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101.
Richard Combes Marie-Noëlle Levelut Bernard Trémillon 《Journal of Electroanalytical Chemistry》1978,91(1):125-131
Reactions between cerium trichloride and oxide ions were studied in NaCl+KCl (1/1) at 1000°K, by potentiometry with a calcia-stabilized zirconia membrane electrode. Titration curves clearly demonstrated the existence of soluble cerium oxychloride (CeO+) and precipitated cerium oxide (Ce2O3), with respective dissociation constants 10?11 and 10?30 (molality scale). The corresponding conditional solubility diagram {log S (CeIII)=f(pO2?)} is presented and discussed. 相似文献
102.
In this work, different extracts from the microalga Spirulina platensis are obtained using pressurized liquid extraction (PLE) and four different solvents (hexane, light petroleum, ethanol and water). Different extraction temperatures (115 and 170 degrees C) were tested using extraction times ranging from 9 to 15 min. The antioxidant activity of the different extracts is determined by means of an in vitro assay using a free radical method. Moreover, a new and fast method is developed using micellar electrokinetic chromatography with diode array detection (MEKC-DAD) to provide a preliminary analysis on the composition of the extracts. This combined application (i.e., in vitro assays plus MEKC-DAD) allowed the fast characterization of the extracts based on their antioxidant activity and the UV-vis spectra of the different compounds found in the extracts. To our knowledge, this work shows for the first time the great possibilities of the combined use of PLE-in vitro assay-MEKC-DAD to investigate natural sources of antioxidants. 相似文献
103.
Hydroxylamine reacts with 1-alkyl-1,2-dihydro-3,1-benzothiazine-4thiones ( 1 ), giving 1-alky1-3-hydroxy-2,3-dihydro-1H-quinazoline-4-thiones ( 2 ). The same reagent, in neutral medium, converts 1-aryl-1,2-dihydro-3,1-benzothiazine-4-thiones ( 3 ) into 1-aryl-4-hydroxyimino-1,4-dihydro-2H-3,1-benzothiazines ( 4 ). In acidic medium, the same starting materials lead to 1-aryl-3-hydroxy-2-3-dihydro-1H-quinazoline-4-thiones ( 5 ). genrally with some quantity of the isomer 4 . Thiones 2 and 5 , as well as oximes 4 , heated at 200°, decomopose, yielding, in varying proportions, 1H-quinazoline-4-thiones ( 6 or 7 ), 1H-quinazoline-4-ones ( 9 ) and 2,3-dihydro-1H-quinazoline-4-thiones ( 11 ). Reacting with methyliodide, 1H-quinazoline-4-thiones ( 7 ) give 4-methylthioquinazolin-1-ium iodidies ( 12 ) which can be hydrolysed into 1H-quinazolin-4-ones ( 9 ). The latter are also obtained by reacting benzonitrile N-oxide with the corresponding thiones. 1-Aryl-1 H-quinazoline-4-thiones ( 7 ) react readily with nitrogen nucleophiles XNH2 to give 1-aryl-4-imino-1,4-dihydro-quinazolines diversely substituted on the imino group. While thiones 7 are S- methylated by methyl iodide, the corresponding 1-aryl-1H-quinazolin-4-ones (9), with the same reagent, ungergo a N-methylation, yielding 1-aryl-3-methyl-4-oxo-3,4-dihydroquinazolin-l-ium iodides ( 18 ). Structure have been confirmed by uv, ir and nmr spectra. 相似文献
104.
Aresta M Tommasi I Quaranta E Fragale C Mascetti J Tranquille M Galan F Fouassier M 《Inorganic chemistry》1996,35(14):4254-4260
Extended labeling experiments have shown that formation of rhodium peroxocarbonate from CO(2) and [RhCl(eta(2)-O(2))(P)(3)] (P is PEt(2)Ph or PEtPh(2)) proceeds through O-O bond cleavage and CO(2) insertion. O-transfer to ancillary phosphine ligand to give R(3)P=O selectively (>85%) involves the Rh-linked O atom of the peroxo group of RhCl(CO(4))(P)(3). 相似文献
105.
Noëlle Ehlinger Monique Perrin 《Journal of inclusion phenomena and macrocyclic chemistry》1995,22(1):33-40
The structure of thep-tetrakis-(4-nitrophenylazo)calix[4]arene-4-picoline (14) complex has been determined by X-ray crystallography. Crystals are monoclinic, space groupC2/c,a=24.9097) Å,b=8.425(6) Å,c=33.81(1) Å, =101.13(2)°,D
c
=1.330 g/cm3,Z=4, finalR value =0.067. The cone conformation adopted by this azocalixarene is disturbed by the positions of the picoline molecules. Two of them are inside the macorocycle cavity and the two others are outside.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. Sup. 82190 (32 pages). 相似文献
106.
A scalable synthesis of (−)-trans-2-(hydroxymethyl)-1,2,3,6-tetrahydropyridin-3-ol, a versatile chiral building block is described along with its transformation to (−)-trans-3-hydroxypipecolic acid. 相似文献
107.
108.
Matouk Zineb Rincón Rocío Torriss Badr Mirzaei Amir Margot Joëlle Dorris Annie Beck Stephanie Berry Richard M. Chaker Mohamed 《Cellulose (London, England)》2021,28(10):6239-6252
Cellulose - Despite promising characteristics such as the biodegradability and the environmentally benign nature of cellulose nanocrystal (CNC) based composites, their poor dispersion and... 相似文献
109.
110.