1 / 18

6.18 Epoxidation of Alkenes

6.18 Epoxidation of Alkenes. CHCH 3. H 2 C. CH 2. H 2 C. O. O. Epoxides. are examples of heterocyclic compounds three-membered rings that contain oxygen ethylene oxide propylene oxide. H 3 C. CHCH 3. CHCH 3. H 2 C. C. H 3 C. O. O. Epoxide Nomenclature.

barid
Download Presentation

6.18 Epoxidation of 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. 6.18Epoxidation of Alkenes

  2. CHCH3 H2C CH2 H2C O O Epoxides • are examples of heterocyclic compounds • three-membered rings that contain oxygen • ethylene oxide propylene oxide

  3. H3C CHCH3 CHCH3 H2C C H3C O O Epoxide Nomenclature • Substitutive nomenclature: named as epoxy-substituted alkanes. • “epoxy” precedes name of alkane • 1,2-epoxypropane 2-methyl-2,3-epoxybutane 1 4 2 3

  4. O H H Problem 6.17 Give the IUPAC name, including stereochemistry, for disparlure. • cis-2-Methyl-7,8-epoxyoctadecane

  5. O C RCOOH C O RCOH C C O Epoxidation of Alkenes + peroxy acid +

  6. O + CH3COOH O + CH3COH O Example (52%)

  7. O C RCOOH C O RCOH C C O Stereochemistry of Epoxidation + syn addition +

  8. O H H Problem 6.18 Give the structure of the alkene,including stereochemistry, that you wouldchoose as the starting material in a preparationof synthetic disparlure.

  9. H H O H H Problem 6.18 Give the structure of the alkene,including stereochemistry, that you wouldchoose as the starting material in a preparationof synthetic disparlure. peroxy acid

  10. Relative Rates of Epoxidation • ethylene H2C=CH2 1 • propene CH3CH=CH2 22 • 2-methylpropene (CH3)2C=CH2 484 • 2-methyl-2-butene (CH3)2C=CHCH3 6526 • More highly substituted double bonds react faster.Alkyl groups on the double bond make itmore “electron rich.”

  11. Mechanism of Epoxidation

  12. 6.19Ozonolysis of Alkenes • Ozonolysis has both synthetic and analytical applications. • synthesis of aldehydes and ketones • identification of substituents on the double bond of an alkene

  13. O C C C C O O Ozonolysis of Alkenes • First step is the reaction of the alkene with ozone.The product is an ozonide. + O3

  14. O C C C C O O O C Ozonolysis of Alkenes • Second step is hydrolysis of the ozonide. Two aldehydes, two ketones, or an aldehyde and a ketone are formed. + O3 H2O, Zn + O C

  15. O C C C C O O O O C C Ozonolysis of Alkenes • As an alternative to hydrolysis, the ozonide canbe treated with dimethyl sulfide. + O3 (CH3)2S +

  16. CH2CH3 CH3 C C H CH2CH3 CH2CH3 CH3 O O C C H CH2CH3 Example 1. O3 2. H2O, Zn + (38%) (57%)

More Related