Reactions groups surrounding carbon atom

The second chemical principle of interest here is that many biochemical reactions involve interactions between nucleophiles (functional groups rich in electrons and capable of donating them) and electrophiles (electron-deficient functional groups that seek electrons). Nucleophiles combine with, and give up electrons to, electrophiles. Common nucleophiles and electrophiles are listed in Figure 6-21. Note that a carbon atom can act as either a nucleophile or an electrophile, depending on which bonds and functional groups surround it. 

Transition state 11 in Section 11.2.1 was shown for the conversion of 9 to 10. The charge distribution is such that the iodide is 6-, the central carbon is 6+, and the leaving group X is 6-. If the solvent is water, the iodide ion will be solvated (surrounded by water molecules) before it collides with the sp carbon atom. This means that solvation will impede the collision of iodide with the carbon atom, and the Sn2 reaction will be slower. Water solvates both the anion and cation and the net result is that the 8 2 reaction is slower. 

Figure 10.3-40. The rating for the disconnection strategy carbon-heteroatom bonds is illustrated, Please focus on the nitrogen atom of the tertiary amino group. It is surrounded by three strategic bonds with different values. The low value of 9 for one ofthese bonds arises because this bond leads to a chiral center. Since its formation requires a stereospecific reaction the strategic weight of this bond has been devalued. In contrast to that, the value of the bond connecting the exocyclic rest has been increased to 85, which may be compared with its basic value as an amine bond.

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