Electron-donor groups dissociation

Electron transfer dissociation (ETD) is an ECD-like method with most of the same characteristics [21]. Like ECD, ETD yields abundant peptide backbone c- and z-type ions while often retaining such labile groups as peptide O/TV-glycosylation and phosphorylation [22]. Unlike ECD, ETD can be performed in the presence of an RF field. Here, anions created in a chemical ionization (Cl) source (see Section 2.1.7) are used as electron donors but the fragmentation pathways are essentially the same as for ECD. Commercial linear QIT instruments have recently become available with the ETD option. 

Dissociation is more efficient when the R chain contains electron donors e.g. an amino group), and this can be rationalized on the basis of the... 

The borate salts (Scheme 7) constitute an analogous group of electron donors [8,29,121]. In this case, PET from the anions to cationic acceptors (Sect. 2.2.1) produces a radical cations, (or alternatively, if a Jt-reservoir is available a n radical cation may be formed). If one of the substituents is an alkyl group the one-electron bond breaks rapidly (possibly in a dissociative process), forming a radical and a neutral. These systems also find applications in imaging. 

The dissociative mechanism of double bond migration via an allylic intermediate can occur at a site, as indicated in Scheme 2, or at a two atom site such as M—which can provide the three vacant coordination positions which are required to bind both the TT-allyl, a four-electron donor, and the hydrido group. Because the surface of a metal provides sites which differ in structure, both mechanisms may operate on a given catalyst, the relative importance being a function of the metal, the alkene and the reaction conditions. - ... 

The lone pair electrons of water (O atom), ammonia (N atom), and amino groups (N atom) influences the behavior and concentrations of hydrogen ions (H+) in water. Hydrogen ions, produced either by dissociation of water or by dissociation of acids, do not occur as free entities in aqueous solutions. They associate with the lone pair electrons of other water molecules to form hydronium ions, H3O+. This association involves the formation of an electron donor-acceptor bond. 

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