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41.
Abdullah A. Al‐Karim Al‐Shara'ey 《中国化学会会志》2004,51(3):547-552
6‐Aryl‐5‐cyano‐4‐pyrimidinone‐2‐thion derivatives 1a‐c reacted with methyl iodide (1:2) to give the corresponding 2‐S,N‐dimethyl pyrimidine‐4‐one derivatives 2a‐c . Compounds 2a‐c were in turn, reacted with hydrazine hydrate to give the sulfur free reaction products 3a‐c . These reaction products were taken as the starting materials for the synthesis of several new heterocyclic derivatives. Reaction of 3a‐c with acetic anhydride and formic acid gave pyrimido triazines 4a‐c and 7a‐c , respectively. Their reactions with active methylene containing reagents gave the corresponding 2‐(1‐pyrazonyl)‐N‐methyl pyrimidine derivatives 9a‐c and 10a‐c , respectively. Their reactions with aromatic aldehydes afforded the corresponding 2‐hydrazono pyrimidine derivatives 11a‐c . The structure of these reactions products were established based on both elemental analysis and spectral data studies. 相似文献
42.
El Khatib M Elagawany M Jabeen F Todadze E Bol'shakov O Oliferenko A Khelashvili L el-Feky SA Asiri A Katritzky AR 《Organic & biomolecular chemistry》2012,10(25):4836-4838
Chemical ligation via O- to N-acyl transfer of O-acylated serine containing peptides affords serine containing native peptides via 8- and 11-membered cyclic transition states opening the door to a wide variety of potential applications to peptide elaboration. The feasibility of these traceless chemical ligations is feasible as supported by computation. 相似文献
43.
IH Alsohaimi ZA Alothman MR Khan MA Abdalla R Busquets AK Alomary 《Journal of separation science》2012,35(19):2538-2543
Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 μg/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water. 相似文献
44.
Mahnaz M.Abdi H.N.M.Ekramul Mahmud Luqman Chuah Abdullah Anuar Kassim Mohamad Zaki Ab.Rahman Josephine Liew Ying Chyi 《高分子科学》2012,(1):93-100
Electrical conductivity and optical properties of polypyrrole-chitosan(PPy-CHI) conducting polymer composites have been investigated to determine the optical transition characteristics and energy band gap of composite films.The two electrode method and I-V characteristic technique were used to measure the conductivity of the PPy-CHI thin films,and the optical band gap was obtained from their ultraviolet absorption edges.Depending upon experimental parameter,the optical band gap(Eg) was found within 1.30-2.32 eV as estimated from optical absorption data.The band gap of the composite films decreased as the CHI content increased.The room temperature electrical conductivity of PPy-CHI thin films was found in the range of 5.84×10-7-15.25×10-7 S·cm-1 depending on the chitosan content.The thermogravimetry analysis(TGA) showed that the CHI can improve the thermal stability of PPy-CHI composite films. 相似文献
45.
Özlem Sarıöz Osman Serindaĝ Meysun İ. Abdullah 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1785-1795
Functionalized bis(amino)phosphines of the type PhP(NHR)2 ( 1a–c ) and aminophosphines of the type Ph2PNHR ( 2a–c ) have been synthesized by treating PhPCl2 or Ph2PCl with corresponding primary amines of H2N-R where R = -CH2SO3H, -C6H4SO3H, and benzo-15-crown-5. The molybdenum(0) complex of the aminophosphine ( 3 ) has been obtained by reacting cis-[Mo(CO)4(bipy)] with aminophosphine ( 2c ). The synthesized aminophosphines, bis(amino)phosphines, and the molybdenum(0) complex have been characterized by IR, 1H NMR, 31P NMR, and MS spectroscopic techniques and by elemental analysis. 相似文献
46.
Calixpyrrole-based oligomeric compounds were synthesized by "click chemistry" from the corresponding alkyne- and azide-functionalized calix[4]pyrroles. Calix[4]pyrrole 3, possessing an alkyne functional group, was prepared through a mixed condensation of pyrrole with acetone and but-3-ynyl 4-oxopentanoate. Another alkyne-group-containing calix[4]pyrrole 5 was obtained by treatment of 4'-hydroxyphenyl-functionalized calixpyrrole 4 with propargyl bromide. Tetrakis(azidopentyl)-functionalized calix[4]pyrrole 7 was synthesized by reacting NaN(3) with tetrabromopentyltetraethylcalix[4]pyrrole 6, which was prepared through a condensation reaction of pyrrole and 7-bromohept-2-one. Oligomeric calixpyrrole compounds were found to be capable of extracting tetrabutylammonium chloride and fluoride salts from aqueous media. Extraction abilities of the oligomeric compounds were monitored by NMR and UV/Vis spectroscopy and thermogravimetric analysis. 相似文献
47.
David J. Miron Shane M. Kendell Alaa M. Munshi Abdullah K. Alanazi Trevor C. Brown 《国际化学动力学杂志》2013,45(6):374-386
Time‐varying linear regression via flexible least squares is used to determine temperature‐dependent kinetic parameters during low‐pressure, steady‐state, temperature‐programmed desorption from catalytic surfaces. The flexible least squares approach optimizes time‐varying parameters by minimizing dynamic and measurement discrepancies between a linear theoretical model and experimental data using linear regression. The effectiveness of this approach is demonstrated by calculation of accurate temperature‐dependent activation energies, preexponential factors, and differential conversion functions for the evolution of 3‐methyl‐2‐oxetanone (β‐lactone) during the selective oxidation of isobutane over aluminum phosphomolybdates. 相似文献
48.
Novel steroidal (6R)‐spiro‐1,3,4‐thiadiazoline derivatives were synthesized by the cyclization of steroidal thiosemicarbazones with acetic anhydride, screened in vitro against antibacterial activity using disc‐diffusion method and the minimum inhibitory concentration. The results showed that steroidal thiadiazoline derivatives exhibited better antibacterial activity than the steroidal thiosemicarbazone derivatives. Chloro and acetoxy substituents on the 3β‐position of the steroidal thiadiazoline ring increased the antibacterial activity. Among all the compounds, compound 7 and 8 were found better inhibitors of both types of bacteria (Gram‐positive and Gram‐negative) as compared to the respective drug amoxicillin. All the synthesized compounds were well characterized by spectroscopic methods such as IR, 1H‐NMR, 13C‐NMR mass, and elemental analysis and their stereochemistry was also discussed. 相似文献
49.
Yusuf Akbaba Halis Türker Balaydın Süleyman Göksu Ertan Şahin Abdullah Menzek 《Helvetica chimica acta》2010,93(6):1127-1135
3,4‐Dibromo‐5‐[2‐bromo‐3,4‐dihydroxy‐6‐(methoxymethyl)benzyl]benzene‐1,2‐diol ( 2 ), a natural product, has been synthesized for the first time starting from (3‐bromo‐4,5‐dimethoxyphenyl)methanol ( 5 ) in five steps and with an overall yield of 34%. The reaction of some methoxymethyl‐substituted aryl methyl ethers with BBr3, followed by the addition of MeOH, afforded the corresponding methoxymethyl‐substituted arylphenols in high yields. 相似文献
50.
A facile and convenient synthesis of bis(2-(1H-benzo[d]imidazol-2(3H)-ylidene)-3-oxopropanenitrile), bis((3-amino-5-(methylthio)-1H-pyrazol-4-yl)methanone) and bis(2-thioxo-1,2-dihydropyrimidine-5-carbonitrile) derivatives incorporating a thieno- [2,3-b]thiophene moiety via versatile, readily accessible diethyl 3,4-dimethylthieno-[2,3-b]thiophene-2,5-dicarboxylate is described. 相似文献