Govt Exams
In Williamson ether synthesis, the alkoxide ion attacks via SN2 mechanism, which prefers primary alkyl halides due to less steric hindrance. Tertiary substrates don't react due to steric hindrance.
Chlorobenzene formed initially is more deactivated than benzene, but further chlorination can occur at ortho/para positions under excess Cl2 conditions, yielding a mixture of polychlorobenzenes.
CF3-COOH is most acidic because fluorine is highly electronegative and strongly withdraws electron density through inductive effects, stabilizing the conjugate base carboxylate ion.
The cumene hydroperoxide undergoes an acid-catalyzed rearrangement (Hock rearrangement) where the isopropyl group rearranges to give phenol and acetone as the cleavage products.
Vicinal coupling (3J) between protons separated by 3 bonds typically has values of 6-18 Hz, with typical values around 7-8 Hz for anti-periplanar and 2-5 Hz for gauche conformations.
Para-xylene has high symmetry: all four aromatic protons are equivalent (one signal) and all six methyl protons are equivalent (one signal), giving only 2 total signals in 1H-NMR.
PCC is a mild oxidizing agent that oxidizes primary alcohols to aldehydes without further oxidation to carboxylic acids (unlike acidic KMnO4 or K2Cr2O7).
This is a dehydration reaction where the OH group leaves, and a rearrangement occurs via hydride shift to form the more stable tertiary carbocation, leading to 2-methylbut-2-ene (more substituted alkene, Zaitsev's rule).
SN2 reactions proceed fastest with primary alkyl halides due to minimal steric hindrance around the carbon bearing the leaving group. CH3CH2Br (primary) > CH3CHBrCH3 (secondary) > (CH3)3CBr (tertiary).
The methyl group is electron-donating through inductive and hyperconjugative effects, making the benzene ring more electron-rich. This activates the ring for EAS and directs incoming electrophiles to ortho and para positions.