- A simple radiometric in vitro assay for acetylcholinesterase inhibitors
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A radiometric method for screening acetylcholinesterase inhibitors has been described. The method is based on the production of [14C]carbon dioxide from the hydrolysis of acetylcholine. The inhibitory concentration at 50% (IC50) values for several known acetylcholinesterase inhibitors were in agreement with literature values. The new radiometric method is simple, inexpensive, and has the potential for automation.
- Guilarte,Burns,Dannals,Wagner Jr.
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Read Online
- Molecular imaging agents
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Provided is radiolabeled ammonium salts and uses thereof as myocardial perfusion agents in molecular imaging.
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Page/Page column 19
(2015/12/25)
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- Design and synthesis of a task-specific ionic liquid as a transducer in potentiometric sensors
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A task-specific ionic liquid called N,N,N-trimethylaniline hexafluorophosphate was synthesized and further employed as an ion-to-electron transducer in potentiometric sensors with excellent performance. The Royal Society of Chemistry 2013.
- Ping, Jianfeng,Wang, Yixian,Ying, Yibin,Wu, Jian
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p. 19782 - 19784
(2013/11/06)
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- MOLECULAR IMAGING AGENTS
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Provided is radiolabeled ammonium salts and uses thereof as myocardial perfusion agents in molecular imaging.
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- Quaternization reaction of aromatic heterocyclic imines in methanol - A case of strong anti-reactivity selectivity principle with isoselective temperature
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Accurate second-order rate constants were measured at 5 °C intervals in the temperature range 20-60 °C for the Menshutkin reaction of 1-methylbenzimidazole, 2-amino-1-methylbenzimidazole and N,N-dimethylaniline with iodomethane and iodoethane in methanol. In every case a good linearity in the Eyring plots was observed. Values for the activation enthalpy and entropy are reported. Analysis in terms of Exner's redefinition of the reactivity-selectivity principle (RSP) identified the present reaction series as a case of strong anti-RSP for selectivity towards the substrate. This case is shown to represent an isoselective relationship with the isoselective temperature lower than the experimental temperatures (β(is) = -52 °C). The isokinetic relationship does not hold in the reaction series with a fixed substrate. These findings suggest an early transition state in the Menshutkin reaction of polyfunctional aromatic imines.
- Alfaia, Antonio J. I.,Calado, Antonio R. T.,Reis, Joao Carlos R.
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p. 3627 - 3631
(2007/10/03)
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- Nitrogen and deuterium kinetic isotope effects on the menshutkin reaction
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Nitrogen and deuterium kinetic isotope effects were measured in the Menshutkin reaction between methyl iodide and a series of para-substituted N,N-dimethylanilines in ethanol. The nitrogen kinetic isotope effect increases for the more electron-donating substituents [0·9989, 1·0032, and 1·0036 for 4-C(O)Me, II and 4-Me, respectively], in agreement with the Hammond postulate. The secondary deuterium isotope effect, however, exhibits the reverse trend (1·045, 0·989, 0·975 per deuterium, for the respective substituents). This discrepancy is rationalized in terms of solvent molecule participation in the transition state.
- Szylhabel-Godala,Madhavan,Rudzinski,O'Leary,Paneth
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- Simple and Rapid Determination of the Activation Parameters of Organic Reactions by Temperature-Dependent NMR Spectroscopy I. Application to Irreversible Reactions
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A rapid and convenient method for the evaluation of activation enthalpies and entropies of reactions in solutions was contrived. This was realized by the stepwise elevation of the temperature of a reaction system using a variable temperature apparatus of NMR spectrometer. A repetition of rapid collection of FIDs (Free Inductive Decays) at every plateau part of temperature at regular intervals allows us to determine the time-conversion curve, from which the rates at various temperatures were obtained as the first derivatives. Several examples of applications are shown.
- Satoh, Masahiro,Hirota, Minoru
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p. 2031 - 2038
(2007/10/03)
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- 13C nuclear magnetic resonance studies of aromatic amine-borane adducts
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13C NMR measurements are reported for 22 aromatic amine-borane, 7 aliphatic amine-borane, and 3 aliphatic amine-trimethylborane adducts.Additivity of the substituent effects on the δ 13C values of the aromatic carbon atoms is observed.The δ 13C values are compared with those of the arylamines of arylammonium salts and of corresponding alkyl-substituted benzenes.The δ 13C values for the borane adducts, ammonium salts and hydrocarbons exhibit the same trends.However, in the borane adducts similar to the ammonium salts, part of the shielding of the ortho-carbon atoms is attributed to electric field effects which are much less pronounced in the hydrocarbon analogues.The comparison of δ 13C values of aliphatic amine-borane adducts with those of corresponding hydrocarbons indicates the importance of steric effects.
- Paz-Sandoval, M. A.,Camacho, C.,Contreras, R.,Wrackmeyer, B.
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p. 1331 - 1336
(2007/10/02)
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- Inclusion Compounds of Organic Onium Salts, IV. Organyl Ammonium Hosts as Versatile Clathrate Formers
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The organyl-oligo-ammonium compounds 1 - 25 and their clathrates with a variety of low molecular weight neutral compounds, especially solvent molecules, are prepared.The inclusion capacity of the new clathrands can be explained by interstices in the host lattice.The conformational flexibility of the voluminous onium branches is responsible for the great number of clathrates; their stability depends on the ion lattice.The X-ray analysis of the ethanol clathrate of the onium host 8 shows that one ethanol molecule is surrounded by the host molecules in a cage-type manner.The great variety of the inclusions obtained up to now demonstrates that the oligo onium host compounds have to be considered as the most universal clathrands of organic chemistry.Hints are given for the syntheses of new onium clathrates.
- Loehr, Hans-Gerd,Josel, Hans-Peter,Engel, Aloys,Voegtle, Fritz,Schuh, Willy,Puff, Heinrich
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p. 1487 - 1496
(2007/10/02)
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