Question

Which bases can deprotonate acetylene? the pka values of the conjugate acids are given in parentheses. select all that apply. ch3ch2s− (pka = 10.5) ch2═ch− (pka = 44) ch3nh− (pka = 40) ch3ch2o− (pka = 16)?

Answer 1

pKa is a value which is related to the acid dissociation constant Ka

pKa = -log Ka

i.e. Ka = 10^-pKa

The deprotonation reaction of acetylene is:

HC≡CH ↔ HC≡C⁻ + H⁺

pKa (HC≡CH) = 25

Solvents with pKa greater than 25 will deprotonate acetylene.

Ans: CH2=CH⁻ pka = 44 and CH3NH⁻ pka = 40