Organic Reactions Susbstitution S N. Dr. Sapna Gupta
|
|
|
- Peregrine Harmon
- 5 years ago
- Views:
Transcription
1 Organic Reactions Susbstitution S N 2 Dr. Sapna Gupta
2 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 1 st order is when rate of reaction doubles when one of the reactants is doubled 2 nd order is when rate of reaction quadruples when two of the reactants are doubled Order of reaction explains the reaction mechanism Dr. Sapna Gupta/Substitution Reactions 2
3 Nucleophilic Substitution Reactions In this reaction a nucleophile is a species with an unshared electron pair which reacts with an electron deficient carbon A leaving group is substituted by a nucleophile Examples of nucleophilic substitution Dr. Sapna Gupta/Substitution Reactions 3
4 The S N 2 Reaction 2 nd order substitution reaction S=substitution N (subscript) = nucleophilic 2 = (bimolecular) both nucleophile and substrate in characteristic step Inversion of stereochemistry occurs Dr. Sapna Gupta/Substitution Reactions 4
5 An S N 2 Reaction The initial rate of the following reaction is measured The rate is directly proportional to the initial concentrations of both methyl chloride (substrate) and hydroxide (nucleophile) 3 The rate equation reflects this dependence S N 2 reaction: substitution, nucleophilic, 2nd order (bimolecular) Dr. Sapna Gupta/Substitution Reactions 5
6 A Mechanism for the S N 2 Reaction A transition state is the high energy state of the reaction It is an unstable entity with a very brief existence (10-12 s) In the transition state of this reaction bonds are partially formed and broken Both chloromethane and hydroxide are involved in the transition state and this explains why the reaction is second order Dr. Sapna Gupta/Substitution Reactions 6
7 S N 2 Energy Diagram One-step reaction. Transition state is highest in energy. Dr. Sapna Gupta/Substitution Reactions 7
8 Examples of Nucleophilic Substitution Negatively charged nucleophiles like HO and HS are used as salts with Li +, Na +, or K + counterions to balance the charge. Since the identity of the counterion is usually inconsequential, it is often omitted from the chemical equation. When a neutral nucleophile is used, the substitution product bears a positive charge. Dr. Sapna Gupta/Substitution Reactions 8
9 Uses for S N 2 Reactions Synthesis of other classes of compounds. Halogen exchange reaction. Dr. Sapna Gupta/Substitution Reactions 9
10 Factors Affecting S N 2 1. Nucleophile Strength 2. Size of the nucleophile 3. Substrate (steric effect) 4. Leaving group 5. Effect of solvent Dr. Sapna Gupta/Substitution Reactions 10
11 1) Nucleophilic Strength Stronger nucleophiles react faster. Strong bases are strong nucleophiles, but not all strong nucleophiles are basic*. Strength of Nu is based on: Charge: In a conjugate acid-base pair, the base (anion) is stronger: OH - > H 2 O, NH 2- > NH 3 Periodicity: Decreases left to right on the Periodic Table. More electronegative atoms less likely to form new bond: OH - > F -, NH 3 > H 2 O Size: Increases down Periodic Table, as size and polarizability increase: I - > Br - > Cl - * Bases are characterised by their ability to abstract a proton while nucleophiles reacts with electrophiles. Dr. Sapna Gupta/Substitution Reactions 11
12 Nucleophiles Some examples Dr. Sapna Gupta/Substitution Reactions 12
13 2) Size of Nucleophile Larger nucleophiles are not good for S N 2 because they will not be able to access the electrophilic carbon. E.g. EtO better than tbuo - even though tbuo - is a stronger base. Note: Alkoxides as Nucleophiles. CH 3 O - Na +, CH 3 CH 2 O - K + - alkoxides are synthesized as salts potassium or sodium. They are synthesized by dissolving solid sodium or potassium in the respective alcohol in a moisture and oxygen free environment. CH 3 OH + Na CH 3 O - Na + + H 2 Nomenclature: CH 3 O - Na +, sodium methoxide, CH 3 CH 2 O - K + potassium ethoxide, (CH 3 ) 3 CO - Na + sodium t-butoxide Dr. Sapna Gupta/Substitution Reactions 13
14 3) Substrate: Steric Hindrance - 1 Nucleophile approaches from the back side hence the electrophilic carbon should not be hindered. Best substrates for S N 2 are primary halides. 1 o > 2 o >3 o Dr. Sapna Gupta/Substitution Reactions 14
15 3) Substrate: Steric Hindrance - 2 The more alkyl groups connected to the reacting carbon, the slower the reaction Dr. Sapna Gupta/Substitution Reactions 15
16 4) Leaving Group Should be electron-withdrawing to provide an electrophilic carbon Stable once it has left (not a strong base) Usually halides are good LG. Weaker bases make best LG. NOTE: weaker base cannot displace stronger base in a S N 2 reaction Examples of leaving groups Dr. Sapna Gupta/Substitution Reactions 16
17 5) Solvents 3 kinds of solvents Solvent Polar protic polar aprotic non polar Examples H 2 O CH 3 OH, CH 3 CH 2 OH DMF (dimethyl formamide), DMSO (dimethyl sulfoxide) Shown below. Hexane Toluene Diethyl ether Dichloromethane Comments Will form H-bonds with Nu and therefore need more energy to form transition state Does not form H- bond with Nu but still helps to solvate ions hence the best kind for S N 2 Not good for S N 2 since they will not stabilize the ions formed. Dr. Sapna Gupta/Substitution Reactions 17
18 The Stereochemistry of S N 2 Reactions Backside attack of nucleophile results in an inversion of configuration In cyclic systems a cis compound can react and become trans product Dr. Sapna Gupta/Substitution Reactions 18
19 S N 1 Reaction Unimolecular nucleophilic substitution. Two step reaction with carbocation intermediate. Rate is first order in the alkyl halide, zero order in the nucleophile. Racemization occurs. Dr. Sapna Gupta/Substitution Reactions 19
20 The S N 1 Reaction Mechanism Dr. Sapna Gupta/Substitution Reactions 20
21 S N 1 Energy Diagram There are three transition states. Step1 crosses the highest energy barrier and is rate determining Dr. Sapna Gupta/Substitution Reactions 21
22 Stereochemistry of S N 1 Racemization: inversion and retention Dr. Sapna Gupta/Substitution Reactions 22
23 Factors Affecting Rates of S N 1 Reactions 1. Substrate: 3 > 2 > 1 >> CH 3 X 2. Leaving group: should be weak base(like S N 2) 3. Nucleophile: no effect since its not part of the transition state but in general weak Nu can also react. 4. Solvent: Polar protic solvent best, it solvates ions strongly with hydrogen bonding. Dr. Sapna Gupta/Substitution Reactions 23
24 1) Nature of Substrate Substrate: 3 > 2 > 1 >> CH 3 X a) Order follows stability of carbocations (opposite to S N 2) b) More stable ion requires less energy to form c) Resonance can also stabilize cation (e.g. allyl cation C=C-C + ) Dr. Sapna Gupta/Substitution Reactions 24
25 2) Leaving Group Leaving group is key in forming the carbocation intermediate for transition state. Larger halides ions are better leaving groups In acid, OH of an alcohol is protonated and leaving group is H 2 O, which is still less reactive than halide p-toluenesulfonate (TosO - ) is excellent leaving group 3) Nucleophile Does not matter since nucleophile is not part of the rate determining step. Dr. Sapna Gupta/Substitution Reactions 25
26 4) Solvent Polar solvents help with ionization and stability of the carbocation. Dr. Sapna Gupta/Substitution Reactions 26
27 S N 2 or S N 1? S N 2 S N 1 Substrate Primary or methyl Tertiary Nucleophile Strong nucleophile Weak nucleophile (may also be solvent) Solvent Polar aprotic solvent Polar protic solvent, silver salts Kinetics [substrate][nu] [substrate] Stereochemistry Inversion Racemic mixture Rearrangement No Yes Dr. Sapna Gupta/Substitution Reactions 27
28 Solved Problems Predict mechanism and stereochemistry of each product Cl + (R)-2-Ch lorobutane CH 3 OH/ H 2 O OH OCH HCl Predict mechanism of the following reaction Br + Na + CN - CN + DMSO Na + Br - Predict mechanism and stereochemistry of each product Br CH 3 S - Na + Na + Br - + acetone + SCH 3 (R)-2- Bromobutane Dr. Sapna Gupta/Substitution Reactions 28
29 Key Words/Concepts Substitution Reaction Nucleophile Electrophile Leaving group 1 st order reaction (unimolecular) 2 nd order reaction (bimolecular) Transition state Rate determining step Carbocation Polar protic solvent Polar aprotic solvent Non polar solvent Solvolysis
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
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"
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
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
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
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
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
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
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
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
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:
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
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
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
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,
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
+ + 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
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
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
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
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
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.
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
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
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
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
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
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)
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
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:
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
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
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
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]
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
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
Chemistry 2321 Last name, First name (please print) April 22, 2008 McMurry, Chapters 10 and 11 Row # Seat #
Test 4 Name Chemistry 2321 Last name, First name (please print) April 22, 2008 McMurry, Chapters 10 and 11 Row # Seat # Part 1. Multiple Choice. Choose the one best answer, and clearly mark that answer
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
Organic Chemistry CHM 314 Dr. Laurie S. Starkey, Cal Poly Pomona Alkyl Halides: Substitution Reactions - Chapter 6 (Wade)
rganic Chemistry CM 314 Dr. Laurie S. Starkey, Cal Poly Pomona Alkyl alides: Substitution Reactions - Chapter 6 (Wade) Chapter utline I. Intro to RX (6-1 - 6-7) II. Substitution Reactions A) S N 2 (6-8,
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](/thumbs/95/123929992.jpg "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.
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
7: Reactions of Haloalkanes, Alcohols, and Amines. Nucleophilic Substitution
7: Reactions of Haloalkanes, Alcohols, and Amines. Nucleophilic Substitution Preview 7-4 7.1 Nucleophilic Substitution Reactions of Haloalkanes 7-5 Nucleophilic Substitution Mechanisms (7.1A) 7-5 The SN1
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
Dehydrohalogenation of Alkyl Halides E2 and E1 Reactions in Detail
Dehydrohalogenation of Alkyl Halides E2 and E1 Reactions in Detail b-elimination Reactions Overview dehydration of alcohols: X = H; Y = OH dehydrohalogenation of alkyl halides: X = H; Y = Br, etc. X C
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
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,
Sn1 or Sn2 Reactions: A Guide to Deciding Which Reaction is Occurring
Sn1 or Sn2 Reactions: A Guide to Deciding Which Reaction is Occurring The following is a discussion of the approach you should use in order to determine if a chemical reaction occurs via a Sn1 or Sn2 mechanism.
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.
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
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
Alcohols, Ethers, & Epoxides
Alcohols, Ethers, & Epoxides Alcohols Structure and Bonding Enols and Phenols Compounds having a hydroxy group on a sp 2 hybridized carbon enols and phenols undergo different reactions than alcohols. Chapter
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
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
1/4/2011. Chapter 18 Aldehydes and Ketones Reaction at the -carbon of carbonyl compounds
Chapter 18 Aldehydes and Ketones Reaction at the -carbon of carbonyl compounds The Acidity of the Hydrogens of Carbonyl Compounds: Enolate Anions Hydrogens on carbons to carbonyls are unusually acidic
Department of Chemistry SUNY/Oneonta. Chem Organic Chemistry I. Examination #4 - December 9, 2002 ANSWERS
INSTRUCTINS Department of Chemistry SUNY/neonta Chem 221 - rganic Chemistry I Examination #4 - December 9, 2002 ANSWERS This examination is in multiple choice format; the questions are in this Exam Booklet
Ethers can be symmetrical or not:
Chapter 14: Ethers, Epoxides, and Sulfides 175 Physical Properties Ethers can be symmetrical or not: linear or cyclic. Ethers are inert and make excellent solvents for organic reactions. Epoxides are very
Writing a Correct Mechanism
Chapter 2 1) Balancing Equations Writing a Correct Mechanism 2) Using Arrows to show Electron Movement 3) Mechanisms in Acidic and Basic Media 4) Electron rich Species: Nucleophile or Base? 5) Trimolecular
b.p.=100 C b.p.=65 C b.p.=-25 C µ=1.69 D µ=2.0 D µ=1.3 D
Alcohols I eading: Wade chapter 10, sections 10-1- 10-12 Study Problems: 10-35, 10-37, 10-38, 10-39, 10-40, 10-42, 10-43 Key Concepts and Skills: Show how to convert alkenes, alkyl halides, and and carbonyl
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!)
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
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
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,
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
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
Ch 18 Ethers and Epoxides
Ch 18 Ethers and Epoxides Ethers (R-O-R ) are compounds with two organic groups attached to an sp 3 oxygen. Epoxides are cyclic ethers where the sp 3 O is a part of a 3-membered ring. Thiols (R-S-H ) and
2/26/18. Practice Questions. Practice Questions B F. How many steps are there in this reaction?
Practice Questions Practice Questions D B F C E A G How many steps are there in this reaction? 1 Practice Questions D B F C E A G What is the highest-energy transitions state? Practice Questions D B F
CHEM 263 Oct 25, stronger base stronger acid weaker acid weaker base
CEM 263 ct 25, 2016 Reactions and Synthesis (Preparation) of R- Breaking the - Bond of R- with Metals R + Li 0 or Na 0 or K 0 metal R Li + 1/2 2 alkoxide Breaking the - Bond of R- by Acid-Base Reaction
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
Chapter 8 Alkyl Halides and Elimination Reactions
Organic Chemistry, Second Edition Janice Gorzynski Smith University of Hawai i Chapter 8 Alkyl Halides and Elimination Reactions Prepared by Rabi Ann Musah State University of New York at Albany Copyright
Effect of nucleophile on reaction
1 Effect of nucleophile on reaction X DS c X c c X DS c + X cleophile not involved in DS of S N 1 so does not effect the reaction (well obviously it controls the formula of the product!) cleophile has
But in organic terms: Oxidation: loss of H 2 ; addition of O or O 2 ; addition of X 2 (halogens).
Reactions of Alcohols Alcohols are versatile organic compounds since they undergo a wide variety of transformations the majority of which are either oxidation or reduction type reactions. Normally: Oxidation
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.
(c) The intermediate carbocation resulting from 3-bromobut-1-ene is resonance stabilized.
KT121 Sem II 09/10 SETIN B: 1.(a) Name of mechanism: E1 elimination. 7 marks (b) (i) + 3 3 3 (ii) + 3 (iii) l 8 marks (c) The intermediate carbocation resulting from 3-bromobut-1-ene is resonance stabilized.
Mechanism: We therefore describe the mechanism as a S N 2 mechanism.
OH Mechanism: This is known as a bimolecular reaction as there are 2 molecules involved in the slow step. We therefore describe the mechanism as a S N 2 mechanism. We see an inversion in this process around
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,
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
Ethers. Synthesis of Ethers. Chemical Properties of Ethers
Page 1 of 6 like alcohols are organic derivatives of water, but lack the labile -OH group. As a result, ethers, except for epoxides, are usually not very reactive and are often used as solvents for organic
Organic Chemistry Review: Topic 10 & Topic 20
Organic Structure Alkanes C C σ bond Mechanism Substitution (Incoming atom or group will displace an existing atom or group in a molecule) Examples Occurs with exposure to ultraviolet light or sunlight,
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
Substitution α to a carbonyl center: Enol and enolate chemistry
Chapter 11 Organic Reaction Mechanisms, Part 2: Substitutions at Aliphatic Centers and Thermal Isomerizations/Rearrangements 11.1 Tautomerization Substitution α to a carbonyl center: Enol and enolate chemistry
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
(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
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
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
Chapter 11 - Alcohols and Ethers 1
Andrew Rosen Chapter 11 - Alcohols and Ethers 1 11.1 - Structure and Nomenclature - The common naming calls alcohols as alkyl alcohols (eg: methyl alcohol) - The common names of ethers have the groups
Learning Guide for Chapter 11 - Alkenes I
Learning Guide for Chapter 11 - Alkenes I I. Introduction to alkenes - p 1 bond structure, classifying alkenes, reactivity, physical properties, occurrences and uses, spectroscopy, stabilty II. Unsaturation
1. Radical Substitution on Alkanes. 2. Radical Substitution with Alkenes. 3. Electrophilic Addition
1. Radical Substitution on Alkanes Only Cl and Br are useful at the laboratory level. Alkane reactivity: tertiary > secondary > primary > methyl Numbers below products give their relative yield. Relative
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
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
CHE1502. Tutorial letter 201/1/2016. General Chemistry 1B. Semester 1. Department of Chemistry CHE1502/201/1/2016
CE1502/201/1/2016 Tutorial letter 201/1/2016 General Chemistry 1B CE1502 Semester 1 Department of Chemistry This tutorial letter contains the answers to the questions in assignment 1. FIRST SEMESTER: KEY
PRACTICE PROBLEMS UNIT 8
PRACTICE PROBLEMS UNIT 8 8A. Identify halides and carbocations as being 1 o, 2 o, or 3 o 8A.1 assify the following halides and carbocations as 1 o, 2 o, or 3 o. 8A.2 Circle the most stable cation in each
Chapter 4. Reactions of alkenes. Addition reactions Carbocations Selectivity of reactions
Chapter 4 Reactions of alkenes Addition reactions Carbocations Selectivity of reactions Prob 47 p192. Give the reagents that would be required (including catalyst). Ch 4 #2 Electrophilic addition Ch 4
Halo Alkanes and Halo Arenes
alo Alkanes and alo Arenes Short Answer Questions: **1. Write the isomers of the compound having formula C 4 9 Br? Sol. There are five isomers of C 4 9 Br. These are: 2-bromobutane is expected to exhibit
1) (100 pts) 5) (20 pts) 3) (35 pts) 4) (25pts. Total (200 pts) More Tutorial at
Name: Perm number: Question 1) (100 pts) 2) (20 pts) 3) (35 pts) 4) (25pts 5) (20 pts) Total (200 pts) Your score 1. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers
I C(CH 3 ) 3. (c)2ch 3 OH+(CH 3 ) 3 CCl (CH 3 ) 3 COCH 3 +CH 3 OH + 2 +Cl - (d) CH 3 CH 2 CH 2 Br+NaCN CH 3 CH 2 CH 2 CN+NaBr
6.1 Writer the following as net ionic reactions and designate the nucleophile, substrate, and leaving group in each reaction. (a) 3 + 3 2 Na 3 2 3 +Na (b) Na+ 3 2 3 2 +Na (c) 2 3 +( 3 ) 3 ( 3 ) 3 3 + 3
75. A This is a Markovnikov addition reaction. In these reactions, the pielectrons in the alkene act as a nucleophile. The strongest electrophile will
71. B SN2 stands for substitution nucleophilic bimolecular. This means that there is a bimolecular rate-determining step. Therefore, the reaction will follow second-order kinetics based on the collision
Chapter 22 Amines. Nomenclature Amines are classified according to the degree of substitution at nitrogen.
CH. 22 Chapter 22 Amines Amines are very important in biological chemistry. Most of the bases in biological acid-base reactions are amines. They are also very important nucleophiles in biochemical reactions.
Chapter 12. Reactions of Arenes: Electrophilic Aromatic Substitution. Class Notes. A. The method by which substituted benzenes are synthesized
Chapter 12 Reactions of Arenes: Electrophilic Aromatic Substitution Chapter 12 suggested problems: 22, 23, 26, 27, 32, 33 Class Notes I. Electrophilic aromatic substitution reactions A. The method by which
Chapter 17. Reactions of Aromatic Compounds
Chapter 17 Reactions of Aromatic Compounds Electrophilic Aromatic Substitution Although benzene s pi electrons are in a stable aromatic system, they are available to attack a strong electrophile to give
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