Explain ethyne is acidic in nature as compared to ethene & ethane.

Asked by GARIMA SRIVASTAVA | 4th Mar, 2011, 02:44: AM

Expert Answer:

Dear Student
In ethyne,the C atoms are in sp hybrid state with 50% s- character. As the s-charater increases , electronegativity of carbon encreases. In this way C strongly attract bond pair electrons of C-----H bond towards itself and ultimately H+ are set free.Hence,ethyne acts as acid. 
Ethyne contains sp hybridized carbons, while ethene and ethane contain sp2 and sp3 hybridized carbons respectively. The sp hybrid orbitals have greater s character than sp2 and sp3, which allows negative charge to be held closer to the nucleus upon protonation, lowering the overall energy, and increasing the acidic character. The same arguement can be made between sp2 and sp3, giving alkenes more acidity.
We hope that clarifies your query.

Answered by  | 4th Mar, 2011, 11:46: AM

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