the selectivity is less affected by the operation conditions and solid particle bed properties. The size reduction of three-phase mini-fluidized bed decreases the mass transfer distance of molecular diffusion, and the solid particles and mini-bubbles not only provide the higher specific interface area but also cause hydrodynamics changes that is to intensify the interface disturbance, which effectively accelerate the mass transfer. Unlabelled Image • The performance of a novel gas-liquid-solid mini-fluidized bed was studied. • The comparison of reactor performance with batch stirred tank reactors was made. • The explanation standpoints are residence time and gas-liquid mass transfer flux. • The presence of solid particles and mini-bubbles accelerate the mass transfer. [ABSTRACT FROM AUTHOR]

Highlights • Porphyrin conjugated microporous polymer rapid fabricated by microwave heating.. • Porphyrin conjugated microporous polymer based SPME coating fabricated. • SPME-GC/MS method for the analysis of VOAs in tobacco with excellent selectivity. • A simulation studies the interaction between targets and Porphyrin-CMP. Abstract Conjugated microporous polymers (CMPs) with permanent microporosity and extended p -conjugated skeletons have recently shown the fascinating application in separation and enrichment. In this report, porphyrin CMP that possessed microporous structure and nitrogen-rich pyrrole building blocks was successfully synthesized by microwave-assisted method. Then, a novel coating based on porphyrin CMP was fabricated on silica fiber for efficient enrichment volatile organic acids (VOAs). The simulation showed the coating exhibited strong interaction with volatile organic acids based on charge transfer interaction, hydrogen bond and size effect. Hence, we proposed a method for determination of volatile organic acids in tobaccos by headspace solid-phase microextraction (HS-SPME) with porphyrin CMP coating by gas chromatography-mass spectrometry. The results showed that the coating provided high enrichment factors for VOAs ranging from 66,657 to 133,970 and low limits of detection from 4.6 to 22 ng/L. A good linearity was observed for propionic acid and crotonic acid ranging from 0.050 to 8.0 μg/L, 2-methylheptanoic acid ranging from 0.063 to 1.5 μg/L, others ranging from 0.025 to 3.0 μg/L with the determination coefficient (R2) between 0.9900 and 0.9980. The strategy for determination of volatile compounds in complex solid samples was successfully applied to the analysis of volatile organic acids in tobacco leaves. The results showed that the method was accurate and reliable. [ABSTRACT FROM AUTHOR]