Question

Draw the structures of the major monohalo products in each of the following reactions:

Hint:

Thionyl chloride (SOCl\textsubscript{2}) is commonly used to convert alcohols into alkyl chlorides.

Answer 1

(a) Conversion of Alcohol to Alkyl Chloride using Thionyl Chloride

In this reaction, a hydroxymethyl group (\(-{CH2OH}\)) reacts with thionyl chloride (\({SOCl2}\)) to form the corresponding chloro derivative.

The product is benzyl chloride, and the reaction proceeds via the conversion of the hydroxyl group into a good leaving group, followed by substitution with chlorine.

Product structure:

\[ {C6H5CH2Cl} \]

Quick Tip:
Thionyl chloride (\({SOCl2}\)) is widely used to convert alcohols into alkyl chlorides with high efficiency.

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(b) Anti-Markovnikov Addition of HBr to Styrene

In this reaction, styrene (\({C6H5CH=CH2}\)) reacts with \({HBr}\) in the presence of a peroxide.

Due to the peroxide effect (Kharasch effect), the reaction follows a free radical mechanism, giving the anti-Markovnikov product. This means that the bromine atom attaches to the less substituted carbon of the double bond.

Major Product: 1-bromo-2-phenylethane

\[ {C6H5CH2CH2Br} \]

This reaction is a classic example of free radical addition to alkenes influenced by the presence of peroxides.