Question

The number of acidic hydrogen atoms in 1-butyne and 2-butyne is respectively.

• A. 1, 0
• B. 0, 1
• C. 1, 1
• D. 1, 2

Answer 1

The correct option is A 1, 0

1-Butyne $(C{H}_3-C{H}_2-CH\equiv \stackrel{1}{C}H)$
According to the structure. The carbon numbered as 1, in, 1- butyne has a hydrogen attached to it. This carbon atom is 'sp' hybridised, which means it has higher s-character that means higher electronegativity, therefore, the tendency to donate the $H^{+}$ ion will be higher in 1-butyne.
Hence 1-butyne has one 1 acidic hydrogen.
and in 2-butyne$(C{H}_3-CH\equiv CH-C{H}_3)$, both the carbons involved in triple bonding does not have a hydrogen atom, and the terminal carbon atoms are $s{p}^3$ hybridised, meaning less 's' character in them, therefore the tendency to donate $H^{+}$ ion will be less.
Hence 2- butyne has 0 acidic hydrogen.
Hence, correct option is a