Question

Order of acidity CH=CH, CH₃-C=CH, CH₃-C=C-CH₃?

• A. CH=CH > CH₃-C=CH > CH₃-C=C-CH₃
• B. CH₃-C=CH > CH=CH > CH₃-C=C-CH₃
• C. CH₃-C=C-CH₃ > CH₃-C=CH > CH=CH
• D. CH₃-C=CH > CH₃-C=C-CH₃ > CH=CH

Hint:

The more electron-donating groups attached to a double bond, the less acidic the compound. For alkenes, consider the effect of substituents on electron density when predicting acidity.

Answer 1

The Correct Option is A

Acidity in alkenes is influenced by the electron-donating or electron-withdrawing effects of substituents attached to the double-bonded carbons. - CH=CH (ethene) has no substituents, making it the most acidic because there are no electron-donating groups to stabilize the conjugate base. - CH₃-C=CH (propene) has a methyl group attached to one of the carbons, which donates electron density and reduces acidity slightly compared to ethene. - CH₃-C=C-CH₃ (butene) has two methyl groups, further donating electron density, which makes it the least acidic. Thus, the order of acidity is CH=CH > CH₃-C=CH > CH₃-C=C-CH₃.