Chemistry, Paper II

Elaborate with examples that how resonance, hyperconjugation and inductive effect, can contribute towards the stability of carbocations.

How does the reaction mechanism work for the electrophilic addition of bromine to ethene? Explain the intermediate (s).

B r ] + + B r − → B r − C H 2 − C H 2 − B r \text{[Cyclic } C_2H_4Br]^+ + Br^- \rightarrow Br-CH_2-CH_2-Br [Cyclic C 2 ​ H 4 ​ B r ] + + B r − → B r − C H 2 ​ − C H 2 ​ − B r Or 3b Describe the IUPAC rules for naming alkenes and alkynes with appropriate examples.

OH + E + → [ Resonance stabilized intermediate at o / p ] \text{C}_6\text{H}_5\text{OH} + E^+ \rightarrow [ \text{Resonance stabilized intermediate at } o/p ] C 6 ​ H 5 ​ OH + E + → [ Resonance stabilized intermediate at o / p ] Alkyl groups stabilize these positions via inductive effect and hyperconjugation. 2. Meta Orientation Deactivating groups (EWGs) like $-NO_2$ destabilize the $ortho$ and $para$ intermediates because they place a positive charge on the carbon already attached to an electron-deficient group (creating electrostatic repulsion). Consequently, meta attack is preferred not because it is "activated," but because it is the least deactivated pathway, avoiding the placement of the positive charge on the substituted carbon. 3. The Halogen Paradox Halogens are $o/p$ directors because their lone pairs can stabilize the sigma complex through resonance ( + R +R + R effect) during $ortho/para$ attack. However, their high electronegativity ( − I -I − I effect) withdraws overall electron density, making the ring less reactive than benzene. Or 4b How did Kekulé propose the benzene structure, and what evidence supported his model?

Compare the reactivity of acid halides, anhydrides, esters, and amides toward nucleophilic substitution. What kind of products do you expect when these react with Grignard reagent (RMgX)?

Explain the reaction mechanism of Williamson synthesis to prepare ethers.

Write a comprehensive note on primary, secondary, tertiary, and quaternary structures of proteins.

Outline the steps of the Krebs cycle, and explain its role in cellular respiration.

What is the main product when nitrobenzene reacts with chlorine in the presence of AlCl 3 ?

Which type of substitution occurs predominantly in benzene?

What is the main product when 1-butyne reacts with excess of HBr?

Which of the following has the highest dipole moment?