Which of the following bases are strong enough to deprotonate CH3CH2CH2CCH so th

Question

Which of the following bases are strong enough to deprotonate CH3CH2CH2CCH so that equilibrium favors the products:

(a)H2O (b) NaOH (c) NaNH2 (d) NH3 (e) NaH (f) CH3Li ? The answer is c,e, and f

I'm specifically confused about why NH3 can't deprotonate the acid. What makes NH3 not strong enough base to deprotonate when compared to NH2-? They're both sp3 hybridized with nitrogen bonded to hydrogen that are both more unstable(stronger) base than CC- because it is sp hybridized, making the equilibrium favor the products.

Explanation / Answer

Solution :-

alkyne proton is the acidic proton

The base should be strong enough to deprotonate the alkyne proton

The bases NaNH2 , NaH and CH3Li are the bases which have the metal element in it which makes them very strong therefore NH2^-, H^- and CH3^- becomes very strong base and therefore they can deprotonate the alkyne.

H2O, NaOH and NH3 are not strong enough to deprotonate the alkyne proton.

The dissociation constant Kb of the NH3 is very small that is 1.8*10^-5 therefore its a weak base therefore it cannot deprotonate the alkyne

Therefore answer is option 'c,e and f.

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