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101.
Water-distilled essential oils from leaves of Hymenocrater yazdianus Rech.f., flowers of Stachys obtusicrena Boiss., and stems and flowers of Nepeta asterotricha Rech.f., which are endemic to Iran, were analyzed by GC and GC/MS. Fifty-five components of the leaf oil of H. yazdianus were characterized, representing 95.1% of the total components detected. The major constituents were identified as 1,8-cineole (17.6%), beta-caryophyllene (13.9%), alpha-pinene (10.6%) and caryophyllene oxide (10.4%). Germacrene-D (37.5%) and alpha-bisabolol (23.5%) were the main components among the twenty constituents characterized in the flower oil of S. obtusicrena, representing 90.8% of the total components detected. Thirty-five compounds representing 93.0% of the stem oil of N. asterotrica were identified among which terpinen-4-ol (22.8%) and gamma-terpinene (14.1%) were the major ones. The flower oil of the species was characterized by higher amounts of terpinen-4-ol (24.8%), 4a alpha, 7a beta-nepetalactone (18.2%) and 1,8-cineole (11.6%) among the thirty-three components comprising 98.5% of the total oil detected. The antibacterial activity of the stem, leaf and flower oils of Hymenocrater yazdianus, Stachys obtusicrena and Nepeta asterotricha against seven Gram-positive and Gram-negative bacteria were determined using the MIC method. The growth inhibitory zone (mm) was also measured. 相似文献
102.
Heterogeneous catalysts were developed by supporting palladium nanoparticles on modified cross‐linked polyacrylamide and successfully applied in Suzuki‐Miyaura cross‐coupling reactions. These catalysts are stable to air and moisture, and no sign of metal leaching was detected during the reactions as judged by elemental analysis of palladium by ICP‐OES technique and hot filtration test, which demonstrates the heterogeneous character of the catalysts. High yields of desired products were resulted by using these phosphine‐free catalysts at temperatures below 80 °C without aid of any additional ligands. The heat stability of the catalysts at the operating temperature was confirmed by thermogravimetric analysis (TGA). These catalysts are easy to use and cost effective. They can be recovered from reaction mixture by a simple filtration and reused in more successive reactions without significant loss in activity. The catalyst activity was restored by an ultrasonication program after deactivation in 10 cycles. 相似文献
103.
Efficient method for direct preparation of 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes through condensation of β‐naphthol with various aromatic aldehydes in the presence of the catalytic amount of [H—NMP]+[HSO4]? under microwave irradiation was described. This method has the advantages such as; very easy reaction workup, absolute separation of catalyst from the reaction mixture and smooth recyclability of catalyst. In this reaction 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes were obtained as desired products in excellent yields and short reaction times via green and one‐pot procedure. 相似文献
104.
CuO‐CeO2 nanocomposite is reported as a highly efficient and recyclable catalyst for the green synthesis of 1,8‐dioxooctahydroxanthenes in water. This catalyst can be recovered by simple filtration and recycled up to 8 consecutive runs without any losing of its efficiency. 相似文献
105.
Gholam‐Reza Nejabat Mehdi Nekoomanesh Hassan Arabi Hamid Salehi‐Mobarakeh Gholam‐Hossein Zohuri Mojtaba Omidvar Stephen A. Miller 《Journal of polymer science. Part A, Polymer chemistry》2013,51(3):724-731
Various elastomeric polypropylenes (PPs) are synthesized through homogeneous propylene polymerization with metallocene catalyst (2‐PhInd)2ZrCl2 in the presence of different cocatalyst mixtures: triethylaluminum (TEA)/methylaluminoxane (MAO) or triisobutylaluminum (TIBA)/MAO in the range of AlAlR3/AlMAO = 0.0–0.9. The cocatalyst formulation impacts the resultant polymer microstructure and the thermal and dynamic mechanical properties of the produced PPs. 13C NMR analysis of the polymers reveals essentially atactic PP, with mmmm = 7.9%, when AlAlR3/AlMAO = 0.0. The mmmm pentad content is maximized when AlAlR3/AlMAO = 0.8; for TIBA, mmmm = 23.5%; and for TEA, mmmm = 17.6%. Differential scanning calorimetry analysis and dynamic mechanical thermal analysis corroborate these findings. Specifically, Tm, ΔHm, and Tg are essentially maximized under these conditions, and the minimum damping is observed for AlAlR3/AlMAO = 0.6–0.8. 1H NMR analysis of the mixtures of catalyst and cocatalysts (without monomer) shows very minor differences for [Zr]:AlAlR3 in the range of 1:1–1:5. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
106.
Majid M. Heravi Fatemeh Nahavandi Samaheh Sadjadi Hossein A. Oskooie Fatemeh F. Bamoharram 《合成通讯》2013,43(4):498-503
Reaction of aldehydes and 4-hydroxycoumarin in the presence of catalytic amount of silica-supported Preyssler nanoparticles led to synthesis of bis-coumarins in excellent yields. 相似文献
107.
1,1‐Diacetates have been synthesized by the reaction of a variety of aldehydes with acetic anhydride in the presence of cupric nitrate as catalyst under solvent‐free conditions. Ketones were not converted to the corresponding diacetates under these conditions. 相似文献
108.
Leila Khoshmaram Hossein Abdolmohammad‐Zadeh Elham Ghaffarzadeh 《Journal of separation science》2019,42(3):736-743
In this work, a new, cheap, simple, fast, and low organic solvent consuming procedure is proposed for isolation, enrichment, and gas chromatographic determination of some phthalate esters in edible oils. The method is based on a combination of air‐assisted liquid–liquid extraction and dispersive liquid–liquid microextraction followed by a drying step under N2 gas. Several experimental parameters affecting both extraction and preconcentration steps were investigated and optimized. Under the optimum conditions for the proposed method, wide linear ranges (0.05–800 μg/L) and low detection limits (0.007–0.023 μg/L) were observed. The ranges of enrichment factors and extraction recoveries were 68–340 and 14–68%, respectively. Eventually, the target analytes were successfully determined in different edible oils using the proposed method. 相似文献
109.
Mohammad Hossein Keshavarz Sahar Belyani Seyyed Mohammad Reza Darbani Masoud Kavosh Tehrani 《无机化学与普通化学杂志》2019,645(16):1057-1061
Laser Induced Breakdown Spectroscopy (LIBS) method is introduced as a novel approach in this work to study catalyst deactivation of V2O5/γ‐‐Al2O3 for gas‐phase dehydration of glycerol and producing acrolein. The LIBS results of V2O5/γ‐Al2O3 samples are compared with those data that are obtained by Inductively Coupled Plasma Optical Emission Spectrometry (ICP‐OES). Experimental data of LIBS data specify that line intensities of vanadium are decreased by deactivation of V2O5/γ‐Al2O3 catalyst. A comparison between the results of LIBS test as well as ICP‐OES analysis shows that the amount of vanadium is decreased in the catalyst. Moreover, coke formation changes the surface of the catalyst. The results of deactivation of V2O5/γ‐Al2O3 are also compared with Pd/C catalyst deactivation. 相似文献
110.
Habibi MH Mokhtari R Mikhak M Amirnasr M Amiri A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1524-1527
Cu(II) and Ni(II) complexes of the general type [M(N2O2)] are described. The N2O2 ligands used are [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine] (HOMeSalpn) and [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,2-diamine (HOMeSalpr). These complexes have been characterized by IR, UV-vis, CV, TG-DTA and 1H NMR spectroscopy. The electrochemical behavior of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Cu(II)-Cu(I) and Ni(II)-Ni(I) is electrochemically irreversible. The new copper complexes have been applied for the preparation of copper nanoparticles using non-ionic surfactant (Triton X-100) by thermal reduction. The copper nanoparticles with average size of 48nm were formed by thermal reduction of [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine]copper(II) in the presence of triphenylphosphine thus releasing the reduced copper and affording the high-purity copper nanoparticles. 相似文献