Furthermore, because the reaction generally takes place cleanly definitely at ambient temperature, we can easily measure equilibrium constants for rearrangement of the diimines. We use the Hammett equation to further examine the electronic and oxyanionic effects. In addition, computations and experiments provide us with new insights into the origin and extent of stereospecificity for this rearrangement reaction.
The diaza-Cope rearrangement, with its unusual interplay between weak forces and the equilibrium constant of the reaction, provides a rare opportunity to study the effects of the fundamental weak forces on a chemical reaction. Among these many weak forces that affect the diaza-Cope rearrangement, the anion effect is the strongest (10.9 kcal/mol) followed by the resonance-assisted hydrogen-bond effect (7.
1 kcal/mol), the steric effect (5.7 kcal/mol), Inhibitors,Modulators,Libraries the conjugation effect (5.5 kcal/mol), and the electronic effect (3.2 kcal/mol). Based on both computation and experimental data, the effects of these weak forces are additive. Understanding the interplay of the weak forces in the [3,3]-sigmatropic reaction is interesting in its own right and also provides valuable insights for the synthesis of chiral diamine based drugs and catalysts in excellent yield and enantiopurity.”
“Graphite oxide sheets, now called Inhibitors,Modulators,Libraries graphene Inhibitors,Modulators,Libraries oxide (GO), can be made from chemical exfoliation of graphite by reactions that have been known for 150 years. Because GO is a promising solution-processable Inhibitors,Modulators,Libraries precursor for the bulk Batimastat production of graphene, interest in this old material has resurged.
The reactions to produce GO add oxygenated functional groups to the graphene sheets on their basal plane and edges, and this derivatization breaks the pi-conjugated network, resulting in electrically insulating but highly water-dispersible gefitinib lung sheets.
Apart from making graphene, GO itself has many intriguing properties. Like graphene, GO is a two-dimensional (2D) sheet with feature sizes at two abruptly different length scales. The apparent thickness of the functionalized carbon sheet is approximately 1 nm, but the lateral dimensions can range from a few nanometers to hundreds of micrometers. Therefore, researchers can think of GO as either a single molecule or a particle, depending on which length scale is of greater interest. At the same time, GO can be viewed as an unconventional soft material, such as a 2D polymer, highly anisotropic colloid, membrane, liquid crystal, or amphiphile.
In this Account, we highlight the soft material characteristics of GO. GO consists of nanographitic patches surrounded by largely disordered, oxygenated domains. Such structural characteristics effectively make GO a 20 amphiphile with a hydrophilic periphery and largely hydrophobic center.