Studies of Substitution Reactions in Chromium(VI)–Fluorine Species

1971 ◽  
Vol 49 (9) ◽  
pp. 1505-1509 ◽  
Author(s):  
A. M. Arena ◽  
D. S. Brown ◽  
D. G. Tuck
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Oxygen Exchange ◽  
Substitution Reactions ◽  
Chromyl Chloride ◽  
Chromium Vi ◽  
Pure Compounds ◽  
Nuclear Magnetic

Nuclear magnetic resonance (n.m.r.) studies show that the exchange between fluorochromate(VI) and fluoride in dimethylsulfoxide is slow, in agreement with previous work on oxygen exchange between water and chromates(VI). No substitution was detected in the system CrO3F−/Cl− in acetonitrile. Mixtures of chromyl fluoride and chromyl chloride show rapid fluorine exchange, both as the pure compounds, and in solution in trichlorofluoromethane. Possible mechanistic implications of these results are discussed.

scholarly journals Diketopiperazine from marine bacterium Pseudoalteromonas ruthenica KLPp3

2018 ◽  
Vol 91 (1) ◽  
Author(s):  
Faiq Sulieman ◽  
Asmat Ahmad ◽  
Gires Usup ◽  
Lu Chung Kuang
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Performance ◽  
Solid Phase ◽  
Flash Chromatography ◽  
Antibiofilm Activity ◽  
The Family ◽  
Pure Compounds ◽  
Layer Chromatography ◽  
Nuclear Magnetic

Sub-minimum inhibitory concentration levels of Pseudoalteromonas ruthenica KLPp3 extract showed antibiofilm activity against Vibrio alginolyticus and Serratia marcescens. The KLPp3 crude extract was fractionated by thin layer chromatography, flash chromatography, solid phase extraction and semi-preparative high performance liquid chromatography. The pure compounds were then identified using H-nuclear magnetic resonance, C-nuclear magnetic resonance, 2D-nuclear magnetic Resonance and mass spectrometry. Nine fractions were collected from purification with two active fractions. One fractions were identified belong to the family of diketopiperazine.

Nuclear magnetic resonance investigation of intermediates formed by the action of nucleophiles on substituted stilbenes

1969 ◽  
Vol 47 (13) ◽  
pp. 2331-2342 ◽  
Author(s):  
C. A. Fyfe
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Negative Charge ◽  
Trans Isomers ◽  
Substitution Reactions ◽  
Resonance Investigation ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Magnetic Resonance Investigation ◽  
Magnetic Resonance Investigation ◽  
Nuclear Magnetic

A nuclear magnetic resonance investigation of the colored species formed by the action of bases on a series of α-cyano-4-nitro-4′-X-stilbenes characterizes these as the intermediate carbanions formed by the addition of base to the β-carbon atom of the double bond. The nuclear magnetic resonance spectra reveal that, whereas there is free rotation about the β-phenyl—Cβ and Cβ—Cα bonds in these adducts, there is restricted rotation around the α-phenyl—Cα bond due to very substantial delocalization of the negative charge into this ring. It has been verified that the same intermediates are formed by the action of bases on either the cis or trans isomers of α-cyano-4-nitrostilbene. The relation of these observations to the theory of alkene nucleophilic substitution reactions is discussed.

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