Organic Chemistry CHM 314 Dr. Laurie S. Starkey, Cal Poly Pomona Alkyl Halides: Substitution Reactions - Chapter 6 (Wade)

Size: px
Start display at page:

Download "Organic Chemistry CHM 314 Dr. Laurie S. Starkey, Cal Poly Pomona Alkyl Halides: Substitution Reactions - Chapter 6 (Wade)"

Transcription

1 rganic Chemistry CM 314 Dr. Laurie S. Starkey, Cal Poly Pomona Alkyl alides: Substitution Reactions - Chapter 6 (Wade) Chapter utline I. Intro to RX ( ) II. Substitution Reactions A) S N 2 (6-8, 6-9, 6-12) B) S N 1 (6-13, 6-14) C) Leaving Groups, LG (6-11, 11-5) D) Nucleophiles, Nu: (6-10) E) S N 2 vs. S N 1 (6-16) III. Competing Reactions A) Carbocation Rearrangements (6-15) B) Intro to Elimination Reactions ( ) (Elimination rxns continued in CM 315 & Ch. 7) IV. Solvent Effects (6-10B, 6-13C) 6-1 I. Introduction to Alkyl alides (RX) Types of alides, X = F,, Br, I R X alkyl halide - can be 1, 2, 3, allylic, benzylic - can be prepared by free-radical halogenation (Chapter 4) X vinyl halide (on pi bond) X aryl halide (on benzene ring) Reactivity of Alkyl alides X Nu: base Substitution (CM 314) (replace X with Nu:) (Nu: = nucleophile) Elimination (CM 315) ( - X) (forms an alkene) II. Substitution Reactions Example: Nu: E + product LG Nucleophile (Nu:) - electron-rich (lone pair or pi bond), often has negative charge - seeks electron-deficient species Electrophile (E + ) - electron-poor (δ+ or +) - seeks electron-rich species Leaving Group (LG) - group leaves and takes 2 electrons with it - stable groups (weak bases) make good LG's (e.g., X -, halide) Why are -, Br - and I - good LGs? General Reaction: Nu: R LG Nu LG R 6-2

2 General Reaction: Nu: R LG Nu LG R What are the possible mechanisms for this substitution reaction? A) simultaneous (concerted) B) stepwise (LG leaves first) 6-2 this is called the S N 2 mechanism (6-8, 6-9, 6-12) this is called the S N 1 mechanism (6-13, 6-14) II. A) S N 2 - Substitution Nucleophilic Bimolecular (Wade 6-8, 6-9, 6-12) Example: C 2 I Mechanism: one step, backside attack S N 2 Kinetics Rate = k [ - ] [ C 2 I] - rate is dependant on both Nu: and E+ - bimolecular reaction - sterics affect the rate of S N 2 R group consider tert-butyl bromide: Kinetics experiment: R Br R Br CN :CN 2 abbrev. carbon type relative rate C 2 C3 C C C C 2 Rate of S N 2 (by type of RX):

3 S N 2 Energy vs. Progress of Reaction Diagram 6-3 If LG carbon is too sterically hindered (e.g., 3 ), then: E PR S N 2 Transition State Structure I I Transition State (TS) (high energy, partial bonds/charges) What is the hybridization of the carbon in the transition state? sp 4?! Note: the presence of a neighboring (conjugated) p orbital would be good for the S N 2 mechanism because TS would be stabilized (see Wade section 15-10) e.g., allylic LG (next to a pi bond)

4 Stereochemistry of the S N 2 Mechanism backside attack inversion of stereochemistry 6-4 Nu C 2 typical line drawing point of view: Nu LG is a wedge - like a flipped umbrella - can only be observed at a chiral center - S N 2 usually changes configuration (R to S or S to R), because usually the LG and the Nu: are both #1 priority group S N 2 Summary - one-step mechanism - inversion of stereochemistry Rate (by RX type) methyl > 1 > 2 >> 3 - requires: 1) unhindered LG (on tetrahedral sp 3 carbon) 2) good Nu: (negative charge or N 3 ) Predict the Major Product(s) (S N 2) Include stereochemistry, where appropriate. Write N.R. if no reaction is expected. I Na Br NaCN Na N 3 Br

5 II. B) Example: S N 1 - Substitution Nucleophilic Unimolecular (Wade 6-13, 6-14) 6-5 C C C C Could this be an S N 2 mechanism? Still a substitution, but a different mechanism (stepwise). S N 1 Mechanism: two key steps (but usually three total steps) Step 1 Loss of the leaving group Step 2 Addition of nucleophile S N 1 Kinetics Rate = k [t-bu] - rate-determining step involves E + only (unimolecular reaction) - rate is independent of [Nu:] - a more stable carbocation will be formed faster Rate of S N 1 (by type of RX): S N 1 Energy vs. Progress of Reaction Diagram Structure of first Transition State, TS-1 E Structure of TS-2? PR

6 Stereochemistry of the S N 1 Mechanism 6-6 carbocation intermediate racemization S N 1 results in racemization (loss of stereochemistry) due to the achiral carbocation intermediate. (S N 1) NaI (R) acetone (solvent) S N 1 Summary - stepwise mechanism via carbocation Rate (by RX type) benzyl/allyl/3 > 2 >> 1, methyl - more stable carbocation = - racemization occurs - requires: 1) stable carbocation (not 1 or methyl) 2) weak Nu: (usually the solvent, 2 or R, is the nucleophile = "solvolysis") Solvolysis: S N 1 Mechanism is three steps (6-13, 6-14) Example: - Nu: is 2 or R - final deprotonation step required Br Br 6-7

7 Predict the Major Product(s) (S N 2 or S N 1 mechanism? See Wade 6-16) Include stereochemistry, where appropriate. Write N.R. if no reaction is expected. 6-7 K I C Na Br NaI Which would be the faster reaction (A or B)? Explain. (Consider first: S N 2 or S N 1 mechanism?) A B 2 2 Br Br II. C) Leaving Groups (Wade 6-11, 11-5) - weak bases make good leaving groups - more stable = less reactive, weaker base - typical leaving group? halide (X - ) (all have strong conj. acids:, Br, I) Leaving groups F < Br < I Is the Forward or Reverse reaction favored? Best substitution reaction has best LG leaving (gives more stable products so Δ < 0 and ΔG < 0) Na Na

8 ydroxide, -, is a poor leaving group BUT we can make it better. There are two methods. 1. Add a strong acid (acid protonates the alcohol to make a great LG, 2 ) 6-8 R / Br / I R / RBr / RI 2 mechanism: Na 2. Make a tosylate LG (see Wade 11-5) Ts base S tosyl chloride, Ts Ts tosylate base (- ) Nu: Nu Ts S Nu: S Ts (tosylate LG) why is this more stable than -? Synthesis/"Transform" Problem - Provide the reagents needed to transform the given starting material into the desired product. More than one step may be required. I II. D) Nucleophilicity (Nucleophile strength) (Wade 6-10)

9 II. D) Nucleophilicity (Nucleophile strength) (Wade 6-10) 1. More electron-rich, better Nu: Periodic Trends: across row: decreasing nucleophilicity N 3 2 down a family: generally increasing nucleophilicity (BUT this trend depends on solvent!) I Good Nucleophiles (Nu:)!!!!!R!! S RS!! CN!N 3!!I!Br!!!! N 3!N 2 R R 3 P!! Weak Nucleophiles (Nu:)!!! 2 R Summary of Substitution Reactions Alkyl Group S N 1 S N 2 3 (tertiary) common rare (N/R) 2 (secondary) sometimes sometimes 1 (primary) rare (N/R) common (methyl) never (N/R) common allyl/benzyl common common (if not 3 )

10 II. E) S N 2 vs. S N 1 (Wade 6-16) 6-10 S N 2 requires strong Nu: and minimal steric hindrance S N 1 requires a stable carbocation and typically involves a weak Nu: See page 6-7 for examples, and S N 2/S N 1 Predict the Product homework for practice problems. After attempting the homework, let's look more closely at the following problems: C 2 C 2 C 2 C Na III. A) Competing Reactions: Carbocation Rearrangements (Wade 6-15) Ts 2 C C C C 2 C C C C C C 2 Alkyl groups can also shift Et

11 IV. Solvent Effects (Wade 6-10B, 6-13C) Both S N 1 and S N 2 reactions need PLAR solvents to stabilize charges in the mechanism Protic - has an group - extremely polar - strongly stabilizes charges Aprotic - has no group Solvent Effects on Reaction Rates if you INCREASE solvent polarity, then S N 1 is and S N 2 is e.g. using a protic solvent instead of an aprotic solvent e.g. going from an 80:20, Et: 2 solvent to 50:50 Why is a more polar solvent GD for an S N 1 mechanism? (speeds it up) 2 - carbocation will be better stabilized by more polar solvent - C+ intermediate and transition state are more stable/lower E polar aprotic - E a (lower height of hill), rate of reaction E - S N 1 is FASTER in a more polar solvent PR Why is a more polar solvent BAD for an S N 2 mechanism? (slows it down) Br Br - nucleophile will be better stabilized by more polar solvent - Nu: is more stable, less reactive polar aprotic - E a (increased height of hill), rate of reaction E - S N 2 is SLWER in a more polar solvent PR

12 CM We Studied Three Types of Reactions 1. Acid-Base Reaction (proton transfer) (Chapter 1) 6-12 B: A B A: base acid * equilibrium shifts to more stable, weaker acid/base pair 2. Free-Radical alogenation Reaction (Chapter 4) R alkane * for bromination, major product comes from the best (most stable) radical 3. Substitution Reactions (Chapter 6) R LG Br 2 hv R Nu: Nu R LG * S N 2 and S N 1 mechanisms * equilibrium shifts to loss of better (more stable) leaving group, LG Br alkyl halide For each type of reaction, be prepared to: - Predict the major product(s) - Provide detailed reaction mechanisms (curved arrows, etc.) - E vs. PR diagrams, drawing transition states, etc. - Explain stuff (e.g., regiochemistry, stereochemistry, reaction rates, equilibrium direction, etc.) III. B) Competing Reactions: Elimination Rxns (Wade ) (9th Ed ) E1 Mechanism - Elimination Unimolecular involves carbocation (like S N 1) (or 2 /hv to make R-) These reactions (and all of Chapters 1-6) will be on the cumulative final exam! E2 Mechanism - Elimination Bimolecular one-step mechanism (like S N 2) involving a strong base Na CM competition between all FUR: Substitution (S N 1/S N 2) and Elimination (E1/E2)!

Chapter 7 Substitution Reactions 7.1 Introduction to Substitution Reactions Substitution Reactions: two reactants exchange parts to give new products

Chapter 7 Substitution Reactions 7.1 Introduction to Substitution Reactions Substitution Reactions: two reactants exchange parts to give new products hapter 7 Substitution eactions 7.1 Introduction to Substitution eactions Substitution eactions: two reactants exchange parts to give new products A-B + -D A-D + B- 3 2 + Br 3 2 Br + Elimination eaction:

More information

CHAPTER 7. Further Reactions of Haloalkanes: Unimolecular Substitution and Pathways of Elimination

CHAPTER 7. Further Reactions of Haloalkanes: Unimolecular Substitution and Pathways of Elimination CHAPTER 7 Further Reactions of Haloalkanes: Unimolecular Substitution and Pathways of Elimination 7-1 Solvolysis of Tertiary and Secondary Haloalkanes The rate of S N 2 reactions decrease dramatically

More information

Glendale Community College Chemistry 105 Exam. 3 Lecture Notes Chapters 6 & 7

Glendale Community College Chemistry 105 Exam. 3 Lecture Notes Chapters 6 & 7 Sevada Chamras, Ph.D. Glendale Community College Chemistry 105 Exam. 3 Lecture Notes Chapters 6 & 7 Description: Examples: 3 Major Types of Organic Halides: 1. Alkyl Halides: Chapter 6 (Part 1/2) : Alkyl

More information

C h a p t e r S e v e n : Substitution Reactions S N 2 O H H H O H H. Br -

C h a p t e r S e v e n : Substitution Reactions S N 2 O H H H O H H. Br - C h a p t e r S e v e n : Substitution Reactions Br Br S N 2 CM 321: Summary of Important Concepts YConcepts for Chapter 7: Substitution Reactions I. Nomenclature of alkyl halides, R X A. Common name:

More information

C h a p t e r S e v e n : Haloalkanes: Nucleophilc Substitution and Elimination Reactions S N 2

C h a p t e r S e v e n : Haloalkanes: Nucleophilc Substitution and Elimination Reactions S N 2 C h a p t e r S e v e n : Haloalkanes: Nucleophilc Substitution and Elimination Reactions S N 2 CHM 321: Summary of Important Concepts Concepts for Chapter 7: Substitution Reactions I. Nomenclature of

More information

Substitution and Elimination reactions

Substitution and Elimination reactions PART 3 Substitution and Elimination reactions Chapter 8. Substitution reactions of RX 9. Elimination reactions of RX 10. Substit n/elimin n of other comp ds 11. Organometallic comp ds 12. Radical reactions

More information

BSc. II 3 rd Semester. Submitted By Dr. Sangita Nohria Associate Professor PGGCG-11 Chandigarh 1

BSc. II 3 rd Semester. Submitted By Dr. Sangita Nohria Associate Professor PGGCG-11 Chandigarh 1 BSc. II 3 rd Semester Submitted By Dr. Sangita Nohria Associate Professor PGGCG-11 Chandigarh 1 Introduction to Alkyl Halides Alkyl halides are organic molecules containing a halogen atom bonded to an

More information

Chapter 5. Nucleophilic aliphatic substitution mechanism. by G.DEEPA

Chapter 5. Nucleophilic aliphatic substitution mechanism. by G.DEEPA Chapter 5 Nucleophilic aliphatic substitution mechanism by G.DEEPA 1 Introduction The polarity of a carbon halogen bond leads to the carbon having a partial positive charge In alkyl halides this polarity

More information

Nucleophilic Substitution and Elimination

Nucleophilic Substitution and Elimination Nucleophilic Substitution and Elimination Alkyl halides react with a nucleophile in one of two ways. Either they eliminate an X to form an alkene, or they undergo a substitution with the nucleophile, Nu,

More information

Chapter 8: Nucleophilic Substitution 8.1: Functional Group Transformation By Nucleophilic Substitution

Chapter 8: Nucleophilic Substitution 8.1: Functional Group Transformation By Nucleophilic Substitution hapter 8: Nucleophilic Substitution 8.1: Functional Group Transformation By Nucleophilic Substitution Nu: = l,, I Nu - Nucleophiles are Lewis bases (electron-pair donor) Nucleophiles are often negatively

More information

Preparation of Alkyl Halides, R-X. Reaction of alkanes with Cl 2 & Br 2 (F 2 is too reactive, I 2 is unreactive): R + X X 2.

Preparation of Alkyl Halides, R-X. Reaction of alkanes with Cl 2 & Br 2 (F 2 is too reactive, I 2 is unreactive): R + X X 2. Preparation of Alkyl alides, R-X Reaction of alkanes with Cl 2 & Br 2 (F 2 is too reactive, I 2 is unreactive): UV R + X 2 R X or heat + X This mechanism involves a free radical chain reaction. A chain

More information

7. Haloalkanes (text )

7. Haloalkanes (text ) 2009, Department of hemistry, The University of Western Ontario 7.1 7. aloalkanes (text 7.1 7.10) A. Structure and Nomenclature Like hydrogen, the halogens have a valence of one. Thus, a halogen atom can

More information

8.8 Unimolecular Nucleophilic Substitution S N 1

8.8 Unimolecular Nucleophilic Substitution S N 1 8.8 Unimolecular Nucleophilic Substitution S N 1 A question. Tertiary alkyl halides are very unreactive in substitutions that proceed by the S N 2 mechanism. Do they undergo nucleophilic substitution at

More information

Chapter 6 Ionic Reactions-Nucleophilic Substitution and Elimination Reactions of Alkyl Halides"

Chapter 6 Ionic Reactions-Nucleophilic Substitution and Elimination Reactions of Alkyl Halides Chapter 6 Ionic Reactions-Nucleophilic Substitution and Elimination Reactions of Alkyl Halides" t Introduction" The polarity of a carbon-halogen bond leads to the carbon having a partial positive charge"

More information

REACTIONS OF HALOALKANES - SUBSTITUTION AND ELIMINATION

REACTIONS OF HALOALKANES - SUBSTITUTION AND ELIMINATION REACTIONS OF HALOALKANES - SUBSTITUTION AND ELIMINATION Haloalkanes (also known as halogenoalkanes and alkyl halides) are organic compounds where one of the hydrogens of an alkane or cycloalkane has been

More information

Chapter 8. Substitution reactions of Alkyl Halides

Chapter 8. Substitution reactions of Alkyl Halides Chapter 8. Substitution reactions of Alkyl Halides There are two types of possible reaction in organic compounds in which sp 3 carbon is bonded to an electronegative atom or group (ex, halides) 1. Substitution

More information

Classes of Halides. Chapter 6 Alkyl Halides: Nucleophilic Substitution and Elimination. Polarity and Reactivity. Classes of Alkyl Halides

Classes of Halides. Chapter 6 Alkyl Halides: Nucleophilic Substitution and Elimination. Polarity and Reactivity. Classes of Alkyl Halides rganic hemistry, 5 th Edition L. G. Wade, Jr. hapter 6 Alkyl alides: Nucleophilic Substitution and Elimination lasses of alides Alkyl: alogen, X, is directly bonded to sp 3 carbon. Vinyl: X is bonded to

More information

Basic Organic Chemistry Course code : CHEM (Pre-requisites : CHEM 11122)

Basic Organic Chemistry Course code : CHEM (Pre-requisites : CHEM 11122) Basic Organic Chemistry Course code : CHEM 12162 (Pre-requisites : CHEM 11122) Chapter 01 Mechanistic Aspects of S N2,S N1, E 2 & E 1 Reactions Dr. Dinesh R. Pandithavidana Office: B1 222/3 Phone: (+94)777-745-720

More information

Reactions of Alkyl Halides with Nucleophiles and Bases a substitution reaction

Reactions of Alkyl Halides with Nucleophiles and Bases a substitution reaction Reactions of Alkyl Halides with Nucleophiles and Bases a substitution reaction Nucleophilic substitution and base induced elimination are among most widely occurring and versatile reaction types in organic

More information

Chapter 11: Nucleophilic Substitution and Elimination Walden Inversion

Chapter 11: Nucleophilic Substitution and Elimination Walden Inversion hapter 11: Nucleophilic Substitution and Elimination Walden Inversion (S)-(-) Malic acid [a] D = -2.3 Ag 2, 2 Pl 5 l Ag 2, 2 ()-2-hlorosuccinic acid l (-)-2-hlorosuccinic acid Pl 5 ()-() Malic acid [a]

More information

Chapter 11, Part 1: Polar substitution reactions involving alkyl halides

Chapter 11, Part 1: Polar substitution reactions involving alkyl halides hapter 11, Part 1: Polar substitution reactions involving alkyl halides Overview: The nature of alkyl halides and other groups with electrophilic sp 3 hybridized leads them to react with nucleophiles and

More information

Organic Reactions Susbstitution S N. Dr. Sapna Gupta

Organic Reactions Susbstitution S N. Dr. Sapna Gupta Organic Reactions Susbstitution S N 2 Dr. Sapna Gupta Kinetics of Nucleophilic Reaction Rate law is order of reaction 0 order is when rate of reaction is unaffected by change in concentration of the reactants

More information

Essential Organic Chemistry. Chapter 9

Essential Organic Chemistry. Chapter 9 Essential Organic Chemistry Paula Yurkanis Bruice Chapter 9 Substitution and Elimination Reactions of Alkyl Halides 9.1 How Alkyl Halides React Substitution Reactions One group takes the place of another.

More information

Walden discovered a series of reactions that could interconvert (-)-malic acid and (+)-malic acid.

Walden discovered a series of reactions that could interconvert (-)-malic acid and (+)-malic acid. Chapter 11: Reactions of alkyl halides: nucleophilic substitutions and eliminations Alkyl halides are polarized in the C-X bond, making carbon δ+ (electrophilic). A nucleophilecan attack this carbon, displacing

More information

10. Organohalides. Based on McMurry s Organic Chemistry, 7 th edition

10. Organohalides. Based on McMurry s Organic Chemistry, 7 th edition 10. Organohalides Based on McMurry s Organic Chemistry, 7 th edition What Is an Alkyl Halide An organic compound containing at least one carbonhalogen bond (C-X) X (F, Cl, Br, I) replaces H Can contain

More information

Elimination reactions

Elimination reactions Chapter 9 Elimination reactions E2 and E1 reactions Competition between S N and E Elimination reactions Ch 9 #2 elimination and/or substitution 2 mechanisms ~ E2 and E1 E2: bimolecular elimination rxn

More information

+ + CH 11: Substitution and Elimination Substitution reactions

+ + CH 11: Substitution and Elimination Substitution reactions C 11: Substitution and Elimination Substitution reactions Things to sort out: Nucleophile Electrophile -- > substrate Leaving Group S N 2 S N 1 E 1 E 2 Analysis Scheme Kinetics Reaction profile Substrates

More information

11. Nucleophilic Substitution Reactions

11. Nucleophilic Substitution Reactions 11. Nucleophilic Substitution Reactions A. Introduction It would be beneficial if you review the chapter on substitution reactions in your textbook prior to lab. This is Ch. 11 in the 9 th edition McMurry

More information

Chapter 9. Nucleophilic Substitution and ß-Elimination

Chapter 9. Nucleophilic Substitution and ß-Elimination Chapter 9 Nucleophilic Substitution and ß-Elimination Nucleophilic Substitution Nucleophile: From the Greek meaning nucleus loving. A molecule or ion that donates a pair of electrons to another atom or

More information

Dr. Anand Gupta Mr Mahesh Kapil

Dr. Anand Gupta Mr Mahesh Kapil Dr. Anand Gupta Mr Mahesh Kapil 09356511518 09888711209 anandu71@yahoo.com mkapil_foru@yahoo.com Preparation of Haloalkanes From Alkanes Alkenes Alcohols Carboxylic Acids (Hundsdicker Reaction) Halide

More information

Some Arrow-Pushing Guidelines (Section 1.14) 1. Arrows follow electron movement.

Some Arrow-Pushing Guidelines (Section 1.14) 1. Arrows follow electron movement. Chem 350 Jasperse Ch. 1 Notes 1 Note: The headers and associated chapters don t actually jive with the textbook we are using this summer. But otherwise this highlights a lot of the chemistry from Organic

More information

Hydrogen iodide is a strong acid and will drive the reverse reaction, meaning the forward reaction will not occur.

Hydrogen iodide is a strong acid and will drive the reverse reaction, meaning the forward reaction will not occur. EM 261 Oct 18, 2018 Photosynthesis and Related Reactions O 2 2 O 6 12 O 6 2 O N 3, S, Fe, u, o, other Natural Products D-Glucose R O R OR Ionic substitution S N 1 & R X X 2 hv Petroleum/ Alkanes R N 2

More information

Elimination Reactions Heating an alkyl halide with a strong base causes elimination of a. molecule of HX

Elimination Reactions Heating an alkyl halide with a strong base causes elimination of a. molecule of HX Elimination eactions eating an alkyl halide with a strong base causes elimination of a molecule of X 1. Potassium hydroxide dissolved in ethanol and the sodium salts of alcohols (such as sodium ethoxide)

More information

Nuggets of Knowledge for Chapter 17 Dienes and Aromaticity Chem 2320

Nuggets of Knowledge for Chapter 17 Dienes and Aromaticity Chem 2320 Nuggets of Knowledge for Chapter 17 Dienes and Aromaticity Chem 2320 I. Isolated, cumulated, and conjugated dienes A diene is any compound with two or C=C's is a diene. Compounds containing more than two

More information

Reaction mechanism 1/17/19. HCl. HCl. 3 radical can form here. Br 2. hint!

Reaction mechanism 1/17/19. HCl. HCl. 3 radical can form here. Br 2. hint! If the reagents or reaction conditions favor radicals, then it is likely to be a radical reaction. Look for hints like peroxide, AIBN, NBS, hn (UV light). 3 radical can form here Reaction mechanism How

More information

CHE 275 NUCLEOPHILIC SUBSTITUTUION CHAP 8 ASSIGN. 1. Which best depicts the partial charges on methyl bromide and sodium methoxide?

CHE 275 NUCLEOPHILIC SUBSTITUTUION CHAP 8 ASSIGN. 1. Which best depicts the partial charges on methyl bromide and sodium methoxide? CHE 275 NUCLEPHILIC SUBSTITUTUIN CHAP 8 ASSIGN 1. Which best depicts the partial charges on methyl bromide and sodium methoxide? 2. Which of the following would be the best (most reactive) nucleophile

More information

Lecture 21 Organic Chemistry 1

Lecture 21 Organic Chemistry 1 CEM 232 Organic Chemistry I at Chicago Lecture 21 Organic Chemistry 1 Professor Duncan Wardrop March 30, 2010 1 Self Test Question Ethanolysis of alkyl halide 1 gives ether 2 as one product; however, several

More information

Homework - Review of Chem 2310

Homework - Review of Chem 2310 omework - Review of Chem 2310 Chapter 1 - Atoms and Molecules Name 1. What is organic chemistry? 2. Why is there an entire one year course devoted to the study of organic compounds? 3. Give 4 examples

More information

Organic Halogen Compounds

Organic Halogen Compounds 8 Organic alogen ompounds APTER SUMMARY 8.1 Introduction Although organic halogen compounds are rarely found in nature, they do have a variety of commercial applications including use as insecticides,

More information

PAPER No. : 5; Organic Chemistry-II MODULE No. : 13; Mixed S N 1 and S N 2 Reactions

PAPER No. : 5; Organic Chemistry-II MODULE No. : 13; Mixed S N 1 and S N 2 Reactions Subject Chemistry Paper No and Title Module No and Title Module Tag 5; Organic Chemistry-II 13; Mixed S N 1 and S N 2 Reactions CHE_P5_M13 TABLE OF CONTENTS 1. Learning Outcomes 2. Introduction 3. Nature

More information

Chapter 8 I. Nucleophilic Substitution (in( II. Competion with Elimination. Nucleophilic Substitution

Chapter 8 I. Nucleophilic Substitution (in( II. Competion with Elimination. Nucleophilic Substitution hapter 8 I. Nucleophilic Substitution (in( depth) II. ompetion with Elimination Nucleophilic Substitution Substrate is a sp3 hybridized carbon atom (cannot be an a vinylic halide or an aryl halide except

More information

CONCERTED sp 2 H. HO Et

CONCERTED sp 2 H. HO Et Alkyl alides Substitution and Elimination 1 Substitutions (Quick Review) 1.1 SN2 Reactions LB nucleophile "backside attack!" NERTED reaction This is fundamentally just a Lewis acid/base reaction, the Lewis

More information

OChem 1 Mechanism Flashcards. Dr. Peter Norris, 2018

OChem 1 Mechanism Flashcards. Dr. Peter Norris, 2018 OChem 1 Mechanism Flashcards Dr. Peter Norris, 2018 Mechanism Basics Chemical change involves bonds forming and breaking; a mechanism describes those changes using curved arrows to describe the electrons

More information

OChem 1 Mechanism Flashcards. Dr. Peter Norris, 2015

OChem 1 Mechanism Flashcards. Dr. Peter Norris, 2015 OChem 1 Mechanism Flashcards Dr. Peter Norris, 2015 Mechanism Basics Chemical change involves bonds forming and breaking; a mechanism describes those changes using curved arrows to describe the electrons

More information

Homework problems Chapters 6 and Give the curved-arrow formalism for the following reaction: CH 3 OH + H 2 C CH +

Homework problems Chapters 6 and Give the curved-arrow formalism for the following reaction: CH 3 OH + H 2 C CH + omework problems hapters 6 and 7 1. Give the curved-arrow formalism for the following reaction: : 3 - : 2 : 3 2-3 3 2. In each of the following sets, arrange the compounds in order of decreasing pka and

More information

Substitution Reactions

Substitution Reactions Substitution Reactions Substitution reactions are reactions in which a nucleophile displaces an atom or group of atoms (the leaving group) from a tetrahedral carbon atom. onsider the following general

More information

1-What is substitution reaction? 2-What are can Nucleophilic Substitution Reaction? 3- SN1 reaction. 4-SN2 reaction 5- mechanisms of SN1&SN2

1-What is substitution reaction? 2-What are can Nucleophilic Substitution Reaction? 3- SN1 reaction. 4-SN2 reaction 5- mechanisms of SN1&SN2 1-What is substitution reaction? 2-What are can Nucleophilic Substitution eaction? 3- SN1 reaction. 4-SN2 reaction 5- mechanisms of SN1&SN2 1- SUBSTITUTION EACTIONS 1-Substitution eaction In this type

More information

Week 4. Even harder stuff!

Week 4. Even harder stuff! Week 4 Even harder stuff! Focus: SN1 and SN2 Two organic reactions Learn about two basic pathways for how these reactions happen Focus on stereochemistry Focus: SN1 and SN2 You need a couple of things

More information

REACTION AND SYNTHESIS REVIEW

REACTION AND SYNTHESIS REVIEW REACTION AND SYNTHESIS REVIEW A STUDENT SHOULD BE ABLE TO PREDICT PRODUCTS, IDENTIFY REACTANTS, GIVE REACTION CONDITIONS, PROPOSE SYNTHESES, AND PROPOSE MECHANISMS (AS LISTED BELOW). REVIEW THE MECHANISM

More information

S N 1 Displacement Reactions

S N 1 Displacement Reactions S N 1 Displacement Reactions Tertiary alkyl halides cannot undergo S N 2 reactions because of the severe steric hindrance blocking a backside approach of the nucleophile. They can, however, react via an

More information

Physical Properties: Structure:

Physical Properties: Structure: Nomenclature: Functional group suffix = -ol Functional group prefix = hydroxy- Primary, secondary or tertiary? Alcohols are described as primary (1 o ), secondary (2 o ) or tertiary (3 o ) depending on

More information

Learning Guide for Chapter 17 - Dienes

Learning Guide for Chapter 17 - Dienes Learning Guide for Chapter 17 - Dienes I. Isolated, conjugated, and cumulated dienes II. Reactions involving allylic cations or radicals III. Diels-Alder Reactions IV. Aromaticity I. Isolated, Conjugated,

More information

3-chloro-1-propene 1-chloropropane 2-chloropropene

3-chloro-1-propene 1-chloropropane 2-chloropropene ANSWERS #1. (from 50 minute exam #3, Fall 2000) 5. (6 points) For each group of 3 compounds, identify the compound that expresses the indicated property the MOST and the compound that expresses it the

More information

How alkyl halides react

How alkyl halides react Chapter 10 1 How alkyl halides react δ+ δ- RCH 2 -X X= halogen X = higher EN C = lower EN This polar carbon-halogen bond causes alkyl halide to undergo S N and elimination reaction. 2 The mechanism of

More information

The Electrophile. S N 2 and E2 least stable most stable least hindered most hindered. S N 1 and E1. > x > >

The Electrophile. S N 2 and E2 least stable most stable least hindered most hindered. S N 1 and E1. > x > > The Electrophile 1 Recall that electrophile means electron- loving. When considering substitution and elimination reactions we must consider the carbon attached to the leaving group. Is it a primary, secondary,

More information

PAPER No. 05: TITLE: ORGANIC CHEMISTRY-II MODULE No. 12: TITLE: S N 1 Reactions

PAPER No. 05: TITLE: ORGANIC CHEMISTRY-II MODULE No. 12: TITLE: S N 1 Reactions Subject hemistry Paper o and Title Module o and Title Module Tag 05, ORGAI EMISTRY-II 12, S 1 Reactions E_P5_M12 EMISTRY PAPER o. 05: TITLE: ORGAI EMISTRY-II TABLE OF OTETS 1. Learning Outcomes 2. Introduction

More information

Acid-Base -Bronsted-Lowry model: -Lewis model: -The more equilibrium lies to the right = More [H 3 O + ] = Higher K a = Lower pk a = Stronger acid

Acid-Base -Bronsted-Lowry model: -Lewis model: -The more equilibrium lies to the right = More [H 3 O + ] = Higher K a = Lower pk a = Stronger acid Revision Hybridisation -The valence electrons of a Carbon atom sit in 1s 2 2s 2 2p 2 orbitals that are different in energy. It has 2 x 2s electrons + 2 x 2p electrons are available to form 4 covalent bonds.

More information

c. Cl H Page 1 of 7 major P (E > Z and more substituted over less substituted alkene) LG must be axial are the same Cl -

c. Cl H Page 1 of 7 major P (E > Z and more substituted over less substituted alkene) LG must be axial are the same Cl - CEM 109A 1. Predict the products of the following reactions (a-c E2, d-f E1 KEY focuses only on elimination products, in most cases there will also be substitution products.) a. - LG must be axial - are

More information

use iso-, tert-, sec- prefixes in your substituent names, where necessary

use iso-, tert-, sec- prefixes in your substituent names, where necessary Chapter 07.2: 1 1) Name. Include E/Z stereochemistry in name, if necessary. a) 3 C b) c) d) e) f) use iso-, tert-, sec- prefixes in your substituent names, where necessary g) Do NT use iso-, tert-, sec-

More information

Reactions SN2 and SN1

Reactions SN2 and SN1 Reactions SN2 and SN1 Reactivity: Functional groups can be interconverted using a great variety of reagents. Millions of organic molecules have been synthesized via a series of functional-group interconversions.

More information

Chap. 8 Substitution Reactions

Chap. 8 Substitution Reactions Chap. 8 Substitution Reactions Y + R X R' Y + X Nucleophilic not necessarily the same as R Electrophilic S N 1 slow (C 3 ) 3 CCl (C + Cl - 3 ) 3 C + (C 3 ) 3 C + OC 2 C 3 C 3 C 2 O C 3 C 2 O d[( C ) 3CCl]

More information

11. Reactions of Alkyl Halides: Nucleophilic Substitutions and Eliminations

11. Reactions of Alkyl Halides: Nucleophilic Substitutions and Eliminations 11. Reactions of Alkyl Halides: Nucleophilic Substitutions and Eliminations Based on McMurry s Organic Chemistry, 6 th edition 2003 Ronald Kluger Department of Chemistry University of Toronto Alkyl Halides

More information

PAPER No. 5: REACTION MECHANISM MODULE No. 2: Types of Organic Reaction Mechanisms

PAPER No. 5: REACTION MECHANISM MODULE No. 2: Types of Organic Reaction Mechanisms Subject Chemistry Paper No and Title Module No and Title Module Tag Paper No. 5:Organic Chemistry-II Module No. 2: Overview of different types of Organic Reaction Mechanisms CHE_P5_M2 TABLE OF CONTENTS

More information

Chapter 8: Alkene Structure and Preparation via Elimination Reactions

Chapter 8: Alkene Structure and Preparation via Elimination Reactions Nature of the pi bond Chapter 8: Alkene Structure and Preparation via Elimination eactions [Sections: 8.1-8.13] C C 3 C C 3 bond length bond strength 2 C C 2 a C=C double bond is stronger than a C C single

More information

Classes of Alkenes. Alkenes and Alkynes. Saturated compounds (alkanes): Have the maximum number of hydrogen atoms attached to each carbon atom.

Classes of Alkenes. Alkenes and Alkynes. Saturated compounds (alkanes): Have the maximum number of hydrogen atoms attached to each carbon atom. Alkenes and Alkynes Saturated compounds (alkanes): ave the maximum number of hydrogen atoms attached to each carbon atom. Unsaturated compounds: ave fewer hydrogen atoms attached to the carbon chain than

More information

ORGANIC - EGE 5E CH. 7 - NUCLEOPHILIC SUBSTITUTION AND ELIMINATION REACTIONS

ORGANIC - EGE 5E CH. 7 - NUCLEOPHILIC SUBSTITUTION AND ELIMINATION REACTIONS !! www.clutchprep.com CONCEPT: INTRODUCTION TO SUBSTITUTION Previously, we discussed the various ways that acids could react with bases: Recall that in these mechanisms, electrons always travel from density

More information

1.13 Acid-Base Reactions: Lone-Pair Donors & Acceptors

1.13 Acid-Base Reactions: Lone-Pair Donors & Acceptors 1.13 Acid-Base Reactions: Lone-Pair Donors & Acceptors I, Cl, N 3, 3 P 4 pka 10 to 5 Super strong acids 3 + pka 1.7 RC 2 pka ~ 5 acids Ph pka ~ 10 get 2, R pka ~ 16 weaker RCC (alkynes) pka ~ 26 RN 2 pka

More information

Lecture 18 Organic Chemistry 1

Lecture 18 Organic Chemistry 1 CEM 232 rganic Chemistry I at Chicago Lecture 18 rganic Chemistry 1 Professor Duncan Wardrop March 9, 2010 1 Nucleophilicity nucleophilicity: measures the strength of the nucleophile ; more nucleophilic

More information

Chapter 6: Organic Halogen Compounds; Substitution and Elimination Reactions

Chapter 6: Organic Halogen Compounds; Substitution and Elimination Reactions Chapter 6: Organic Halogen Compounds; Substitution and Elimination Reactions Halogen compounds are important for several reasons. Simple alkyl and aryl halides, especially chlorides and bromides, are versatile

More information

Learning Guide for Chapter 10 - Alkyl Halides II

Learning Guide for Chapter 10 - Alkyl Halides II Learning Guide for Chapter 10 - Alkyl Halides II I. Elimination Reactions of Alkyl Halides Introduction Mechanisms Beta hydrogens, constitutional isomers, and stereoisomers E2 vs E1 Strong and Weak Bases

More information

Organic Reactions Susbstitution S N. Dr. Sapna Gupta

Organic Reactions Susbstitution S N. Dr. Sapna Gupta Organic Reactions Susbstitution S N 2 Dr. Sapna Gupta Kinetics of Nucleophilic Reaction Rate law is order of reaction 0 order is when rate of reaction is unaffected by change in concentration of the reactants

More information

Chapter 7 Substitution Reactions

Chapter 7 Substitution Reactions Chapter 7 Substitution Reactions Review of Concepts Fill in the blanks below. To verify that your answers are correct, look in your textbook at the end of Chapter 7. Each of the sentences below appears

More information

Chapter 8: Alkene Structure and Preparation via Elimination Reactions

Chapter 8: Alkene Structure and Preparation via Elimination Reactions 1. Nature of the pi bond Chapter 8: Alkene Structure and Preparation via Elimination eactions [Sections: 8.1-8.13] C C bond length bond strength 3 C C 3 3 C C 3 3 C C 3 3 C 2 C C 2 3 C a C=C double bond

More information

(CH 3 ) 3 COH. CH 3 ONa

(CH 3 ) 3 COH. CH 3 ONa 1. Rank the following compounds in the trend requested. (15 points each) a. Rank by nucleophilicity. The strongest nucleophile is 1, while the weakest nucleophile is 5. C 3 PNa (C 3 ) 3 C C 3 Na C 3 C

More information

Learning Guide for Chapter 15 - Alcohols (II)

Learning Guide for Chapter 15 - Alcohols (II) Learning Guide for Chapter 15 - Alcohols (II) I. Introduction to alcohol reactivity II. Reactions of alcohols with acids III. Reactions of alcohols with electrophiles alogenated phosphorus and sulfur compounds

More information

2311A and B Practice Problems to help Prepare for Final from Previous Marder Exams.

2311A and B Practice Problems to help Prepare for Final from Previous Marder Exams. 2311A and B Practice Problems to help Prepare for Final from Previous Marder Exams. Disclaimer.: Use only to help learn what you need to know and don t expect the final to be in the same form. 1 1. Short

More information

CHAPTER 8 HW SOLUTIONS: ELIMINATIONS REACTIONS

CHAPTER 8 HW SOLUTIONS: ELIMINATIONS REACTIONS APTER 8 W SLUTNS: ELMNATNS REATNS S-TRANS SMERSM 1. Use a discussion and drawing of orbitals to help explain why it is generally easy to rotate around single bonds at room temperature, while it is difficult

More information

Alcohols: Contain a hydroxy group( OH) bonded to an sp 2 or sp 3 hybridized

Alcohols: Contain a hydroxy group( OH) bonded to an sp 2 or sp 3 hybridized Lecture Notes hem 51B S. King hapter 9 Alcohols, Ethers, and Epoxides I. Introduction Alcohols, ether, and epoxides are 3 functional groups that contain σ-bonds. Alcohols: ontain a hydroxy group( ) bonded

More information

ζ ε δ γ β α α β γ δ ε ζ

ζ ε δ γ β α α β γ δ ε ζ hem 263 Nov 17, 2016 eactions at the α-arbon The alpha carbon is the carbon adjacent to the carbonyl carbon. Beta is the next one, followed by gamma, delta, epsilon, and so on. 2 ε 2 δ 2 γ 2 2 β α The

More information

ORGANIC - CLUTCH CH. 8 - ELIMINATION REACTIONS.

ORGANIC - CLUTCH CH. 8 - ELIMINATION REACTIONS. !! www.clutchprep.com CONCEPT: THE E2 MECHANISM A strong nucleophile reacts with an inaccessible leaving group to produce beta-elimination in one-step. E2 Properties (Circle One) Nucleophile = Strong /

More information

Chapter 10 Radical Reactions"

Chapter 10 Radical Reactions Chapter 10 Radical Reactions Radicals are intermediates with an unpaired electron H. Cl. Hydrogen radical t Often called free radicals What are radicals? Chlorine radical t Formed by homolytic bond cleavage

More information

Lecture Topics: I. Electrophilic Aromatic Substitution (EAS)

Lecture Topics: I. Electrophilic Aromatic Substitution (EAS) Reactions of Aromatic Compounds Reading: Wade chapter 17, sections 17-1- 17-15 Study Problems: 17-44, 17-46, 17-47, 17-48, 17-51, 17-52, 17-53, 17-59, 17-61 Key Concepts and Skills: Predict and propose

More information

LECTURE #14 Thurs., Oct.20, Midterm exam: Tues.Oct.25 during class Ch.1, , 7.10, 2, Sections

LECTURE #14 Thurs., Oct.20, Midterm exam: Tues.Oct.25 during class Ch.1, , 7.10, 2, Sections CHEM 221 section 01 LECTURE #14 Thurs., Oct.20, 2005 Midterm exam: Tues.Oct.25 during class Ch.1, 7.2-7.5, 7.10, 2, 3.1-3.5 ASSIGNED READINGS: TODAY S CLASS: NEXT LECTURE: Sections 4.7-4.10 finish Ch.4,

More information

Chapter 9:Nucleophiles & Substitution Reactions

Chapter 9:Nucleophiles & Substitution Reactions 1. a. Place the following nucleophiles in order of strength (1= strongest; 3 = weakest). i. ii. b. Place the following in order of leaving group ability (1= best; 7 = worst). (A pka table may help you!)

More information

Lab 11 Guide: Nucleophilic Substitution (Nov 10 16)

Lab 11 Guide: Nucleophilic Substitution (Nov 10 16) Lab 11 Guide: Nucleophilic Substitution (Nov 10 16) Nucleophilic Substitution of Alkyl Halides, Exp. 17A, B, and C, pages 187-192 in Taber This week you will be doing examining real life S N 1 and S N

More information

Alkyl Halides. Alkyl halides are a class of compounds where a halogen atom or atoms are bound to an sp 3 orbital of an alkyl group.

Alkyl Halides. Alkyl halides are a class of compounds where a halogen atom or atoms are bound to an sp 3 orbital of an alkyl group. Alkyl Halides Alkyl halides are a class of compounds where a halogen atom or atoms are bound to an sp 3 orbital of an alkyl group. CHCl 3 (Chloroform: organic solvent) CF 2 Cl 2 (Freon-12: refrigerant

More information

1. The Substrate: CH3, 1 o, 2 o, 3 o, Allyl or Benzyl

1. The Substrate: CH3, 1 o, 2 o, 3 o, Allyl or Benzyl Putting it all together: Substitution and elimination reactions are almost always in competition with each other. In order to predict the products of a reaction, it is necessary to determine which mechanisms

More information

Chem 232. Problem Set 9. Question 1. D. J. Wardrop

Chem 232. Problem Set 9. Question 1. D. J. Wardrop Chem 232 D. J. Wardrop wardropd@uic.edu Problem Set 9 Question 1. a. Rank in order of increasing number of chirality centers (1 = fewest chirality centers; 5 = most chirality). 3 C C 3 b. Rank in order

More information

Chem 350 Jasperse Ch. 6 Summary of Reaction Types, Ch. 4-6, Test 2 1. Radical Halogenation (Ch. 4)

Chem 350 Jasperse Ch. 6 Summary of Reaction Types, Ch. 4-6, Test 2 1. Radical Halogenation (Ch. 4) Chem 350 Jasperse Ch. 6 Summary of Reaction Types, Ch. 4-6, Test 2 1. Radical alogenation (Ch. 4) 2, hv resonance stabilized>3º>2º>1º>alkenyl 1 Recognition: X 2, hv Predicting product: Identify which carbon

More information

Homework for Chapter 17 Chem 2320

Homework for Chapter 17 Chem 2320 Homework for Chapter 17 Chem 2320 I. Cumulated, isolated, and conjugated dienes Name 1. Draw structures which fit the following descriptions. Use correct geometry! a conjugated diene with the formula C

More information

Alkyl Halides and Nucleophilic Subs5tu5on Reac5ons. S N 2 and S N 1 Reac,ons

Alkyl Halides and Nucleophilic Subs5tu5on Reac5ons. S N 2 and S N 1 Reac,ons Alkyl Halides and Nucleophilic Subs5tu5on Reac5ons S N 2 and S N 1 Reac,ons 1 Alkyl Halides The electronega5ve halogen atom in alkyl halides creates a polar C X bond, making the carbon atom electron deficient.

More information

Chapter 7 Alkenes; Elimination Reactions

Chapter 7 Alkenes; Elimination Reactions hapter 7 Alkenes; Elimination Reactions Alkenes Alkenes contain a carbon-carbon double bond. They are named as derivatives of alkanes with the suffix -ane changed to -ene. The parent alkane is the longest

More information

Objective 11. Apply Reactivity Principles to Substitution and Elimination Reactions: compare size and strength of nucleophile to predict major product

Objective 11. Apply Reactivity Principles to Substitution and Elimination Reactions: compare size and strength of nucleophile to predict major product Objective 11 Apply Reactivity Principles to Substitution and Elimination Reactions: compare size and strength of nucleophile to predict major product Given Reactants ----> Predict Products How to figure

More information

17.3 REACTIONS INVOLVING ALLYLIC AND BENZYLIC ANIONS

17.3 REACTIONS INVOLVING ALLYLIC AND BENZYLIC ANIONS 798 HAPTER 17 ALLYLI AND BENZYLI REATIVITY Because the unpaired electron is shared by two different carbons, this radical can react in the final propagation step to give two different products. Reaction

More information

The C-X bond gets longerand weakergoing down the periodic table.

The C-X bond gets longerand weakergoing down the periodic table. Chapter 10: Organohalides Organic molecules containing halogen atoms (X) bonded to carbon are useful compounds in synthesis and on their own. 10.2 Structure of alkyl halides The C-X bond gets longerand

More information

UCF - ORGANIC CHEMISTRY 1 - PROF. DAOUDI UCF PROF. DAOUDI EXAM 3 REVIEW.

UCF - ORGANIC CHEMISTRY 1 - PROF. DAOUDI UCF PROF. DAOUDI EXAM 3 REVIEW. UCF PROF. DAOUDI EXAM 3 REVIEW www.clutchprep.com 1 PRACTICE: Identify the most stable and the least stable alkene PRACTICE: Create the full arrow pushing mechanism which shows all intermediates and all

More information

Chemistry 35 Exam 2 Answers - April 9, 2007

Chemistry 35 Exam 2 Answers - April 9, 2007 Chemistry 35 Exam 2 Answers - April 9, 2007 Problem 1. (14 points) Provide the products for the reactions shown below. If stereochemistry is important, be sure to indicate stereochemistry clearly. If no

More information

Chem 263 Nov 7, elimination reaction. There are many reagents that can be used for this reaction. Only three are given in this course:

Chem 263 Nov 7, elimination reaction. There are many reagents that can be used for this reaction. Only three are given in this course: hem 263 Nov 7, 2013 Preparation of Ketones and Aldehydes from Alcohols xidation of Alcohols [] must have at least 1 E elimination reaction [] = oxidation; removal of electrons [] = reduction; addition

More information

Chapter 19: Aromatic Substitution Reactions

Chapter 19: Aromatic Substitution Reactions Chem A225 Notes Page 52 Chapter 19: Aromatic Substitution Reactions Topic One: lectrophilic Aromatic Substitution I. Introduction to lectrophilic Aromatic Substitution (AS) A. eneral Reaction Pattern B.

More information

L substrate (Leaving group,l)

L substrate (Leaving group,l) Aliphatic Nucleophilic Substitution Nu + Nucleophile L substrate (Leaving group,l) conditions products Nucleophiles are chemical species that react with centers of positive ionic character. When the center

More information