1 / 9

Elimination Reactions

IB Chemistry Power Points Topic 20 Organic Chemistry. www.pedagogics.ca. Elimination Reactions. Elimination of HBr from halogenoalkanes. Recall: nucleophilic substitution of a bromoalkane. Elimination of HBr from halogenoalkanes.

reid
Download Presentation

Elimination Reactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. IB Chemistry Power Points Topic 20 Organic Chemistry www.pedagogics.ca Elimination Reactions

  2. Elimination of HBr from halogenoalkanes Recall: nucleophilic substitution of a bromoalkane

  3. Elimination of HBr from halogenoalkanes Recall: nucleophilic substitution of a bromoalkane

  4. Elimination of HBr from halogenoalkanes Recall: nucleophilic substitution of a bromoalkane Reaction occurs when bromoethane is added to a dilute NaOH solution. If conditions change, the nature of the reaction will change

  5. Elimination of HBr from halogenoalkanes An elimination reaction is one where a small molecule is removed from the reactant molecule. Substitution OH- + C2H5Br  C2H5OH + Br- Elimination OH- + C2H5Br  C2H4 + H2O + Br- Which reaction occurs depends on the reacting conditions.

  6. Elimination of HBr from halogenoalkanes

  7. Elimination reaction mechanisms • E2 mechanism • - similar to SN2 - bimolecular process • transition state, no intermediates • typical of secondary or tertiary substituted alkyl halides

  8. Elimination reaction mechanisms • E1 mechanism • - similar to SN1 • - unimolecular process • carbocation intermediate • typical of tertiary substituted alkyl halides

  9. Elimination reaction mechanisms How the reactions happen – the role of OH- The hydroxide ion hits one of the hydrogen atoms in the alkyl halide and pulls it off. This leads to a cascade of electron pair movements resulting in the formation of a carbon-carbon double bond, and the loss of the halogen as R-.

More Related