Acid Strength

[Nisha Patel 3I]

In this problem, how do you know that H has more electron withdrawing ability than CH₃?

Fall 2013 Final Exam: #Q7B

"List the following acids in order of increasing strength and explain why: CF₃COOH (1), CH₃COOH (2), CCl₃COOH (3), C(CH₃)₃COOH (4)"

Answer: 4<2<3<1
Electron withdrawing ability F>Cl>H>CH₃

[Sandeep Gurram 2E]

Dr. Lavelle had an excellent explanation of this exact problem in his review session for the final. Basically, CH₃ is a more electron rich species than H is, and therefore has more of a negative charge associated with it. In fact H is basically considered a positive species. Because of this, CH₃ does not pull on electron dense regions as hard as H can. Hope that helped.