Explain the mechanism of nitration of benzene.b) Draw the staggered conformation of ethane.

a) Nitration of Benzene:

Step 1: Protonation of Nitric Acid The first step in the nitration of benzene is the protonation of nitric acid by sulfuric acid. This forms the nitronium ion (NO2+), which is a powerful electrophile.

HNO3 + H2SO4 -> NO2+ + HSO4- + H2O

Step 2: Electrophilic Attack The benzene ring, being rich in electrons, then attacks the nitronium ion. This forms a cyclohexadienyl cation, which is a resonance-stabilized intermediate.

C6H6 + NO2+ -> C6H5NO2+

Step 3: Deprotonation Finally, a base (usually the bisulfate ion, HSO4-) removes a proton from the cyclohexadienyl cation, restoring the aromaticity of the benzene ring.

C6H5NO2+ + HSO4- -> C6H5NO2 + H2SO4

b) Staggered Conformation of Ethane:

The staggered conformation of ethane is one in which the hydrogen atoms attached to one carbon atom are as far apart as possible from the hydrogen atoms attached to the other carbon atom. This is the most stable conformation of ethane.

To draw this, imagine two circles representing the two carbon atoms. Around each circle, draw three lines spaced 120 degrees apart, representing the three hydrogen atoms attached to each carbon. Now, arrange the two circles so that the lines from one circle fall in between the lines from the other circle. This is the staggered conformation of ethane.