Chloro-l-phenylethane

Uses Intermediate in production of styrene, acetophenone, ethylcyclohexane, benzoic acid, 1-bromo-l-phenylethane, 1-chloro-l-phenylethane, 2-chloro-l-phenylethane, p-chloroethylbenz-ene, p-chlorostyrene, and many other compounds solvent in organic synthesis. 

Propose a mechanism for the formation of l,l-dichloro-l-phenylethane from 1-chloro-l-phenylethane. 

Chloro-l-phenylethane ionizes easily under El conditions to form a benzylic carbocation intermediate. The ion is stabilized due to the delocalization of the positive charge to the aromatic ring. Draw resonance structures that indicate the stability of this ion. 

The use of chiral substrates has allowed the importance of solvent and nucleophile-associated cation to be probed. For example, as shown in Scheme 7.10, when chiral 1-chloro-l-phenylethane is heated in ethanoic acid (acetic acid,CH3C02H]) at 50°C in the presence of potassium ethanoate (potassium acetate, CH3C02 K+), the ethanoic acid (acetic acid, CH3CO2H) ester of 1-phenylethanol is obtained. In this weakly nucleophilic system, about 15% excess inverted product is found (i.e., 85% of the product is racemic and the substitution reaction occurred with about 57.5% inversion and 42.5% retention). Presumably, the carbocation formed first and then... 

With 1-phenylethanol, 1-phenylethanethiol, 1-chloro-l-phenylethane, D-a-phenylglycine-N-d3 and (S)-methyl mandelate, the VCD of the methine stretching vibration is enhanced by ring currents. For methyl mandelate, a very large value of A = 5 x 10" is found for the O-H stretching vibration. 

---