2)- Briefly prioritize the order of acidity of the alcohols by giving the approx

Question

2)- Briefly prioritize the order of acidity of the alcohols by giving the approximate Pka values of the compounds below in decreasing order. Note, you must place your answer within the underlined area below. SO3H ?? ?? ?? NO2 NO IA] IB] ICI DI E] FI 3)- Show two routes as to how you would synthesize molecule A using appropriate organo-lithium, Grignard or hydride reagents. Note, a total of three products are expected. Make sure you display all intermediates and the complete mechanism demonstrating bond retro-breaking in all synthetic steps (i.e., show all reactive electr ?? IAI

Explanation / Answer

A) As the -F atom is more than two carbon away from the -OH, its electron withdrawing inductive effect does not work on -OH. So, the pKa should be similar to that of cyclohexanol , about 16)

B) -CH3 group adjacent to -OH gives electron donating inductive effect (+I). Therefore basicity is more than A. pKa>16.

C) Phenol readily gives away its proton to PhO- ion. This ion is highly stable due to its delocalization through phenyl ring. Presence of electron withdrawing -F at para position further increases its acidity. Therefore, its pKa < that of phenol<9.95.

D) Between C and D, -I is less electron withdrawing than -F. So pKa of D will be higher than that of C, but lesser than that of phenol.

E) -NO2 is electron withdrawing group. Presence of two -NO2 group at ortho and para position will increase the acidity. pKa << 9.95.

F) Benzene sulfonic anion is stabilized through delocalization over two S=O bonds, whereas, benzoic acid has delocalization over only another C=O. Therefore, pKa of F will be less than that of benzoic acid (which is around 4.2).

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