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Slide 1: 

CHEM2310 Ch 7 1 Naming Alkyl Halides We’ve already been naming alkyl halides. Mainly this is a review. However, some simple alkylhalides are named halides. Br CH 2 CH 3 C CH 2 CH 3 CH 3 CH CH 3 CH 3 CH However, some simple alkylhalides are named halides. a) b) Br c) Br

Naming Alkyl Halides Suggested Homework: Chapter 7 Exercises: 1, 2, 26 – 28: 

CHEM2310 Ch 7 2 Naming Alkyl Halides Suggested Homework: Chapter 7 Exercises: 1, 2, 26 – 28

Slide 3: 

CHEM2310 Ch 7 3 Preparing Alkyl Halides We’ve already studied some ways of making alkyl halides. CH 4 + Cl 2 CH 3 Cl + HCl h ν CH 4 h ν CH 3 Cl Cl 2 h ν CH 2 Cl 2 Cl 2 CHCl 3 h ν Cl 2 CCl 4 h ν Cl 2 From our study of alkane reactions:

Slide 4: 

CHEM2310 Ch 7 4 Preparing Alkyl Halides We’ve already studied some ways of making alkyl halides. From our study of alkene reactions: Addition of Br 2 or Cl 2 in CH 2 Cl 2 Mechanism: Anti addition due to a bridged halonium ion intermediate. (In the case of bromine, a bromonium ion intermediate.)

Slide 5: 

CHEM2310 Ch 7 5 Preparing Alkyl Halides We’ve already studied some ways of making alkyl halides. From our study of alkene reactions: pent-1-ene + HCl → Markovnikov Addition Mechanism: What mechanism is responsible for a Markovnikov addition?

Slide 6: 

CHEM2310 Ch 7 6 Preparing Alkyl Halides The most general method of making alkyl halides is from alcohols: HCl Ether, 0°C H O H O H O SOCl 2 H O PBr 3 Ether, 35°C Cl Br Cl SOCl 2 H O PBr 3 Ether, 35°C Cl Br What is the difference in the alcohols shown?

Slide 7: 

CHEM2310 Ch 7 7 Preparing Alkyl Halides What difference does the type of alcohol make? C H H OH R C R H R C R R R primary 1 ° secondary 2 ° tertiary 3 ° OH OH Which is the most reactive? It depends upon the _____________________.

Slide 8: 

CHEM2310 Ch 7 8 Preparing Alkyl Halides The most general method of making alkyl halides is from alcohols: HCl Ether, 0°C H O H O H O SOCl 2 H O PBr 3 Ether, 35°C Cl Br Cl SOCl 2 H O PBr 3 Ether, 35°C Cl Br What is the difference in the alcohols shown and the corresponding reactant?

Slide 9: 

CHEM2310 Ch 7 9 Preparing Alkyl Halides The most general method of making alkyl halides is from alcohols: HCl Ether, 0°C H O H O H O SOCl 2 H O PBr 3 Ether, 35°C Cl Br Cl SOCl 2 H O PBr 3 Ether, 35°C Cl Br Primary: ROH + HX → RX Secondary or Tertiary: ROH + SOCl 2 → RCl ROH + PBr 3 → RBr

Slide 10: 

CHEM2310 Ch 7 10 Preparing Alkyl Halides Primary: ROH + HX → RX Secondary or Tertiary: ROH + SOCl 2 → RCl ROH + PBr 3 → RBr Starting with alcohols, outline a synthesis of each of the following: a) benzyl bromide (C 6 H 5 CH 2 Br) b) cyclohexyl chloride c) butyl bromide

Preparing Alkyl Halides Suggested Homework: Chapter 7 Exercises: 3 – 5, 36ab: 

CHEM2310 Ch 7 11 Preparing Alkyl Halides Suggested Homework: Chapter 7 Exercises: 3 – 5, 36ab

Slide 12: 

CHEM2310 Ch 7 12 Reactions of Alkyl Halides: Grignard Reagents skipping

Slide 13: 

CHEM2310 Ch 7 13 Overview: _________________ Reactions What type of reactions are these? HCl Ether, 0°C H O H O H O SOCl 2 H O PBr 3 Ether, 35°C Cl Br Cl SOCl 2 H O PBr 3 Ether, 35°C Cl Br

Slide 14: 

CHEM2310 Ch 7 14 Overview: Substitution Reactions We will study 2 types of substitution mechanisms: S N 1 and S N 2 S N = Substitution Nucleophilic In this reaction, a bond to C will form and a bond to C will break S N 1 = Substitution Nucleophilic, mechanism involves 1 bond at a time R X Nu : S N 2 = Substitution Nucleophilic, mechanism involves 2 bonds at a time R X Nu : note: this illustration does NOT show charges.

Slide 15: 

CHEM2310 Ch 7 15 Overview: Substitution Reactions We will study 2 types of substitution mechanisms: S N 1 and S N 2 S N = Substitution Nucleophilic In this reaction, a bond to C will form and a bond to C will break S N 1 = Substitution Nucleophilic, mechanism involves 1 bond at a time R X Nu : S N 2 = Substitution Nucleophilic, mechanism involves 2 bonds at a time R X Nu : note: this illustration does NOT show charges.

Slide 16: 

CHEM2310 Ch 7 16 Overview: Substitution Reactions S N 1 = Substitution Nucleophilic, mechanism involves 1 bond at a time

Slide 17: 

CHEM2310 Ch 7 17 Overview: Substitution Reactions S N 2 = Substitution Nucleophilic, mechanism involves 2 bonds at a time

Slide 18: 

CHEM2310 Ch 7 18 Overview: Substitution Reactions We will study 2 types of substitution mechanisms: S N 1 and S N 2 S N = Substitution Nucleophilic In this reaction, a bond to C will form and a bond to C will break S N 1 = Substitution Nucleophilic, mechanism involves 1 bond at a time S N 2 = Substitution Nucleophilic, mechanism involves 2 bonds at a time note: this illustration does NOT show charges NOR stereochemistry. RX RX

Slide 19: 

CHEM2310 Ch 7 19 Overview: Substitution Reactions

Slide 20: 

CHEM2310 Ch 7 20 Overview: Substitution Reactions

Slide 21: 

CHEM2310 Ch 7 21 Overview: Substitution Reactions

Overview: Substitution Reactions Suggested Homework: Chapter 7 Exercises: 8, 9 Additional Exercises: Cover up product on slides 19-21 and determine the products.: 

CHEM2310 Ch 7 22 Overview: Substitution Reactions Suggested Homework: Chapter 7 Exercises: 8, 9 Additional Exercises: Cover up product on slides 19-21 and determine the products.

Slide 23: 

CHEM2310 Ch 7 23 The S N 2 Reaction What does S N 2 stand for? S? N? 2? In this reaction, a bond to C will form and a bond to C will break. Nu: bimolecular

Slide 24: 

CHEM2310 Ch 7 24 S N 2 = Substitution Nucleophilic, mechanism involves 2 bonds at a time The S N 2 Reaction molecules Bimolecular from the standpoint concerning: the mechanism the rate of reaction whether the reaction tends to go forward

Slide 25: 

CHEM2310 Ch 7 25 The S N 2 Reaction Bimolecular from the standpoint concerning: the mechanism How many steps are in the mechanism? How does this affect the stereochemistry of the product?

Slide 26: 

CHEM2310 Ch 7 26 The S N 2 Reaction

Slide 27: 

CHEM2310 Ch 7 27 The S N 2 Reaction Bimolecular from the standpoint concerning: the rate of reaction a) What happens if you double the concentration of nucleophile? b) What happens if you double the concentration of the substrate? c) What happens if you double both the concentration of the nucleophile and the substrate? d) What happens if you triple the concentration of the nucleophile and quadruple the concentration of the substrate?

Slide 28: 

CHEM2310 Ch 7 28 The S N 2 Reaction Bimolecular from the standpoint concerning: whether the reaction tends to go forward What similarities do you notice when you compare the nucleophile and the leaving group?

The SN2 Reaction Suggested Homework: Chapter 7 Exercises: 10, 32, 33: 

CHEM2310 Ch 7 29 The S N 2 Reaction Suggested Homework: Chapter 7 Exercises: 10, 32, 33

Slide 30: 

CHEM2310 Ch 7 30 Stereochemistry of S N 2 Reactions Bimolecular from the standpoint concerning: the mechanism The stereochemistry is only important if the reaction involves stereoisomers. C CH 3 H H OH Br C CH 3 H H OH + C CH 3 H H Br Br + OH d d

Slide 31: 

CHEM2310 Ch 7 31 Stereochemistry of S N 2 Reactions Which of the following reactions will require taking time to consider the change in the stereochemistry? Br a) b) Br OH + OH + c) Br OH + d) OH + Br OH

Slide 32: 

CHEM2310 Ch 7 32 Stereochemistry of S N 2 Reactions Which of the following reactions will require taking time to consider the change in the stereochemistry? a) b) HO Br HO Br OH + OH +

Slide 33: 

CHEM2310 Ch 7 33 Stereochemistry of S N 2 Reactions C CH 3 H OH Br C CH 3 H OH + C CH 3 H Br Br + OH d d CH 2 CH 3 CH 2 CH 3 CH 2 CH 3 (S)-2-bromobutane

Slide 34: 

CHEM2310 Ch 7 34 Stereochemistry of S N 2 Reactions C CH 3 H OH Br C CH 3 H OH + C CH 3 H Br Br + OH d d CH 2 CH 3 CH 2 CH 3 CH 2 CH 3 (S)-2-bromobutane (R)-butan-2-ol Can you assume that an S enantiomer will always go to an R enantiomer?

Slide 35: 

CHEM2310 Ch 7 35 Stereochemistry of S N 2 Reactions C CH 3 H OH Br C CH 3 H OH + Br + CH 2 CH 3 CH 2 CH 3 (S)-2-bromobutane (R)-butan-2-ol You can, however, use the fact that the enantiomer is created whenever 2 substituents are switched. CH 3 Br C H CH 2 CH 3 Drawing trick : 1) redraw switching 2 substituents 2) substitute Nu for LG This is just scratch work!! } CH 3 C H CH 2 CH 3 OH (R)-butan-2-ol

Slide 36: 

CHEM2310 Ch 7 36 Stereochemistry of S N 2 Reactions (S)-2-iodooctane You can, however, use the fact that the enantiomer is created whenever 2 substituents are switched. I NaCN C N (R)-enantiomer Important Notes : 1) You can NOT just add CN − , it is not the full reagent. 2) You have to determine where the nucleophile will add.

Slide 37: 

CHEM2310 Ch 7 37 Stereochemistry of S N 2 Reactions Give the products of the following displacement reactions and determine the stereochemistry of the product(s): a) ( R )-CH 3 CHBrCH 2 CH 3 + NaOMe b) cis -4-iodoethylcyclohexane + NaOH c) (S)-BrCH(CH 3 )COOEt + NaCN

Stereochemistry of SN2 Reactions Suggested Homework: Chapter 7 Exercises: 11, 12 Note for #12: ball-stick molecule shown is (S)-4-bromo-2-methylpentane: 

CHEM2310 Ch 7 38 Stereochemistry of S N 2 Reactions Suggested Homework: Chapter 7 Exercises: 11, 12 Note for #12: ball-stick molecule shown is (S)-4-bromo-2-methylpentane

Slide 39: 

CHEM2310 Ch 7 39 Steric Effects of S N 2 Reactions

Slide 40: 

CHEM2310 Ch 7 40 Steric Effects of S N 2 Reactions C H H R C R H R C R R R primary 1 ° secondary 2 ° tertiary 3 ° Br Br Br

Steric Effects of SN2 Reactions Suggested Homework: Chapter 7 Exercises: 13, 31, 35: 

CHEM2310 Ch 7 41 Steric Effects of S N 2 Reactions Suggested Homework: Chapter 7 Exercises: 13, 31, 35

Slide 42: 

CHEM2310 Ch 7 42 Leaving Groups in S N 2 Reactions Acid Approximate pK a Conjugate base HI -10 I - H 2 SO 4 -9 SO 4 2- HBr -9 Br - HCl -7 Cl - : : : HF 3.2 F - : : : C 6 H 5 OH 9.9 C 6 H 5 O - : : : CH 3 OH 15.5 CH 3 O - H 2 O 15.74 HO - CH 3 CH 2 OH 15.9 CH 3 CH 2 O - : : : NH 3 38 NH 2 - : : : How stable is the leaving group? Which are the most stable leaving groups?

Leaving Groups in SN2 Reactions Suggested Homework: Chapter 7 Exercises: 14, 30: 

CHEM2310 Ch 7 43 Leaving Groups in S N 2 Reactions Suggested Homework: Chapter 7 Exercises: 14, 30

Slide 44: 

CHEM2310 Ch 7 44 The S N 1 Reaction What does S N 1 stand for? S? N? 1? In this reaction, a bond to C will form and a bond to C will break. Nu: unimolecular

Slide 45: 

CHEM2310 Ch 7 45 S N 1 = Substitution Nucleophilic, mechanism involves 1 bond at a time molecules Unimolecular from the standpoint concerning: the mechanism the rate of reaction whether the reaction tends to go forward The S N 1 Reaction

Slide 46: 

CHEM2310 Ch 7 46 Unimolecular from the standpoint concerning: the mechanism How many steps are in the mechanism? How does this affect the stereochemistry of the product? Which step is the most important? Why? The S N 1 Reaction

Slide 47: 

CHEM2310 Ch 7 47 The S N 1 Reaction

Slide 48: 

CHEM2310 Ch 7 48 The S N 1 Reaction Unimolecular from the standpoint concerning: the rate of reaction a) What happens if you double the concentration of nucleophile? b) What happens if you double the concentration of the substrate? c) What happens if you double both the concentration of the nucleophile and the substrate? d) What happens if you triple the concentration of the nucleophile and quadruple the concentration of the substrate?

Slide 49: 

CHEM2310 Ch 7 49 Unimolecular from the standpoint concerning: whether the reaction tends to go forward What similarities do you notice when you compare the nucleophile and the leaving group? The S N 1 Reaction

The SN1 Reaction Suggested Homework: Chapter 7 Exercises: 15, 29: 

CHEM2310 Ch 7 50 The S N 1 Reaction Suggested Homework: Chapter 7 Exercises: 15, 29

Slide 51: 

CHEM2310 Ch 7 51 Stereochemistry of S N 1 Reactions C CH 3 OH Br C CH 3 OH + C CH 3 + CH 2 CH 3 CH 2 CH 3 CH 2 CH 3 (S)-2-bromo-2-methylhexane (R)-2-methylhexan-3-ol Can you assume that an S enantiomer will always go to a racemic mixture? H CH 2 CH 2 CH 3 CH 2 CH 2 CH 3 CH 2 CH 2 CH 3 C CH 3 + CH 2 CH 3 CH 2 CH 2 CH 3 OH (S)-2-methylhexan-3-ol

Slide 52: 

CHEM2310 Ch 7 52 Give the products of the following displacement reactions and determine the stereochemistry of the product(s): a) (CH 3 ) 2 CHBrCH 2 CH 3 + NaOMe b) (R)-2-iodo-3-methylpentane + NaOH c) + NaCN Stereochemistry of S N 1 Reactions CH 2 CH 2 CH 3 CH 2 CH 3 CH 3 Br Assume that (c) is showing stereochemistry.

Stereochemistry of SN1 Reactions Suggested Homework: Chapter 7 Exercises: 16, 17 Note for #17: ball-stick molecule shown is (S), with the chiral C having the substituents Br, methyl, ethyl, and a phenyl (benzene ring).: 

CHEM2310 Ch 7 53 Stereochemistry of S N 1 Reactions Suggested Homework: Chapter 7 Exercises: 16, 17 Note for #17: ball-stick molecule shown is (S), with the chiral C having the substituents Br, methyl, ethyl, and a phenyl (benzene ring).

Slide 54: 

CHEM2310 Ch 7 54 Steric Effects of S N 1 Reactions C H H R C R H R C R R R primary 1 ° secondary 2 ° tertiary 3 ° Br Br Br

Steric Effects of SN1 Reactions Suggested Homework: Chapter 7 Exercises: None at this time but you will need this for comparison of when a reaction proceeds as SN1 or SN2.: 

CHEM2310 Ch 7 55 Steric Effects of S N 1 Reactions Suggested Homework: Chapter 7 Exercises: None at this time but you will need this for comparison of when a reaction proceeds as S N 1 or S N 2.

Slide 56: 

CHEM2310 Ch 7 56 Leaving Groups in S N 1 Reactions Acid Approximate pK a Conjugate base HI -10 I - H 2 SO 4 -9 SO 4 2- HBr -9 Br - HCl -7 Cl - : : : H 3 O + -1.74 H 2 O : : : HF 3.2 F - : : : C 6 H 5 OH 9.9 C 6 H 5 O - : : : CH 3 OH 15.5 CH 3 O - H 2 O 15.74 HO - CH 3 CH 2 OH 15.9 CH 3 CH 2 O - : : : NH 3 38 NH 2 - : : : In an acidic solution, water is also a leaving group. Which are the most stable leaving groups?

Leaving Groups in SN1 Reactions Suggested Homework: Chapter 7 Exercises: No new problems now but will be used in later problems.: 

CHEM2310 Ch 7 57 Leaving Groups in S N 1 Reactions Suggested Homework: Chapter 7 Exercises: No new problems now but will be used in later problems.

Slide 58: 

CHEM2310 Ch 7 58 Summary of S N 1 Vs. S N 2 Reactions Substrate S N 1 S N 2 methyl or 1 ° 2 ° 3 ° Common Common Rare Rare

Summary of SN1 Vs. SN2 Reactions Suggested Homework: Chapter 7 Exercises: 37abc, 38, 39abce: 

CHEM2310 Ch 7 59 Summary of S N 1 Vs. S N 2 Reactions Suggested Homework: Chapter 7 Exercises: 37abc, 38, 39abce

Slide 60: 

CHEM2310 Ch 7 60 E2 Reactions

Slide 61: 

CHEM2310 Ch 7 61 E2 Reactions 2-bromobutane + KOH → but-2-ene + but-1-ene major product minor product Zaitsev’s rule

Slide 62: 

CHEM2310 Ch 7 62 E2 Reactions b) ( trans )-2-chloromethylcyclopropane + KOH → a) ( cis )-2-chloromethylcyclopropane + KOH →

E2 Reactions Suggested Homework: Chapter 7 Exercises: 18, 19: 

CHEM2310 Ch 7 63 E2 Reactions Suggested Homework: Chapter 7 Exercises: 18, 19

Slide 64: 

CHEM2310 Ch 7 64 E1 Reactions tert -butylchloride + KOH → 2-methylpropene

Slide 65: 

CHEM2310 Ch 7 65 E1 Reactions 2-chloro-2-methylpropane + H 2 O → 2-methylpropan-2-ol + 2-methylpropene

E1 Reactions Suggested Homework: Chapter 7 Exercises: 20: 

CHEM2310 Ch 7 66 E1 Reactions Suggested Homework: Chapter 7 Exercises: 20

Slide 67: 

CHEM2310 Ch 7 67 Summary of S N 1, S N 2, E1, E2 Reactions Substrate S N 1 S N 2 E1 E2 methyl or 1 ° 2 ° 3 ° Common Common Rare Rare Rare Common Common (strong base)

Slide 68: 

CHEM2310 Ch 7 68 Summary of S N 1, S N 2, E1, E2 Reactions Acid Approximate pK a Conjugate base HI -10 I - H 2 SO 4 -9 SO 4 2- HBr -9 Br - HCl -7 Cl - : : : H 3 O + -1.74 H 2 O : : : HF 3.2 F - : : : C 6 H 5 OH 9.9 C 6 H 5 O - : : : CH 3 OH 15.5 CH 3 O - H 2 O 15.74 HO - CH 3 CH 2 OH 15.9 CH 3 CH 2 O - : : : NH 3 38 NH 2 - : : :

Slide 69: 

CHEM2310 Ch 7 69 Summary of S N 1, S N 2, E1, E2 Reactions Sub-strate S N 1 S N 2 E1 E2 methyl or 1 ° Common 2 ° 3 ° Common Common a) Write a structural formula for the major product of: 2-chloro-2-methylbutane + NaOH → b) Write a structural formula for the product(s) of: 2-chloro-2-methylbutane + H 2 O →

Slide 70: 

CHEM2310 Ch 7 70 Summary of S N 1, S N 2, E1, E2 Reactions Sub-strate S N 1 S N 2 E1 E2 methyl or 1 ° Common 2 ° 3 ° Common Common a) Write a structural formula for the major product of: 2-bromohexane + NaOEt → b) Write a structural formula for the product(s) of: 4-bromo-2-methylbutane + N(C 2 H 5 ) 3 →

Summary of SN1, SN2, E1, E2 Reactions Suggested Homework: Chapter 7 Exercises: 21, 31ab, 32 – 35, 36abd, 37abc, 38abdef, 39abce, 40bc, 41 – 50, 55 – 58, 60, 62abcdef: 

CHEM2310 Ch 7 71 Summary of S N 1, S N 2, E1, E2 Reactions Suggested Homework: Chapter 7 Exercises: 21, 31ab, 32 – 35, 36abd, 37abc, 38abdef, 39abce, 40bc, 41 – 50, 55 – 58, 60, 62abcdef