1 כימיה אורגנית לתלמידי רפואה, מדעי הרפואה, ורפואת שיניים ד"ר עידית תשובה המחלקה לכימיה אי אורגנית בניין לוס-אנג'לס, חדר האוניברסיטה העברית

2 כימיה אורגנית לתלמידי רפואה, מדעי הרפואה ורפואת שיניים תוכן הקורס Organic Chemistry, 4 th Edition, Paula Yurkanis Bruice Organic Chemistry, 5 th Edition, Paula Yurkanis Bruice OR אתר הקורס:

3 ChaptersTopic *** 1 *** *** Electronic structure and bonding acids and bases; Mandatory self reading *** 22An introduction to organic compounds; nomenclature, properties, structures 3-4 Alkenes; structure, nomenclature, reactivity 55Stereochemistry 66Alkynes 7-87Delocalization and resonance, Dienes 911Reactions of alkanes Substitutions and eliminations; alkyl halides, alcohols, ethers, epoxides, Griniard reactions 1514Aromaticity 1615Reactions of aromatic compounds Carbonyl compounds 2019Oxidation-reduction 22,23,26,2721,22,26,27 Bioorganic compounds; carbohydrates, proteins, lipids, nucleic acids -*** 25 ****** The Chemistry of metabolism; Highly recommended self reading *** כימיה אורגנית לתלמידי רפואה, מדעי הרפואה ורפואת שיניים סילבוס 4th5th

4 Organic Chemistry, 4 th Edition, Paula Yurkanis Bruice Chapter 4 Pg , Reaction of Alkenes Irene Lee Case Western Reserve University Cleveland, OH ©2004, Prentice Hall קריאה מלווה מחייבת Chapter 4 Pg , , (+ Chapter 11 Pg ) The Reaction of Alkenes Organic Chemistry, 5 th Edition, Paula Yurkanis Bruice

5 Electrophilic Addition of Alkenes

6 Addition of Hydrogen Halides

7 What is the product?

8 a more stable carbocation Carbocation formation is the rate-limiting step Formation of the carbocation is the rate-limiting step. The more stable carbocation will form, and consequently react rapidly with the nucleophile.

9 Carbocation Stabilities

10 Alkyl groups decrease the concentration of positive charge in the carbocation

11 Delocalization of Electrons

12 Reaction Rate more stable transition state faster reaction rate

13 In a regioselective reaction, one constitutional isomer is the major or the only product Markovnikov’s Rule The electrophile (here hydrogen ion) adds to the sp 2 carbon that is bonded to the greater number of hydrogens

14 Addition of Water to Alkene The H 2 O nucleophile is present in a much higher amount than the counter ion of the acid catalyst

15 Acid-Catalyzed Addition of Alcohol

16 Rearrangement of Carbocation 1,2-hydride shift a more stable carbocation

17 a more stable carbocation Rearrangement of Carbocation 1,2-methyl shift

18 Carbocation does not always rearrange …

19 Carbocation Rearrangement a more stable carbocation Ring Expansion

20 Addition of Halogens to Alkene Br–Br behaves like Br + –Br - Reaction occurs with Cl 2, but not utilized for F 2 (explosive) or I 2 (product unstable).

21 No carbocation – no rearrangements

22 Addition of Halogens in the Presence of Water

23 Consider the transition states … Other nucleophiles may be added, such as alcohols or other halide ions

24 Oxymercuration and Mercuration of Alkene No possibly harmful acidic conditions, No rearrangements (no carbocations)

25 Demercuration by Reduction Similarly with alcohols

26 Addition of Borane Hydroboration–Oxidation Anti-Markovnikov’s rule in product formation

27 Anti-Markovnikov addition Markovnikov addition A pericyclic reaction: cyclic rearrangements of electrons Concerted reaction, no intermediate stronger bond weaker bond

28 Formation of Alkyl Boranes Steric factors play a part as well

29 OH Replacement of Boron H 2 O 2 + OH -

30 Anti-Markovnikov Addition of an OH Group

31 Generation of Radicals Homolytic bond cleavage

32 Addition of Radicals to Alkene

33 Addition of Radicals to Alkene

34 Addition of Radicals to Alkene

35 Relative Stabilities of Alkyl Radicals Like carbocations, radicals are stabilized by electron donating alkyl groups Less rearrangements occur with radical reactions

36 Catalytic Addition of Hydrogen to Alkenes: hydrogenation

37 Catalytic Hydrogenation of an Alkene Heterogeneous catalysis

38 Potential Energies of Pentene Isomers

39 Relative Stabilities of Alkenes

40 Steric Strain in Alkenes

41 Relative Stabilities of Dialkyl- Substituted Alkenes