共查询到20条相似文献,搜索用时 0 毫秒
1.
O. Bonesso M. J. Ozafran H. O. Mosca M. E. Vazquez O. A. Capurro S. J. Nassiff 《Journal of Radioanalytical and Nuclear Chemistry》1991,152(1):189-197
A stack of natural copper was bombarded with -particles. Cumulative cross-sections for65Ga,66Ga and65Zn production, and the excitation functions for68Ga and67Ga production, were measured using high resolution gamma-ray spectroscopy. The data are compared with the theoretical result provided by equilibrium and pre-equilibrium reaction model, for this purpose we used the code ALICE of Blann. The overall agreement with theory is good. Besides, we present the experimental data obtained by other authors. 相似文献
2.
Yu-Gui Li Yun-Shan Liu Fang-Ming Miao Xiao-Lan Liu Jin-Hong Cao Wei Zhou 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):57-60
Abstract Twenty-three new α -aryl-β -nitroalkylphosphinates 3a - g were synthesized in high yields under very mild conditions. Compounds 3 consist of two pairs of diastereomeric isomers (A) and (B) 相似文献
3.
《Tetrahedron letters》1987,28(42):4973-4976
Reaction of organolithium reagents with glyoxylate and pyruvate derived oximes provides a direct route for the synthesis of unusual α-N-hydroxy amino acids. 相似文献
4.
The reaction of nitroso chlorides of natural monoterpene hydrocarbons, 3-carene and -pinene, with simple ,-diamines (1,2-diaminoethane, 1,3-diaminopropane, piperazine, 1,6-diaminohexane, diethylenetriamine) results in the formation of -amino oximes and bis--amino oximes. The product structures were proved by spectroscopy. The procedures of separation and purification of diamino oximes and diamino dioximes are described. Detailed analysis of the 1H and 13C NMR spectra of the new chiral nitrogen-containing derivatives was carried out. 相似文献
5.
《Tetrahedron: Asymmetry》1998,9(10):1703-1712
The additions of organolithium reagents to the CN bond of several chiral oxime ethers derived from erythrulose afforded protected amino polyols with high diastereoselectivity. Four of the latter compounds have been converted into the α,α-disubstituted α-amino acids (R)-2-(−)-methylserine, (S)-2-(+)-methylserine, (R)-(+)-2-phenylserine and (R)-(−)-2-n-butylserine. 相似文献
6.
Xiaoqing Chen Weijie Yang Xinyu Jiang Feipeng Jiao Lingxing Tian 《Tetrahedron: Asymmetry》2012,23(17):1227-1233
Herein we focused on using a novel separation technology, solvent sublation, for the enantioseparation of α-cyclohexylmandelic acid (CHMA). The experiment was carried out in a conventional bubble column using d-iso-butyl tartrate (d-IBTA) and sodium dodecyl sulfate (SDS) as a chiral selector and surfactant, respectively (Fig. 7). Several important parameters influencing the separation performance, such as the type of organic phase, the pH in the aqueous phase, and the concentrations of CHMA, d-IBTA, and SDS were investigated. Under the optimal operating conditions, the enantiomeric excess and separation factor were 54.85% and 4.5, respectively. The yields of d-enantiomer and l-enantiomer were 82.20% and 38.94%, respectively. Finally, the thermodynamic properties of the separation were investigated, which indicated an enthalpy-controlled process. This technique is an efficient chiral separation method, with many advantages, such as low amounts of organic solvent and chiral selector required and easier realization of the multi-stage operation. 相似文献
7.
8.
Gislaine Aparecida Honorato Ricardo Vieira de Lima Bhaskar Reddy Manda Derisvaldo Rosa Paiva Tairine Pimentel Roberto da Silva Gomes 《Tetrahedron letters》2017,58(23):2240-2243
The comparison in several reaction conditions for synthesis of nonracemic α-methylsulfinylation of 3,4-dihydronaphthalen-1(2H)-one was achieved. The sulfanylation reactions of 3,4-dihydronaphthalen-1(2H)-one-O-methyloxime and 2-(methylsulfinyl)-3,4-dihydronaphthalen-1(2H)-one-O-methyloxime by homogenous reaction medium are reported. The products were obtained in good yields and de. The yields, diastereoselectivity and theoretical calculations to all obtained compounds to support the experimental data are compared and discussed. 相似文献
9.
The stereochemistry of the substitution of the α-dimethylamino group by dimethylzinc in the presence of acetyl chloride in the chiral benzylferrocene backbone was examined. The reaction with the benzylferrocene bearing an o-bromo substituent at both ferrocene and the phenyl ring proceeded with inversion of configuration, while the reaction with the benzylferrocene bearing an o-bromo substituent at either ferrocene or the phenyl ring proceeded with retention of configuration. 相似文献
10.
《中国化学快报》1997,(10)
TheanalwisofMSdataofl4substitutalatwcbocacidsindicateSaclassofpeificfragmenpeakS(Tatrl)'fllcdevelopn1en1oftLhesefragmentPeaksistnggeredb)].3-shift[1J7-heMSIYapoenta[1onpattenlot'compotmdf;8belou'illustratesthegenera1mechanjs1nScbemc.lTbemajorMShagmentationpatternofa-phenysubstitutedcinnamicacidAstheSCheInshows,afterthel,3-shiftofhydr0xyinCOmpoUndE8-tberesultinginterInwhatewhllosetheRCX=0grOUfollowinthebondeq,chchleadstOtheformationofmlZl25anditscomPleInentaIyPeakYnlzl63,withthebo… 相似文献
11.
Shahkhatuni AA Shahkhatuni AG Panosyan HA Sahakyan AB Byeon IJ Gronenborn AM 《Magnetic resonance in chemistry : MRC》2007,45(7):557-563
Alignment media used for measuring residual dipolar couplings, such as solutions of filamentous phages, phospholipid mixtures, polyacrylamide gels and various lyotropic liquid crystalline systems were investigated with respect to solvent effects on molecular structure. Structural parameters of the small rigid model compound 13C-acetonitrile were calculated from dipolar couplings and variations from expectation values were used for assessment of solvent effects. Only minor solvent effects were observed for most of the media employed and the measured structural data are in good agreement with microwave data and theoretical predictions. 相似文献
12.
M. I. Kabachnik L. S. Zakharov E. I. Goryunov P. V. Petrovskii T. M. Shcherbina 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract The methods of synthesis unsymmetrical polyfluoroalkyl phosphates (II) by catalytic phosphorylation of phenols or polyfluoroalkanols by chlorophosphates (I) were elaborated 相似文献
13.
The reactions of the tert-butyldimethylsilylated acyloins of five-, six- and seven-membered rings with the lithium reagents of benzyltrimethylsilane, thiophenoxymethyltrimethylsilane and tri-methylsilyl acetonitrile were studied. These reactions favor formation of the substituted (Z) exo methylidene silyl ethers in moderate yields. 相似文献
14.
Dissociation of α-alkyl-substituted dicarboxylic acids low-soluble in water was studied by the method of pH-potentiometry titration. Equilibrium constants of the dissociation at 25°C were determined. 相似文献
15.
A. R. Garifzyanov G. Kh. Nuriazdanova S. V. Zakharov R. A. Cherkasov 《Russian Journal of General Chemistry》2004,74(12):1885-1889
Two-phase potentiometric titration was used to determine partition constants for a series of -aminophosphonates (RO)2P(O)CH2NR1R2 [R = Alk (C2-C5), R1, R2 = Me, Et, (CH2)5] between water and organic solvents, such as chloroform, carbon tetrachloride, toluene, octane, n-octanol, nitrobenzene, o-xylene, and cyclohexane. Correlations between the partition constants and the number of carbon atoms in substrate molecules were obtained. Solvent effects on partition constants were discussed, and solution parameters of -aminophosphonates were calculated.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 1998–2002.Original Russian Text Copyright © 2004 by Garifzyanov, Nuriazdanova, Zakharov, Cherkasov.This revised version was published online in April 2005 with a corrected cover date. 相似文献
16.
Aromatic α-sulfinyl carboxylic acids can be rearranged to hemithioacetals or other derivatives of glyoxylic acid under the action of acid reagents was first reported by Pummerer1. Later, Russell and coworkers applied this rearrangement to β-ketosulfoxides, synthesized α-ketohemithioacetal2, which can be transformed to α-keto alcohol, α-keto aldehyde and α-hydroxy alcohol, α-hydroxy acid3. Furthermore, Hall and Poet reported that α-ketohemithio-acetal can be rearranged to the corresponding α-hydroxythioester in the presence of magnesium nitrate and sodium acetate or tertiary amine4. However, few reports of reaction of α-ketohemithioacetal can be seen in literature. 相似文献
17.
《中国化学快报》1997,(11)
a-ThiocaIbonylthiOformnddesareOfalmostunexploredclassOfcomPOundsll],althoughtheyhavebeenpreParedsincel98Ol2-3].ThisattractSustoexploretheirchendStryandutilityinSynthesisOfheteropcles.Accordingtoourpreviousmethodl`1,a-benzOylthiOfOrmyl-morpholine1wasprePaIedfirst,fOllowedbysumirizationOfcarbonylwithLawessenreagnttoaffordtheexpeCtedcr-thjobenzoylthiOformylmorpholine2,whchhastWothiotnylgrous.onthebasisOfstructUreof2,itcanbereactedwithcomPOundsbearingdrinctionalgrouP,suchasdidrineandsen… 相似文献
18.
López X Fernández JA Romo S Paul JF Kazansky L Poblet JM 《Journal of computational chemistry》2004,25(12):1542-1549
DFT calculations were driven for a set of differently charged polyoxoanions in the gas phase and in solution. We have calculated and analyzed their geometries and orbital energies to trace simple rules of behavior regarding the modeling of anions in isolated form. We discuss the quality of the results depending on the molecular charge, q, and the size of the cluster in terms of the number of metal centers, m. When the q/m ratio reaches a value of approximately 0.8, DFT calculations for the isolated anion fail to describe the gap between the band of occupied oxo orbitals and the set of unoccupied orbitals delocalized among the metal atoms. In these cases the incorporation of the stabilizing external fields generated by the solvent through continuum models improves the geometries and orbital energies. 相似文献
19.
The reaction of unprotected sugar hydroxylamines and oximes with α-ketoacids leads to the chemoselective formation of glycosyl amides following the decarboxylative condensation pathway of Bode’s ketoacid hydroxylamine (KAHA) ligation. Sugar oximes with gluco configuration stereoselectively form β-linked products. This method can be used for the convergent synthesis of N-acylated sugars and oligosaccharides bearing small labels, spacers, or peptides in the acyl part. 相似文献
20.
Zizhan Chen 《Journal of fluorine chemistry》2010,131(3):340-8313
Two methods of nucleophilic fluorination to prepare α-fluoroacetophenones from α-bromoacetophenones by using KF with PEG-400 or TBAF with ZnF2 are described. On the fundamental of nucleophilic fluorination, a novel method of one-pot fluorination to prepare α-fluoroacetophenones directly from acetophenones in DES was developed. 相似文献