Question

1. Consider the options below and enter the number that best satisfies the boldfaced statement on your NEITHER option applies or "B" if BOTH options apply. answer sheet. Enter "N" if f) p-methoxyphenol p-nitrophenol Smaller Band Gap vs g) N-phenylbenzamide vs methylbenzoate Lower pKa h) CH3MgBr vs (CH3)2CuLi Converts Phenol to Anisole (after workup) If PhBr was in the stockroom then (Ph) CuLi could be an "Off the Shelf" reagent. i) True False vs LiAlH4 vS NaBH4 Will reduce Pyruvic Acid to a 2° alcohol Grignards perform conjugate addition with MVK k) True vs False Sodium metal introduced to benzophenone produces a colored indicator for solvent purity by creating a Radical anion vS Radical cation PCC NaBH4 NAD is Nature's vs NaBH4 NaH More nucleophilic vs

Answer 1

f) The p-nitrophenol shows absorption maxima at 317 nm. The p-methoxyphenol shows absorption maxima at 300 nm. para positioned methoxy group is an electron donating group, whereas nitro group para to phenolic OH is a electron withdrwaing group. Hence we can expect a sammler band gap for p-methoxyphenol.

g) -C(=O)-O-R, R group is an electron donating, while -C(=O)-NH-Phenyl, phenyl group is electron withdrawing in nature. Hence N-phenylbenzamide will have a lower pka value. the electron withdrawing effect of the phenyl group in N-phenyl benzamide will increase the acidity of the NH proton leading to increased anion formation hence more acidic than methylbenzoate.

h) grignard reagents are sensitive to acidic protons and for this reason we always wants anhydrous condtion most probably dry ethyl ether. Phenol has an acidic proton. Hence our option is Gilman's reagent dialkyl copper lithium salt (CH₃)₂CuLi only.

CH₃MgBr + H⁺ --> CH₄ (g)

i) PhBr +2 Li --> 2 PhLi ; 2PhLi + Cu --> (Ph)₂CuLi ---- Gilman's reagent.

j) LiAlH₄ is strong reducing reagent than mild NaBH₄.

k) Grignards perform conjugate addition with methyl vinyl ketone.

l) Na --> Na⁺ + e^- its like Na/NH₃ (Birch reduction) proceeds through radical anion.

m) NAD⁺ + H^- (hydride ion) --> NADH like a PCC (Pyridinium Chloro Chromate - oxidizing agent) not like NaBH4 (reducing agent). As we know that removal of Hydrogen OR addition of oxygen is oxidation.

n) NaH is more polarized than NaBH₄ as NaH is completely ionic bond, Na gives Na⁺ and H^-. H^- is a more nucleophilic than B-H boned one.