{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

1057-RG_9-09 - Chem 1057 J Walcott LEARNING STRATEGIES...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 1057 J. Walcott LEARNING STRATEGIES CENTER Fall 2009 Review Guide #9 Lectures: 10/26/09 – 10/30/09 : Chapters 8 and 9 I. Reactions of Alkyl Halides ( Please see Review Guide #8 for S N 2 and E2 Reactions) A. The S N 2 Reaction 1. The nucleophile replaces the leaving group in a concerted, one-step mechanism (backside attack) that always occurs with inversion. S N 2 reactions will occur with methyl, primary and secondary alkyl halides but not tertiary ones. 2. The S N 2 reaction is overall second order (rate depends on the concentration of both the nucleophile and the substrate). It is a bimolecular reaction (both the nucleophile and the substrate are involved in formation of the rate-determining transition state). 3. S N 2 reactions give complete stereochemical control and will produce one product from a single reactant. 4. The rate of the S N 2 reaction is affected by nucleophilicity and leaving group ability. a. Nucleophilicity correlates roughly with Bronsted basicity. b. The best leaving groups are the weakest bases. 5. The solvent effect is important. a. In aprotic solvents, a nucleophile does not become well solvated or stabilized and is therefore more reactive. b. A protic solvent stabilizes an anion through formation of hydrogen bonds. The stronger the stabilizing interaction between an anion and the solvent is, the less reactive (and less nucleophilic) the anion will be. c. For S N 2 reactions, a polar aprotic solvent is desirable (eg. Acetone, DMSO, DMF). B. The E2 Reaction 1. The E2 reaction is a single-step, concerted, bimolecular reaction. It is a second order reaction with a bimolecular rate-determining step. The reaction involves the removal of a β -proton by a base, with a concerted loss of a leaving group.
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
Image of page 2
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