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51.
Rajnikant V. K. Gupta E.H. Kahn S. Shafi S. Hashmi Shafiullah B. Varghese Dinesh 《Crystal Research and Technology》2001,36(11):1281-1288
The crystal structure of 3b‐acetoxy‐5a‐cholestan‐6‐one‐semicarbazone (C30H51O3N3) has been determined by X‐ray diffraction methods. It crystallizes in the orthorhombic space group P212121 with cell parameters a = 11.641(1), b = 16.552(1) c = 31.181(4) Å and Z = 8. The structure has been refined to an R‐value of 0.050 for 4407 observed reflections. Two molecules in the asymmetric unit have been observed. In both the crystallographically independent molecules, all the three six‐membered rings (A, B and C ) of steroid nucleus exist in chair conformation, while the five‐ membered ring D exists in 13β distorted‐envelope in molecule‐I and 13β, 14α half‐chair conformation in molecule‐II. Three intermolecular N‐H … O hydrogen bonds have been observed. 相似文献
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Syed Farooq Adil Mohamed E. Assal Mohammed Rafi Shaik Mufsir Kuniyil Azhar Hashmi Mujeeb Khan Aslam Khan Muhammad Nawaz Tahir Abdulrahman Al-Warthan Mohammed Rafiq H. Siddiqui 《应用有机金属化学》2020,34(8):e5718
Graphene–metal nanocomposites have been found to remarkably enhance the catalytic performance of metal nanoparticle-based catalysts. In continuation of our previous report, in which highly reduced graphene oxide (HRG)-based nanocomposites were synthesized and evaluated, we present nanocomposites of graphene oxide (GRO) and ZnO nanoparticle-doped MnCO3 ([ZnO–MnCO3/(1%)GRO]) synthesized via a facile, straightforward co-precipitation technique. Interestingly, it was noticed that the incorporation of GRO in the catalytic system could noticeably improve the catalytic efficiency compared to a catalyst (ZnO–MnCO3) without GRO, for aerial oxidation of benzyl alcohol (BzOH) employing O2 as a nature-friendly oxidant under base-free conditions. The impacts of various reaction factors were thoroughly explored to optimize reaction conditions using oxidation of BzOH to benzaldehyde (BzH) as a model substrate. The catalysts were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, Energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and Raman spectroscopy. The (1%)ZnO–MnCO3/(1%)GRO exhibited significant specific activity (67 mmol.g−1.hr−1) with full convversion of BzOH and >99% BzH selectivity within just 6 min. The catalytic efficiency of the (1%)ZnO–MnCO3/(1%)GRO nanocomposite was significantly better than the (1%)ZnO–MnCO3/(1%)HRG and (1%)ZnO–MnCO3 catalysts, presumably due to the existence of oxygen-possessing groups on the GRO surface and as well as a very high surface area that could have been instrumental in uniformly dispersing the active sites of the catalyst, i.e., ZnO–MnCO3. Under optimum circumstances, various kinds of alcohols were selectively transformed to respective carbonyls with full convertibility over the (1%)ZnO–MnCO3/(1%)GRO catalyst. Furthermore, the highly effective (1%)ZnO–MnCO3/(1%)GRO catalyst could be successfully reused and recycled over five consecutive runs with a marginal reduction in its performance and selectivity. 相似文献
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Gold‐Catalyzed Regiospecific C−H Annulation of o‐Ethynylbiaryls with Anthranils: π‐Extension by Ring‐Expansion En Route to N‐Doped PAHs 下载免费PDF全文
Zhongyi Zeng Hongming Jin Dr. Kohei Sekine Dr. Matthias Rudolph Frank Rominger Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2018,57(23):6935-6939
We describe a novel, short, and flexible approach to diverse N‐doped polycyclic aromatic hydrocarbons (PAHs) through gold‐catalyzed π‐extension of anthranils with o‐ethynylbiaryls as reagents. This strategy uses easily accessible starting materials, is simple due to high step and atom economy, and shows good functional‐group compatibility as well as scale‐up potential. Mechanistically, the tandem reaction is proposed to involve a nucleophilic addition/ring opening/regiospecific C?H annulation/protodeauration sequence terminated by a Friedel–Crafts‐type cyclization. Photophysical studies of the products indicated violet‐blue fluorescence emission with quantum yields up to 0.45. 相似文献
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M. H. Hashmi Abdus Subhan Adil N. A. Chughtai Farhat Rafique Chughtai M. A. Shahid 《Mikrochimica acta》1968,56(2):291-296
Summary A method has been developed for the separation and identification of 20 common amino acids by circular thin-layer chromatography. The amino acids are separated to neutral, acid, and basic groups by electrolysis and then identified by circular TLC. The method is simple and development of a chromatoplate is complete in about 3 minutes. The application of the method is illustrated by the analysis of amino acids in foods and in urine.
Zusammenfassung Zur Trennung und Identifizierung 20 gewöhnlicher Aminosäuren wurde ein chromatographisches Verfahren entwickelt. Die Aminosäuren werden elektrolytisch in neutrale, basische und saure getrennt und dann auf kreisförmiger Dünnschichte chromatographiert. Die Entwicklung des Chromatogramms ist in 3 Minuten beendet. Die Anwendung zur Analyse von Lebensmitteln und Harn wird beschrieben.相似文献
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Patrick W. Antoni Alexandra V. Mackenroth Dr. Florian F. Mulks Dr. Matthias Rudolph Prof. Dr. Günter Helmchen Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8235-8238
A sulfilimine-based Group 9 transition-metal-catalysed C−H amidation procedure is reported. Dibenzothiophene-based sulfilimines were shown to constitute a class of novel amidation reagents which enable the transfer of a wide range of N-sulfonyl and N-acyl moieties. It was demonstrated that sulfilimines, which are easily accessible from cheap reagents, are safe-to-handle and represent broadly applicable amidation reagents. The dibenzothiophene can be recycled after use. The C−H amidation was shown to proceed with high selectivity and gave the mono-amidated products, mostly in good to excellent yields. 相似文献