The Electrophile. S N 2 and E2 least stable most stable least hindered most hindered. S N 1 and E1. > x > >
|
|
- Audrey Simpson
- 5 years ago
- Views:
Transcription
1 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, or tertiary carbon? S N 1 and E1 Electrophile Type Favors Disfavors Methyl S N 2 S N 1, E1, E2 Primary S N 2, E2 S N 1, E1 Secondary < < < methyl and primary carbocation too unstable to exist. No S N 1 or E1 S N 1, S N 2, E1, E2 Resonance Stabilized S N 1, S N 2 E1, E2 Primary Tertiary S N 1, E2, E1 S N 2 S N 2 and E2 least stable most stable least hindered most hindered LG methyl electrophile has no β hydrogen. No E2 > x > > LG LG LG Tertiary electrophile is too sterically crowded for direct nucleophilic attack. No S N 2
2 2 The Electrophile: S N 1 and E1 Reactions, Carbocation Stability The first step in a S N 1 and E1 reaction is to form a carbocation. If the carbocation is too unstable, then regardless of how good the leaving group is the carbocation will not form. To determine the stability of a carbocation we must consider inductive and resonance effects C 3 C 3 C 3 What is happening when we say > > > inductive effects? 3 C C 3 3 C 3 o = 3 carbons 2 o = 2 carbons 1 o = 1 carbon methyl Primary carbocations may be formed if they have resonance stabilization hyperconjugation C C substituted carboncation Empty p orbital C methyl carboncation N N
3 Examining the Leaving Group and Electrophile 3 weak bases= GD leaving group strong base = BAD leaving group Potential Leaving Groups no S N 2 3 Favors S N 1, E1, E2 1 Favors S N 2, E2 2 Favors S N 1, S N 2, E1, E2 Electrophilic centers sterically hindered (no S N 2) not sterically hindered (allows for E2) Zaitsev s Rule: the most substituted alkene will be most stable and therefore the most favored product most substituted is the E2 product
4 The Leaving Group and the Electrophile: Examples 4 The leaving group here would be -, a bad leaving group No reaction is likely to take place here without further modifying the the substrate. 2 The leaving group here would be -, a good leaving group The electrophile is a secondary electrophile, SN1, SN2, E1, and E2 are all possible C C aloalkane produced by red algea The leaving group here would be -, a good leaving group. owever, it is attached to an Sp2 carbon, no substitution or elimination reaction will occur here.
5 Practice Question 5 Which substrate will undergo the fastest S N 2 reaction? A F F bad LG 1 o electrophile B I I good LG 3 o electrophile C bad LG 1 o electrophile D good LG 2 o electrophile
6 The Nucleophile 6 Recall that nucleophile means nucleus loving or positive-charge loving Nucleophiles donate a pair of electrons to an electrophile. (Lewis base!) When the nucleophile donates a pair of electrons to a proton it is called a onsted base or simply a base. The proton is acting like an electrophile. Nucleophile Type Favors Disfavors Strong Nuc/Strong Base Strong Nuc/ Weak Base Weak Nuc/ Strong Base S N 2, E2 S N 2 E2 S N 1, E1 S N 1, E1, E2 S N 1, S N 2, E1 Weak Nuc/Weak Base S N 1, E1 S N 2, E2
7 7 The Nucleophile: Factors That Affect Nucleophilicity and Basicity ow do we know if a nucleophile is acting as a nucleophile or a base? Consider the following properties: Charge Steric indrance Strength of nucleophile/base Electronegativity Solvent
8 The Nucleophile: Charge and Electronegativity 8 Charge The greater the electron density on the nucleophile the greater its nucleophilicity Increased electron density results in an increased desire to donate those electrons; ie: increased nucleophilicity neutral = S N 1, E1 charged = S N 2, E2 The conjugate base is always a stronger nucleophile Electronegativity Electronegativity relates how tightly held a pair of electrons are. The more tightly they are held the less the ability for them to be donated is. Electronegativity= Electronegativity= Nucleophilicity Basicity
9 9 Rank the Following Nucleophiles in rder of Increasing Nucleophilicity (1 being the weakest 5 being the strongest) N no charge, weakest less electronegative than oxygen, strongest
10 The Nucleophile: Steric indrance 10 Nucleophilicity decreases with increasing steric bulk Nucleophiles generally are reacting at electrophilic carbon. The orbitals that participate in the reactions are less accessible than those orbitals on hydrogen. 3 C! + LG bulky nucleophile = E2 N Non-Nucleophilic Bases N N N Li N If your nucleophile is bulky then its electrons may not be able to reach the antibonding orbitals at the carbon
11 Practice Question 11 t-butoxide has the following structure. Based on what you know about nucleophilicity what type of reaction or reactions are favored? A. Both S N 1, E1 B. Both S N 2, E2 C. Primarily E1 D. Primarily E2 E1 or S N 1 unlikely as this is a charged nucleophile (not A or C) bulky nucelophiles do not allow for S N 2 (not B)
12 Solvent Effects : The Electrophile 12 Solvent Type Favors Disfavors Polar Protic S N 1, E1 Polar Aprotic S N 2, E2 S N 1, E1 Non-Polar S N 1, S N 2, E1, E2 Polar protic has hydrogen bound to an electronegative atom Eg. 2 Polar aprotic no hydrogens, but still contains a dipole Eg. C 2 2 Non-polar has no dipoles Eg. hexanes, benzene S N 1 and E1 reactions proceed more quickly in polar protic solvents Intermediates are solvated through hydrogen bonding Leaving Group Stabilization δ+ δ- Carbocation Stabilization δ- δ- δ- δ- δ+ LG δ+ δ+ δ+ Polar protic solvents favour S N 1 and E1 reactions because the intermediates are solvated
13 Solvent effects: The Nucleophile 13 Nucleophilicity can be affected by solvent Polar protic solvents cause nucleophilicity to increase going down the periodic table Polar aprotic solvents cause nucleophilicity to decrease going down the periodic table
14 Solvent Effects: The Nucleophile 14 Polar protic 3 C water alcohols carboxylic acids Polar aprotic F < ydrogen bonding between lone pairs and polar protic solvents result in dispersion of negative charge. Lone pairs are tied up in -bond and less available to be donated I Na Favour S N 2, E2 Polar aprotic solvents have dipoles present which could interact with the nucleophile, however the partial positive charge created from the dipole is sterically hindered and therefore the nucleophile is unable to interact with these solvent. Polar aprotic solvents help in the solvolysis of cations which result in naked anions Non-polar solvent é interaction with solvent = ê nucelophilicity ether hexane Recall that like dissolves like. as many nucleophiles are charged or very polar they will not dissolve in non-polar solvents
15 15 Can you rank the following nucleophiles in order of increasing nucleophilicity? (1 being the weakest 5 being the strongest) 3 C Polar protic solvent S Se q ow would the rate of the reaction change if the solvent was changed from methanol to DMF NaS Me or DMF protic aprotic The protic solvent can interact with the nucelophile and keep it from reacting with the alkyl bromide. Therefore, DMF increases the rate of reaction.
16 Temperature Effects 16 When all else is equal increased temperatures will favor elimination reactions over substitution reactions Temperature Favors Disfavors igh E1, E2 S N 1, S N 2 Low S N 1, S N 2 E1, E2 ΔG 2 ΔG<0 reaction is spontaneous ΔG>0 reaction is non-spontaneous ΔG=0 reaction is in equilibrium ΔG=Δ-TΔS ΔG 1 ΔG LG LG B Nuc B Nuc LG LG 2 products 3 products Elimination reaction produces more products, this is favoured in the presence of heat as it increases the universe s entropy.
17 Mind Map 17
18 Practice Question 18 What is the most likely reaction to occur under the following conditions? What is the most likely product of the following reaction. C 3 heat 1. LG? or is a better LG 2. Electrophile? 3 o S N 1, E1, E2 possible Which product is formed? C or D? 3. Nucleophile? Strong Recall Zaitsev s Rule! favours S N 2, E2 The most stable product is C. 4. Solvent? N.A. 5. Temperature? Yes eliminations preferred Therefore, E2 reaction occurs (not A or B) A B C D 3 C C 3
19 Substitution and Elimination 19 Reactions Acetone Room Temp Stereochemistry is inverted 1. LG: 2. Electrophile: 2 o, Favours SN1, SN2, E1, E2 3. Nucleophile: Charged, Favours SN2, E2 4: Solvent: Polar Aprotic, Favours SN2, E2 5. Temperature: Room Temp, Favours SN2 so SN2 Reaction N DMS eat 1. LG: 2. Electrophile: 3 o, Favours SN1, E1, E2 3. Nucleophile: Neutral but strong and Bulky, Favours E2 4: Solvent: Polar Aprotic, Favours SN2, E2 5. Temperature: eat, Favours E2 so E2 Reaction N
20 LG: 2. Electrophile: 3 o, Favours SN1, E1, E2 3. Nucleophile: Neutral, Favours SN1, E1 4: Solvent: N/A 5. Temperature: N/A so Mixture of SN1 and E1 SN1 products: mixture of stereochemistry E1 product: most stubstituded alkene favoured (Zaitsev s Rule) 3 C C 3 C 3 room temp 3 C C 3 C 3 3 C C 3 C 3 3 C C 3 C 3 1. LG: 2. Electrophile: 3 o, Favours SN1, E1, 3. Nucleophile: neutral, favours SN1, E1 4: Solvent: Polar protic, Favours SN1, E1 5. Temperature: Room Temp, Favours SN1 so SN1 Reaction
21 21 heat 1. LG: 2. Electrophile: 2 o, Favours SN1, E1,SN2, E2 3. Nucleophile: Charged, favours SN2, E2 4: Solvent: N/A 5. Temperature: E2 so E2 Reaction heat Zaitsev s Rule: most substitutted alkene is most stable and therefore most favoured product Less substituted alkene due to steric hinderance of t-butyl group on substrate and nucleophile 1. LG: 2. Electrophile: 2 o, Favours SN1, E1,SN2, E2 3. Nucleophile: Charged but bulky, favours,e2 4: Solvent: N/A 5. Temperature: E2 so E2 Reaction too sterically hindered for base to deprotonate
22 22 What Reaction Is occuring? Which Isomer will undergo the fastest reaction? K FAST K K Favoured Chair conformation but no anti-coplanar hydrogen Less Favoured Chair conformation (axial t-butyl group) BUT anticoplanar hydrogen 1. LG: 2. Electrophile: 2 o, Favours SN1, E1,SN2, E2 3. Nucleophile: Charged but bulky, favours,e2 4: Solvent: N/A 5. Temperature: E2 so E2 Reaction 2 C C 2
23 Additional Practice Questions 23 Textbook Problems Solomons+Fryhle+Snyder (12 edition ) Leaving Group and Electrophile Q. 6.20, 6.22 Nucleophile and Solvent Effects Q.6.21, Q6.29 Deciding between SN1 and SN2 Q. 6.28, 6.35, 6.40 Challenge Problems 6.41, 6.42, 6.46, 6.47 Group Discussion Problems
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 informationHomework 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 informationChapter 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 informationBasic 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 information7. 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 informationChapter 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 informationChapter 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 informationCHAPTER 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 informationChapter 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 informationCONCERTED 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 informationWalden 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 informationReactions 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 informationAcid-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 informationLecture 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 informationReaction 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 informationAlkyl 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 informationS 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 informationEffect 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
More informationOrganic 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 informationChapter 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 informationORGANIC - 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 informationNucleophilic 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 informationElimination 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 informationCHE1502. 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
More informationChapter 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 informationCHAPTER 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 informationChapter 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 informationPAPER 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 informationReactions 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 information1-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 informationBSc. 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 informationC 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 informationChapter 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 informationC 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 informationClasses 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 informationREACTIONS 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 informationOrganic 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,
More information+ + 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 informationDepartment 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
More informationSubstitution 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 informationChapter 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 informationNuggets 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 informationPRACTICE 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
More informationChapter 8. Acidity, Basicity and pk a
Chapter 8 Acidity, Basicity and pk a p182 In this reaction water is acting as a base, according to our definition above, by accepting a proton from HCl which in turn is acting as an acid by donating a
More informationLecture 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 informationDepartment of Chemistry SUNY/Oneonta. Chem Organic Chemistry I
Department of Chemistry SUNY/Oneonta Chem 221 - Organic Chemistry I Examination #4 - ANSWERS - December 11, 2000 Answer to question #32 corrected 12/13/00, 8:30pm. INSTRUCTIONS This examination is in multiple
More informationOrganic 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 informationGlendale 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 informationChapter 6. Chemical Reactivity and Reaction Mechanisms
hapter 6 hemical Reactivity and Reaction Mechanisms hemical Reactivity Enthalpy A simple chemical reaction can be broken down into bond creating and bond breaking components: A-B + Y-Z A-Y + B-Z A-B A
More information75. 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
More informationElimination Reactions The E2 Mechanism
Elimination Reactions The E2 Mechanism The E2 Mechanism X X- B: B- δ- B:- δ+ R 1 δ- R 2 δ+ X δ- The E2 Mechanism R 3 R 4 transition state Free energy (G) Eact B:- B R 1 R 2 X R 1 R 2 R 3 R 4 R 4 R 3 X:-
More informationSubstitution 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 information8.8 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 informationORGANIC - BROWN 8E CH.4 - ACIDS AND BASES.
!! www.clutchprep.com CONCEPT: FREE ENERGY DIAGRAMS Atoms save energy by forming bonds. Free energy diagrams show overall changes in potential energy during reactions. Free energy diagrams give us information
More information(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 informationORGANIC - 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 informationChemistry 304B, Spring 99 Lecture 2 1
Chemistry 04B, Spring 99 Lecture 2 1 Consider Acidity and Basicity Recall carboxylic acids and amines (base). Jones: p 27-8; 149, 291, 822-826, 1086-1090, 958-96, 878-882 General terms: Lewis acid: capable
More informationc. 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 informationPreparation 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 informationOrganic 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 informationWriting 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
More informationSn1 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.
More information11. 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 informationLearning 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 information11. 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 information5. Reactions of Alkenes (text )
2009, Department of hemistry, The University of Western Ontario 5.1 5. Reactions of Alkenes (text 5.1 5.5) A. Addition Reactions In hapter 4, we saw that π bonds have electron density on two sides of the
More informationPhysical 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 informationElimination Reactions. Chapter 6 1
Elimination Reactions Chapter 6 1 E1 Mechanism Step 1: halide ion leaves, forming a carbocation. Step 2: Base abstracts H + from adjacent carbon forming the double bond. Chapter 6 2 E1 Energy Diagram E1:
More informationζ 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 informationH H H H S H H H NO 2 O H H 3 C. OMe CH 3
Fall Workshop #9 Question #1 Using the tables on pages 18-19 of SAM, the table inside the back cover of Jones, and the figure we created in class: (a) Report an estimated pka value for each hydrogen atom
More informationHydrogen 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 informationOrganic Chemistry. Second Edition. Chapter 19 Aromatic Substitution Reactions. David Klein. Klein, Organic Chemistry 2e
Organic Chemistry Second Edition David Klein Chapter 19 Aromatic Substitution Reactions Copyright 2015 John Wiley & Sons, Inc. All rights reserved. Klein, Organic Chemistry 2e 19.1 Introduction to Electrophilic
More information10. 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 informationLab 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 informationChapter 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 informationCHE1502. Tutorial letter 203/1/2016. General Chemistry 1B. Semester 1. Department of Chemistry
E1502/203/1/2016 Tutorial letter 203/1/2016 General hemistry 1B E1502 Semester 1 Department of hemistry This tutorial letter contains the answers to the questions in assignment 3. FIRST SEMESTER: KEY T
More informationORGANIC - CLUTCH CH. 3 - ACIDS AND BASES.
!! www.clutchprep.com CONCEPT: OVERVIEW OF CHEMICAL REACTIONS There are 4 types of common chemical reactions that we need to be familiar with in organic chemistry 1. Acid-Base Reactions: Two molecules
More informationStructure and Preparation of Alkenes: Elimination Reactions
Structure and Preparation of Alkenes: Elimination Reactions Alkene Nomenclature First identify the longest continuous chain that includes the double bond. Replace the -ane ending of the corresponding unbranched
More informationCHEM 2312 practice final. Version - II
EM 2312 practice final Version - II The following standardized final examination covers the entire introductory year of organic chemistry (EM 2311 and 2312 at Georgia Tech). The exam consists of 70 multiple
More informationPAPER 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 informationPractice Hour Examination # 1-1
CHEM 346 Organic Chemistry I Fall 2013 Practice Hour Examination # 1-1 Solutions Key Page 1 of 12 CHEM 346 Organic Chemistry I (for Majors) Instructor: Paul J. Bracher Practice Hour Examination # 1-1 Monday,
More information1. 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 information1. What are the respective hybridizations of the atoms numbered 1 to 4 in this compound?
CEM 331: Chapter 1/2: Structures (Atoms, Molecules, Bonding) 1. What are the respective hybridizations of the atoms numbered 1 to 4 in this compound? N C 2 C N C 2 C N 1 2 3 4 1: three sigma bonds and
More informationC C. sp 2. π M.O. atomic. orbitals. carbon 1. σ M.O. molecular. orbitals. H C C rotate D. D H zero overlap of p orbitals: π bond broken!
Alkenes Electrophilic Addition 1 Alkene Structures chemistry of double bond σ BDE ~ 80 kcal/mol π = BDE ~ 65 kcal/mol The p-bond is weaker than the sigma-bond The, electrons in the p-bond are higher in
More informationChapter 3 An Introduction to Organic Reactions: Acids and Bases
There are 4 types of Organic Reactions Chapter 3 An Introduction to Organic Reactions: SUBSTITUTION: ADDITION: X Y + A X A + Y Example Example A B + X Y A B X Y ELIMINATION There are 4 Types of Organic
More informationAlcohols: 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 information1. methyl 2. methylene 3. methine 4. primary 5. secondary 6. tertiary 7. quarternary 8. isopropyl
hem 201 Sample Midterm Beauchamp Exams are designed so that no one question will make or break you. The best strategy is to work steadily, starting with those problems you understand best. Make sure you
More information1. 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
More informationDr. 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(b) (CH 3 ) 2 CCH 2 CH 3 D 2 O. (e) A. CH 3 CCl OSO 2 CH 3 C 6 H 5 H 3 C
278 h a p t e r 7 Further Reactions of aloalkanes 3. arbocations are stabilized by hyperconjugation: Tertiary are the most stable, followed by secondary. Primary and methyl cations are too unstable to
More informationCHEM Lecture 7
CEM 494 Special Topics in Chemistry Illinois at Chicago CEM 494 - Lecture 7 Prof. Duncan Wardrop ctober 22, 2012 CEM 494 Special Topics in Chemistry Illinois at Chicago Preparation of Alkenes Elimination
More informationAldehydes and Ketones : Aldol Reactions
Aldehydes and Ketones : Aldol Reactions The Acidity of the a Hydrogens of Carbonyl Compounds: Enolate Anions Hydrogens on carbons a to carbonyls are unusually acidic The resulting anion is stabilized by
More informationConjugated Systems, Orbital Symmetry and UV Spectroscopy
Conjugated Systems, Orbital Symmetry and UV Spectroscopy Introduction There are several possible arrangements for a molecule which contains two double bonds (diene): Isolated: (two or more single bonds
More informationOrganic Chemistry I: Reactions and Overview
Organic Chemistry I: Reactions and Overview Andrew Rosen Editor: Raghav Malik January 13, 2013 Contents I Library of Synthetic Reactions 3 II Organic Trends and Essentials 4 1 The Basics: Bonding and Molecular
More informationMolecular Orbitals for Alkyl Halide Electrophiles. Chemistry 335 Supplemental Slides: Chapter 2
Molecular Orbitals for Alkyl Halide Electrophiles To build molecular orbitals, first recall that the energy of the starting atomic orbitals depends the electronegativity of the element, which you can get
More informationan axial "X" is necessary for a succesful E2 reaction and also works better for S N 2
cleophilic Substitution & Elimination hemistry 1 Templates for predicting S2 and E2 reactions primary - β α α β two different perspectives secondary - β β α β β α two different perspectives tertiary -
More information20 Halogenoalkanes:substitution and elimination reactions
20 alogenoalkanes:substitution and elimination reactions s to worked examples WE 20.1 Allylic halogenations (on p. 922 in Chemistry 3 ) 1-(Chloromethyl)benzene (benzyl chloride, PhC 2 ) is made on a large
More informationLecture 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 informationOrganic Chemistry Practice Problems: Solutions
rganic Chemistry Practice Problems: Solutions 1. 2. a. B, A b. D, B c. A, D d. D, A a. Resonance b. Electronegativity of fluorine atoms F F c. Neither is very acidic, but the oxygen will help stabilise
More informationChapter 7: Alkenes and Alkynes
Chapter 7: Alkenes and Alkynes ydrocarbons Containing Double and Triple Bonds Unsaturated Compounds (Less than Maximum Atoms) Alkenes also Referred to as Olefins Properties Similar to those of Corresponding
More information