Alpha bond

Cracking, or beta-scission, is a key feature of ionic cracking. Beta-scission is the splitting of the C-C bond two carbons away from the positive-charge carbon atom. Beta-scission is preferred becau.se the energy required to break this bond is lower than that needed to break the adjacent C-C bond, the alpha bond. In addition, short-chain hydrocarbons are less reactive than long-chain hydrocarbons. The rate of... 

Incorporation of alpha bonds directly into the nomenclature allows various isomorphisms to be more accurately described. For example [14], hydrogen fluoride in the solid (and probably in the liquid) state consists of a long (unspecified length) chain of hydrogen bonded H-F molecules in a zig-zag (/HFH = 120.1°) chain. This would be nomenclated as ... 

This representation is compatible with a total coordination of 1 (1/2 for each a) for each hydrogen atom. Furthermore, for diborane(6), which had been nomenclated in Chapter 2 as (EaHa)2, attention is directed to the observation that each boron atom is singly-bonded to two hydrogen atoms and alpha-bonded to two other hydrogen atoms thereby yielding the traditional valence of 3 for each boron atom. 

In other words, once again, as desired, the proposed name is completely dependent on the geometric description of the molecule. In the case of this particular molecule, the problem is minor. As suggested in [2], it is readily corrected by introducing a fluxional model containing two additional noncontiguous alpha bonds (Figure 5) ... 

Further improvement is effected by incorporating into the name six additional alpha bonds (from the two axial boron atoms to each of the three... 

As well as the various [3c-2e] covalent compounds involving boron, similar principles are next extended to compounds of the next element in Group 13 of the periodic table, aluminum, and to extended alpha bonds that... 

In the transition state, the carbon atom has five bonds — three traditional single bonds to each of the hydrogen atoms as well as alpha bonds to the leaving Br atom and the income O of the hydroxyl group. The connectivity matrix (Table 4), although requiring the segregation of the constitutionally... 

The alpha bond to the radical cation site can be broken by a radical-site-initiated reaction, that is by a transfer of the unpaired electron to form a new bond to an adjacent atom (a atom) with concomitant cleavage of another bond of this atom. The new bond compensates energetically for the cleaved bond. In this case we speak about a radical-site-initiated a fragmentation ... 

By Stevenson s rule, the cleavage of the alpha bond could involve radical retention and charge migration if the ionization energy of CfI2 YR is more than of R. This counterpart reaction is classified as a special case of a a bond cleavage and can be written as follows ... 

Competition Between the Cleavages of the Adjacent and the Alpha Bonds... 

Thus the halogens preferentially cause the loss of the radical X through a cleavage of the adjacent bond, whereas the amines preferentially lose a radical through a cleavage of the alpha bond. 

Scheme 4. Large isotope effect. C-labeling experiments consistent with alpha bond...

Turecek, F. N-C-alpha bond dissociation energies and kinetics in amide, and peptide radicals. Is the dissociation a non-ergodic process J. Am. Chem. Soc. 2003, 125, 5954-5963. 

Patriksson, A. Adams, C. Kjeldsen, F Raber, J. van der Spoel, D. Zubarev, R. A. Prediction of N-C-alpha bond cleavage frequencies in electron capture dissociation of Trp-cage dications by force-field molecular dynamics simulations. Int. J. Mass Spectrom. 2006, 248, 124-135. 

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