Proton-containing

Aziridinones undergo two types of selective ring opening by nucleophiles <68AG(E)25). Reaction with proton-containing nucleophiles, e.g. water, alcohols, thiols, amines and mineral acids, leads exclusively to amides (339), corresponding to an C —N bond rupture. 

These results are consistent with active sites consisting of highly distorted octahedral WOx clusters on Zr02. Acid sites formed by these octahedral WO surface species are more effective isomerization sites than previously reported tetrahedral WOx species on AI2O3 [17], possibly because of the ability of WOx clusters to form metastable proton-containing complexes during catalytic isomerization reactions. 

In aqueous solutions we see enhanced mobility and conductivity of the hydrogen ions, which is caused by additional proton transfer along chains of water molecules linked by hydrogen bonds (see Section 7.2.4). Solutions with nonaqueous, proton-containing solvents (e.g., in ammonia) sometimes also exhibit enhanced hydrogen... 

The proton signal acquired is the superposition of the signals from all proton-containing components in the sample. 

First, we shall discuss reaction (5.7.1), which is more involved than simple electron transfer. While the frequency of polarization vibration of the media where electron transfer occurs lies in the range 3 x 1010 to 3 x 1011 Hz, the frequency of the vibrations of proton-containing groups in proton donors (e.g. in the oxonium ion or in the molecules of weak acids) is of the order of 3 x 1012 to 3 x 1013 Hz. Then for the transfer proper of the proton from the proton donor to the electrode the classical approximation cannot be employed without modification. This step has indeed a quantum mechanical character, but, in simple cases, proton transfer can be described in terms of concepts of reorganization of the medium and thus of the exponential relationship in Eq. (5.3.14). The quantum character of proton transfer occurring through the tunnel mechanism is expressed in terms of the... 

Figure 12.6 Two sections of the proton NMR spectrum for a protein product after the protein has been removed. Only the formulation buffer (25 mM citrate) and a small amount ( 1 pg/ml) of residual Tris (a component of the penultimate buffer used in the recovery process prior to the final UF/DF formulation step) are observed after the filtration. The signal-to-noise ratio of Tris is about 70. The absence of any other significant proton NMR signals provides compelling evidence for good clearance of any other small proton-containing molecule impurities.

Specificity NMR spectroscopy is a specific analytical method by its nature. Each type of proton located in a different chemical or magnetic environment in the same or different molecule can be differentiated through its characteristic resonance frequency (Figure 12.1A). Thus, every proton-containing chemical has a unique set of proton NMR signals that can be readily identified. Although the NMR signals may be dependent on the solvent conditions (for example, temperature, pH, hydrophobicity, etc.), each molecule still can be uniquely identified in an NMR spectrum. 

Proton-containing admixtures in a solvent or in benzaldehyde can act like water. The superoxide ion abstracts such labile proton and generates the HOO base. The base in its turn abstracts proton from a solvent, for example, AN. If benzaldehyde is present, it is converted into cinnamyl nitrile according to the following simple reactions ... 

The first species produced in cationic polymerizations are carbocations, and these were unknown as such prior to World War II. It is now known that pure Lewis acids, such as boron trifluoride and aluminum chloride, are not effective as initiators. A trace of a proton-containing Lewis base, such as water, is also required. The Lewis base coordinates with the electrophilic Lewis acid, and the proton is the actual initiator. Since cations cannot exist alone, they are accompanied by a counterion, also called a gegenion. 

Atomic Number the number of protons contained in the nucleus of an atom of an element... 

Figure 11.4—The n — a transition in primary amines. This transition corresponds to an increase in the weight of the mesomeric form. Absorption corresponding to this transition disappears when a proton-containing hydrogen halide is added. This effect is due to the formation of a quaternary ammonium salt that mobilises the electron pair of the nitrogen atom, which is necessary for this transition (see formula in brackets).

It seems essential to include unstable particles in any coherent schema. Even the simplest isotopic doublet, neutron-proton, contains one stable and one unstable particle, and the more refined group theoretical classifications introduce both stable and unstable particles on the same footing.17 This is especially true since the discovery of resonances which are not only produced by strong interactions but also decay through strong interactions. 

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