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1.
R. Illés Cs. Kassai Gy. Pokol J. Madarász E. Fogassy D. Kozma 《Journal of Thermal Analysis and Calorimetry》2000,61(3):745-755
Thermal behaviour of O,O'-dibenzoyl-(2R,3R)-tartaric acid (DBTA), its monohydrate, and its potential supramolecular compounds
with achiral alcohols and phenols were investigated with TG, DSC, EGD. The structural differences among the anhydrous DBTA,
its monohydrate, and the supramolecular derivatives were investigated with X-ray powder diffraction. The thermal behaviour
of DBTA-supramoleculars with isopropyl, tert-butyl, and 5-cyclohexyl alcohols is found to be similar to each other but essentially different from that of both DBTA and
its monohydrate. On heating they melt and decompose between 60–180°C while they loose in one or two steps the bound alcohol.
The thermal stability of the supramolecular compounds increases with the boiling point of the alcohol component. According
to the X-ray powder diffraction patterns each supramolecular substance has different structure, that may also result in the
different thermal stability of the compounds. The molar ratio of DBTA:achiral alcohol samples is 1:1.01–1:1.57 estimated from
the corresponding mass losses. The XRD patterns of the prepared two DBTA-phenol materials are different from those of DBTA-achiral
alcohol samples. The phenol compounds melt with slow mass losses and give an endothermic peak between 73–83°C but the melting
point of the anhydrous DBTA cannot be observed. DBTA:phenol molar ratio is estimated to be 1:0.41 and 1:0.65 for phenol and
2-methylphenol, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Illés R. Kassai Cs. Pokol G. Fogassy E. Kozma D. 《Journal of Thermal Analysis and Calorimetry》2002,68(2):679-685
The enantioselectivity of the diastereomeric supramolecular compound (SMC) formation between O,O'-dibenzoyl-(2R,3R)-tartaric
acid (DBTA) and chiral secondary alcohols was investigated. On the basis of TG measurements the DBTA:chiral alcohol molar
ratio in the SMC-s is nearly 1:1. Among the investigated complexes the most stable SMC is trans-2-iodo-cyclohexanol-DBTA. The SMC forming capability and the enantioselectivity depends on the space filling of the alcohol
side chain or ring. In the case of trans-2-halogen-cyclohexanols a relationship can be observed between the thermal stability of the SMC-s and the enantioselectivity
of SMC forming.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
H. Simon K. Marthi Gy. Pokol E. Fogassy D. Kozma 《Journal of Thermal Analysis and Calorimetry》2003,74(1):155-162
O,O'-di-p-toluoyl-(2R,3R)-tartaric acid (DPTTA) was investigated as supramolecular complex (SMC) forming resolving agent with three racemic alcohols
(menthol, 4-methyl-2-pentanol, trans-2-iodo-cyclohexanol) by preparative scale experiments and thermoanalytical measurements.
Despite the very small structural difference (two methyl groups) between the O,O'-dibenzoyl-(2R,3R)-tartaric acid (DBTA) and DPTTA, their SMC forming properties with water and racemic alcohols is very different. While DBTA
forms SMC with all the three investigated alcohols, DPTTA forms SMC only with trans-2-iodo-cyclohexanol. DPTTA binds the guest compound less strongly and the stoichiometry of the SMC is also different. The
weaker interactions resulted in less effective optical resolutions. The results of these investigations remind us, that in
optical resolutions during the chiral discrimination process the weaker interactions have a determining role, since DBTA and
DPTTA have the possibility to form the same strong (O-H···O and N-H···O) hydrogen bond network.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Yaremenko F. G. Pivnenko N. S. Kutulya L. A. Kondratyuk Zh. A. Novikova N. B. Shkolnikova N. I. 《Russian Chemical Bulletin》2009,58(5):1072-1083
New (E)-16-arylidene derivatives of 3β-hydroxyandrost-5-en-17-one and their acetates containing different substituents in the arylidene
fragment were synthesized. The ability of the synthesized chiral compounds to induce helical supramolecular ordering (their
helical twisting power) upon the introduction into the nematic liquid crystal (LC) 4-cyano-4′-pentylbiphenyl (5CB) and into
multicomponent mixtures E63 and LC-1289 characterized by a wide mesophase interval. The dependence of the helical twisting
power of the studied chiral additives (CAd) on their molecular structure was analyzed. The highest helical twisting power
(44.6–67.1 μm−1) was revealed for the synthesized acetates. It was found that the composites based on LC-1289 and E63 containing the studied
CAd in very low concentrations (≤10–11 mol.%) have selective light reflection in the visible spectral region. The helical
twisting power of the studied α,β-unsaturated ketones is determined by the combined influence of the anisotropy of polarizability
of CAd molecules and specific features of their molecular shape. 相似文献
5.
Jinmao You Wenjian Lao Qingyu Ou Xuejun Sun 《Fresenius' Journal of Analytical Chemistry》1999,365(6):521-528
A simple and sensitive HPLC method for the determination of hydroxyl compounds including volatile alcohols from spiked plasma,
using a fluorescent condensation agent, namely carbazole-9-N-(2-methyl)-acetyl-benzene-disulfonate (CMABS), has been developed.
A mixture of alcohols and pyridine in dichloromethane was treated with CMABS to give a quantitative yield of esters. The maximum
fluorescence emissions for the derivatized alcohols are at 365 nm (λex 335 nm). Studies on derivatization conditions indicate that alcohols react very fast with CMABS in presence of pyridine in
dichloromethane to give the corresponding fluorescent derivatives. The method, in conjunction with a multi-step gradient,
offers a baseline resolution of the common alcohol derivatives on a reversed-phase C18 column, which is more convenient and more efficient than previous methods which require the prior conversion of the carboxylic
acids to the acyl chlorides. The application of this method to the analysis of volatile alcohols in plasma was also investigated.
The LC separation shows good selectivity and reproducibility for alcohol derivatives. The relative standard deviations ?(n = 5) for 100 pmol of each alcohol are < 4%. The detection limits are at the fmol level for C1–C3 alcohols and pmol level for C4–C9 alcohols.
Received: 9 November 1998 / Revised: 3 May 1999 / Accepted: 6 May 1999 相似文献
6.
L. A. Kutulya V. V. Vashchenko O. V. Shishkin T. G. Drushlyak 《Russian Chemical Bulletin》1998,47(11):2182-2188
It was established by X-ray diffraction analysis that 2-(1′-hydroxy-1′-biphenylyl)methyl-3-methyl-6-isopropylcyclohexanone,
one of the minor products of the directed aldol reaction of (−)-menthone bromomagnesium enolate with 4-phenylbenzaldehyde,
has the2R,3R,6S, 1′R configuration. The characteristic features of the spatial structure of this β-hydroxyketone were compared with those of the
major stereoisomeric product of the above-mentioned reaction. The latter has the2R,3R,6S,1′S configuration. In the crystals, both stereoisomers have the cyclohexanone ring in a chair-like conformation with the three
substituents in equatorial positions and are characterized by the presence of the annelated (cis-fused) pseudoring with an −OH…O=C< intramolecular hydrogen bond. The structures of the stereoisomers differ in the orientation
of the aryl group and the hydrogen atom at the C(1′) chiral center with respect to the cyclohexanone ring. The results of
X-ray diffraction analysis were compared with the data of molecular mechanics calculation for the energetically most favorable
conformations of the isolated molecules of β-hydroxyketones under study.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2251–2257, November, 1998. 相似文献
7.
Asymmetric reduction of prochiral ketones to optically active chiral secondary alcohols was achieved using a reagent prepared by modifying lithium aluminium hydride with a chiral auxiliary, (+)threo-1,16-dibenzyloxy,7,8-dihydroxy hexadecane and various additive alcohols. (+)threo-1,16-dibenzyloxy,7(R),8(R)-dihydroxy hexadecane was prepared from (+)threo-9(R),10(R),16-trihydroxy hexadecanoic acid. Alcohols such as CH3(CH2)n-OH of different chain length (n = 0–11) and (R)-hydnocarpic alcohol were used. Complex prepared from (+)threo-1,16-dibenzyloxy,7(R),8(R)-dihydroxy hexadecane, LAH and (R)-hydnocarpic alcohol reduced acetophenone in moderate enantioselectivity (maximum of 70% ee). Various arylalkylketones were reduced with the same complex. 相似文献
8.
H. Grabowska R. Klimkiewicz L. Syper J. Wrzyszcz 《Research on Chemical Intermediates》2000,26(4):357-364
The results of gas-phase conversion of ω-phenyl-substituted alcohols (benzyl alcohol, 2-phenylethanol, 3-phenyl-1-propanol)
and their equimolar mixtures with primary normal alcohol (1-octanol) are presented. Reactions were carried out at atmospheric
pressure in the presence of an iron catalyst in the temperature range of 568–673 K and load of 2.0 h−1. 2-Phenylethanol and 3-phenyl-1-propanol undergo dehydrogenation to aldehydes and condensation to esters. At higher temperatures
symmetrical ketones containing ω-phenyl group as substituent are formed. Mixtures of these alcohols with 1-octanol give among
others asymmetrical aromatic-aliphatic ketones. 相似文献
9.
Synthesis of camphor derived chiral allenes and their hydroboration-oxidation reactions are described. Reaction of (1R)-(+)-camphor with alkynyllithium followed by the reduction of the resulted propargyl alcohol derivatives using AlH3 furnished chiral allenes 2a-g in excellent yields with high diastereoselectivity. Reduction of the propargyl alcohols with aluminum hydride proceeded through selective intermolecular anti-addition of hydride ion. The stereochemistry of the chiral allenes 2 was assigned based on lanthanide shift studies and chemical correlations. Diastereoselectivity was observed in the hydroboration-oxidation of 2 which produced a mixture of (E,R) and (E,S) stereoisomers in a ratio of 6:1 to 18:1. 相似文献
10.
A novel tunable multi-chiral supramolecular host system was developed from non-chiral dicarboxylic acid and (1R, 2R)-diphenylethylenediamine via chirality transfer, which enabled highly efficient optical resolution of secondary alkyl alcohols by simple crystallization of host compounds from alcohol solution. 相似文献
11.
A. A. Bredikhin E. I. Strunskaya N. M. Azancheev Z. A. Bredikhina 《Russian Chemical Bulletin》1998,47(1):174-176
The use of enantiomerically pure cyclic chlorophosphite obtained by the reaction of PCl3 withN,N,N′,N′-tetramethyldiamide of naturall-(+)-tartaric acid for analysis of the enantiomeric composition of chiral primary and secondary alcohols by31P NMR spectroscopy is considered.
Translated fromIzvestiya Akademii Nauk., Seriya Khimicheskaya, No. 1, pp. 172–175, January, 1998. 相似文献
12.
J. Banaś B. Stypuła K. Banaś J. Światowska-Mrowiecka M. Starowicz U. Lelek-Borkowska 《Journal of Solid State Electrochemistry》2009,13(11):1669-1679
Electrochemical and corrosion behaviour of metals in alcohols are the subject of numerous investigations because of the application
of mentioned solvents in chemical engineering, production of oxide nanoparticles (sol-gel techniques) and application of alcohols
as fuels. Despite relatively rich bibliography related to electro-catalytic oxidation of alcohols on metal surface in mixed
aqueous–alcohol solutions, the knowledge of the mechanism of reactions on metal/anhydrous alcohol interface is still not sufficient.
Anodic oxidation of metal surface in alcohol leads to several electro-catalytic reactions with formation of surface compounds
being the product of metal and alcohol oxidation. Identification of these products is very difficult. Therefore, our knowledge
of the composition and structure of passive films or corrosion products on metal surface in anhydrous alcohol solvents is
poor. Our paper presents the investigations of anodic behaviour of metals (Cu, Zn, Fe, Ni, Al and Ti) and semiconductors (p-Si)
in methanol solutions of electrolytes, performed in our laboratory within the last 10 years. On the base of electrochemical
measurements (linear sweep voltammetry, electrochemical impedance spectroscopy), spectroscopic investigations (X-ray photoelectron
spectroscopy, ultraviolet photoelectron spectroscopy and low-energy electron diffraction) and scanning electron microscopy
techniques, the role of metal–alcohol intermediates in the formation of surface and soluble compounds is discussed. The practical
application of electrochemical etching of metals as a method of production of micro- and nanoparticles of metals and oxides
is also shown. 相似文献
13.
《Tetrahedron: Asymmetry》2006,17(19):2821-2832
The enantiomeric excess of chiral reagents used in asymmetric syntheses directly affects the reaction selectivity and product purity. In this work, 84 of the more recently available chiral compounds were evaluated to determine their actual enantiomeric composition. These compounds are widely used in asymmetric syntheses as chiral synthons, catalysts, and auxiliaries. These include chiral alcohols, amines, amino alcohols, amides, carboxylic acids, epoxides, esters, ketones, and oxolanes among other classes of compounds. All enantiomeric test results were categorized within five impurity levels (i.e., <0.01%, 0.01–0.1%, 0.1–1%, 1–10%, and >10%). The majority of the reagents tested were determined to have enantiomeric impurities over 0.01%, and two of them were found to contain enantiomeric impurities exceeding the 10% level. The most effective enantioselective analysis method was a GC approach using a Chiraldex GTA chiral stationary phase (CSP). This method worked exceedingly well with chiral amines and alcohols. 相似文献
14.
《Tetrahedron: Asymmetry》1999,10(5):913-921
Several chiral diastereoisomerically pure epoxy alcohols were prepared diastereoselectively in high yields after epoxidation of allyl and homoallyl alcohols containing the 1R-fenchone skeleton with VO(acac)2/t-butyl hydroperoxide. The configurations of some of the new chiral compounds were determined by NMR methods. An interesting rearrangement reaction of an epoxy alcohol to an olefinic diol catalyzed by V5+ ions was observed. 相似文献
15.
16.
Capillary GLC was applied to study the sorption ofn-butanol,n-hexanol,n-octanol, and linalood from aqueous solutions by com starch cryotextures. The concentrations of alcohols in aqueous solutions
were varied from 0.5 to 15 mmol L−1. The sorption of alcohols by crytotextures formed of sols containing these alcohols and the coefficients of their. distribution
depend on the initial concentration and structure of the alcohols.n-Butanol is not sorbed by the corn starch cryotextures over the range of 0.5–80 mmol L−1. The sorption of other alcohols increases with increasing length of the alkyl substituent and the concentration of the alcohol.
The highest sorption capacity of the cryotexture (88%) was observed forn-octanol. The sorption of linalool decreases due to the double bonds and branching in its molecules.
Translated fromIzestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 734–737, April, 1999. 相似文献
17.
T. M. Varlamova E. M. Rubtsova S. P. Mushtakova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(8):1340-1344
The solubilities of the components of the iodine-water-propanol (1-C3H7OH) ternary system at 25°C and atmospheric pressure were measured for the first time. The solubility diagram of this system
is a ternary system diagram with salting out. Iodine stratifies water-propanol mixtures containing 16.2–73.0 wt % alcohol.
The solubility of crystalline iodine increases as the content of alcohol in the mixed solvent grows and is maximum in a mixture
containing 79.0 wt % alcohol. A comparative analysis of the phase diagrams of the iodine-water-alkanol (ethanol, propanol-1,
and propanol-2) systems was performed. The differences between them can likely be explained by an increase in the electron
donor ability of the alcohols, which is also in agreement with the enthalpies of solution of the alcohols in water. 相似文献
18.
Jiabo Li Tianhai Zhu Gregory D. Hawkins Paul Winget Daniel A. Liotard Christopher J. Cramer Donald G. Truhlar 《Theoretical chemistry accounts》1999,103(1):9-63
We present eight new parameterizations of the SM5.42R solvation model: in particular we present parameterizations for HF/MIDI!,
HF/6-31G*, HF/6-31+G*, HF/cc-pVDZ, AM1, PM3, BPW91/MIDI!, and B3LYP/MIDI!. Two of the new cases are parameterized using the reaction-field operator
presented previously, and six of the new cases are parameterized with a simplified reaction-field operator; results obtained
by the two methods are compared for selected examples. For a training set of 2135 data for 275 neutral solutes containing
H, C, N, O, F, S, P, Cl, Br, and I in 91 solvents (water and 90 nonaqueous solvents), seven of the eight new parameterizations
give mean unsigned errors in the range 0.43–0.46 kcal/mol, and the eighth – for a basis set containing diffuse functions –
gives a mean unsigned error of 0.53 kcal/mol. The mean unsigned error for 49 ionic solutes (containing the same elements)
in water is 3.5–3.9 kcal/mol for the Hartree–Fock, Becke–Perdew–Wang-1991 and Becke three-parameter Lee–Yang–Parr cases and
4.1 and 4.0 kcal/mol for parameterized model 3 and Austin model 1, respectively. The methods are tested for sensitivity of
solvation free energies to geometry and for predicting partition coefficients of carbonates, which were not included in the
training set.
Received: 24 November 1998 / Accepted: 31 December 1998 / Published online: 7 June 1999 相似文献
19.
By the reaction of 1H-imidazole-4,5-dicarbonitrile, 3-nitro-1,2,4-triazole, and 1H-tetrazole, containing one proton at each
of the two proton-donating atoms separated by one covalent bond, it was shown that uncharged crystalline supramolecular compounds
can be obtained on account of the proton-donating characteristics of the aromatic heterocycles.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1302–1305, September, 2006. 相似文献
20.
WANG Hui PEI Wei-wei YE Wei-ping 《高等学校化学研究》2005,21(5):536-539
ovel chiral β-amino alcohols containing sulfide or sulfonyl groups were synthesized from (R)-cysteine. Their chiral induction in the asymmetric borane reduction of prochiral ketones was investigated. Optically active secondary alcohols with moderate or high e. e. values were obtained, and the causes of different enantioselectivities between these two sulfur-containing chiral β-amino alcohols were researched. 相似文献