1 / 18

Reactions Involving Alkenes

Reactions Involving Alkenes. Section 12.5 Pages 337-346. Addition Reaction. Addition of two atoms or groups of atoms to a double bond. R can be carbon or hydrogen. Types of Addition Reactions. The major alkene addition reactions include Addition of hydrogen (H 2 ) – hydrogenation

liluye
Download Presentation

Reactions Involving Alkenes

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. Reactions Involving Alkenes Section 12.5 Pages 337-346

  2. Addition Reaction • Addition of two atoms or groups of atoms to a double bond. • R can be carbon or hydrogen.

  3. Types of Addition Reactions • The major alkene addition reactions include • Addition of hydrogen (H2) – hydrogenation • Addition of halogens (Cl2 or Br2) – halogenation • Addition of water (H2O) – hydration • Addition of hydrogen halides (HBr or HCl) – hydrohalogenation • Note: Double bond becomes a single bond.

  4. Hydrogenation: Adding H2 • Double bond is broken • H atom added to both sides of double bond • Platinum, palladium, or nickel catalyst required • Heat and/or pressure may also be needed

  5. Examples of Hydrogenation • Hydrogenation of 1-propene to propane • Hydrogenation of trans-2-butene

  6. YOU TRY THESE! • Write hydrogenation reactions for: • 1-pentene • 2-methyl-2-butene • ethene

  7. Halogenation: Adding Br2 orCl2 • This reaction occurs easily and does not require a catalyst.

  8. Examples of Halogenation • Bromination of 1-propene to form 1,2-dibromopropane • Chlorination of trans-2-butene to form 2,3-dichlorobutane

  9. YOU TRY THESE! • Write halogenation reactions for: • 1-pentene with bromine • 2-methyl-2-butene with chlorine • Ethene with chlorine

  10. Hydration: Addition of H2O • Requires a trace of acid (H+) as a catalyst • The product is an alcohol • Markovnikov’s rule applies

  11. Markovnikov’s Rule • A mixture of products is formed when an unsymmetrical alkene is hydrated. • One product is always favored over the other. • Vladimir Markovnikov came up with a rule to determine the major product formed. • The carbon of the carbon-carbon double bond that originally has more hydrogen atoms receives the hydrogen atom being added. • “The rich get richer.”

  12. Example of Markovnikov’s Rule • Hydration of 1-propene to form 2-propanol (major) and 1-propanol (minor)

  13. YOU TRY THESE! • Write the hydration equation for each of the following molecules. Indicate the major and minor products for the reactions where applicable. • 1-pentene • 2-methyl-2-butene • ethene

  14. Hydrohalogenation: Adding HCl or HBr • Follows Markovnikov’s rule

  15. Examples of Hydrohalogenation • Hydrobromination of 1-propene to form 2-bromopropane (major) and 1-bromopropane (minor)

  16. YOU TRY THESE! • Write the hydrohalogenation equation for each of the following molecules. Indicate the major and minor products for the reactions where applicable. • 1-pentene with HCl • 2-methyl-2-butene with HBr • Ethene with HCl

  17. Oxidation Reactions Carbon-carbon double bonds are very susceptible to attack by oxidizing agents, such as potassium permanganate.

  18. Oxidation of Ethene Because of the dramatic color change from purple to brown, this is an easy test for the presence of alkenes. (alkanes do NOT undergo the oxidation reaction and remain purple).

More Related