1. Mòdul MD2301 - Formació general; 564497 – Química orgànica i inorgànica MASTER ON DRUGS, COSMETICS AND FOOD QUALITY Dr. Antonio Delgado Universitat de Barcelona October 2009

2. Session 2 Addition reactions . Electrophilic adittion to alkenes. Catalytic hydrogenation. Electrophilic addition of halogens. Electrophilic addition of hydrogen halides. Hydration of alkenes. Mechanistic considerations and synthetic applications. Nucleophilic addition and nucleophilic “addition-elimination” at the carbonyl group . Reactivity of ketones and carboxylic acid derivatives. The enolate as nucleophile: the aldol reaction. Synthetic applications.

5. Catalytic hydrogenation

7. Hydrogenation is a sterospecific process (syn addition)

8. Electrophilic addition of halogens to alkenes The reaction with bromine results in a color change from red to colorless , which is sometimes used as a test for unsaturation

9. Bromination is a sterospecific process (anti addition)

10. A cyclic bromonium ion explains the stereochemistry

14. Electrophilic Addition of Hydrogen Halides to alkenes

15. This result is known as Markovnikov’s rule and is based on the stability of the carbocation formed by the addition of the proton

17. Electrophilic hydration of alkenes: synthesis of alcohols by thermodynamic control

19. Nucleophilic addition at the carbonyl group

20. Nucleophilic addition at the carbonyl group

21. Nucleophilic addition of hydrides and Grignard reagents

28. Enolates as nucleophiles (C-C bond formation)

30. One molecule of aldehyde acts as the nucleophile and the other as the electrophile