This can lead to molecules like benzyl chloride or benzyl alcohol. In such cases the CH3 side chain is part of the molecule and an R side chain is attached to it. Figure 53 shows benzyl chloride and benzyl alcohol:
Figure 53.
This can lead to a number of side chains that are also attached to the benzyl ring. This can lead to 2,4-fluorobenzyl chloride. The numbering system leads to the lowest number assigned to side chains as possible on the benzene ring.
BENZENE CHEMISTRY Benzene is considered relatively unreactive because of the stability of its aromaticity, making it inert to compounds like bromine gas and hydrochloric acid. As you remember, this aromaticity comes from delocalization of the p-orbital carbons on the sp2 hybridized carbons. This creates a “doughnut”-shaped singular orbital above and below the carbon atoms that can have electrons anywhere in it. This planar molecule has a bond angle between carbon atoms of about 120 degrees. The bond length is 1.39 Angstroms, which is between that of a single and a double bond. If there is a great deal of temperature or a catalyst, substitution reactions can occur rather than addition reactions that are seen in alkenes. This is directly related to the fact that this is a stable resonance molecule. The addition of hydrogen to make cyclohexane leads to a release of heat amounting to 28.6 kilocalories per mole. This is about 35 kilocalories per mole more stable than expected.
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