Phthalic Anhydride Research Articles

Synthesis, Crystal Structure, DFT Calculations, Hirshfeld Surface Analysis and In Silico Drug-Target Profiling of (R)-2-(2-(1,3-Dioxoisoindolin-2-yl)propanamido)benzoic Acid Methyl Ester.

The work here reflects synthesis, DFT studies, Hirshfeld charge analysis and crystal data exploration of pharmacologically important (R)-2-(2-(1,3-dioxoisoindolin-2-yl)propanamido)benzoic acid methyl ester (5) to understand its properties for further chemical transformations. The methyl anthranilate (2) was produced by the esterification of anthranilic acid in an acidic medium. The phthaloyl-protected alanine (4) was rendered by the fusion of alanine with phthalic anhydride at 150 °C, followed by coupling with (2) furnished isoindole (5). The characterization of products was performed using IR, UV-Vis, NMR and MS. Single-crystal XRD also verified the structure of (5) in which N-H⋯O bonding stabilizes the molecular configuration of (5), resulting in the formation of S(6) hydrogen-bonded loop. The molecules of isoindole (5) are connected in the form of dimers, and the π⋯π stacking interaction between aromatic rings further stabilizes the crystal packing. DFT studies suggest that HOMO is over the substituted aromatic ring, the LUMO is present mainly over the indole side, and nucleophilic and electrophilic corners point out the reactivity of the product (5). In vitro and in silico analysis of (5) shows its potential as an antibacterial agent targeting DNA gyrase and Dihydroorotase from E. coli and tyrosyl-tRNA synthetase and DNA gyrase from Staphylococcus aureus.

Sequence Control in Asymmetric Terpolymerizations of meso-Epoxides, CO2 , and Phthalic Anhydride: Unprecedented Statistical Ester-Carbonate Distributions.

The statistical terpolymerization of epoxides, CO2 and cyclic anhydrides remains challenging, mainly because epoxide/CO2 and epoxide/anhydride copolymerizations typically proceed at considerably different rates. Herein, we report the syntheses of novel chiral terpolymers with unprecedented statistical distributions of carbonate and ester units (up to 50 % junction units) via the one-pot reaction of cyclohexene oxide, phthalic anhydride, and CO2 under mild conditions using enantiopure bimetallic aluminum-complex-based catalyst systems. Notably, all resulting terpolymers exhibited excellent enantioselectivities (≥96 % ee) that were independent of the carbonate-ester distribution. The statistical compositions of the carbonate and ester units in the resulting terpolymers were determined via 1 H and 13 C NMR spectroscopies. Furthermore, thermal properties were tuned by altering the ester content of the chiral terpolymer without influencing the enantioselective ring-opening step involving the meso-epoxide. This asymmetric terpolymerization methodology is also compatible with a variety of meso-epoxides to afford the corresponding terpolymers with 17 %-25 % junction units and excellent enantioselectivities (94 %-99 % ee). The present study is expected to provide new guidelines for preparing a broad range of biodegradable polymers with excellent enantioselectivities and adjustable properties.

Sequence Control in Asymmetric Terpolymerizations of meso‐Epoxides, CO2, and Phthalic Anhydride: Unprecedented Statistical Ester–Carbonate Distributions

AbstractThe statistical terpolymerization of epoxides, CO2 and cyclic anhydrides remains challenging, mainly because epoxide/CO2 and epoxide/anhydride copolymerizations typically proceed at considerably different rates. Herein, we report the syntheses of novel chiral terpolymers with unprecedented statistical distributions of carbonate and ester units (up to 50 % junction units) via the one‐pot reaction of cyclohexene oxide, phthalic anhydride, and CO2 under mild conditions using enantiopure bimetallic aluminum‐complex‐based catalyst systems. Notably, all resulting terpolymers exhibited excellent enantioselectivities (≥96 % ee) that were independent of the carbonate–ester distribution. The statistical compositions of the carbonate and ester units in the resulting terpolymers were determined via 1H and 13C NMR spectroscopies. Furthermore, thermal properties were tuned by altering the ester content of the chiral terpolymer without influencing the enantioselective ring‐opening step involving the meso‐epoxide. This asymmetric terpolymerization methodology is also compatible with a variety of meso‐epoxides to afford the corresponding terpolymers with 17 %–25 % junction units and excellent enantioselectivities (94 %–99 % ee). The present study is expected to provide new guidelines for preparing a broad range of biodegradable polymers with excellent enantioselectivities and adjustable properties.

N-Substituted (Hexahydro)-1H-isoindole-1,3(2H)-dione Derivatives: New Insights into Synthesis and Characterization

Novel phthalimide derivatives, namely N-(1,3-dioxoisoindolin-2-yl)-2-(2-methyl-4-oxoquinazolin-3(4H)-yl)acetamide (1a) and N-(1,3-dioxoisoindolin-2-yl)thiophene-2-carboxamide (1b), and hexahydrophthalimide derivative N-(1,3-dioxohexahydro-1H-isoindol-2(3H)-yl)-2-(2-methyl-4-oxoquinazolin-3(4H)-yl)acetamide (2), have been synthesized. The phthalimide derivatives were synthesized from phthalic anhydride and 2-(2-methyl-4-oxoquinazolin-3(4H)-yl)acetohydrazide or thiophene-2-carbohydrazide, and the hexahydrophthalimide derivative has been synthesized from hexahydrophthalic anhydride and 2-(2-methyl-4-oxoquinazolin-3(4H)-yl)acetohydrazide. The chemical structures of the compounds are elucidated by Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectra. The new in vitro antioxidant activities of the obtained substances were evaluated using the DPPH method. All tested compounds showed antioxidative activity, the most active compound being 1b. Bioinformatics tools were used for the prediction of pharmacokinetics and pharmacodynamics profiles. Our results showedthat all compounds have a suitable intestinal absorption rate, good BBB and CNS permeabilities and have as molecular targets MAO B, COX-2 and NF-KB, important for antioxidant activities.

Bimetallic Nickel Complexes as Effective and Versatile Catalysts for Copolymerization of Epoxides with Carbon Dioxide or Phthalic Anhydride: Catalysis and Kinetics

This study reported three novel structurally well-characterized dihalide dinuclear nickel complexes containing benzotriazole-based 1,3-diamine-linked bisphenolate ligands, which were high-performance catalysts for ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and carbon dioxide (CO2). The dinickel diiodo 3 was shown to catalyze CO2 copolymerization of CHO with high activity (turnover frequency up to 2250 h-1), excellent selectivity (>99% polycarbonates, >99% carbonate repeated units), and good molecular weight controllability. Apart from CO2/CHO copolymerization, the most active complex 3 was found to effectively catalyze ROCOP of CHO with phthalic anhydride (PA). Not only has the controllable manner of 3 for PA/CHO copolymerization been proven but also a broad substrate scope for PA copolymerization of epoxides by the same complex has been achieved. Diverse terminal or internal epoxides were demonstrated to copolymerize PA by 3, producing the corresponding semiaromatic polyesters with good activity and excellent product selectivity. Kinetic studies for CHO copolymerization of CO2 or PA mediated by 3 were systematically investigated. For kinetics of PA/CHO copolymerization, it allowed us to propose the rate equation of -d[CHO]/dt = kp[3]1[PA]0[CHO]1, and such catalysis displayed a first-order dependence on both dinickel complex and CHO concentrations as well as a zero order for PA. This work offers a bimetallic dihalide nickel complex as an efficient and versatile catalyst for two different types of copolymerization catalysis.

Synthesis and study of poly (phthalic anhydride-β-cyclodextrin) for the efficient adsorption of cationic dyes from industrial wastewater

In this study, a novel adsorbent capable of efficiently adsorbing cationic dyes, poly (phthalic anhydride-β-cyclodextrin) (PhAEs-β-CD), was synthesized by self-cross-linking of phthalic anhydride (PhA)-modified-β-cyclodextrin. The PhA cross-linker plays a dual role of providing coordination sites for cationic dye binding and contributing to the large specific surface area owing to the existence of rigid aromatic groups. The adsorption properties of PhAEs-β-CD for cationic dyes were investigated, and the results revealed that the adsorbent contains numerous functional groups and has a high specific surface area (332.14 m2/g), which is highly beneficial for cationic dye removal. The maximum adsorption capacities of PhAEs-β-CD were found to be 3288.80 mg·g−1 for basic green 4, 2407.87 mg·g−1 for crystal violet, 2264.40 mg·g−1 for astrazon pink FG, and 1401.33 mg·g−1 for methylene blue. The adsorption mechanism and system were modeled by using the Langmuir isotherm model and the pseudo-second-order kinetic model. The removal efficiency of the adsorbent for basic green 4 reached more than 90 % even after five regeneration cycles, indicating that the adsorbent had good regenerative capacity. These findings demonstrated the potential application of PhAEs-β-CD in dye wastewater treatment.

COPOLYMERIZATION OF UNSATURATED OLIGOESTERS MODIFIED WITH NITROGEN-CONTAINING COMPOUNDS WITH METHYL METHACRYLATE

In the present work, the kinetics of radical copolymerization in solution at the initial stages of polyglycol maleinate phthalates modified with nitrogen-containing compounds with methyl methacrylate in a ratio of 1:1 was studied. Cyclohexanone was used as a solvent, and benzoyl peroxide was used as an initiator. The study was carried out at temperatures of 50 and 60 °C by dilatometry using collapsible dilatometers and a centrifuge. 13 amine-containing compounds of different types were chosen as modifiers. Also, for comparison, the possibility of using amides and hydrazines as modifiers was checked. Polycondensation was carried out in an oil bath at 175 °C and with vigorous stirring with water withdrawal until a constant acid number was reached. It is shown that the addition of 0.1 mol/l modifier during the polycondensation of a mixture of maleic and phthalic anhydrides with ethylene glycol makes it possible to obtain an unsaturated oligoester, for which the temperature coefficient of the reaction of its copolymerization with methyl methacrylate is significantly reduced. This allows for non-isothermal curing to increase the volume of the copolymer block without the risk of overheating and destruction. Of the studied amines, para-aminoacetophenone turned out to be the most effective; its use as a modifier makes it possible to reduce the temperature coefficient of the reaction from 2.1 to 1.7. The rate of copolymerization at the initial stages for the studied modified systems decreases from 2 to 20 times. The results of the work allow us to propose a technology for the production of polymeric materials by molding them in blocks of much larger sizes than with the use of traditional unsaturated oligomers. Also, calculations were carried out according to a special technique and the maximum size of a copolymer block in the form of a cylinder was determined, in which the height is equal to the radius, which can be obtained by forming it in a non-isothermal mode in a thin layer form with convection air cooling and the maximum allowable temperature in the system is 90 °C. It is shown that the volume of such a block, when using some modified oligomers, increases significantly. Some physical and mechanical characteristics of the obtained copolymers with methyl methacrylate were determined, and it was shown that modification with nitrogen-containing compounds does not improve or worsen the studied characteristics.

Synthesis of Sequence-specific Poly(ester-carbonate) Copolymers via Chemoselective Terpolymerization Controlled by the Stoichiometric Ratio of Phosphazene/Triethylborane.

Chemoselective terpolymerization can produce polymer materials with diverse compositions and sequential structures, and thus have attracted considerable attention in the field of polymer synthesis. However, the intrinsic complexity of three-component system also brings great chanllenge, in regard to the reactivity and selectivity of different monomers. Herein, we report the terpolymerization of CO2 /epoxide/anhydride by a binary organocatalytic C3 N3 -Py-P3 /TEB (triethylborane) system. Both the activity and chemoselectivity were highly dependent upon the molar ratio of C3 N3 -Py-P3 to TEB, and sequence-controlled poly(ester-carbonate) copolymers were readily synthesized through one-pot/one-step methodology by tuning the stoichiometric ratio of phosphazene/TEB. In particular, C3 N3 -Py-P3 /TEB with a molar ratio of 1/0.5 exhibited an unprecedentedly high chemoselectivity for ring-opening alternating copolymerization (ROAC) of cyclohexene oxide (CHO) and phthalic anhydride (PA) first and then ROAC of CO2 /CHO. Thus, well-defined triblock polycarbonate-b-polyester-b-polycarbonate copolymers can be produced from the mixture of CO2 , CHO and PA using a bifunctional initiator. With C3 N3 -Py-P3 /TEB=1/1, tapered copolymers were obtained, while random copolymers with high content of polycarbonate (PC) were synthesized with further increasing the amount of TEB. The mechanism of the unexpected chemoselectivity was further investigated by DFT calculations.

Synthesis of Sequence‐specific Poly(ester‐carbonate) Copolymers via Chemoselective Terpolymerization Controlled by the Stoichiometric Ratio of Phosphazene/Triethylborane

AbstractChemoselective terpolymerization can produce polymer materials with diverse compositions and sequential structures, and thus have attracted considerable attention in the field of polymer synthesis. However, the intrinsic complexity of three‐component system also brings great chanllenge, in regard to the reactivity and selectivity of different monomers. Herein, we report the terpolymerization of CO2/epoxide/anhydride by a binary organocatalytic C3N3‐Py‐P3/TEB (triethylborane) system. Both the activity and chemoselectivity were highly dependent upon the molar ratio of C3N3‐Py‐P3 to TEB, and sequence‐controlled poly(ester‐carbonate) copolymers were readily synthesized through one‐pot/one‐step methodology by tuning the stoichiometric ratio of phosphazene/TEB. In particular, C3N3‐Py‐P3/TEB with a molar ratio of 1/0.5 exhibited an unprecedentedly high chemoselectivity for ring‐opening alternating copolymerization (ROAC) of cyclohexene oxide (CHO) and phthalic anhydride (PA) first and then ROAC of CO2/CHO. Thus, well‐defined triblock polycarbonate‐b‐polyester‐b‐polycarbonate copolymers can be produced from the mixture of CO2, CHO and PA using a bifunctional initiator. With C3N3‐Py‐P3/TEB=1/1, tapered copolymers were obtained, while random copolymers with high content of polycarbonate (PC) were synthesized with further increasing the amount of TEB. The mechanism of the unexpected chemoselectivity was further investigated by DFT calculations.

Exploiting the Use of Salvia Hispanica L. (chia) Oil as a Renewable Raw Material to Produce Air‐Drying Alkyd Resins: A Comparative Study

AbstractThis work addresses a comparative study focused on the synthesis of alkyd resins from different renewable resources such as chia, castor and palm vegetable oils through the alcoholysis–polycondensation process. The formed alkyd resins are analyzed by Fourier transform infrared (FTIR), 1H NMR, and 13C NMR. Besides, intrinsic viscosity and gel permeation chromatography (GPC) assays are conducted to evaluate the differences between the obtained resins focusing on their molecular weight and physicochemical properties. FTIR shows a satisfactory conversion from vegetable oils to alkyd resins. Both 1H NMR and 13C NMR indicate that alkyd resins are successfully synthesized. The values for molecular‐weight dispersity (ÐM) obtained for the resins are 2.3, 1.3, and 1.7 from chia, palm, and crude castor, along with the weight‐average molecular weight (Mw) of 4516, 1025, and 2451 g mol−1, respectively. The chia alkyd resin shows a 571.92 cP and is the highest viscosity obtained. It is also observed that an increase in phthalic anhydride can increase the molecular weight of the alkyd resin. This comparative study indicates that chia oil alkyd resin has enormous potential to be employed as a surface coating agent.

Design of Topology‐Controlled Polyethers toward Robust Cooperative Hydrogen Bonding

AbstractTopology control of polymers is critical for determining their physical properties and potential applications; in particular, topologies that incorporate numerous hydrogen bonding (H‐bonding) donors and acceptors along the polymer chains considerably influence the formation of different inter‐ and intramolecular H‐bonding motifs. In this study, the high‐level control of inter‐ and intramolecular H‐bonding is investigated in topology‐controlled poly(glycidoxy carbonyl benzoic acid)s (PGCs). Three types of topology‐controlled PGCs (i.e., linear, hyperbranched, and branched cyclic structures having a similar degree of polymerization) are prepared by introducing aromatic carboxylic acids into the corresponding polyglycidols (PGs) via quantitative post‐polymerization modification with phthalic anhydride. The obtained three types of PGCs demonstrated the high‐level interplay between the inter‐ and intramolecular H‐bonding in polymer chains by exhibiting the pH‐dependent self‐association properties in the solution state and the strong adhesion properties in the bulk state with high transparency. Interestingly, the dramatically enhanced adhesive property by 2.6‐fold is demonstrated by simple mixing of branched cyclic PGC and topology‐controlled PGs to promote the cooperative H‐bonding between polymer chains. The new class of cooperative H‐bonding is anticipated between topology‐controlled polymers to contribute to the development of advanced adhesive and the high potential in biological and biomedical applications due to its excellent biocompatibility.

1-Butanol dehydration and oxidation over vanadium phosphate catalysts

The transformation of 1-butanol into either butenes or maleic anhydride was carried out both with and without oxygen, using V/P/O catalysts. With vanadyl pyrophosphate prepared by coprecipitation, at temperature lower than 240 °C and without oxygen, selectivity to butenes was higher than 90%, but a slow deactivation took place. At temperature higher than 300 °C and in the presence of air, maleic and phthalic anhydrides were the prevailing products, with selectivity of 60% and 14%, respectively. Catalytic performance was affected by crystallinity and acidity. αI-VOPO4 showed a poor performance in the absence of air, with a quick deactivation due to coke accumulation; but it displayed an excellent selectivity to butenes (close to 98%) at temperatures lower than 320 °C in the presence of air, with stable performance. At temperature higher than 360 °C, α I-VOPO4 was reduced to vanadyl pyrophosphate and catalyzed the direct oxidation of 1-butanol into maleic anhydride, but with 35% selectivity.

Salts and double tartratogermanates/stannates of 3d-metals as modifiers of unsaturated oligoesters

The paper presents the results of the systematic research into effects of 3d-metals acetates, acetylacetonates and double tartrategermanates/stannates on the modification of polyglycol maleine phthalate. The copolymerization parameters of the prepared modified oligoesters with methyl methacrylate monomer and threeethyleneglycoldimethacrylate oligomer were determined. Modifiers were added to the reaction mixture before the start of polycondensation of maleic and phthalic anhydrides with ethylene glycol at the temperature of 1750C. The kinetics of copolymerization at the initial stages was determined by the dilatometry at the temperatures of 500C to 600C. It was established that the modification of polyglycol maleinate phthalate with the studied compounds allows significantly increasing the rate and reducing the temperature coefficient of the copolymerization reaction. There advantages of the investigated double multi-metal mixed ligand coordination compounds as modifiers were proved as compared to the standard industrial systems, acetylacetonates and metal acetates. The presented modifiers are able to improve significantly the characteristics of the semi-finished products in the industrial manufacturing of copolymers without the significant change of the technological process.

Allylic hydroxylation of enones useful for the functionalization of relevant drugs and natural products

Enones are privileged structural motifs in bioactive natural products and pharmaceuticals, but the γ-hydroxylation of enones is challenging. Here we show a mild and efficient method for the direct C(sp3)–H hydroxylation of enones via visible-light-induced hydrogen-atom transfer (HAT), which facilitates γ-hydroxylation of primary, secondary, and tertiary C–H bonds of different enones without involving metal and peroxide. The mechanism study shows that Na2-eosin Y serves as both the photocatalyst and the source of catalytic bromine radical species in the HAT-based catalytic cycle, and finally sacrifices itself completely by oxidative degradation to produce bromine radical and a major product phthalic anhydride in an environmentally friendly way. This scalable method was demonstrated by plenty of substrates (41 examples) including 10 clinical drugs and 15 natural products to be useful for the late-stage functionalization of enone-containing compounds, and, in particular, has potential application in industry for large-scale production.

Chemical characterization and source attribution of organic pollutants in industrial wastewaters from a Chinese chemical industrial park

Accelerated urbanization and industrialization have led to an alarming increase in the generation of wastewater with complex chemical contents. Industrial wastewaters are often a primary source of water contamination. The chemical characterization of different industrial wastewater types is an essential task to interpret the chemical fingerprints of wastewater to identify pollution sources and develop efficient water treatment strategies. In this study, we conduct a non-target chemical analysis for the source characterization of different industrial wastewater samples collected from a chemical industrial park (CIP) located in southeast China. The chemical screening identified volatile and semi-volatile organic compounds that included dibutyl phthalate at a maximum concentration of 13.4 μg/L and phthalic anhydride at 35.9 μg/L. Persistent, mobile, and toxic (PMT) substances among the detected organic compounds were identified and prioritized as high-concern contaminants given their impact on drinking water resources. Moreover, a source analysis of the wastewater collected from the wastewater outlet station indicated that the dye production industry contributed the largest quantities of toxic contaminates (62.6%), and this result was consistent with the ordinary least squares and heatmap results. Thus, our study utilized a combined approach of a non-target chemical analysis, a pollution source identification method, and a PMT assessment of different industrial wastewater samples collected from the CIP. The results of the chemical fingerprints of different industrial wastewater types as well as the results of the PMT assessment benefit risk-based wastewater management and source reduction strategies.

Chromium Complexes Supported by Salen-Type Ligands for the Synthesis of Polyesters, Polycarbonates, and Their Copolymers through Chemoselective Catalysis.

Salen, Salan, and Salalen chromium (III) chloride complexes have been investigated as catalysts for the ring-opening copolymerization reactions of cyclohexene oxide (CHO) with CO2 and of phthalic anhydride (PA) with limonene oxide (LO) or cyclohexene oxide (CHO). In the production of polycarbonates, the more flexible skeleton of salalen and salan ancillary ligands favors high activity. Differently, in the copolymerization of phthalic anhydride with the epoxides, the salen complex showed the best performance. Diblock polycarbonate-polyester copolymers were selectively obtained by one-pot procedures from mixtures of CO2, cyclohexene oxide, and phthalic anhydride with all complexes. In addition, all chromium complexes were revealed to be very active in the chemical depolymerization of polycyclohexene carbonate producing cyclohexene oxide with high selectivity, thus offering the opportunity to close the loop on the life of these materials.

Simultaneous Determination by Selective Esterification of Trimellitic, Phthalic, and Maleic Anhydrides in the Presence of Respective Acids.

Trimellitic, phthalic, and maleic anhydrides are important building blocks to produce polymers and additives, such as plasticizers. In humans, the exposure to these compounds can cause several health issues. In European Union and USA, their presence in substances and mixtures is restricted by CLP Regulation (no. 1272/2008) and HCS/HazCom 2012, respectively, but no information about the corresponding acids is reported. For this reason, a selective method to determine anhydrides in mixtures, in the presence of acids, could be interesting. Nowadays, methods in the literature are either not selective or use explosive and toxic reagents (as diazomethane). In this work, an innovative, greener, and safer method for the simultaneous recognition and quantification of anhydrides and acids, via direct injection gas chromatography-mass spectrometry, is developed. The sample pretreatment consists in selective esterification with absolute ethanol on the anhydride, followed by a treatment with boron trifluoride-methanol for the methylation of remaining carboxylic groups. The optimization of the functionalization, a crucial step of the method, was optimized by experimental design. The limit of detection-limit of quantification (LOD-LOQ) values for trimellitic, phthalic, and maleic anhydrides are 0.31-0.93, 0.47-1.41, and 0.06-0.18 μg/mL, respectively.

Exploratory study on noninvasive biomarker of silicosis in exhaled breath by solid-phase microextraction-gas chromatography-mass spectrometry analysis.

As a chronic occupational disease, silicosis could cause irreversible and incurable impair to the lung. The current diagnosis of silicosis relies on imaging of X-ray or CT, but these methods cannot detect lung lesions in the early stage of silicosis. To establish a regular screening and early diagnosis methods for silicosis, which could be helpful for the prevention and treatment of silicosis. A total of 161 subjects were enrolled in the study, including 69 patients with silicosis (SILs) and 92 healthy controls. The exhaled breath samples of the subjects were collected with breath sampler and Tedlar bag. The analysis of volatile organic compounds (VOCs) in exhaled breath was performed by solid-phase microextraction (SPME) combined with gas chromatography mass spectrometry (GC-MS). After excluding the pollutants from sampling bags and instruments, 86 VOCs have been identified in the exhaled breath. The orthogonal partial least squares-discriminant analysis (OPLS-DA) was employed for the screening of potential biomarkers of silicosis. Those components that related to smoking were also excluded from the biomarkers. Finally, nine possible biomarkers for silicosis were screened out, including 2,3-butanedione, ethyl acetate, chlorobenzene, o-cymene, 4-ethylhex-2-ynal, 3,5-dimethyl-3-heptanol, hydroquinone, phthalic anhydride and 5-(2-methylpropyl)nonane. Based on these biomarkers screened, a predicted model for silicosis was generated with the accuracy of 89.61%. The nine biomarkers in exhaled breath were preliminarily screened out for the early diagnosis of silicosis, which can be helpful to the establishment of a noninvasive screening method for silicosis. Follow-up studies should be conducted to further verify these markers.

Synthesis and identification of aromatic poly (Ester-Amide) containing chalcone groups in backbone chain

The purpose of this research is to synthesize a new monomer (E)-5-(3-(4-aminophenyl)-3-oxoprop-1-en-1-yl)-2-hydroxybenzoic acid and poly (ester-amide) polymer. Chalcone compound, α, β- unsaturated ketone is a new monomer that includes both the functional group (-CO-CH=CH-) and α, β - unsaturated carbonyl group of the present system. It is prepared via the condensation of aryl ketone with an aromatic aldehyde in the presence of suitable condensation agents which is known as condensation of aldol. The monomer was reacted with (phthalic anhydride and maleic anhydride) by solution polycondensation reactions to yield polymer. The synthesized monomer and polymer were characterized via FT.IR-spectra, Nuclear magnetic resonance13 C.NMR-spectra, 1H.NMR-spectra] and DSC (Differential scanning calorimetry)]. The polymer demonstrated excellent thermal stability. The findings revealed that poly (ester-amide) was successfully synthesized by providing a good spectrum that improved the existing amide functional group (-CONH-) and ester functional group (-COO-) in the spectrum of prepared polymer, as well as the presence of chalcone functional groups(CO-CH=CH-) improved in the spectrum of monomer.

Molecular Weight Distribution of Branched Polymers: Comparison between Monte Carlo Simulation and Flory-Stockmayer Theory.

It is challenging to predict the molecular weight distribution (MWD) for a polymer with a branched architecture, though such information will significantly benefit the design and development of branched polymers with desired properties and functions. A Monte Carlo (MC) simulation method based on the Gillespie algorithm is developed to quickly compute the MWD of branched polymers formed through step-growth polymerization, with a branched polyetherimide from two backbone monomers (4,4'-bisphenol A dianhydride and m-phenylenediamine), a chain terminator (phthalic anhydride), and a branching agent (tris[4-(4-aminophenoxy)phenyl] ethane) as an example. This polymerization involves four reactions that can be all reduced to a condensation reaction between an amine group and a carboxylic anhydride group. A comparison between the MC simulation results and the predictions of the Flory-Stockmayer theory on MWD shows that the rates of the reactions are determined by the concentrations of the functional groups on the monomers involved in each reaction. It further shows that the Flory-Stockmayer theory predicts MWD well for systems below the gel point but starts to fail for systems around or above the gel point. However, for all the systems, the MC method can be used to reliably predict MWD no matter if they are below or above the gel point. Even for a macroscopic system, a converging distribution can be quickly obtained through MC simulations on a system of only a few hundred to a few thousand monomers that have the same molar ratios as in the macroscopic system.