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101.
Ludovic Jean 《Tetrahedron letters》2006,47(13):2141-2145
The first systematic screening of chiral phosphines in the cycloaddition reaction between 2,3-butadienoates and arylimines has led to the identification of fairly efficient catalysts. 2-Aryl-3-pyrrolines have been obtained with enantiomeric excesses up to 64%. In one instance, the enantiomeric excess could be increased to 91% ee by combining the enantioselective cyclization reaction with a crystallization step. 相似文献
102.
Jean M. J. Tronchet Bernard Gentile Alain P. Bonenfant Olivier R. Martin 《Helvetica chimica acta》1979,62(3):696-699
Further examples of O-isopropylidenaldehydosugars in the furanose series Formyl-bearing furanose derivatives 1–3 (α-D -xylo or α-D -erythro configurations) and 5–8 (configurations α-D -ribo, α-D -lyxo, β-L -threo and D -arabino) have been prepared by classical synthetic steps and their properties mainly spectroscopic, reported. The coupling constant between the formyl and the vicinal proton is always small. Like other members of the series, these new aldehydosugars constitute very useful and flexible synthetic intermediates. 相似文献
103.
Adenier A Chehimi MM Gallardo I Pinson J Vilà N 《Langmuir : the ACS journal of surfaces and colloids》2004,20(19):8243-8253
The electrochemical oxidation of aliphatic amines (primary, secondary, and tertiary) has been investigated by cyclic voltammetry and preparative electrolysis. The oxidation mechanisms have been established, and the lifetimes of the radical cations have been measured for secondary and tertiary amines. These results have been put in parallel with the attachment of amines to glassy carbon, Au, and Pt electrodes by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and infrared reflection-absorption spectroscopy (IRRAS). It is then possible to show that it is not the radical cation but the radical obtained after the deprotonation which reacts with the electrode surface. XPS results also point to the existence of a covalent bond between Au or Pt and the organic moiety. 相似文献
104.
Marfisi S Rodríguez MP Alvarez G Celis MT Forgiarini A Lachaise J Salager JL 《Langmuir : the ACS journal of surfaces and colloids》2005,21(15):6712-6716
Commercial ethoxylated nonionic surfactant mixtures containing alcohol cosurfactant exhibit a three-phase behavior whose formulation strongly varies with the water/oil ratio. As a consequence, a change in water/oil ratio can result in a sequence of up to three different emulsion inversion processes, through a combination of formulation and composition effects. 相似文献
105.
We describe a versatile, efficient method for the preparation of ether analogues of (S,S)-lysobisphosphatidic acid (LBPA) and its enantiomer from (S)-solketal. Phosphorylation of a protected sn-2-O-octadecenyl glyceryl ether with 2-cyanoethyl bis-N,N-diisopropylamino phosphine and subsequent deprotection generated the bisether LBPA analogues. By simply changing the sequence of deprotection steps, we obtained the (R,R)- and (S,S)-enantiomers of 2,2'-bisether LBPA. An ELISA assay with anti-LBPA monoclonal antibodies showed that the bisether LBPAs were recognized with the same affinity as the natural 2,2'-bisoleolyl LBPA. [reaction: see text] 相似文献
106.
Two synthetic routes to a novel class of sterically overcrowded alkenes, bithioxanthylidene crown ethers 1, are described. The 1H spin-lattice relaxation times (T1) of the crown ethers as well as those of the corresponding complexes with Li+, Na+, K+, Rb+ and Cs+ in CDCl3 were measured and the results were interpreted in terms of complexation affinities. 相似文献
107.
Bosman AW Vestberg R Heumann A Fréchet JM Hawker CJ 《Journal of the American Chemical Society》2003,125(3):715-728
A new strategy for the preparation of functional, multiarm star polymers via nitroxide-mediated "living" radical polymerization has been explored. The generality of this approach to the synthesis of three-dimensional macromolecular architectures allows for the construction of nanoscopically defined materials from a wide range of different homo, block, and random copolymers combining both apolar and polar vinylic repeat units. Functional groups can also be included along the backbone or as peripheral/chain end groups, thereby modulating the reactivity and polarity of defined portions of the stars. This modular approach to the synthesis of three-dimensional macromolecules permits the application of these tailored materials as multifunctional hosts for hydrogen bonding, nanoparticle formation, and as scaffolds for catalytic groups. Examples of applications of the functional stars in catalysis include their use in a Heck-type coupling as well as an enantioselective addition reaction. 相似文献
108.
Philippe Remuzon Daniel Bouzard Claire Clemencin Christian Dussy Munir Essiz Jean-Pierre Jacquet Jean Saint-Germain 《Journal of heterocyclic chemistry》1993,30(2):517-523
The synthesis of (1S,4S,7S)- and (1R,4R,7S)-2-(4-tolylsulfonyl>5-phenylmethyl-7-rnethyl-2,5-diazabicyclo-[2.2.1]heptanes ( 20 ) and ( 22 ) from trans 4-hydroxy-L-proline is described. 相似文献
109.
In seeded emulsion polymerization, during the second stage, new interfaces appear and the surface area changes. A thermodynamic equilibrium approach is presented which predicts particle morphology of a whole range of non-spherical particles upon polymer conversion. Simulation takes into account swelling ratio, molar volumes and interfacial tension. As the particle geometry is complex, a new mathematical procedure is detailed.The computed data are useful to discuss either the stability or the instability of the particles morphology. These results must be compared with actual experimental structures.Abreviations and symbols G
Gibbs' free energy
-
reduced Gibbs' free energy
- i
interfacial tension
- 12
interfacial tension between polymer 1 and polymer 2
- 1w
interfacial tension between polymer 1 and water
- 2w
interfacial tension between polymer 2 and water
-
r
1
polymer 1 swollen by monomer 2 sphere radius
-
r
2
polymer 2 swollen by monomer 2 sphere radius
-
r
i
interfacial radius
-
h
1
sphere 1 distance to minimal section
-
h
2
sphere 2 distance to minimal section
-
h
i
interfacial sphere distance to minimal section
-
sign ofh
i, positive when the interface sphere is on the side of the sphere 2, negative when the interface sphere is on the side of the sphere 1
-
A
12
surface between polymer 1 and polymer 2
-
A
1w
surface between polymer 1 and water
-
A
1w
0
surface between polymer 1 and water before polymerization
-
A
2w
surface between polymer 2 and water
-
v
1
volume of the polymer 1 swollen by monomer 2
-
v
i
volume of the polymer 1 swollen by monomer 2 before polymerization
-
v
2
volume of the polymer 2 swollen by monomer 2
-
V
p1
polymer 1 molar volume
-
V
p2
polymer 2 molar volume
-
V
m2
monomer 2 molar volume
-
n
p2
polymer 2 number of mole
-
n
p1
polymer 1 number of moles
-
n
m21
monomer 2 number of mole in the swollen polymer 1
-
n
m22
monomer 2 number of mole in the swollen polymer 2
-
n
m2
monomer 2 total number of mole
-
n
m2
monomer 2 number of mole before polymerization
-
TGn
1
polymer 1 swelling rate
-
TGn
2
polymer 2 swelling rate
-
TGn
i
maximum number of mole of monomer 2 in polymeri by mole of polymeri
-
x
polymer 2 conversion rate
-
K, p, q
mathematical variables
-
D, r, a
mathematical variables 相似文献
110.
Hans‐Ruedi Mürner Rosario Scopelliti Jean‐Claude G. Bünzli 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):m434-m435
In the title compound, [TbCl(C27H35N3)2(H2O)](ClO4)2·2C2H6O, the TbIII ion has a coordination number of eight, composed of two tridentate substituted‐terpyridine ligands, a water molecule and a bound Cl? anion. The first coordination shell can be described as a distorted bicapped trigonal prism. The dihedral angles between pyridine rings belonging to the same tpy ligand range from 5.2 (5) to 16.8 (5)°. 相似文献