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141.
The reaction between Grignard reagents and perfluoroacid fluorides provides a convenient synthesis procedure for ketones RfORfC(O)R′, where RfORf is perfluoroalkylether group and R' is either an aromatic or aliphatic group. Reaction temperature is an important factor in producing higher yields of ketones. Meta and para-bromophenyl Grignard reagents, which thus far have not been prepared as pure mono Grignards, present secondary competing reactions which detract from their synthetic utility. 相似文献
142.
The excess volumes of four isomeric butanols with di-n-butyl ether were determined at 30°C. The isomeric effect was distinctly observed in the excess volume profiles. 1-Butanol
and 2-methyl-l-propanol systems exhibited negative excess volumes throughout the concentration range. The 2-butanol system
had positive excess volumes up to 0.9 mol fraction of alcohol after which it became negative, while the 2-methyl-2-propanol
system exhibited positive excess volumes throughout the concentration range.
NCL Communication No. 4678 相似文献
143.
The [3+3] cyclization of 1,3-bis-silyl enol ethers with 1,1-diacylcyclopentanes allows a convenient synthesis of spiro[5.4]decenones. Treatment of these compounds with trifluoroacetic acid (TFA) afforded a great variety of bicyclo[4.4.0]deca-1,4-dien-3-ones containing an angular alkyl group. This core structure occurs in a number of pharmacologically relevant natural products. 相似文献
144.
Someswara Rao Kosuru Hsin‐Yu Lai Chien‐Yi Yang Gopal Chandru Senadi Yi‐Chun Lai Hsuan‐Ying Chen 《中国化学会会志》2019,66(1):110-113
The palladacycle complex [LsPdOAc]2 bearing 2‐phenyl benzothiazole was synthesized and characterized by NMR and X‐ray crystallography. [LsPdOAc]2 was used as a catalyst in the Suzuki–Miyaura cross coupling reaction of 4‐bromotoluene with phenylboronic acid, which resulted in a conversion of >90% with 5 mol% of the Pd complex within 10 min at 60°C. 相似文献
145.
Linear π‐conjugated oligomers are known to form organogels through noncovalent interactions. Herein, we report the effect of π‐repeat units on the gelation and morphological properties of three different oligo(p‐phenylene‐ethynylene)s: OPE3 , OPE5 , and OPE7 . All of these molecules form fluorescent gels in nonpolar solvents at low critical gel concentrations, thereby resulting in a blue gel for OPE3 , a green gel for OPE5 , and a greenish yellow gel for OPE7 . The molecule–molecule and molecule–substrate interactions in these OPEs are strongly influenced by the conjugation length of the molecules. Silicon wafer suppresses substrate–molecule interactions whereas a mica surface facilitates such interactions. At lower concentrations, OPE3 formed vesicular assemblies and OPE5 gave entangled fibers, whereas OPE7 resulted in spiral assemblies on a mica surface. At higher concentrations, OPE3 and OPE5 resulted in super‐bundles of fibers and flowerlike short‐fiber agglomerates when different conditions were applied. The number of polymorphic structures increases on increasing the conjugation length, as seen in the case of OPE7 with n=5, which resulted in a variety of exotic structures, the formation of which could be controlled by varying the substrate, concentration, and humidity. 相似文献
146.
Indium trichloride (20 mol%) in nitromethane permits ionic Diels–Alder reaction of a variety of 2,3-olefinic acetals to form the corresponding cycloadducts in good yields with good endo selectivities. 相似文献
147.
The present work deals with the anomalies in ionospheric slab thickness of F-region associated with strong seismic activity.
In this regard we have considered ionosonde data of Critical frequency of F2 layer (foF2) and Ionospheric Total Electron Content
(ITEC) observed for Athens [38°N, 24°E] and Rome [42°N, 13°E] stations. We have considered three cases of earthquake occurring
on December 20, 2007, June 08, 2008 and April 06, 2009 and analyzed the ionosonde data of foF2 and ITEC for slab thickness
of F-region of the ionosphere in one-hour interval time series record by filtering the geomagnetic disturbances. The result
of the study shows that some unusual perturbations were observed in slab thickness of F-region for some days before the main
seismic event. It may be due to the generation of seismogenic electric field above the surface of the earth well before the
seismic event. This anomalous behavior of perturbations may be used as earthquake precursor. 相似文献
148.
Electron and x-ray diffraction studies on Al86Fe14, Al82Fe18 and Al75Fe25 quasicrystals 总被引:1,自引:0,他引:1
J A Sekhar T Rajasekharan P Rama Rao G Parthasarathy S Ramkumar E S R Gopal C S Lakshmi R M Mallya 《Pramana》1986,27(1-2):267-273
Electron and x-ray diffraction experiments on the metlt-spun Al100−x
Fe
x
(x=14, 18, 25) alloys are carried out. It is observed that all the melt-spun alloys possessing the quasi-crystalline phases
have icosahedral point-group symmetry.
The authors felicitate Prof. D S Kothari on his eightieth birthday and dedicate this paper to him on this occasion. 相似文献
149.
150.
S. Guha V. C. Vani Y. Jayalaxmi A. Kumar B. Ravi Gopal E. S. R. Gopal 《Journal of solution chemistry》1987,16(8):691-697
The determination of the capillary parameter for the partially miscible binary liquid system acetonitrile + cyclohexane has been reported. The system has closely matched densities and the data points are affected by gravity only when the fractional change of the temperature from the critical temperature is about 10–6. The system also exhibits very interesting wetting properties. The interfacial tension has been fitted to a power law =0.061 (Tc-T)1.26. The effect of doping with water and the instability of the wetting layer, which crucially depends on the interfacial tension, are studied. 相似文献