{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

week 2 - 4 - Chemistry S-20ab Chemistry E-2a Lecture 6 Week...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
E2 vs. S N 2: The “GFP” Reaction Hierarchy To help decide which reaction will predominate, apply the “GFP” (good-fair-poor) reaction hierarchy. If all else is equal , choose the reaction that is at the top of the list: 1. S N 2 reactions: Require good steric interactions Good if the halide is methyl or 1° Fair if the halide is 2° Poor if the halide is 3° or if the nucleophile is very bulky (e.g. t BuO ) 2. E2 reactions: Require a strong base Good if the base is at least as strong as OH Fair if the base is between H 2 O and OH in strength Poor if the base is weaker than H 2 O Let’s see some examples: Determine the primary product (and identify possible secondary products) for each of the following reactions: O Br Br Br O Br Br CH 3 I + OH CH 3 I + + OH + CN + CN + + OH Reading : Section 9.5 Chemistry S-20ab Week 2 116
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Reactions Involving Carbocations: S N 1 and E1 Consider the following reaction. Why is it unlikely that this reaction proceeded by either an S N 2 or E2 mechanism? Br EtOH O + 81% 19% 25°C Can you propose a mechanism for this reaction? Hint: the rate law for this reaction is simply: rate = k [tBuBr] What do you suppose is a requirement for this reaction? Reading : Section 9.6 Chemistry S-20ab Week 2 117
Image of page 2
The Stereochemistry of the S N 1 Reaction Given that the S N 1 mechanism proceeds through a carbocation intermediate, what would you expect to find when you subject the following alkyl halide to S N 1 conditions: H Cl H 2 O H OH HO H + S S R In fact, the products are: 33% S and 67% R . How can we explain this observation?
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern