(a) (b)
Figure 10.6 (a) Drawing of a methyl radical showing the sp^2 -hybridized carbon
atom at the center, the unpaired electron in the half-filled p orbital,
and the three pairs of electrons involved in covalent bonding. The
unpaired electron could be shown in either lobe. (b) Calculated
structure for the methyl radical showing the highest occupied
molecular orbital, where the unpaired electron resides, in red and blue.
The region of bonding electron density around the carbons and
hydrogens is in gray.
10.8 REACTIONS THAT GENERATE TETRAHEDRAL
STEREOCENTERS
- When achiral molecules react to produce a compound with a single tetrahedral
stereocenter, the product will be obtained as a racemic form.
- The radical chlorination of pentane:
Cl (^2) Cl ClCH
CH 3 CH 2 CH 2 CH 2 CH (^3) (achiral) CH 3 CH 2 CH 2 CH 2 CH 2 +CH 3 CH 2 CH 2 CH 3
- Pentane 1-Chloropentane (±)-2-Chloropentane
(achiral) (achiral) (a racemic form)
- CH 3 CH 2 CHClCH 2 CH 3
3-Chloropentane (achiral)
- Neither 1-chloropentane nor 3-chloropentane contains a stereocenter, but
2-chloropentane does, and it is obtained as a racemic form.