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Öğe A DES or LTTM: Eco-friendly solvent mediums for conversion of biomass to levulinic acid as a key chemical(Elsevier, 2024) Nis, Berna; Ozsel, Burcak Kaya; Kaya, YunusIn this study, the effect of using environmentally friendly, less toxic, low cost, and easily recyclable deep eutectic solvent (DES) and low-transition temperature mixture (LTTM), which are alternatives to ionic liquids, on the conversion of biomass to levulinic acid (LA) was investigated. The reaction conditions such as temperature, the amount of feedstock, and the water ratio were optimized to ensure maximum product formation in DES (ChClEG)-water medium. The highest amount of LA (143.2 +/- 2.5 mg) under optimum reaction conditions was achieved by using glucose in a newly designed LTTM (SA:EG)-water solvent medium. Newly designed low-transition temperature mixture (SA:EG) characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and differential scanning calorimetry (DSC) analyses. A comprehensive theoretical study was also performed to provide a deep understanding of the formation mechanisms of new LTTM by density functional theory (DFT), reduced density gradient (RDG), frontier molecular orbitals (FMOs), and molecular electrostatic potential (MEP) methods. The glucose conversion ratio increased from 70.2 % to 96.1 % in SA:EG-water medium. When microcrystalline cellulose, corn straw, and sorghum were used under the same conditions, 118.9 +/- 5.4, 36.8 +/- 9.4, and 32.6 +/- 3.4 mg of LA were obtained per g of feedstock. A typical Br & oslash;nsted acid; phosphotungstic acid (H3O40PW12) showed high catalytic activity, resulting in 229.0 +/- 0.32 mg of LA per g of glucose in SA:EG-water medium. This shows that the use of SA:EG LTTM for cellulosic/lignocellulosic biomass sources can be used favorably in conversion reactions.Öğe Bor Katkılı ZnO Nanopartiküllerin Sentezi ve Yapısal, Morfolojik, Optik Özelliklerinin Deneysel/Kuramsal İncelenmesi(Bilecik Şeyh Edebali Üniversitesi, 2021) Kaya, Yunus; Baydır, Enver; Aras, ÖmürBu çalışmada, sprey piroliz yöntemi ile farklı molar oranlarda (%0, 0.2, 0.5, 1, ve 2) bor katkılı ZnO nanoparçacıkları elde edilmiştir. Katkısız ve katkılı ZnO nanoparçacıklarının karakterizasyonu, X-ışını kırınımı (XRD) tekniği, yüzey morfolojisi Taramalı Elektron Mikroskobu (SEM) ve optik özellikler ultraviyole-görünür bölge spektrumu ölçülerek yapılmıştır. XRD analiz sonuçları, wurtzite kristal yapıda ZnO nanoparçacıklarının elde edildiğini göstermektedir. Bant aralığı enerjisi (Eg) her bir numune için 2.98 –3.15 eV aralığında bulunmuş ve katkı maddelerinin bant enerjisini artırdığı gözlemlenmiştir. Ayrıca 10 metal ve oksijen atomundan oluşan küme yapıları yarı deneysel/pm6 yöntemi ile optimize edilmiş, kuramsal band boşluğu enerjisi hesaplanmıştır.Öğe Characteristics and seasonal variation of microplastics in the wastewater treatment plant: The case of Bursa deep sea discharge(Pergamon-Elsevier Science Ltd, 2023) Can, Tugba; Ustuen, Gokhan Ekrem; Kaya, YunusMicroplastics (MPs) are an emerging pollutant that can be detected in all ecosystems, especially aquatic ecosystems. Wastewater treatment plants (WWTPs) are important point sources of MP release into the sea. In this study, the characteristics of MPs in wastewater and sludge samples taken from different units of WWTP in BursaGemlik district for 12 months were investigated. Wastewater and sludge samples collected from 7 different points were classified as size, shape, color, and counted. The amount of MP in the influent and effluent of the WWTP, respectively; 107.1 & PLUSMN; 40.2 MP/L and 4.1 & PLUSMN; 1.1 MP/L. Although the MP removal efficiency of the WWTP is 96.17 %, approximately 74,825,000 MP is discharged into the Marmara Sea every day. The amount of MP in the sludge is 14.3 & PLUSMN; 7.1 MP/g. The amount of MP accumulated in 22tons of waste sludge formed daily in WWTP was calculated as 314,600,000 MP, and the annual accumulated amount was calculated as approximately 1.15 x 1011 MP. The MPs in the WWTP were mainly 1-0.5 mm in size. Fibers were the dominant MP shape in both the wastewater and sludge samples. Black and transparent were the dominant MP colors. Seven different polymer types of MPs were detected, which were mainly types of polyethylene, polypropylene, and polyethylene terephthalate. Despite the high removal efficiency in the investigated WWTP, it has been shown that it acts as an important source of MPs to the sea ecosystem due to the high discharge rates.Öğe Conformational analysis, spectroscopic (FTIR, NMR and UV-Vis.), molecular docking and quantum chemical simulation studies of 1-phenylethanone-O-pyropyl oxime ether(Bursa Teknik Üniversitesi, 2018) Kucuk, İlhan; Kaya, YunusThe stable conformer of the synthesized 1-phenylethanone-O-pyropyl oxime ether (PEPOE) has been determined by potential energy profile analysis. All the structural parameters of PEPOE were identified by Density Functional Theory (DFT) with B3LYP method and 6-311++G(d,p) basis set. The spectroscopic properties, FTIR, NMR and UV-Vis results have been theoretically calculated and compared with experimental data. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energies and the electron density distribution were performed by same level. The heat capacity, entropy, and enthalpy of the PEPOE have been calculated at temperature range from 100 to 1000 °C. In addition, the molecular docking studies with DNA and Human Serum Albumin (HSA) structures have been performed to find the most preferred binding mode of the ligand inside the DNA and HSA cavity. As a result of these studies, the binding free energies of DNA and HSA have been calculated as -20.92 and -26.78 kJ/mol, respectively. The results show that these calculations are valuable for providing insight into molecular properties of the oxime ether compounds.Öğe Conformational, spectroscopic, optical, physicochemical and molecular docking study of 4-methoxy-benzaldehyde oxime and 4-hydroxy-3-methoxy-benzaldehyde oxime(Taylor & Francis Ltd, 2020) Kaya, Yunus; Kucuk, Ilhan; Kaya, Asli A.In this study, the conformational, spectroscopic, optical, physicochemical and molecular docking studies of two oxime molecules, namely 4-methoxy-benzaldehyde oxime (mboH) and 4-hydroxy-3-methoxy-benzaldehyde oxime (hmboH) were reported. The conformational analyses and spectroscopic properties were performed by DFT/B3LYP method and 6-311++G(d,p) basis set to find the most probable geometries of both molecules. The optical properties, energy gap and nonlinear optical (NLO) properties were investigated in different solvents which are benzene, chloroform, ethanol, dimethyl sulfoxide (DMSO) and water. Some physicochemical properties were also performed. The stability of the mboH and hmboH arising from hyper-conjugative interaction and charge delocalisation has been analysed using natural bond orbital (NBO) analysis. The stability of the molecules arising from hyper conjugative interactions and charge delocalisation has been also analysed using NBO study. In addition, molecular docking studies with DNA and protein structures to find the most preferred binding mode of the ligands inside the DNA and protein cavity.Öğe Determination of the active molecule as a potential drug against covid-19 virus using molecular docking and hybrid AHP-GRA method(Yildiz Technical Univ, 2023) Kaya, Yunus; Yildiz, AytacIn this study, it is aimed to determine the most effective molecule to be used as an active ingredient against the covid-19 virus among the 15 molecules proposed by adding some elec-tronegative groups to some molecules used in the ebola virus. In the first stage of the study, the proposed molecules are optimized in DFT / B3LYP method and 6-311G ++ (d, p) basis set, dipole moment, entropy, energy of HOMO and LUMO orbitals and band gap energies are calculated. In addition, the interactions of these molecules with the Covid-19 main protease enzyme (PDB no = 6LU7) are examined with the Autodock vina program. Correlation anal-ysis is performed using the IBM SPSS Statistics 23 program with the values obtained from molecular docking and DFT calculations, and it is determined that there is no statistically significant relationship between the band gap factor and free docking energy. In the second stage of the study, the importance weights of the parameters belonging to the molecules are determined by the Analytical Hierarchy Process (AHP) method. Then, the mol-ecules are ranked by preference using the Gray Relational Analysis (GRA) method. According to the results of the sensitivity analysis performed at the end of the study, it is determined that the 1D6-CN molecule is the most effective molecule to be used as an active ingredient against the covid-19 virus.Öğe Effect of Reactive and Non-Reactive Diluent on Mechanical Properties of Epoxy Resin(Bilecik Şeyh Edebali Üniversitesi, 2021) Aras, Ömür; Kaya, YunusEpoxy resins, which are frequently preferred among thermoset plastics in the industry, are materials with high viscosity, and good mechanical performance. The biggest disadvantage of epoxy resins is that they encounter difficulties in application alone due to their high viscosity. For this reason, various diluents are added to reduce their viscosity and applications are conducted. In this study, the mechanical properties of the epoxy resin, which is used in many fields, were observed with the addition of certain sizes of reactive and non-reactive diluents. Diglycidyl ether was used as the reactive diluents, and benzyl alcohol was used as the non-reactive diluent. In addition, ethylene diamine and diethylene triamine were used as curing agents. It was tried to determine the optimum modification of the hardened epoxy resin by measuring the mechanical strengths in the electromechanical test device. The results indicated the optimum composition that does not dramatically affect the mechanical performance of the epoxy resin is the composition containing 7.5% DE and 10% EDA, its tensile strength measured as 53.27 N/mm2.Öğe Evaluation of polycarboxylate ether-based grinding aids on clinker grinding performance: the influence of pH(Taylor & Francis Ltd, 2025) Kaya, Yahya; Kobya, Veysel; Samadpour, Nasim; Altun, Okay; Ozcan, Aydin; Kaya, Yunus; Mardani, AliThis study introduces an innovative approach by synthesizing PCE-based grinding aids (GAs) at three different pH levels (4, 7, and 9) to investigate how pH-induced structural variations impact grinding performance and cement quality. The GAs were applied at dosages of 0.025%, 0.05%, and 0.1% (by total weight of clinker and gypsum). Milling performance and final product properties were assessed, while thermogravimetric analysis (TGA) evaluated the thermal stability of the synthesized GAs. Additionally, molecular dynamics (MD) simulations were conducted to quantify the adsorption energies of the GAs on C-A and C-S clinker phases. Results showed that the low-pH PCE-based GA significantly enhanced grinding efficiency, achieving up to 17% improvement over the control, and delivered superior cement performance. This research provides new insights into the pH-dependent behavior of PCE-based GAs and offers a novel strategy for optimizing molecular design to achieve high-efficiency, performance-driven cement production.Öğe Exploring Hierarchically Porous Functional PolyHIPEs for Polymeric Support Designs: Synergistic Effects of VBC Content and Crosslinking on Surface Properties(Wiley, 2025) Suslukaya, Merve; Deniz, Erhan; Kaya, YunusIn this study, high internal phase emulsions (HIPEs) with ranging vinyl benzyl chloride (VBC) contents (50-80 v/v%) were prepared to synthesize polyHIPEs with 90% nominal porosity having different ratios of -Cl content. The resulting polyHIPEs were then hypercrosslinked for a duration of either 15 or 30 min through Friedel-Crafts alkylation reaction. The chemical and morphological properties of the materials have been characterized by FTIR analysis, SEM image analysis, EDS surface mapping and elemental analysis, Mohr's precipitation titration for -Cl (wt%) content determination, surface area and porosity analysis by using N2 adsorption/desorption isotherms, TGA analysis, and WCA measurements. It has been shown that the optimal VBC and DVB monomer phase ratios (v/v) which yield the highest BET surface area (SBET) were found to be 7/10 and 0.6/10, respectively. Hierarchically porous functional polyHIPEs possessing tunable surface area (SBET = 5.30-851.33 m2 g-1) with uniform micro-meso pore (1.31-9.91 nm) distribution and -Cl content (2.13-17.81 w/w%) exhibited high temperature stability and oleophilicity.Öğe ?-Glycosidase activity of novel coumarin-triazole-coumarin dyads(Tubitak Scientific & Technological Research Council Turkey, 2025) Sirin, Ersin; Sevimli, Esra; Seyhan, Gokce; Barut, Burak; Kaya, Yunus; Koksoy, BaybarsNovel coumarin-triazole-coumarin dyads were synthesized and characterized, and their alpha-glycosidase inhibitory activities were evaluated spectrophotometrically. Compound 4e exhibited the most pronounced inhibitory effect, with an IC50value of 38.98 +/- 0.77 mu M. The IC50 values for 4d and 4a were 93.55 +/- 1.70 mu M and 95.04 +/- 3.55 mu M, respectively. The Lineweaver-Burk plot showed that 4e inhibited alpha-glycosidase in a mixed type. In addition, the Ki value obtained from the Dixon plot was 19.95 +/- 0.15 mu M for alpha-glycosidase.Öğe High diastereoselectivity induced by intermolecular hydrogen bonding in [3+2] cycloaddition reaction: experimental and computational mechanistic approaches(Wiley, 2017) Yildirim, Ayhan; Kaya, YunusA diastereoselective [3 + 2] cycloaddition of N-aryl substituted maleimides with N, a-diphenyl nitrone possessing 11-hydroxyundecyloxy as a flexible substituent was performed. Experimental and comprehensive mechanistic density functional theory studies reveals that intermolecular H-bonding and steric repulsive interaction predominate exo-Z and exo-E cycloaddition transition states, respectively. The reaction proceeded smoothly depending on the reactants and gave a good yield of (syn) cis-isoxazolidine or (anti) trans-isoxazolidine as a single diastereomer.Öğe Impact of PCE-based grinding aids on hydration kinetics in fly ash substituted systems: Influence of pH and dosage(Elsevier Sci Ltd, 2025) Kaya, Yahya; Kobya, Veysel; Kaya, Yunus; Mardani, AliWhile the use of grinding aids (GAs) is commonly favored for their cost and energy efficiency benefits, these additives can also present challenges, such as incompatibility with water-reducing admixtures. This has led to interest in polycarboxylate-based water-reducing admixtures (PCEs) as potential grinding aid (GA). However, there is a significant gap in the literature concerning the interaction between these PCE-based GA properties and cementitious systems' morphological characteristics and hydration kinetics. This study investigated the effects of PCE-based GAs with varying pH levels on hydration kinetics, flowability, and compressive strength in cementitious systems containing fly ash. PCE-based GAs were synthesized at three different pH levels (4, 7, 9), while other parameters were held constant. Using these GAs, a total of 10 Portland cements, including one control, were produced at three different dosages. Additionally, two different fly ash substitution levels were used to prepare paste and mortar mixtures with these cements. This approach has enabled the investigation of fly ash substitution systems in the presence of PCE-based GAs and the assessment of environmental impact through life cycle analysis. The study aimed to contribute to the existing literature and offer an alternative approach to sustainable production. The findings revealed that the PCE-based GA with a low pH value (4) was the most optimal in terms of the evaluated properties.Öğe Investigation of structural, spectral, optical and nonlinear optical properties of nanocrystal CdS: Electrodeposition and quantum mechanical studies(Elsevier GmbH, 2021) Erturk, Kadir; Isik, Seref; Aras, Ömür; Kaya, YunusNanocrystalline CdS semiconductor was synthesized by electrodeposition technique, and characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and FTIR spectroscopic methods. XRD analysis result showed that it is a hexagonal crystal structure. SEM micrographs showed that the CdS nanocrystal is homogeneously distributed on the surface. The roughness of the CdS thin films was measured by AFM. The presence of band in the FTIR spectrum at 558 cm−1 corresponds to the stretching of CdS. CdS nanocrystals were modeled separately and calculated in the Gaussian program. Structural, spectroscopic, and nonlinear optical (NLO) properties were investigated using the DFT/Lanl2dz and semi-empirical/pm6 level. Besides, by making energy calculations, Homo, Lumo, band gap, and total state density (TDOS) were calculated. The experimental band gap was measured at 2.40 eV, while this calculated for hexagonal and cubic structure as 2.21 and 2.01 eV with semiemprical/pm6 model, 2.44 and 2.25 eV with DFT/lanl2dz level.These results support that CdS nanostructures are crystallized in hexagonal structure. With this study, the obtaining of nano structured CdS films by electrodeposition method, their structural, optical and surface properties were experimentally examined, supported by theoretical calculations, and additionally NLO properties were investigated. It has been determined that the nanocrystals obtained are suitable material for optoelectronic applications.Öğe L-(+)-Tryptophan methyl ester derived polymeric microbeads as an efffiicient heterogeneous catalyst for green synthesis of 2-amino-4-(nitromethyl)-4H-chromene-3-carbonitriles(Tubitak Scientific & Technological Research Council Turkey, 2022) Poslu, Ayse Halic; Osman, Bilgen; Kaya, Yunus; Koz, Omer; Koz, GamzeThe cross-linked microbeads with average diameter of 106-300 mu m, [poly(EGDMA-MATrp)], were obtained by copolymerization reaction of N-methacryloyl-L-(+)-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA) and successfully applied as a heterogeneous catalyst in conjugate addition reaction of nitromethane to substituted 2-iminochromenes in aqueous media. A variety of 2-amino-4-(nitromethyl)-4H-chromene-3-carbonitriles has been synthesized in good yields. Polymeric microbeads were very durable and reused 5 times without a significant loss of activity. DFT calculations and experimental results revealed the significant role of Tr-Tr interactions as well as hydrogen bonding in the reaction mechanism.Öğe Naftalen-2-il-etanon-o-propil-oksimin Kuantum Kimyasal Çalışmaları(2020) Küçük, İlhan; Kaya, YunusBu çalışmada, biyolojik aktif özellik gösterebilen 1-naftalen-2-il-etanon-O-propil-oksim (NEOPO) molekülününkuantum kimyasal özellikleri, yapısal, spektroskopik, elektronik ve moleküler yerleştirme olarak sunulmuştur.Tüm kuantum kimyasal çalışmalar B3LYP / 6-311 ++ G (d, p) yöntem ve temel seti ile yoğunluk fonksiyonelteorisi (DFT) ile gerçekleştirilmiştir. Spektroskopik özellikleri, atom yükleri, HOMO-LUMO molekülerorbitalleri, kimyasal reaktivite ve moleküler elektrostatik potansiyeli (MEP) teorik olarak araştırılmıştır.Spektroskopik özellikler deneysel olarak desteklenmiştir. Ayrıca, moleküler yerleştirme çalışmaları içinAutodock / Vina programı kullanılmış ve bağlanma serbest enerjileri DNA-molekül ve protein-molekületkileşimleri için sırasıyla -27.20 ve -34.73 kJ / mol olarak hesaplanmıştır.Öğe Optimizing the Use of PCE-Based Grinding Aids: The Critical Role of pH on Early-Age Cement Hydration Kinetics(Asce-Amer Soc Civil Engineers, 2026) Kobya, Veysel; Kaya, Yahya; Mardani, Ali; Kaya, Yunus; Assaad, Joseph; Hamad, BilalPolycarboxylate ether (PCE) water-reducing admixtures have emerged as promising solutions to optimize clinker grinding and properties. The increased adsorption ability of PCE and creation of narrow particles, despite maintaining constant Blaine fineness, has sparked the interest of their use as grinding aids (GAs) in the cement industry. This study aims at synthesizing different PCEs at three distinct pH values (i.e., 4, 7, and 9), and assessing their interactions with the cement hydration kinetics and strength development at early ages. Ten cements were produced by incorporating the synthesized PCEs at three dosage rates of 0.025%, 0.05%, and 0.1%, by weight of clinker and gypsum materials. The mixtures were tested for Fourier-transform infrared spectroscopy (FTIR) spectra, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, setting time, heat calorimetry, and early-age strength. This comprehensive analysis revealed the significant pH impact on clinker comminution and sieve residues as well as the early-age hydration kinetics, formation of hydrated products, and strength development.Öğe Qualitative study on the effects of hydroxyl functionalized multiwall carbon nanotube and silica doped-epoxy composites(John Wiley and Sons Inc, 2022) Yaşaroğlu, İnci; Aras, Ömür; Kaya, YunusEpoxy resins have great potential for industrial applications because of their excellent properties such as good adhesion, durability, higher strength, and so forth. But, their high-viscosity limits industrial usage. Reducing the viscosity with suitable diluents provides an advantage on industrial scale processing, but this also causes a decrease in their chemical and mechanical properties. The production of epoxy-based composite materials provides good mechanical, heat, and solvent resistance properties. Therefore, determination of additives amount and dilution ratio for specific working area are important for these materials. In this context, this study first includes synthesis of bisphenol A-based epoxy resin and characterization with fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Second, chemical, mechanical, thermal, and surface properties of the resin were investigated by varying the reactive/nonreactive diluents and additives. Multiwall carbon nanotube (MWCNT-modified with triton X-405 nonionic surfactant) and fumed silica as additives were used in this study. Mechanical and chemical tests were applied to 49 types of materials. In order to see the significance levels and synergistic effects of diluents on tensile strength, 3D graphs were obtained with the experimental and modeled data. ANOVA was also performed for significance levels of the diluents. After that, the effects of silica and carbon nanotube additive on tensile strength were investigated. As a result of the tensile test and TGA analysis of the pure epoxy, the ultimate tensile strength was measured as 59.07 MPa, Tg (°C), and Tm (°C) values were found as 175.5 and 304.0°C. These results increased for the nanocomposite material prepared with 2% fumed silica and 0.1% MWCNT (modified YAM) as 81.64 MPa, 192.2 and 333.3°C. It was also shown that the ultimate tensile strength, which decreased with dilution of pure epoxy, could be increased significantly with the additivesÖğe Quantum Chemical Studies of 1-Naphthalen-2-yl-ethanone-o-propyl-oxime(Bilecik Şeyh Edebali Üniversitesi, 2020) Kaya, Yunus; Küçük, İlhanIn this work, quantum chemical properties of 1-naphthalen-2-yl-ethanone-O-propyl-oxime (NEOPO) molecule which may be biologically active have been presented as a structural, spectroscopic, electronic and molecular docking. All quantum chemical studies were performed by density functional theory (DFT) with the B3LYP / 6-311++G(d,p) method and basis set. The spectroscopic properties, atomic charges, HOMO-LUMO molecular orbitals, chemical reactivity and molecular electrostatic potential (MEP) were investigated as theoretically. The spectroscopic properties have been supported as experimentally. In addition, the Autodock/Vina program was used for molecular docking studies and the binding free energies were calculated as -27.20 and -34.73 kJ/mol for DNA-molecule and protein-molecule interactions, respectively.Öğe Quantum Chemical Studies of the Substituent Effect on the Reaction of Carbonyl Oxime with Amine(Amer Chemical Soc, 2016) Kaya, YunusThe reaction of the two different substitue carbonyl oximes (isonitrosoacetylnaphthaline, inanH and nitro-isonitrosoacetophenone, ninapH) with two different amines (1-phenylethanol amine, pea, and ethanol amine, ea) was carried out and characterized by elemental analyses, IR, and H-1 and C-13 NMR spectroscopic methods. As a result of these experimental studies, two different levels for all reactions were determined: (I) formation of imine oxime and (II) rearrangement of imine oxime or formation of amido alcohol. After a mechanism was suggested for all of these reactions, the reaction mechanism of carbonyl oxime with amine was first studied by means of the B3LYP/6-311G(d,p) method. Because of the deficiency of density functional theory (DFT) on dispersion effects, the wB97X-D/6-311G(d,p) method, which includes dispersion correction, was used to obtain the reaction heat and free energy barriers to explain why the formation (imine oxime) and unexpected rearrangement products (amido alcohol) occurred or did not occur. The statistical thermodynamic method was used to obtain the changes in thermodynamic properties of the studied molecules between 100 and 500 K. From a kinetic viewpoint, the slowest step of the reactions is the IN1-TS2-IN2 step, which determines the steps of the reaction kinetics. In addition, spectroscopic properties such as vibrational and NMR chemical shifts were studied for all of the molecules. The frontier molecular orbitals (FMOs), highest occupied molecular orbitals (HOMOs), and lowest unoccupied molecular orbitals (LUMOs) were monitored for all of the molecules.Öğe Screening of simple carbohydrates as a renewable organocatalyst for the efficient construction of 1,3-benzoxazine scaffold(Elsevier Ltd, 2021) Yıldırım A.; Kaya, Yunus; Göker M.A convenient protocol for the two component preparation of 1,3-benzoxazines by using several protected and unprotected carbohydrate molecules as organocatalysts have been developed which is broadly applicable to condensation reaction between variety of Mannich bases and paraformaldehyde. This study revealed that fructose have much higher catalytic activity than the other carbohydrates and can be an alternative to metal-containing catalysts as a green renewable organocatalyst for efficient and rapid construction of 1,3-benzoxazine skeleton. In this context, 21 benzoxazine compounds were successfully synthesized and spectral characterizations of these compounds were carried out by spectroscopic methods and elemental analysis. Furthermore, density functional theory (DFT) calculations have been performed to study the detailed mechanism of organocatalyst assisted synthesis of the benzoxazine monomers. The results obtained from these calculations showed that the more realistic reaction pathway involves formation of a phenolate based intermediate which loses a water molecule to form benzenaminium ion. Subsequently, this ion provides the formation of the corresponding benzoxazines with good yields through the intramolecular ring closure step.
