Fundamentals of Organic ChemistryChemistryGeneral Organic Chemistry
Identify the correct order of acidic strength for the indicated protons (i), (ii), and (iii) in the given compound.
Options
- A(iii) > (i) > (ii)
- B(i) > (ii) > (iii)
- C(ii) > (iii) > (i)
- D(i) > (iii) > (ii)
Correct answer
D. (i) > (iii) > (ii)
Step-by-step solution
The acidic strength of a proton attached to a carbon atom is directly proportional to the electronegativity of the carbon atom. The electronegativity of a carbon atom increases with an increase in its s-character. The percentage s-character for different hybridizations is 50 % for sp , 33.3 % for sp^2 , and 25 % for sp^3 . Thus, the electronegativity and the resulting acidic strength follow the order sp > sp^2 > sp^3 . In the given compound, proton (i) is attached to a terminal alkyne carbon which is sp hybridized.