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941.
Pseudo-first order rate constants (kobs) for alkaline hydrolysis of phthalimide (PTH), obtained at constant concentration of cetyltrimethylammonium bromide (CTABr) and 35°C, vary with the concentration of organic salts ([MX]) according to the relationship: kobs = (k0 + K [MX])/(1 + K [MX]) where and K are empirical parameters. The values of K at 0.01 M CTABr are nearly 2 times larger than the corresponding K values at 0.02 M CTABr for sodium benzoate, disodium phthalate and disodium isophthalate. 相似文献
942.
Treatment of N-phenylsulfonylarenehydrazonoyl chlorides (II) with equivalent amounts of aroylhydrazines (III) in ethanol gave 3,5-diaryl-4-phenylsulfonylamino-1,2,4-triazoles (IV). Reaction of II with two equivalents of III in tetrahydrofuran gave 2,5-diaryl-1,3,4-oxadiazoles (V), in addition to IV. Addition of triethylamine to II or its mixture with III yielded only the tetrazenes (VIII). The possible pathways leading to IV-V and VIII are discussed. J. Chem. Soc., 14, 1089 (1977) 相似文献
943.
Nehal A. Hamdy Hatem A. Abdel-Aziz Ahmad M. Farag Issa M. I. Fakhr 《Monatshefte für Chemie / Chemical Monthly》2007,60(4):1001-1010
3-(3-Methylthiazolo[3,2-a]benzimidazol-2-yl)-3-oxopropionitrile was synthesized by refluxing ethyl 3-methylthiazolo[3,2-a]benzimidazole-2-carboxylate, acetonitrile, and sodium hydride. Treatment of 3-(3-methylthiazolo[3,2-a]benzimidazol-2-yl)-3-oxopropionitrile with phenyl isothiocyanate, in the presence of KOH, furnished the corresponding potassium
salt which was converted into thioacetanilide derivative upon neutralization. The thioacetanilide derivative reacts with α-chloroacetylacetone
and ethyl α-chloroacetoacetate to give the 1,3-thiazole derivatives, while the reaction of the'thioacetanilide derivative
with hydrazonyl chlorides gave 1,3,4-thiadiazole derivatives. On the other hand, 3-(3-methylthiazolo[3,2-a]benzimidazol-2-yl)-3-oxopropionitrile reacted with the diazonium salt of both 3-phenyl-5-amino-(1H)-pyrazole and 5-amino-l,2,4-(1H)-triazole to afford the corresponding hydrazones. The latter hydrazones underwent an intramolecular cyclization upon boiling
in pyridine to give pyrazolo[5,1-c]-1,2,4-triazine and 1,2,4-triazolo[5,1-c]-1,2,4-triazine derivatives. Moreover, the behavior of thiazolo[3,2-a]benzimidazol-3(2H)-one towards phenyl isothiocyanate followed by the reaction with α-chloroketones or hydrazonyl chlorides was investigated.
Some of the latter compounds exhibited moderate effects against some bacterial and fungal species. 相似文献
944.
G. A. El-Shobaky A. S. Ahmad M. Mokhtar 《Journal of Radioanalytical and Nuclear Chemistry》1997,219(1):89-94
A copper, zinc and aluminium mixed oxides sample having the nominal composition 0.25 CuO/0.03 ZnO/Al2O3 was prepared by impregnating Al(OH)3 with copper and zinc nitrate solutions, drying at 100 °C then heating in air at 600 °C. The obtained solid was exposed to different doses of -rays (20–160 Mrad). The surface characteristics namelyS
BETVP andr of different treated adsorbents were determined from N2 adsorption isothems measured at –196 °C. The catalytic activity of various irradiated solids was determined by following up the kinetics of CO-oxidation by O2 at 150–200 °C. The results showed that the doses up to 80 Mrad resulted in no significant change in theS
BET but increased slightly theV
P (20%) of the treated adsorbents. The irradiation at 160 Mrad caused an increase of 20% in theS
BET of the irradiated solid sample. The catalytic activity increased progressively by increasing the dose, a dose of 160 Mrad brought about an increase of 140% in the catalyst's activity. The apparent activation energy of the catalytic reaction decreased monotonically by increasing the absorbed dose of -rays which was attributed to a parallel induced decrease in the value of pre-exponential term of the Arrhenius equation. The observed increase in the catalytic activity due to -irradiation has been interpreted as a result of increasing the concentration of catalytically-active sites contributing in chemisorption and catalysis of CO-oxidation via a possible fragmentation of CuO crystallites. 相似文献
945.
Ahmad Rouhollahi Mohammad Reza Ganjali Abolghasem Moghimi Gerald W. Buchanan Mojtaba Shamsipur 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(4):361-376
A synthetic procedure has been developed for the preparation of 4-carboxy-benzo-30-crown-10. The formation of Na+, K+, Rb+, Cs+ and Tl+ complexes with the large crown ether was investigated conductometrically in acetonitrile solution at various temperatures. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data. It was found that the stability of the complexes vary in the order Tl+ > K+ > Rb+ > Cs+ > Na+. The data obtained in this study support the existence of a wrap around structure for the above complexes in solution. The enthalpy and entropy of complexation reactions were determined from the temperature dependence of the formation constants. In all cases, the complexes were enthalpy stabilized but entropy destabilized. The resulting TS° vs. H°plot showed a fairly good linear correlation, indicating the existence of an entropy-enthalpy compensation in the large crown complexation reactions. 相似文献
946.
Permanganate supported on active manganese dioxide can be used effectively for the oxidation of organic compounds under heterogeneous or solvent-free conditions. The residue that remains after extraction of the organic products, manganese dioxide, can be recycled, making the process infinitely sustainable, in theory. The use of this approach for the oxidation of arenes, alcohols and sulfides is described. 相似文献
947.
Sawaya WN al-Awadhi FA Saeed T al-Omair A Ahmad N Husain A Khalafawi S al-Omirah H Dashti B al-Amiri H al-Saqer J 《Journal of AOAC International》1999,82(6):1458-1465
The State of Kuwait in cooperation with the U.S. Food and Drug Administration (FDA) conducted a Total Diet Study (TDS) to estimate intakes of pesticide residues by the population. The levels of organochlorine (OC) pesticides, carbamates, benzimidazoles, and phenylureas in the TDS core list are reported here. The TDS core list was established through a national food consumption survey. All food items (140 for the Kuwaiti adult) were prepared as eaten and analyzed for the pesticides mentioned above. The FDA's multiresidue methods in Volume I of the Pesticide Analytical Manual were used in gas, liquid, and gel permeation chromatographic analyses. Only vegetable and fruit samples contained pesticide residues (mg/kg), including the carbamates 1-naphthol (1.4) and 3H-carbofuran (0.94) in carrots; the OC pesticide vinclozolin (0.47), 3H-carbofuran (0.66), and fenuron (0.6) in kiwi fruit; the OC pesticide procymidone (0.32) and carbendazim (0.5) in grapes; 3H-carbofuran (5.0) in apricots; the OC pesticides captan (0.013) and thiabendazole (0.63) in pears; captan (0.035) in plums; and carbendazim (0.4) in mandarin oranges. The levels of 3H-carbofuran found in both apricots and kiwi fruit exceeded the maximum residue limits (MRLs) of the Food and Agriculture Organization/World Health Organization (FAO/WHO) of the United Nations. The daily intakes of pesticides by the different population groups are discussed in light of the FAO/WHO acceptable daily intakes. 相似文献
948.
M. S. Ahmad M. Mushfiq G. A. S. Ansari Miss F. Waris 《Journal of mass spectrometry : JMS》1974,8(1):1-10
The mass spectra of several structurally related ring B seco 5-keto compounds (I to VII) have been examined. The mass spectra of I, II, III and IV are conspicuous by an intense peak at m/e112(C7H12O) and those of V (highest mass peak at [M ? CH3COOH]), VI and VII by a prominent peak at m/e 100 (C7H10O), which apparently results from McLafferty rearrangement involving 5-keto function and an appropriate γ-hydrogen at C-8 and C-11. This rearrangement, leading to the aforementioned ions, is of diagnostic value in the characterisation of such compounds. The mass spectrum of VIII exhibits a prominent ion peak at m/e 332 (C23H40O) resulting from McLafferty rearrangement involving the 5-keto function and C2? H. This offers an excellent means of differentiating between the isomeric acids (III and VIII). The fragmentation pathways suggested are supported by accurate mass measurement of the salient fragment ions and in some cases by appropriate metastable peaks. 相似文献
949.
S. A. Ahmad Pushpa M. Rao G. D. Saksena 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,6(3):227-229
We report here the experimental evaluation of crossed-second-order (CSO) effects in the field shift of8 F and6 F terms of 4f 6(7 F)6s configuration of singly ionised samarium. Our experimental value of CSO field shift difference between8 F and6 F terms for148Sm and154Sm is ?11.8(3.2) mK, which is in good agreement with the theoretical value of ?13.8 mK evaluated using known parameters. 相似文献
950.
Ahmad O. Baghlaf Khalid Banaser Hussain Y. Hashem Ahmed Albishry Muhammad Ishaq 《Transition Metal Chemistry》1996,21(1):16-18
Summary [RuCl2(CO)2]
n
reacts with the Schiff base 1-acetylferrocenethiosemicarbazone, [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)] to give [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)RuCl2(CO)2] and with 1-acetylferrocenesemicarbazone [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)] to give [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)RuCl2-(CO) 2]. Spectroscopic data indicate that the Schiff bases act as bidentate ligands and coordinate to ruthenium via the hydrazinic N and either the S or O atoms, respectively, giving stable heterobimetallic complexes, which have been characterized by i.r. and 1H-n.m.r. spectroscopies, and elemental analyses.Part of this work was presented at the First International Conference in Chemistry and its applications in Doha, Qatar, 1993. 相似文献