1 / 10

Hemiacetal and Acetal Functional Groups

Hemiacetal and Acetal Functional Groups. Hemiacetal: alcohol and ether on same carbon Acetal: Two ethers on same carbon. Mechanism. Must be acid-catalyzed. Adding H + to carbonyl makes it more reactive with weak nucleophile, ROH.

marinel
Download Presentation

Hemiacetal and Acetal Functional Groups

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. Hemiacetal and Acetal Functional Groups • Hemiacetal: alcohol and ether on same carbon • Acetal: Two ethers on same carbon

  2. Mechanism • Must be acid-catalyzed. • Adding H+ to carbonyl makes it more reactive with weak nucleophile, ROH. • Hemiacetal forms first, then acid-catalyzed loss of water, then addition of second molecule of ROH forms acetal. • All steps are reversible. =>

  3. Hemiacetal Synthesis: aldehyde + alcohol • Alcohol + aldehyde --> hemiacetal • Ethanal + methanol • Alcohol oxygen becomes an ether • Carbon double bond oxygen becomes an alcohol

  4. => Mechanism for Hemiacetal

  5. Aldehyde and Ketone Reactions

  6. Synthesis of Acetal Functional Group • Acetal: alcohol plus hemiacetal (ether synthesis) • Acetal: Two ethers on same carbon

  7. =>

  8. Aldehyde and Ketone Reactions

  9. => Mechanism Hemiacetal to Acetal

  10. => Cyclic Acetals • Addition of a diol produces a cyclic acetal. • Sugars commonly exist as acetals or hemiacetals.

More Related