Electrophilic Aromatic Substitution Questions And Answers

However, aromatic systems do not reaction in the same fashion as alkene containing systems, in part due to their remarkable stability. A two-step mechanism has been proposed for these electrophilic substitution reactions. Some schools teach this in Orgo 1, others in Orgo 2. As a result, the meta hydrogen is substituted. Lecture Notes Chem 51B S. The rate determining step in an electrophilic aromatic substitution is the formation of a resonance stabilized radical. Proton is removed by the breaking of C-H σ bond. Pearsons Prentice Hall Filesize: 354 KB. CCl 4) induces a weaker dipole in Br-Br as compared to the polar solvent (i. an example of an electrophilic aromatic substitution (Friedel-Crafts Alkylation) that incorporates the effect of substitution of the aromatic ring into the experiment. Answers outside the provided box will not receive credit. 2) Explain why reaction of benzene with Br2/FeBr3 results in the product bromobenzne instead of 5,6-dibromo-1,3-cyclohexadiene. question? question? question? question? methyl group activates the benzene ring towards electrophilic aromatic substitution! question? relative rates other groups answer. Hence, it undergoes. question_answer. Nitro groups deactivate the ring. reaction in question. d) Acetylation of benzene with acetic anhydride requires more than one equivalent of a Lewis acid. But it doesn’t end there, this topic is often tested on the MCAT, DAT and similar – with a focus on your ability to understand and deduce mechanism intermediates and reaction products. Because the starting point in an S E Ar reaction is inherently low in energy (due to aromaticity), the activation. There are 6 nucleophilic substitution mechanisms encountered with aromatic systems. I’m going to discuss a general mechanism for the electrophilic substitution first then focus in on the peculiarities of the different examples quoted in. Consider the data below to answer the following question(s). Electrophilic Aromatic Substitution The most characteristic reaction of aromatic compounds is electrophilic aromatic substitution, in which one of the ring hydrogens is substituted by a halogen, nitro group, sulfonic acid group, alkyl or acyl group. Faster No Knead Bread - So Easy ANYONE can make (but NO BOILING WATER!!) - Duration: 7:18. Explain why. Reactivity for electrophilic e + - density of aromatic substitution reaction in the aromatic ring. pdf), Text File (. The General mechanism for electrophilic Aromatic Substitution (EAS) is: In order to nitrate the benzene ring… 1. none of the above 🤓 Based on our data, we think this question is relevant for Professor Nasiri's class at UCD. Answer and Explanation: The first reaction is a bromination reaction and the second reaction is a nitration reaction. Show the mechanism for each of the following electrophilic aromatic substitution reaction. Synthetic equations: Physical Properties & Hazards of Reagents. Parker Paradigms, Inc. Electrophilic Aromatic Substitution is immediately associated with the undergraduate organic chemistry course. These acids will form complexes with the amine and deactivate the ring and convert the o/p-directing amino group into a m-directing ammonium ion (-NH3+) group. calculate the number of moles of no2 present if the equilibrium 1. Write your answer in the space provided or on a separate sheet of paper. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. As a result, the meta hydrogen is substituted. The intermediate structures for the mechanism of this reaction are given below. In this procedure, the positive charge of the electrophile is to be shifted to the adjacent ring carbon atom that is termed carbocation. Chlorine withdraws electrons through inductive effect and releases electrons through resonance. Answer:Formation of a sigma complex. water), a weaker electrophile (Br+) is produced that undergoes electrophilic aromatic substitution with the benzene ring. The N-arylation of aniline derivatives is a useful reaction for implementing nucleophilic aromatic substitution into the undergraduate curriculum. The initial step is attack by the electrophile to form. UNIT 16 – PRACTICE PROBLEMS 16A. This means that the characteristic reactions of alkenes are electrophilic addition reactions. Aromatic molecules like benzene don’t react like regular alkenes, so catalysts or special conditions are required. Your answers will be evaluated and graded on quality, not quantity of response! You are to complete this post-lab questions assignment. 5 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF SUBSTITUTED BENZENES 765 bons of the ring. Nitro groups deactivate the ring. “Electrophilic Aromatic Substitution Chemistry & Nuclear Magnetic Resonance Spectroscopy. Universiteit / hogeschool. Arrange the following products according to the % yield obtained from the nitration of t-butylbenzene. This tutorial extends the discussion of electrophilic aromatic substitution reactions to polysubstituted benzene rings. edu is a platform for academics to share research papers. This ring is activated toward electrophilic attack because the atom directly attached to the benzene ring can donate an shared electron pair to it can accept an unshared electron pair from it can donate electron density through inductive effects can withdraw electron density through inductive effects. Since the aldehydic group (-CHO) and ketonic group (-COR or -COAr) are electron-withdrawing, they are deactivating and m-directing. Construct a table showing the electrophile and the electrophilic substitution. Everybody studying electrophilic substitution is likely to have met the nitration of benzene, but other parts of the Chemguide material on this topic may not be required by your syllabus. p-propyltoluene C. General Mechanism for an Electrophilic Aromatic Substitution: The general mechanism for all electrophilic aromatic substitutions is summarized below. What is the electrophile, E+ in this case and what is the base? 2. UNIT 16 – PRACTICE PROBLEMS 16A. Organic Chemistry. B)is an activator and a m-director. This activity contains 15 questions. The overall mechanism is known as an addition-elimination mechanism. chapter 18: electrophilic aromatic substitution what is the first step in the general mechanism for electrophilic aromatic substitution? protonation of the. These questions cover all of the work on electrophilic substitution. (Image) By signing up, you'll get thousands of. Short Answer Type Questions [II] [3 Marks] Question 57: Although chlorine is an electron withdrawing group, yet it is ortho-, para¬directing in electrophilic aromatic substitution reactions. A would be the first one, and D the last one, that's easy since R2N is strong activator (ortho-. 8% CH3 NO2 0. However, substituted aromatic five-membered heterocycles may also be synthesized through the cyclization of 1,4-diketones in combination with ammonia ( N H 3 ), amines, phosphorus pentoxide ( P 2 O 5 ), or phosphorus pentasulfide ( P 2 S 5 ). The correct IUPAC name for the molecule O CO 2H is A. So, in your case, the only possible answer is ( b. This is a two-step reaction mechanism with a carbocation intermediate. This browser cannot play the embedded video file. What is the electrophile, E+ in this case and what is the base? 2. Loratadine (current news) 20 Question 2. ” The Final Learning Experience Friday - Monday, May 9 - 13, 2002, Take-Home Publish May 9, 8pm & collect May 13, 5:30pm, 321 Chem. Parker Paradigms, Inc. Summary: The Six Key Electrophilic Aromatic Substitution Reactions We’ve shown six key electrophilic aromatic substitution reactions (chlorination, bromination, nitration, sulfonylation, and the Friedel-Crafts alkylation and acylation) and that they all involve the breakage of C-H and the formation of C-E (where “E” is the electrophile in question). 3 down vote favorite 1 Regioselectivity in electrophilic aromatic substitution of benzofuran and indole. Please note. (b) Explain your answer. Alone, nitric acid is not a strong enough electrophile to react with bromobenzene. Electrophilic Substitution : Electrophilic substitution reactions are chemical reactions in which an electrophile displaces another group, typically but not always hydrogen. An electrophilic aromatic substitution consists of three main fundamental components: During the reaction, a new σ bond is formed from a C=C in the arene nucleophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration, aromatic halogenation, aromatic sulfonation, and alkylation and alkylating Friedel-Crafts reaction. Electrophilic aromatic substitution is an important way of introducing functional groups on benzene rings. Both ethene and benzene are attractive for electrophiles because of the exposed pi bonds. An electrophile — an electron‐seeking reagent — is generated. Lecture Notes Chem 51B S. Q: A methane molecule may be considered as. Your mechanism must include curved arrows show the flow of electrons for all bonds made and broken. Se1 And Se2 Reaction Mechanism Ppt. Chapter 7: Multiple choice questions. question? question? question? question? methyl group activates the benzene ring towards electrophilic aromatic substitution! question? relative rates other groups answer. 143 Lecture Notes Chem 51B S. Housecroft and E. Answer to: Devise an efficient synthesis for the product using the starting aromatic source. Parker Paradigms, Inc. Write the word or phrase that best completes each statement or answers the question. C)is a deactivator and a m-director. Although the  electrons are in a stable aromatic system, they are still available for reaction with strong electrophiles. Your email address:. Just like an alkene, benzene has clouds of  electrons above and below its sigma bond framework. The nitronium ion (NO 2 +) and sulfur trioxide (SO 3) are the electrophiles and individually react with benzene to give nitrobenzene and benzenesulfonic acid respectively. none of the above e. QUIZ #9 ANSWER KEY (hit the RETURN Button to return to the Main Quiz Page) QUESTION 1 MC32n For the following reactions indicated as 1, 2 and 3, which is the correct order of INCREASING rate of electrophilic aromatic substitution? NH2 Cl Cl2 AlCl3 Cl2 AlCl3 Cl2 AlCl3 2 1 3 A 1 (slowest) < 2 < 3 (fastest) B 2 (slowest) < 3 < 1 (fastest). 2-furoic acid C. Making statements based on opinion; back them up with references or personal experience. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. This section. 1), 2) and 3) b. Electrophilic Aromatic Substitution The most characteristic reaction of aromatic compounds is electrophilic aromatic substitution, in which one of the ring hydrogens is substituted by a halogen, nitro group, sulfonic acid group, alkyl or acyl group. The reaction to form 4-nitroacetanilide is an electrophilic aromatic substitution. Jul 1, 2019 - Benzene has 3 π bonds and as expected shows some similarities to alkenes in being reactive towards electrophilic species. Electrophilic Aromatic Substitution. The right and left arrows allow you to move back and forth between problems. Use a blank sheet of paper if more space is needed to answer these questions. Write the word or phrase that best completes each statement or answers the question. Friedel Crafts Alkylation and Acylation Reaction Mechanism - Electrophilic Aromatic Substitution - Duration: 20:11. Use MathJax to format equations. Note why we're calling it substitution: we're breaking C-H and we're forming a different bond at C (e. Answer the following questions and then press 'Submit' to get your score. , Reactivity (12 min) Previous. • Provide the mechanisms of each of the five electrophilic aromatic substitution reactions with benzene. Electrophilic Aromatic Substitution: Friedel-Crafts Acylation Study Questions 1) A carbocation produced during a Friedel-Crafts alkylation may undergo rearrangement. The electrophilic aromatic substitution mechanism is an electrophilic attack followed by an alpha elimination. 40 Questions Show answers. 30 (as well as those you drew in Problem 16. However, nucleophilic aromatic substitution is not. CHEM 2P20 Study Guide - Midterm Guide: Benzoic Acid, Electrophilic Aromatic Substitution, Nucleophile Exam. 1) Why are some groups which appear to be electron withdrawing, -NO 2 for example, deactivating and meta directing as expected, while others, -NH. This means that the characteristic reactions of alkenes are electrophilic addition reactions. Pyrrole undergoes electrophilic aromatic substitution mainly at 2-Position and 5-Position. C)is a deactivator and a m-director. properties and reactions of arenes (aromatic hydrocarbons). Here's some key points: The aromatic ring is the nucleophile here. Given each of the following electrophiles, provide a mechanism for electrophilic aromatic substitution. Then, the leaving group, usually a proton, is split off and the aromaticity is restored. This reaction is a typical example of "Electrophilic Aromatic Substitution". In a second fast step, a proton is eliminated forming a substituted benzene. This diazonium salt undergoes electrophilic aromatic substitution on activated aromatic rings to yield brightly colored azo compounds that are widely used as dyes. Answer to One ring of phenyl benzoate undergoes electrophilic aromatic substitution much more readily than the other. A nucleophile adds to the aromatic ring at a carbon bearing a good leaving group, most commonly -Cl. Crystallization was used. E)none of the above 13) SHORT ANSWER. Electrophilic Aromatic Substitution Friedel-Crafts Acylation of Toluene 12. Electrophilic Aromatic Substitution A. 9-Electrophilic Aromatic Reactions - Free download as Powerpoint Presentation (. Electrophilic Aromatic Substitution Self-paced. Practical, Electrophilic aromatic substituion of salicylamide, Questions and answers. electrophilic aromatic substitution of benzene. I have seen the reaction between benzene and Br2/FeBr3, also I have seen the reaction between benzene and Cl2/AlCl3. Arrange the following products according to the % yield obtained from the nitration of t-butylbenzene. , nitration and sulfonylation) or powerful Lewis acids (F-C reactions). Thanks for contributing an answer to Chemistry Stack Exchange! Please be sure to answer the question. Both the C-H and C-D bonds are broken so quickly and easily, by comparison, that we don't really notice the difference between them. Write the word or phrase that best completes each statement or answers the question. In what orbitals are the lone pairs of electrons on the oxygen atom in furan? How many ring atoms have a partial positive charge in the carbocation intermediate that is formed in an electrophilic aromatic substitution reaction of benzene? Answer choices in this exercise appear in a different order. Pearsons Prentice Hall Filesize: 354 KB. An investigation into students’ strategies and pitfalls for solving electrophilic aromatic substitution mechanism questions. Hydrohalogenation, addition of H-Cl, H-Br or H-I. p-propyltoluene C. The correct IUPAC name for the molecule O CO 2H is A. The Organic Chemistry Tutor 94,228 views 20:11. 9-Electrophilic Aromatic Reactions - Free download as Powerpoint Presentation (. CHEM 2P20 Study Guide - Midterm Guide: Benzoic Acid, Electrophilic Aromatic Substitution, Nucleophile Exam. 5 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF SUBSTITUTED BENZENES 765 bons of the ring. Electrophilic Aromatic Substitution Objective The objective of this experiment was to illustrate electrophilic aromatic substitution by synthesizing p-nitroanilide (as well as ortho) from acetanilide by nitration. The study of aromatic heterocyclic reactivity can be said to have begun with the results of electrophilic substitution processes. 1), 2) and 3) b. In carboxylic acid: Aromatic acids …other aromatic compounds, also undergo electrophilic substitution reactions. Sn1 Sn2 E1 E2 Multiple Choice Questions. Explain why it is so ? $\begin{array}{1 1}\text{(a) Chlorine. Electrophilic Aromatic Substitution Friedel-Crafts Acylation of Toluene 12. 2-furoic acid C. Answer to One ring of phenyl benzoate undergoes electrophilic aromatic substitution much more readily than the other. Electrophilic Aromatic Substitution is one of the more exciting topics covered in organic chemistry. Answer the following questions and then press 'Submit' to get your score. Some nucleophilic aromatic substitution reactions occur via a two-step mechanism in which the first step, by definition, is an addition and the second step an elimination. Electrophilic aromatic substitution (EAS) is the primary method used to add substituents to benzene. Electrophilic-substitution-of-an-indole-as-opposed-to-benzofuran-and-benzothioph. Thanks for contributing an answer to Chemistry Stack Exchange! Naproxene syntheses: electrophilic aromatic substitution on activated naphthalene. - Most of the electron density of aromatic compounds with electron withdrawing groups is on the meta positions, because the ortho and para positions have a partial positive charge. Substituents on an aromatic ring can have several effects on electrophilic aromatic substitution reactions. ABSTRACT: The electrophilic aromatic substitution reaction is the attack of a benzene ring on an electrophilic species resulting in the substitution of a proton with a functional group. Substitution of an aromatic molecule, typically benzene, C_6H_6. There are 6 nucleophilic substitution mechanisms encountered with aromatic systems. Since the aldehydic group (-CHO) and ketonic group (-COR or -COAr) are electron-withdrawing, they are deactivating and m-directing. Electrophilic Substitution : Electrophilic substitution reactions are chemical reactions in which an electrophile displaces another group, typically but not always hydrogen. Most electrophilic substitution is done under strongly acid conditions with protonic reagents (i. Both ethene and benzene are attractive for electrophiles because of the exposed pi bonds. furanylcarboxylic acid D. The study of aromatic heterocyclic reactivity can be said to have begun with the results of electrophilic substitution processes. An illustration describing the electrophilic substitution of a hydrogen atom (belonging to a benzene molecule) with a chlorine atom is provided below. Compare the reactivity of pyridine to that of Benzene in nucleophilic aromatic substitution. Electrophilic Aromatic Substitution Self-paced. Join our community and share your wisdom by answering Simple Aromatic Ring questions. The first one is a Friedel-Crafts acylation: the products a. Your answers will be evaluated and graded on quality, not quantity of response! You are to complete this post-lab questions assignment. • Provide the mechanisms of each of the five electrophilic aromatic substitution reactions with benzene. 3-furoic acid 17. The periodic table, physical constants and relative atomic masses needed for these problems are given on the inside covers of Chemistry, fourth edition by C. Rank the following aromatic compounds in order of reactivity towards electrophilic aromatic substitution (from most reactive to least reactive): A. Formation of the substituted benzene is highly exergonic. I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand. C he m g ui d e - an s we r s ELECTROPHILIC SUBSTITUTION 1. Substitution reaction of chemistry. The correct IUPAC name for the molecule O CO 2H is A. Although the  electrons are in a stable aromatic system, they are still available for reaction with strong electrophiles. 2), 3), 4) and 5) c. electrophilic substitution reaction at these various positions? To answer the questions raised above, we will need to begin by looking at the mechanism of the reaction in question. C)is a deactivator and a m-director. The initial step is attack by the electrophile to form. A) Nucleophilic aromatic substitution by addition-elimination. A two-step mechanism has been proposed for these electrophilic substitution reactions. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. 3), 4), 5) and 2) Cheers :). 10pts Chapter 8 Questions 1. Complete the mechanism by drawing curved arrows, the structure of the charged intermediate, and the structure of the major uncharged product. An electrophilic aromatic substitution reaction starts in an alike way. So if we make the electron ring more electron rich, we'll increase the rate of reaction [groups like OH, OCH3, NH2, or alkyl groups are good examples]. I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand. 13 Answered Questions for the topic Aromatic Compounds Why is a hydroxyl group more activating than a methoxy group in electrophilic aromatic substitution? Why is phenol more reactive towards electrophilic substitution than methoxybenzene? Isn't the lone pair on the methoxy group oxygen more available for participating in resonance into the. (Image) By signing up, you'll get thousands of. The African Virtual University (AVU) is a Pan African Intergovernmental Organization established. Electrophilic aromatic substitution in furan is preferentiallly at positiion A. However, aromatic systems do not reaction in the same fashion as alkene containing systems, in part due to their remarkable stability. -Electrophilic aromatic substitution is a multistep process. The actual electrophile here is SO3. Multiple choice questions. Nitration of Methyl Benzoate Introduction: Most aromatic rings are unreactive and stable. Birch reduction reaction conditions involve sodium metal, in an alcoholic solution of ammonia. Pyrrole undergoes nitration by electrophilic aromatic substitution. Electrophilic substitution in case of aromatic amines takes place more readily than in benzene. The periodic table, physical constants and relative atomic masses needed for these problems are given on the inside covers of Chemistry, fourth edition by C. A would be the first one, and D the last one, that's easy since R2N is strong activator (ortho-. directive effects. Abstract from Australian Conference on Science and Mathematics Education, Clayton, Australia. Answer questions. Electrophilic Aromatic Substitution The most characteristic reaction of aromatic compounds is electrophilic aromatic substitution, in which one of the ring hydrogens is substituted by a halogen, nitro group, sulfonic acid group, alkyl or acyl group. Once you have answered the questions, click on. Which potential energy reaction diagram best describes the three steps in this reaction? 6. electrophilic aromatic substitution. b is a deactivator and an o,p-director c. Practical, Electrophilic aromatic substituion of salicylamide, Questions and answers. Everybody studying electrophilic substitution is likely to have met the nitration of benzene, but other parts of the Chemguide material on this topic may not be required by your syllabus. To enhance this initial addition a. ) Electrophilic Aromatic Substitution Mechanism: Please fill in the following structures depicting the correct mechanism. Using the drawing window on the left below, draw the major product from each of the electrophilic aromatic substitution reactions shown below. Apr 30, 2020 - Electrophilic Aromatic Substitution: Practice problems and introduction to the key reactions. Not The Aromatic Substitution Reaction You Were Expecting Let's review electrophilic aromatic substitution (EAS). Show all electron flow with arrows for this mechanism on the structures provided. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. During the second week, students will analyze the products by TLC analysis and melting point determination. UNIT 16 – PRACTICE PROBLEMS 16A. furanylcarboxylic acid D. These acids will form complexes with the amine and deactivate the ring and convert the o/p-directing amino group into a m-directing ammonium ion (-NH3+) group. This ring is activated toward electrophilic attack because the atom directly attached to the benzene ring can donate an shared electron pair to it can accept an unshared electron pair from it can donate electron density through inductive effects can withdraw electron density through inductive effects. Answer questions. The ferrocene then is the nucleophile and the rest of the reaction is a standard electrophilic aromatic substitution leaving the formyl oxonium, which is quenched to the formyl on work-up. Our mission is to provide a free, world-class education to anyone, anywhere. 13)In electrophilic aromatic substitution reactions a bromine substituent: A)is a deactivator and an o,p-director. Organic II Chemistry - Electrophilic Aromatic Substitution (EAS) Worksheet Complete the resonance structures for each sigma complex resulting from electrophilic aromatic substitution at the ortho, meta, and para positions as shown below. The electrophilic aromatic substitution reaction of benzene can be represented as below. Therefore the reactions take place at the most electron rich carbons in an aromatic ring. The electrophile attack results in the so-called σ-complex, a transition state in which the aromatic system is abolished. They may be converted into substituted aromatic heterocycles through an electrophilic substitution. Nitro groups deactivate the ring. Join our community and share your wisdom by answering Simple Aromatic Ring questions. Reagents that acquire an electron pair in chemical reactions are said to be electrophilic ("electron-loving"). Explain why. 1-furoic acid B. I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand. Start with the Aromaticity Review + Videos, then see how. Methyl benzoate undergoes a nitration by electrophilic aromatic substitution when reacted with a mixture of concentrated nitric and sulfuric acids. Activated is just the opposite, the rate of electrophilic substitution is faster than for benzene. Your mechanism must include curved arrows show the flow of electrons for all bonds made and broken. Become a member and unlock all Study Answers Try it risk-free for 30 days. place your cursor over the graphic and click on right arrow that appears to see the answer. Electrophilic Aromatic Substitution: Friedel-Crafts Acylation Study Questions 1) A carbocation produced during a Friedel-Crafts alkylation may undergo rearrangement. What have we learned? The aromatic ring behave as a nucleophile, and attacks an added electrophile An electron-deficient carbocation intermediate is formed (that is, the rate-determining step) which is then deprotonated to restore aromaticity electron-donating groups on the. Choose from 500 different sets of electrophilic aromatic substitution flashcards on Quizlet. 8 Nucleophilic Substitution and Elimination Reactions pair. So negative 1 formal charge, it could function as a nucleophile. Try the following multiple choice questions to test your knowledge of this chapter. question? question? question? question? methyl group activates the benzene ring towards electrophilic aromatic substitution! question? relative rates other groups. Write the mathematical expression for the relation between heat of reaction at the constant pressure and constant volume Iist two properties of carbon due to which it is able to form numerous compounds Trans dioxilato diaqua chromate 3 ions ka structure 1 mole of n2o4 was sealed in a tube under one atmospheric conditions at 25c. Therefore the reactions take place at the most electron rich carbons in an aromatic ring. RELATIVE RATES OF ELECTROPHILIC AROMATIC SUBSTITUTION Juris Marie G. I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand. Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. BUT, two questions. Thin Layer Chromatography and Melting Point; Extraction; Recrystallization; Distillation; Isolation of Limonene; Regiochemistry of Eliminations; Oxidation of Alcohols; Epoxidation of Cholesterol; Diels-Alder Reaction; Electrophilic Aromatic Substitution; Microscale Column Chromatography; Identification of Unknowns. The N-arylation of aniline derivatives is a useful reaction for implementing nucleophilic aromatic substitution into the undergraduate curriculum. The electrophilic aromatic substitution reaction nitration is used to nitrate methyl benzoate and acetanilide with a nitronium ion. As a result, the meta hydrogen is substituted. Answer to: Devise an efficient synthesis for the product using the starting aromatic source. p-isopropyltoluene B. What is the electrophile, E+ in this case and what is the base? 2. Therefore the electrophilic aromatic substitution reaction will occur at the meta position giving 3-nitrophenyl ethanoate. electrophilic aromatic substitution reaction is as follows, where E is the electrophile: (Note that in this reaction and in others that follow, only one of the six benzene hydrogens is shown explicitly to emphasize that one hydrogen is lost in the reaction. ) Electrophilic Aromatic Substitution Mechanism: Please fill in the following structures depicting the correct mechanism. Electrophilic Substitution, Benzene Mechanism - Organic Chem In this video we want to discuss the electrophilic substitution mechanism of benzene using 2 reactions as example. Alone, nitric acid is not a strong enough electrophile to react with bromobenzene. Please note. Friedel Crafts Alkylation and Acylation Reaction Mechanism - Electrophilic Aromatic Substitution - Duration: 20:11. Which of the following is a secondary (2°) alcohol? A) I B) II C) III D) IV E) V 2. Understand and be able to draw the mechanism of an Electrophilic Aromatic Substitution (EAS) reaction, Nucleophilic Aromatic Substitution (S N Ar), and an Elimination-Addition mechanism. 1), 2) and 3) b. NOZ A) I B) II C) III D) IV. I think both of these are rather broad categories as. If a question looks completely unfamiliar to you leave it out. CHEM 2P20 Study Guide - Midterm Guide: Benzoic Acid, Electrophilic Aromatic Substitution, Nucleophile Exam. 8% CH3 NO2 0. electrophilic aromatic substitution reaction is as follows, where E is the electrophile: (Note that in this reaction and in others that follow, only one of the six benzene hydrogens is shown explicitly to emphasize that one hydrogen is lost in the reaction. water), a weaker electrophile (Br+) is produced that undergoes electrophilic aromatic substitution with the benzene ring. Basically, electrophilic addition is the same thing as nucleophilic addition; just different jargon. Jul 1, 2019 - Benzene has 3 π bonds and as expected shows some similarities to alkenes in being reactive towards electrophilic species. 3 > 5 > 2 > 4 > 1. Do not draw hydrogen atoms. The reaction to form 4-nitroacetanilide is an electrophilic aromatic substitution. 10pts Chapter 8 Questions 1. c is an activator and a m-director d. D)is an activator and an o,p-director. Which of the following is a secondary (2°) alcohol? A) I B) II C) III D) IV E) V 2. (vi) Electrophilic Aromatic Substitution Reactions - SAQs (vii) Electrophilic Aromatic Substitution in substituted benzene derivatives - an introduction (viii) Electrophilic Aromatic Substitution in substituted benzene derivatives – reactivity compared to benzene itself (ix) Orientation of Substitution in C 6 H 5 Y (x) Electrophilic Aromatic. CCl 4) induces a weaker dipole in Br-Br as compared to the polar solvent (i. furanylcarboxylic acid D. The electrophilic aromatic substitution reaction nitration is used to nitrate methyl benzoate and acetanilide with a nitronium ion. Which potential energy reaction diagram best describes the three steps in this reaction? 6. The actual electrophile here is SO3. This diazonium salt undergoes electrophilic aromatic substitution on activated aromatic rings to yield brightly colored azo compounds that are widely used as dyes. Multiple choice questions. The African Virtual University (AVU) is a Pan African Intergovernmental Organization established. Hence, it undergoes. Qu 1: What are the major products of the following reactions ? (a) (b) (c) Qu 2: (a) Arrange the following in according to their relative rate of reaction with bromine / Fe. 31)When pyrrole undergoes electrophilic aromatic substitution, at which position does substitution occur? A)2-position B)4-position C)3-position 31) 32)Which of the following chloropyridines readily undergo nucleophilic substitution upon treatment. Answer:Formation of a sigma complex. An electrophilic aromatic substitution reaction starts in an alike way. Para - directing in electrophilic aromatic substitution reaction. 8 Nucleophilic Substitution and Elimination Reactions pair. Answer:Formation of a sigma complex. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. The -O- atom with it's lone pairs next to the ring makes this an electron donor, so ortho- and para- substitution occurs. Using the reactions of Objective 1, propose syntheses of substituted aromatic derivatives. that is IF you truly understand, not merely memorize: when you know what to look for to identify aromatic, antiaromatic and non aromatic compounds. by charter with the mandate of significantly increasing access to quality higher education and. a) NO 2 + b) CH 3 CH 2 + c) SO 3 H + d) CH 3 CO + This site is written and maintained by Chris P. Rather, aromatic double bonds undergo electrophilic substitution reactions, (abbreviated S E Ar), which are mechanistically very similar to the substitutive addition-elimination reactions of alkenes. Show all electron flow with arrows for this mechanism on the structures provided. Pyridine undergoes electrophilic aromatic substitution at the C3 position. This response as to the regioselectivity of the electrophilic aromatic substitution of indole left me with a few more questions than it did answers. Free redical substitution. Electrophilic Aromatic Substitution reaction-[EAS] It is a reaction in which one of the aromatic hydrogen atoms are replaced by another atom such as a halogen or group of atoms such as a nitro, or view the full answer. ) All electrophilic aromatic substitution reactions occur by similar mechanisms. First, the aromatic ring attacks an electrophile. Draw in all of the curly arrows and any required charges to complete the step-by-step mechanisms for each of the following reaction schemes. training through the innovative use of information communication technologies. 5 Penn Plaza, 23rd Floor New York, NY 10001 Phone: (845) 429-5025 Email: [email protected] Electrophilic substitution in case of aromatic amines takes place more readily than in benzene. The question asks to order by reaction rate of electrophilic aromatic substitution in marked carbons. First, benzene is very stable and thus less reactive. Arrange relative rates of electrophilic aromatic substitution in order of increasing reactivity they are reacted with Br2 in acetic acid, can you please explain it to me Diphenylamine Diphenylether 4-bromophenol Phenol Nitrobenzene Anisole Bromobenzene Benzoic Acid Acetanilide 4-hydroxybenzoic acid. Organic Chemistry. Electrophilic Aromatic Substitution Answers Qu 1 (a) First a Friedel-Crafts alkylation reaction using EtCl to add an Et group to the benzene followed by a radical bromination at the 2 o benzylic position (since it is the most stable radical), to give 1-bromo-1-phenylethane. Answer questions. CHEM 242 - Electrophilic Aromatic Substitution Post-Lab Questions Post-lab Questions: Answer these post-lab questions neatly and concisely on the back of the lab report sheet. B) Nucleophilic aromatic substitution by elimination-addition. ABSTRACT: The electrophilic aromatic substitution reaction is the attack of a benzene ring on an electrophilic species resulting in the substitution of a proton with a functional group. Electrophilic substitution is characteristic of aromatic compounds. First, the aromatic ring attacks an electrophile. The hard part of the reaction is already done. Electrophilic aromatic substitution: Aromatic compounds Directing effects: Aromatic compounds Other reactions and synthesis: Community questions. Question: Question 10 What Will Be The Site That Leads To The Major Mono Substitution Product For An Electrophilic Aromatic Substitution Reaction Of The Following Compound? U NHCOCH3. Abstract from Australian Conference on Science and Mathematics Education, Clayton, Australia. Rijksuniversiteit Groningen. Identify the following components of this reaction. calculate the number of moles of no2 present if the equilibrium 1. An illustration describing the electrophilic substitution of a hydrogen atom (belonging to a benzene molecule) with a chlorine atom is provided below. These acids will form complexes with the amine and deactivate the ring and convert the o/p-directing amino group into a m-directing ammonium ion (-NH3+) group. Choose the one alternative that best completes the statement or answers the question. Electrophilic aromatic substitution is an important way of introducing functional groups on benzene rings. Solvation trend: 3 O halide > 2 O halide > 1 O halide > vinylic halide. Practice Questions on Aromatic Substitution. «Previous Next ». Qu 1: What are the major products of the following reactions ? (a) (b) (c) Qu 2: (a) Arrange the following in according to their relative rate of reaction with bromine / Fe. The −NH 2 group is listed in our textbook as the strongest o,p -directing activator in electrophilic aromatic substitution reactions. Organic II Chemistry - Electrophilic Aromatic Substitution (EAS) Worksheet Complete the resonance structures for each sigma complex resulting from electrophilic aromatic substitution at the ortho, meta, and para positions as shown below. List the procedural steps in order to convert methyl benzoate into methyl nitrobenzoate. Best Answer: The ethyl group will dontate electron density in by hyperconjugation, the Nitro group is electron withdrawing, the nitrogen isposiitve and wants some electrons. CCl 4) induces a weaker dipole in Br-Br as compared to the polar solvent (i. The aromatic ring can donate a lone pair of electrons d. Answers is the place to go to get the answers you need and to ask the questions you want para directing in electrophilic aromatic substitution generally it under goes electrophilic. Some nucleophilic aromatic substitution reactions occur via a two-step mechanism in which the first step, by definition, is an addition and the second step an elimination. So negative 1 formal charge, it could function as a nucleophile. Garcia Institute of Chemistry, University of the Philippines, Diliman, Quezon City Date Performed: February 27, 2015 Date Submitted: March 13, 2015 Answers to Questions: 1. With this in mind, draw the curved arrow mechanism for the first step of the electrophilic aromatic substitution of naphthalene with l^+ generated from l_2 and. Rank the following aromatic compounds in order of reactivity towards electrophilic aromatic substitution (from most reactive to least reactive): A. Please note. A would be the first one, and D the last one, that's easy since R2N is strong activator (ortho-. an example of an electrophilic aromatic substitution (Friedel-Crafts Alkylation) that incorporates the effect of substitution of the aromatic ring into the experiment. I have seen the reaction between benzene and Br2/FeBr3, also I have seen the reaction between benzene and Cl2/AlCl3. m-isopropyltoluene D. question? question? question? question? methyl group activates the benzene ring towards electrophilic aromatic substitution! question? relative rates other groups. In this procedure, the positive charge of the electrophile is to be shifted to the adjacent ring carbon atom that is termed carbocation. Answer the following questions and then press 'Submit' to get your score. Let's look at the possibility of a nucleophilic aromatic substitution. • Provide the mechanisms of each of the five electrophilic aromatic substitution reactions with benzene. Pearsons Prentice Hall Filesize: 354 KB. E E E E E H. Alkyl groups activate the ring. To enhance this initial addition a. We've done a lot of electrophilic aromatic substitution reactions. Which of the following is a secondary (2°) alcohol? A) I B) II C) III D) IV E) V 2. Answer: b Explanation: Because the non-polar solvent (i. I'm going to discuss a general mechanism for the electrophilic substitution first then focus in on the peculiarities of the different examples quoted in. Mechanisms Halogenation. Why a mixture in this case ?? (assuming 1:1) o,p-directing groups win. [Note: the identity of the electrophile E is specific to each reaction, and generation of the active electrophile is a mechanistic step in itself. C) a deactivator and an o,p-director. In contrast to arenas, aliphatic hydrocarbons do not undergo nitration. all of the above d. Through inductive effect, chlorine destabilises the intermediate carbocation formed during the Electrophilic substitution Through resonance, halogen tends to stabilise the carbocation and the effect is more pronounced at ortho-and Para-position. , College of Saint Benedict / Saint John's University (with contributions from other authors as noted). Pyridine undergoes electrophilic aromatic substitution at the C3 position. Scribd is the world's largest social reading and publishing site. - Aromatic compounds with electron donating groups have most of their electron density on the ortho and para positions, so these react at the ortho and para positions. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. a) NO 2 + b) CH 3 CH 2 + c) SO 3 H + d) CH 3 CO + This site is written and maintained by Chris P. Answer the following questions and then press 'Submit' to get your score. Ask just about any Simple Aromatic Ring question to be answered by millions of our community from across the world. Electrophilic Substitution. For example, the π-bond in 1-hexene is brominated to give 1,2-dibromohexane, while. Organic Chemistry. An with benzenes, that is electrophilic aromatic substitution, which generates a strong electrophile that is desperately seeking electrons from the stable benzene ring. The increasing order of reactivity of the following compounds towards aromatic electrophilic substitution reaction is : asked May 14, 2019 in Chemistry by Ruksar ( 68. 143 Lecture Notes Chem 51B S. Data was analysed by marking the electrophilic aromatic substitution question, generating a mean confidence quotient from diagnostic tests and coding interviews. Do not draw hydrogen atoms. I really need to understand this substitution. chapter 18: electrophilic aromatic substitution what is the first step in the general mechanism for electrophilic aromatic substitution? protonation of the. What is the electrophile, E+ in this case and what is the base? 2. We can picture this in a general way as a heterolytic bond breaking of compound X:Y by an electrophile E such that E becomes bonded to Y by the electron pair of the XY bond. The benzene are sulphonated using acid sufuric. Electrophilic Aromatic Substitution, Intro (13 min) click on right arrow that appears to see the answer. Electrophilic Addition to 1,1-Diphenylethylene and Electrophilic Aromatic Substitution of Acetanilide questions I have to calculate the percent yield for each reaction but I am a bit unsure of some things. Answer: b Explanation: Because the non-polar solvent (i. In the first, slow or rate-determining, step the electrophile forms a sigma-bond to the benzene ring. electrophilic aromatic substitution of benzene. Consider the data below to answer the following question(s). Question about the Electrophilic Aromatic Substitution reaction? Aromatic compounds with electron donating groups have most of their electron density on the ortho and para positions, so these react at the ortho and para positions. Hydrohalogenation, addition of H-Cl, H-Br or H-I. In electrophilic aromatic substitution reactions a bromine substituent: a. Answer the following questions and then press 'Submit' to get your score. So we have to find where do positive and charges. b) Friedel-Crafts alkylation of benzene can be reversible. a) NO 2 + b) CH 3 CH 2 + c) SO 3 H + d) CH 3 CO + This site is written and maintained by Chris P. 3-furoic acid 17. Become a member and unlock all Study Answers Try it risk-free for 30 days. The increasing order of the reactivity of the following compounds towards electrophilic aromatic substitution reactions is: Option 1)II < I < IIIOption 2)III < II < IOption 3)III < I < IIOption 4)I < III < II. Answer to One ring of phenyl benzoate undergoes electrophilic aromatic substitution much more readily than the other. 22) to assess relative rates. The electrophilic aromatic substitution reaction nitration is used to nitrate methyl benzoate and acetanilide with a nitronium ion. Housecroft and E. Organic Chemistry. REACTIONS OF AROMATIC COMPOUNDS Electrophilic Aromatic Substitution: The mechanism of many reactions of aromatic compounds are explained by minor variations of electrophilic aromatic substitution. The use of a mixture of Sulfuric Acid and Nitric Acid is the "classic" way to make the Nitronium Ion (NO2+). King Chapter 18 Electrophilic Aromatic Substitution I. 2) Explain why reaction of benzene with Br2/FeBr3 results in the product bromobenzne instead of 5,6-dibromo-1,3-cyclohexadiene. Using the reactions of Objective 1, propose syntheses of substituted aromatic derivatives. benzene doesn't respond nucleophilic substitution respond electrophilic substitution it is electrophilic then due to resonance there is a partial double bond between. Electrophilic Aromatic Substitution: Friedel-Crafts Acylation Study Questions 1) A carbocation produced during a Friedel-Crafts alkylation may undergo rearrangement. Sn1 Sn2 E1 E2 Multiple Choice Questions. 3 > 5 > 2 > 4 > 1. The increasing order of the reactivity of the following compounds towards electrophilic aromatic substitution reactions is: Option 1)II < I < IIIOption 2)III < II < IOption 3)III < I < IIOption 4)I < III < II. Answer: b Explanation: The solvation of above compound can be compared by this trend, i. Jul 1, 2019 - Benzene has 3 π bonds and as expected shows some similarities to alkenes in being reactive towards electrophilic species. reactions. " The Final Learning Experience Friday - Monday, May 9 - 13, 2002, Take-Home Publish May 9, 8pm & collect May 13, 5:30pm, 321 Chem. Practice Questions on Aromatic Substitution. C)is a deactivator and a m-director. 4 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF BENZENE 755 Step 2 Reaction of the benzene p electrons with the electrophile to form a carbocation inter- mediate. 3 > 5 > 2 > 4 > 1. The increasing order of the reactivity of the following compounds towards electrophilic aromatic substitution reactions is : asked May 15, 2019 in Chemistry by Ruksar (68. Write the word or phrase that best completes each statement or answers the question. c is an activator and a m-director d. The nitration and bromination both are electrophilic. Our mission is to provide a free, world-class education to anyone, anywhere. Electrophilic Aromatic Substitution Mechanism - Master Organic Chemistry Let's review what we know so far and propose a mechanism for electrophilic aromatic substution. pdf), Text File (. Rank the following aromatic compounds in order of reactivity towards electrophilic aromatic substitution (from most reactive to least reactive): A. Why is a hydroxyl group more activating than a methoxy group in electrophilic aromatic substitution? Why is phenol more reactive towards electrophilic substitution than methoxybenzene? Isn't the lone pair on the methoxy group oxygen more available for participating in resonance into the ring than. (a) Which one is it? (b) Explain your answer Students also viewed these Organic Chemistry questions. An electrophile — an electron‐seeking reagent — is generated. E)none of the above 13) SHORT ANSWER. do not bother placing all of the lone pairs of electrons on the F atoms, but be sure to place them on all other atoms as nedded. Once you have answered the questions, click on. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. Activated is just the opposite, the rate of electrophilic substitution is faster than for benzene. The study of aromatic heterocyclic reactivity can be said to have begun with the results of electrophilic substitution processes. Reagents that acquire an electron pair in chemical reactions are said to be electrophilic ("electron-loving"). m-isopropyltoluene D. Although chlorine is an electron withdrawing group, yet it is ortho-, paradirecting in electrophilic aromatic substitution reaction Explain why it is so answer fast - Chemistry - NCERT Solutions Board Paper Solutions. B) a deactivator and a m-director. We can picture this in a general way as a heterolytic bond breaking of compound X:Y by an electrophile E such that E becomes bonded to Y by the electron pair of the XY bond. 1-furoic acid B. In an electrophilic aromatic substitution reaction, the aromatic ring must be the nucleophile. Trole undergoes nitration by electrophilic aromatic substitution. i think the question is wrong. The study of aromatic heterocyclic reactivity can be said to have begun with the results of electrophilic substitution processes. Consider the data below to answer the following question(s). Question 1 Which of the following statements regarding electrophilic aromatic substitution is wrong? a) Sulfonation of toluene is reversible. Rijksuniversiteit Groningen. Loratadine (current news) 20 Question 2. Universiteit / hogeschool. Get an answer for 'One of these compounds will react more slowly with electrophiles in electrophilic aromatic substitution than benzene does, and one of them will react more quickly. Electrophilic Aromatic Substitution Reactions, Course Notes Archive, 4 Disclaimer: All images are borrowed from: Bruice, P. Substitution reaction of chemistry. If you draw the resonance structures of the neutral compounds, those. Answer: b Explanation: Because the non-polar solvent (i. When two substituents direct to the same position O CH3 NO 2 m-director o,p director HNO 3 H2SO 4 O CH 3 NO 2 NO2 major product CH3 NO2 NO2+ CH3 NO2 NO2 99. H3CO i) Would you expect the aromatic ring in compound A to be (choose one): (5 pts) a) deactivated by induction and resonance b) deactivated by induction but activated by resonance c) activated by induction but deactivated by resonance. Which of the following is a secondary (2°) alcohol? A) I B) II C) III D) IV E) V 2. 10pts Chapter 8 Questions 1. To be completed while reading Chapter 15. Reagents that acquire an electron pair in chemical reactions are said to be electrophilic ("electron-loving"). Reactions Practice Questions. aromatic electrophilic substitution reactions. The electrophilic aromatic substitution reaction of benzene can be represented as below. 22) to assess relative rates. Practicum chemie voor Levenswetenschappen (WLB07101) Academisch jaar. (Image) By signing up, you'll get thousands of. furanylcarboxylic acid D. Incorrect! The carbocation intermediate formed in electrophilic aromatic substitution reactions is a benzenium ion. When two substituents direct to the same position O CH3 NO 2 m-director o,p director HNO 3 H2SO 4 O CH 3 NO 2 NO2 major product CH3 NO2 NO2+ CH3 NO2 NO2 99. 62) In electrophilic aromatic substitution reactions, a -CO2 H substituent on the aromatic ring is: A) an activator and a m-director. Each of the following are classified as reactions that occur by an electrophilic aromatic substitution mechanism. ) NO2 Putting the positive charge next to the nitro group is a particularly bad situation. Answer: b Explanation: The solvation of above compound can be compared by this trend, i. Because the starting point in an S E Ar reaction is inherently low in energy (due to aromaticity), the activation. 1 Answer to Pyrrole undergoes electrophilic aromatic substitution more readily than benzene, and mild reagents and conditions are sufficient. Best Answer: The ethyl group will dontate electron density in by hyperconjugation, the Nitro group is electron withdrawing, the nitrogen isposiitve and wants some electrons. reactivity in electrophilic aromatic substitution. Answers outside the provided box will not receive credit. Mechanisms Halogenation. A: The question of directing effect is not relavant to nucleophilic aromatic substitution. d) Acetylation of benzene with acetic anhydride requires more than one equivalent of a Lewis acid. Explain why it is so ? $\begin{array}{1 1}\text{(a) Chlorine. 7k points) jee mains 2019 (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students. All electrophilic aromatic substitution reactions share a common mechanism. Answer to: Devise an efficient synthesis for the product using the starting aromatic source. txt) or view presentation slides online. (Image) By signing up, you'll get thousands of. Pyrrole undergoes electrophilic aromatic substitution mainly at 2-Position and 5-Position. a) An electrophile is a species (a positive ion or the slightly positive end of a polar molecule) which is attracted to electron-rich areas of other molecules. To be completed while reading Chapter 15. benzene doesn't respond nucleophilic substitution respond electrophilic substitution it is electrophilic then due to resonance there is a partial double bond between. Data was analysed by marking the electrophilic aromatic substitution question, generating a mean confidence quotient from diagnostic tests and coding interviews. Ethers possess a net dipole moment even if the alkyl radicals in the molecule is identical. Such reactions are used for the synthesis of important intermediates that can be used as precursors for the production of pharmaceutical , agrochemical and industrial products. properties and reactions of arenes (aromatic hydrocarbons). " The Final Learning Experience Friday - Monday, May 9 - 13, 2002, Take-Home Publish May 9, 8pm & collect May 13, 5:30pm, 321 Chem. These acids will form complexes with the amine and deactivate the ring and convert the o/p-directing amino group into a m-directing ammonium ion (-NH3+) group. Loratadine (current news) 20 Question 2. This intermediate is stabilized by resonance. It answers the question "where will a reaction take place on the benzene ring if it already contains a substituent?" (Runtime = 24:18). reactivity. Practical, Electrophilic aromatic substituion of salicylamide, Questions and answers. 1 Explain why electrophilic additions are among the most common reactions of alkenes. Best Answer: The ethyl group will dontate electron density in by hyperconjugation, the Nitro group is electron withdrawing, the nitrogen isposiitve and wants some electrons. electrophilic aromatic substitution) Directing effect if more than one substituent is present. electrophilic aromatic substitution. The reaction to form 4-nitroacetanilide is an electrophilic aromatic substitution. The benzene are sulphonated using acid sufuric. a) An electrophile is a species (a positive ion or the slightly positive end of a polar molecule) which is attracted to electron-rich areas of other molecules. Question 1 Which of the following statements regarding electrophilic aromatic substitution is wrong? a) Sulfonation of toluene is reversible. However, there are two key differences between their reactions with electrophiles. Under what reaction conditions does the electrophilic chlorination of aromatic compounds usually occur? Electrophilic Substitution. Draw the mechanism of electrophilic aromatic substitution.