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111.
Bibi Narjes Haerizade Mohammad Zaman Kassaee Hassan Zandi Maryam Koohi Ali A. Ahmadi 《Journal of Physical Organic Chemistry》2014,27(11):902-908
High‐level Density Functional Theory calculations, coupled with appropriate isodesmic reaction, are employed to investigate the effects of α‐carbon, ammonium, phosphorus, and sulfur ylides, cyclization, and unsaturation on the stability, multiplicity, and reactivity of novel singlet (S) and triplet (T) carbenes. Among them the highly π‐donating α‐ammonium ylide is found to exert the highest stabilizing effect on the carbenic center. α‐Ammonium ylides resist dimerization and hydrogenation. They show wider singlet–triplet energy gap (ΔΕS–T), broader band gap (ΔΕHOMO–LUMO), and higher nucleophilicity compared to the reported stable N‐heterocyclic carbenes. Aromatic cyclic unsaturated ammonium, phosphorus, and sulfur ylide carbenes appear more stable than their saturated cyclic analogs which are in turn more viable than their acyclic counterparts. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
112.
Summary Eleven complexes of the type K[M(acac)(Rxan)2] and K[M(TTA)2(Rxan)], where M=CoII or NiII, acac=acetylacetonate, TTA=thenoyltrifluoroacetonate, and Rxan=alkylxanthate, R=methyl-, ethyl-, propyl-, butyl-, or cyclohexyl-, have been prepared. The magnetic and spectral data indicate that the complexes are octa-hedral and that the xanthate group is attached in a bidentate fashion to the metal ions. The conductivity data are commensurate with the ionic character in the complexes. T.g.a. were made for some of the complexes.Presented at the XXVI International Conference on Coordination Chemistry in Porto, Portugal, 28 August–2 September 1988. 相似文献
113.
Puri SC Handa G Bhat BA Gupta VK Amna T Verma N Anand R Dhar KL Qazi GN 《Journal of chromatographic science》2005,43(7):348-350
The present work describes the isolation of camptothecin and 9-methoxycamptothecin from the aerial parts of Nothapodytes foetida by semipreparative high-performance liquid chromatography because the separation of compounds by conventional procedures is tedious and cumbersome. The purity of the isolates is determined by physicochemical data and liquid chromatography-mass spectrometry. 相似文献
114.
H3PW12O40/SiO2 or (PW/SiO2) promotes the regio‐, stereo‐ and chemoselective Claisen‐Schmidt condensation with improved yields. 相似文献
115.
Ostadakbari Farnoosh Yazdian Fatemeh Rashedi Hamid Ghaemi Amirhossein Haghirosadat Bibi Fatemeh Azizi Marzieh 《Journal of Cluster Science》2022,33(6):2617-2624
Journal of Cluster Science - Incorporation of nanomaterials and nanostructures into sensors causes remarkable advances in device operation due to sensitivity, selectivity, multiplexed detection... 相似文献
116.
117.
Ambreen Ikram Amna Khatoon Salman Khalid Ahmed Samina Abdul Sattar Shaheen Faizi 《Natural product research》2016,30(7):768-775
Two new esters of dammarane triterpenoids ixorene isovalerate (1), ixorene 3′,8′-dimethyloctanoate (2) and a new ursane-type triterpenoids Ixoroid acid (3) were isolated from the methanolic extract of flowers of Ixora coccinea Linn., along with the three known constituents. The structures of compounds 1 and 3 were elucidated on the basis of extensive 1D,2D NMR studies and mass spectrometry as 17β-dammara-12,20-diene-3β-isovelarate and 3β-hydroxy-18β-urs-12ene-29β-oic acid, respectively, whereas 2 was identified as 17β-dammara-12,20-diene-3β-3′,8′-dimethyloctanoate through 1H NMR and mass spectral data. Compounds 1, 2, 4 and 5 were evaluated for their in vitro cytotoxic activity, which exhibited weak activity against the 3T3, PC3 and HeLa cell lines with the IC50 value >30 μM. Antioxidant results of 1 – 5 revealed that only compound 5 showed antioxidant activity in DPPH radical scavenging inhibition with the IC50 1.31 × 10? 6 ± 0.005 μm mL? 1. Both activities are the first records of these isolated compounds from the flowers of Ixora coccinea Linn. 相似文献
118.
Muhammad Asim Farooq Md Aquib Sana Ghayas Rabia Bushra Daulat Haleem Khan Amna Parveen Bo Wang 《先进技术聚合物》2019,30(9):2183-2191
Natural polymers have been extensively utilized in the past decades due to their outstanding features. Among these natural excipients, protein‐based polymers have superb features owing to their high drug binding capacity and biodegradability. Whey protein is a versatile protein‐based vehicle for drug delivery systems. It has been shown to be nontoxic, biocompatible, and biodegradable. Therefore, it has been considered as an ideal biomaterial for the design of advanced drug delivery systems. Protein‐based cargo acts as synthetic polymers counterpart for innovative delivery systems. The current review is mainly focused on application of whey proteins as an emerging carrier in drug delivery systems, achieved during the past. 相似文献
119.
Naixu Li Qi Zhang Rehana Bibi Quanhao Shen Richard Ngulube Yunyi Liu Jiancheng Zhou 《中国化学》2019,37(7):709-719
The large‐scale industrial production of acetic acid (HAc) from carbonylation of methanol has enabled intense research interest from direct hydrogenation of HAc to acetaldehyde (AA). Herein, a series of cerium‐iron oxide solid solution supported metallic cobalt catalysts were prepared by modified sol‐gel method and were applied in gas‐phase hydrogenation of HAc to AA. A synergistic effect between the hydrogenation metal cobalt and Ce‐Fe oxide solid solution is revealed. Specifically, oxygen vacancies provide the active sites for adsorption of HAc, while highly uniformly dispersed metallic Co adsorbs H2 and activates the reduction of HAc into AA. Moreover, the metallic Co can also assist the cyclical conversion between Fe3+/Fe2+ and Ce3+/Ce4+ on the surface of Ce1‐xFexO2‐δ supports. The unique effect substantially enhances the ability of the support material to rapidly capture oxygen atoms from HAc. It is found that the catalyst of 5% Co/Ce0.8Fe0.2O2‐δ with the highest concentration of oxygen vacancy presents the best catalytic performance (i.e. acetaldehyde yield reaches 49.9%) under the optimal reaction conditions (i.e. 623 K and H2 flow rate = 10 mL/min). This work indicates that the Co/Ce‐Fe oxide solid solution catalyst can be potentially used for the selective hydrogenation from HAc to AA. The synergy between the metallic Co and Ce1‐xFexO2‐δ revealed can be extended to the design of other composite catalysts. 相似文献
120.
Mohammad Mehdi Khodaei Peyman Salehi Ateesa Yazdanipoor Bibi Fatemeh Mirjalili 《中国化学会会志》2006,53(4):881-886
Acetals, ketals and trimethylsilyl ethers mildly and selectively underwent oxidative deprotection to carbonyl compounds by silica gel supported γ‐picolinium chlorochromate under non‐aqueous conditions in good to excellent yields. 相似文献