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141.
Navzer D. Sachinvala David L. Winsor Roger K. Menescal Iraj Ganjian Walter P. Niemczura Morton H. Litt 《Journal of polymer science. Part A, Polymer chemistry》1998,36(13):2397-2413
Two sets of sucrose-based epoxy monomers, namely, epoxy allyl sucroses (EAS), and epoxy crotyl sucroses (ECS), were prepared by epoxidation of octa-O-allyl and octa-O-crotyl sucroses (OAS and OCS, respectively). Synthetic and structural characterization studies showed that the new epoxy monomers were mixtures of structural isomers and diastereoisomers that contained varying numbers of epoxy groups per sucrose. EAS and ECS can be tailored to contain an average of one to eight epoxy groups per sucrose. Quantitative 13C-NMR spectrometry and titrimetry were used independently to confirm the average number of epoxy groups per sucrose. Sucrose-based epoxy monomers were cured with diethylenetriamine (DETA) in a differential scanning calorimeter (DSC), and their curing characteristics were compared with those of diglycidyl ether of bisphenol A (DGEBA) and diepoxycrotyl ether of bisphenol A (DECEBA). EAS and DGEBA cured at 100 to 125°C and exhibited a heat of cure of about 108.8 kJ per mol epoxy. ECS and DECEBA cured at 150 and 171°C, respectively, and exhibited a heat of cure of about 83.7 kJ per mol epoxy. Depending upon the degree of epoxidation (average number of epoxy groups per sucrose) and the concentration of DETA, glass transition temperatures (Tgs) of cured EAS varied from −17 to 72°C. DETA-cured ECS containing an average of 7.3 epoxy groups per sucrose (ECS-7.3) showed no DSC glass transition between −140 and 220°C when the ratio of amine (NH) to epoxy group was 1:1 and 1.5:1. Maximum Tgs obtained for DETA-cured DGEBA and DECEBA polymers were 134 and 106°C, respectively. DETA-cured bisphenol A-based epoxy polymers degraded at about 340°C, as observed by thermogravimetric analysis (TGA). DETA-cured sucrose-based epoxy polymers degraded at about 320°C. Sucrose-based epoxies cured with DETA were found to bind aluminum, glass, and steel. Comparative lap shear tests (ASTM D1002–94) showed that DETA-cured epoxy allyl sucroses with an average of 3.2 epoxy groups per sucrose (EAS-3.2) generated a flexible adhesive comparable in bond strength to DGEBA. However, DETA-cured ECS-7.3 outperformed the bonding characteristics of both DGEBA and EAS-3.2. All sucrose-based epoxy polymers were crosslinked and insoluble in water, N,N-dimethylformamide, tetrahydrofuran, acetone, and dichloromethane. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2397–2413, 1998 相似文献
142.
Nasrin Alishahi Mahboobeh Nasr-Esfahani Iraj Mohammadpoor-Baltork Shahram Tangestaninejad Valiollah Mirkhani Majid Moghadam 《应用有机金属化学》2020,34(8):e5681
In this study, an acidic nicotine-based ionic liquid supported on magnetic nanoparticles ([NicTC]HSO4@MNPs) was synthesized and characterized by different techniques. The activity of this catalyst was evaluated in a multi-component reaction of 2-aminobenzothiazole , aldehydes / dialdehydes and β-ketoesters/1,3-diketones to afford a series of novel mono- and bis-4H-pyrimido[2,1-b]benzothiazole derivatives. In addition, mild reaction conditions, high yields, excellent selectivity as well as easy recovery and reusability of the catalyst, make this method an economic and environmentally-benign process. 相似文献
143.
Iraj Behroz Leonardo Kleebauer Kay Hommernick Maria Seidel Dr. Stefan Grätz Dr. Andi Mainz Dr. John B. Weston Prof. Dr. Roderich D. Süssmuth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):9077-9086
The natural product albicidin is a highly potent inhibitor of bacterial DNA gyrase. Its outstanding activity, particularly against Gram-negative pathogens, qualifies it as a promising lead structure in the search for new antibacterial drugs. However, as we show here, the N-terminal cinnamoyl moiety of albicidin is susceptible to photochemical E/Z isomerization. Moreover, the newly formed Z isomer exhibits significantly reduced antibacterial activity, which hampers the development and biological evaluation of albicidin and potent derivatives thereof. Hence, we synthesized 13 different variants of albicidin in which the vulnerable para-coumaric acid moiety was replaced; this yielded photostable analogues. Biological activity assays revealed that diaryl alkyne analogues exhibited virtually undiminished antibacterial efficacy. This promising scaffold will therefore serve as a blueprint for the design of a potent albicidin-based drug. 相似文献
144.
We report the synthesis of magnetically separable Fe3O4@Silica‐Threonine‐Pd0 magnetic nanoparticles with a core–shell structure. After synthesis of Fe3O4@Silica, threonine as an efficient stabilizer/ligand was bonded to the surface of Fe3O4@Silica. Then, palladium nanoparticles were generated on the threonine‐modified catalyst. The threonine stabilizer helps to generate palladium nanoparticles of small size (less than 4 nm) with high dispersity and uniformity. Magnetically separable Fe3O4@Silica‐Threonine‐Pd0 nanocatalyst was fully characterized using various techniques. This nanocatalyst efficiently catalysed the Heck cross‐coupling reaction of a variety of substrates in water medium as a green, safe and inexpensive solvent at 80°C. The Fe3O4@Silica‐Threonine‐Pd0 catalyst was used for at least eight successful consecutive runs with palladium leaching of only 0.05%. 相似文献
145.
Niloufar Afzali Shahram Tangestaninejad Majid Moghadam Valiollah Mirkhani Adam Mechler Iraj Mohammadpoor‐Baltork Reihaneh Kardanpour Farnaz Zadehahmadi 《应用有机金属化学》2018,32(1)
A heterogeneous catalyst was synthesized by immobilizing Mo(CO)3 in a UiO‐66 metal–organic framework. The benzene ring of the organic linker in UiO‐66 was modified via liquid‐phase deposition of molybdenum hexacarbonyl, Mo(CO)6, as starting precursor to form the (arene)Mo(CO)3 species inside the framework. The structure of this catalyst was characterized using X‐ray diffraction, and chemical integrity was confirmed using Fourier transform infrared and diffuse reflectance UV–visible spectroscopic methods. The metal content was analysed with inductively coupled plasma. Field emission scanning electron microscopy was used to measure particle size and N2 adsorption measurements to characterize the specific surface area. This catalytic system was efficiently applied for epoxidation of alkenes and oxidation of sulfides. The Mo‐containing metal–organic framework was reused several times without any appreciable loss of its efficiency. 相似文献
146.
Majid Moghadam Iraj Mohammadpoor‐Baltork Shahram Tangestaninejad Valiollah Mirkhani Parvin Yazdani Saeedeh Ghorjipoor 《Heteroatom Chemistry》2009,20(3):131-135
Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3‐dioxanes and 1,3‐dioxolane with 1,3‐propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf)2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:131–135, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20523 相似文献
147.
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149.
A simple, efficient, and rapid sample preparation method based on aeration‐assisted homogeneous liquid–liquid microextraction was developed for determination of curcumin in food samples by high‐performance liquid chromatography. The centrifuge step has been eliminated in this procedure. The effects of some variables, such as pH, volume of extraction solvent, extraction time, and salt effect, were studied through a Box–Behnken design method. Under the optimum conditions, calibration curves of curcumin were linear in the range of 0.08‐4000 μg/mL with R2 = 0.997. Limit of detection and relative standard deviation were 0.019 μg/mL and 3.01%, respectively. The preconcentration factor achieved was 166. The proposed method was successfully applied to determination of curcumin in various food samples. 相似文献
150.
Aneseh Khalatbari Jafari Reihaneh Kardanpour Shahram Tangestaninejad Valiollah Mirkhani Majid Moghadam Iraj Mohammadpoor-Baltork Farnaz Zadehahmadi 《Journal of the Iranian Chemical Society》2018,15(5):997-1006
In this work, the metallo Schiff base-functionalized metal–organic framework was prepared by post-synthetic method and used as an electron-deficient catalyst for the alcoholysis of epoxides. In this manner, the aminated MIL-101 was modified with 2-pyridine carboxaldehyde and then the prepared Schiff base reacted with RuCl3. This new catalyst, MIL-101–NH2–PC–Ru, was characterized by Fourier transform infrared, UV–Vis spectroscopic techniques, X-ray diffraction, BET, inductively coupled plasma atomic emission spectroscopy and field-emission scanning electron microscopy. In the presence of this heterogeneous catalyst, ring opening of epoxides was performed under mild condition to show the significant ability and successful applications of Lewis acid containing catalysts in corporation with metal–organic frameworks. The reusability of the catalyst was also investigated. No noticeable decrease in the catalytic activity was found after four consecutive times. 相似文献