Nucleophilic And Electrophilic Substitution Reactions Both Aromatic And Aliphatic

Conversion of Propene to 1-Iodopropane

To convert propene to 1-iodopropane, hydroiodic acid (HI) is used in an electrophilic addition reaction.

The double bond in propene reacts with HI. According to Markovnikov's rule, the hydrogen atom from HI attaches to the carbon with more hydrogen atoms, and the iodine attaches to the other carbon, forming the desired product.

Reaction Equation:

Product: 1-iodopropane

Bromination of Phenol

When phenol reacts with bromine in carbon disulfide (CS₂), an electrophilic substitution reaction occurs. The hydroxyl group (-OH) on the phenol ring activates the ring towards substitution at the ortho and para positions relative to the hydroxyl group.

Reaction:

The reaction between phenol and bromine in CS₂ can be represented as: In this reaction, bromine atoms are added to the ortho and para positions relative to the hydroxyl group on the benzene ring.

Mechanism:

The hydroxyl group (-OH) is an electron-donating group, which activates the benzene ring by increasing the electron density at the ortho and para positions. This makes the ring more reactive toward electrophilic substitution, specifically towards bromine (Br₂), which acts as the electrophile.

Major Product:

The major product of this reaction is **2,4,6-Tribromophenol**, where three bromine atoms are substituted at the ortho and para positions relative to the hydroxyl group.

Conclusion:

The bromination of phenol in the presence of bromine and carbon disulfide (CS₂) leads to the formation of **2,4,6-Tribromophenol** as the major product. The reaction occurs due to the activating effect of the hydroxyl group, which makes the ring more reactive to electrophilic substitution.

The reaction involves a bromination in the presence of heat, which typically leads to the formation of a benzylic bromination product. In this case, the hydrogen at the benzylic position (the carbon adjacent to the benzene ring) will be replaced by a bromine atom, forming 1-bromo-2-phenylethane as the major product. The structure of the product is: