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Use uppercase for the first character in the element and lowercase for the second character. Answer (1 of 7): Agree with Dr. Luong, however I'd note two points: (1) that the reaction is preferably called an elimination, rather than a dehydration, although I personally like the term dehydration because it emphasizes the strong dehydrating power of H2SO4 that is unfotunately forgotten t. How Do We Know Methane (CH4) Is Tetrahedral? a =CH_2. Use the calculator below to balance chemical equations and determine the type of reaction (instructions). The final class of alcohols to be concerned about is primary alcohols. With a tertiary alcohol like the one drawn below, this proceeds through an SN1 mechanism. The carbocation itself is the (alpha) carbon]. Learn how your comment data is processed. A wide variety of basic nucleophiles can be used for the ring opening of an epoxide including, amines, hydrides, Grignard reagents, acetylide anions, and hydride. Plus there is heat involved in the reaction..which is favourable for elimination reactionsthank u n feel free to correct if wrong. identify the product formed from the reaction of a given epoxide with given base. However, there is a reaction called the Corey-Winter reaction that will reduce diols to alkenes. A carbon-carbon triple bond may be located at any unbranched site within a carbon chain or at the end of a chain, in which case it is called terminal.Because of its linear configuration ( the bond angle of a sp-hybridized carbon is 180 ), a ten-membered carbon ring is the smallest that can accommodate this function without excessive strain. This is an E1 process[elimination (E) , unimolecular (1) rate determining step]. Propose the mechanism of the following chemical reaction. Reactants are H2SO4 and heat. HSO,methyl hydrogen sulphate is obtained in first step.This on further treatment with another mole of methanol gives methoxy methane along with HSO. Step 1: Electrophilic attack of H 3 O + to the alkene, carbocation intermediate formed. Attack takes place preferentially from the backside (like in an SN2 reaction) because the carbon-oxygen bond is still to some degree in place, and the oxygen blocks attack from the front side. For example, C6H5C2H5 + O2 = C6H5OH + CO2 + H2O will not be balanced, but XC2H5 + O2 = XOH + CO2 + H2O will. Under the reaction conditions, I readily decomps. A: The Grignard reaction is an organometallic chemical reaction in which alkyl, allyl, vinyl, or question_answer Q: Propose a mechanism for the following reaction: Give the mechanism of the following reaction: Give a mechanism for the following reaction. Acid makes the OH a better leaving group, since the new leaving group will be the weaker base H2O, not HO(-). Step 3: Deprotonation to get neutral product. Step 2: Loss of water as the leaving group to create a Our experts can answer your tough homework and study questions. 14 Kinetics Rates of Reaction Integrated Rate Laws Activation Energy Reaction Mechanisms Catalysts Experiments Common Mistakes to Avoid Review Questions Rapid Review . Recall that alkyl substituents can donate electron density through hyper conjugation and stabilize a positive charge on a carbon. [Protonation of alcohol, then loss of H2O to form a carbocation, then attack of nucleophile on carbocation]. provide the mechanism of the organic reaction bellow. These solvents also act as nucleophiles. This is the pattern of an elimination reaction. This lesson introduces the organic functional group ethers, and ethers' preparation from an alkoxide ion. Epoxides can also be opened by other anhydrous acids (HX) to form a trans halohydrin. Let us examine the basic, SN2 case first. In Step 2, the alcohol attacks the carbocation and forms an oxonium ion. please check the formulas of acids and their corresponding anions in the text; some appear like this: H2SO4 as acid (or H3PO4 (they are written correctly in the images). The proton becomes attached to one of the lone pairs on the oxygen which is double-bonded to the carbon. Chemical Properties of Ethers (with H2SO4) On heating with dilute sulfuric acid under pressure, ethers are hydrolysed to alcohols. Please show the mechanism of the following reactions. It is OK to show the mechanism with H^+ instead of H_2SO_4. Get more out of your subscription* Access to over 100 million course-specific study resources; 24/7 help from Expert Tutors on 140+ subjects; Full access to over 1 million Textbook Solutions Under aqueous basic conditions the epoxide is opened by the attack of hydroxide nucleophile during an SN2 reaction. The solvent has two functions here: 1) It serves as the source of a proton (H +) once the reduction is complete. Predict the major product(s) of the ring opening reaction that occurs when the epoxide shown below is treated with: Hint: be sure to consider both regiochemistry and stereochemistry! Write a mechanism for the following reaction. Provide the synthesis of the following reaction. Maybe they should call them, "Formal Wins" ? But strong acid can lead to complications (carbocation rearrangements, cough cough) and we might ask: isnt there an easier way? The nonenzymatic ring-opening reactions of epoxides provide a nice overview of many of the concepts we have seen already in this chapter. Why Are Endo vs Exo Products Favored in the Diels-Alder Reaction? There should be two key carbocation intermediates and arrows should be used correctly. (10 pts) H2SO4 CH3OH. Arrow-pushing Instructions no XT . In Step 1, a hydronium or oxonium ion is attacked by the bond.. The second step of the mechanism involves the protonation of the alkoxide to form an alcohol. (Remember stereochemistry). Label each compound (reactant or product) in the equation with a variable to represent the unknown coefficients. If we add a strong base here (to perform an E2) it will just end up neutralizing this species. The reaction of cyclohexanol with (1) H_2SO_4 + heat, followed by (2) H_2, Pt. William Reusch, Professor Emeritus (Michigan State U. You might ask: if we treat a primary alcohol (say, 1-butanol) with a strong acid like H2SO4, will also get elimination to an alkene? It *can* be true that rearrangements of tertiary carbocations occur, but generally only in situations where they would be more stabilized (e.g. Complete and write a mechanism for the following reaction. I posted a message a few days ago, but somehow it was erased. After protonation of OH, the phenyl group acts as an internal nucleophile, leading to a bridged intermediate. Your email address will not be published. Weve seen this type of process before actually! For that reason we usually just stick to H2SO4 or H3PO4! However, if one of the epoxide carbons is tertiary, the halogen anion will primarily attack the tertialy cabon in a SN1 like reaction. Here is the reaction off. If the epoxide is asymmetric, the structure of the product will vary according to which mechanism dominates. 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"showtoc:no", "license:ccbyncsa", "cssprint:dense", "licenseversion:40" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FAthabasca_University%2FChemistry_360%253A_Organic_Chemistry_II%2FChapter_18%253A_Ethers_and_Epoxides_Thiols_and_Sulfides%2F18.06_Reactions_of_Epoxides%253A_Ring-opening, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), Epoxide ring-opening reactions - SN1 vs. SN2, regioselectivity, and stereoselectivity, status page at https://status.libretexts.org. The carboxyl carbon of the carboxylic acid is protonated. Become a Study.com member to unlock this answer! Step 1: Protonation of the hydroxy group. Select Draw Ring H CI CH;CH,C=CCH, CH, + 2Cl, . Provide the structure of the product of the following reaction. We formed C-C () and broke C-OH and C-H. (We also formed H-O , in that molecule of water that formsas a byproduct). Predict the product and provide the mechanism for the following reaction. This hydration of an epoxide does not change the oxidation state of any atoms or groups. Learning New Reactions: How Do The Electrons Move? If the alcohol is a primary or secondary alcohol, this can then be oxidized to an aldehyde or ketone, or onwards. ; If a strong acid such as H 2 SO 4 or p-TsOH is used, the most likely result is . Next Post: Elimination Of Alcohols To Alkenes With POCl3. Unlike in an SN1 reaction, the nucleophile attacks the electrophilic carbon (step 3) before a complete carbocation intermediate has a chance to form. What's The Alpha Carbon In Carbonyl Compounds? Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Ring-opening reactions can proceed by either S N 2 or S N 1 mechanisms, depending on the nature of the epoxide and on the reaction conditions. It covers the E1 reaction where an alcohol is converted into an alkene. What happens if you use two cis or trans OH in the educt? Nonpolar? If the epoxide is asymmetric, the structure of the product will vary according to which mechanism dominates. There should be two key carbocation intermediates and arrows should be used correctly. CuO + H2SO4 arrow. C. nucleophilic attack is the only step. The carbon-bromine bond is a polar covalent bond. Diels-Alder Reaction: Kinetic and Thermodynamic Control, Regiochemistry In The Diels-Alder Reaction, Electrocyclic Ring Opening And Closure (2) - Six (or Eight) Pi Electrons, Aromatic, Non-Aromatic, or Antiaromatic? Balance the equation CH3OH + H2SO4 = (CH3)2SO4 + H2O using the algebraic method. Balance CH3OH + H2SO4 = (CH3)2SO4 + H2O by inspection or trial and error with steps. Indeed, larger cyclic ethers would not be susceptible to either acid-catalyzed or base-catalyzed cleavage under the same conditions because the ring strain is not as great as in the three-membered epoxide ring. Concentrated HNO3 contains some NO2+ which is an excellent electrophile, which the alcohol can add to, leading to R-ONO2 . When an asymmetric epoxide undergoes alcoholysis in basic methanol, ring-opening occurs by an SN2 mechanism, and the less substituted carbon is the site of nucleophilic attack, leading to what we will refer to as product B: Conversely, when solvolysis occurs in acidic methanol, the reaction occurs by a mechanism with substantial SN1 character, and the more substituted carbon is the site of attack. This is an electrophilic addition reaction. Draw the mechanism of the following reaction shown below: Draw a stepwise mechanism for the following reaction. (a) HBr (b) H_2SO_4 (c) CrO_3. The str. Phosphoric acid (H3PO4) as well as tosic acid (p-toluenesulfonic acid) also tend to form elimination products. sorry I put my e mail wrong, posting my question again. All About Solvents, Common Blind Spot: Intramolecular Reactions, The Conjugate Base is Always a Stronger Nucleophile, Elimination Reactions (1): Introduction And The Key Pattern, E1 vs E2: Comparing the E1 and E2 Reactions, Antiperiplanar Relationships: The E2 Reaction and Cyclohexane Rings, E1cB - Elimination (Unimolecular) Conjugate Base, Elimination (E1) Practice Problems And Solutions, Elimination (E2) Practice Problems and Solutions, Rearrangement Reactions (1) - Hydride Shifts, Carbocation Rearrangement Reactions (2) - Alkyl Shifts, The SN1, E1, and Alkene Addition Reactions All Pass Through A Carbocation Intermediate, Identifying Where Substitution and Elimination Reactions Happen, Deciding SN1/SN2/E1/E2 (1) - The Substrate, Deciding SN1/SN2/E1/E2 (2) - The Nucleophile/Base, Deciding SN1/SN2/E1/E2 (4) - The Temperature, Wrapup: The Quick N' Dirty Guide To SN1/SN2/E1/E2, E and Z Notation For Alkenes (+ Cis/Trans), Addition Reactions: Elimination's Opposite, Regioselectivity In Alkene Addition Reactions, Stereoselectivity In Alkene Addition Reactions: Syn vs Anti Addition, Alkene Hydrohalogenation Mechanism And How It Explains Markovnikov's Rule, Arrow Pushing and Alkene Addition Reactions, Addition Pattern #1: The "Carbocation Pathway", Rearrangements in Alkene Addition Reactions, Alkene Addition Pattern #2: The "Three-Membered Ring" Pathway, Hydroboration Oxidation of Alkenes Mechanism, Alkene Addition Pattern #3: The "Concerted" Pathway, Bromonium Ion Formation: A (Minor) Arrow-Pushing Dilemma, A Fourth Alkene Addition Pattern - Free Radical Addition, Summary: Three Key Families Of Alkene Reaction Mechanisms, Palladium on Carbon (Pd/C) for Catalytic Hydrogenation, OsO4 (Osmium Tetroxide) for Dihydroxylation of Alkenes, Synthesis (4) - Alkene Reaction Map, Including Alkyl Halide Reactions, Acetylides from Alkynes, And Substitution Reactions of Acetylides, Partial Reduction of Alkynes With Lindlar's Catalyst or Na/NH3 To Obtain Cis or Trans Alkenes, Hydroboration and Oxymercuration of Alkynes, Alkyne Reaction Patterns - Hydrohalogenation - Carbocation Pathway, Alkyne Halogenation: Bromination, Chlorination, and Iodination of Alkynes, Alkyne Reactions - The "Concerted" Pathway, Alkenes To Alkynes Via Halogenation And Elimination Reactions, Alkyne Reactions Practice Problems With Answers, Alcohols Can Act As Acids Or Bases (And Why It Matters), Ethers From Alkenes, Tertiary Alkyl Halides and Alkoxymercuration, Epoxides - The Outlier Of The Ether Family, Alcohol Oxidation: "Strong" and "Weak" Oxidants, Demystifying The Mechanisms of Alcohol Oxidations, Intramolecular Reactions of Alcohols and Ethers, Calculating the oxidation state of a carbon, Oxidation and Reduction in Organic Chemistry, SOCl2 Mechanism For Alcohols To Alkyl Halides: SN2 versus SNi, Formation of Grignard and Organolithium Reagents, Grignard Practice Problems: Synthesis (1), Organocuprates (Gilman Reagents): How They're Made, Gilman Reagents (Organocuprates): What They're Used For, The Heck, Suzuki, and Olefin Metathesis Reactions (And Why They Don't Belong In Most Introductory Organic Chemistry Courses), Reaction Map: Reactions of Organometallics, Degrees of Unsaturation (or IHD, Index of Hydrogen Deficiency), Conjugation And Color (+ How Bleach Works), UV-Vis Spectroscopy: Absorbance of Carbonyls, Bond Vibrations, Infrared Spectroscopy, and the "Ball and Spring" Model, Infrared Spectroscopy: A Quick Primer On Interpreting Spectra, Diastereotopic Protons in 1H NMR Spectroscopy: Examples, Natural Product Isolation (1) - Extraction, Natural Product Isolation (2) - Purification Techniques, An Overview, Structure Determination Case Study: Deer Tarsal Gland Pheromone, Conjugation And Resonance In Organic Chemistry, Molecular Orbitals of The Allyl Cation, Allyl Radical, and Allyl Anion, Reactions of Dienes: 1,2 and 1,4 Addition, Cyclic Dienes and Dienophiles in the Diels-Alder Reaction, Stereochemistry of the Diels-Alder Reaction, Exo vs Endo Products In The Diels Alder: How To Tell Them Apart, HOMO and LUMO In the Diels Alder Reaction. In the diagram below, note how that negative charge is delocalized over three different oxygens [the same is true for the TsO and H2PO4 anions]. Longer answer: yes, but it depends on the concentration of HNO3 and the type of alcohol. Reactants. identify the product formed when an epoxide ring is opened by a hydrogen halide under anhydrous conditions. Reaction (2) because the ethyl sulde ion is a stronger nucleophile than the ethoxide ion in a protic solvent. Why we use H2SO4 in case of alcohols reacting with HBr and that of we use H3PO4 in case of alcohols reacting with HI . Draw a mechanism for the following reactions. I would assume that secondary alcohols can undergo both E1 and E2 reactions. Since there isnt a good nucleophile around, elimination occurs in such a way that the most substituted alkene is formed. Video transcript. Like in other SN2 reactions, nucleophilic attack takes place from the backside, resulting in inversion at the electrophilic carbon. Download Citation | Investigation of Cr-MIL-100 and Cr-MIL-101 activity and stability in amidation reaction of fatty acid methyl esters | Chromium containing metal-organic frameworks (MOFs) Cr . Propose a mechanism for the following transformation reaction. Provide a mechanism for the following reaction shown below. Draw the mechanism of the following reaction: Draw a mechanism for the following reaction. 2. Ring-opening reactions can proceed by either SN2 or SN1 mechanisms, depending on the nature of the epoxide and on the reaction conditions. The Hg(II) ion reacts with CH4 by an electrophilic displacement mechanism to produce an observable species, MeHgOSO3H (I). I have this doubt. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Download scientific diagram | (a1) Cyclic voltammograms of catalysts in 1 M H2SO4 at a scan rate of 50 mV s and (a2) calculated ECSA values; (b1-b2) Mass activities of MOR in a mixture of 0.5 . The H+ ions react with the water molecules to form the hydronium ions. of Hg22+ with H2SO4 to regenerate Hg(II) and byproducts SO2 and H2O. NaCN, 2. write an equation to describe the opening of an epoxide ring under mildly acidic conditions. The answer is that theHSO4 anion is a very poor nucleophile, being quite stabilized by resonance. Predict the product and provide the mechanism for the following reaction below. ), Virtual Textbook ofOrganicChemistry. What is the mechanism for the following reaction? So far weve learned two ways to convert alcohols to alkenes: Ideally, wed like to just use one step. Get more out of your subscription* Access to over 100 million course-specific study resources; 24/7 help from Expert Tutors on 140+ subjects; Full access to over 1 million Textbook Solutions Thank you for your keen eye, as always! Base makes the OH a better nucleophile, since RO(-) is a better nucleophile than the neutral alcohol ROH. By no means is H2SO4 the only acid that does this. What is the best mechanism for the following reaction? H_2SO_4, H_2O, What is the major product of this reaction? After deprotonation to reform the acid catalyst a 1,2-diol product is formed. Therefore the addition . Provide the mechanism of the following reaction. As we saw with the reactions of HCl, HBr, and HI with secondary alcohols, Elimination Of Alcohols To Alkenes With POCl, Valence Electrons of the First Row Elements, How Concepts Build Up In Org 1 ("The Pyramid"). (15 points) Write a complete mechanism for the reactions shown below. The air-water counterflowing heat exchanger given in earlier problem has an air exit temperature of 360 K 360 \mathrm{~K} 360 K.Suppose the air exit temperature is listed as 300 K 300 \mathrm{~K} 300 K; then a ratio of the mass flow rates is found from the energy equation to be 5 5 5.Show that this is an impossible process by looking at air and water temperatures at several locations inside . Createyouraccount. Label each compound (reactant or product) in the equation with a variable to represent the . HSO4- is an extremely poor nucleophile for the SN2. Replace immutable groups in compounds to avoid ambiguity. Provide a reasonable mechanism for the following reaction: Write a mechanism for the following reaction. predict the major product from the acidic cleavage of a given unsymmetrical epoxide. CH3OH + H2SO4 = (CH3)2SO4 + H2O might be a redox reaction. Predict the product of the following reaction. Reactants Reagents Products Help; Na2Cr2O7 H2SO4, H2O: Note: Oxidation of primary alcohols to carboxylic acids: Na2Cr2O7 H2SO4, H2O: Note: Oxidation of secondary alcohols to ketones: Na2Cr2O7 H2SO4, H2O: No Products Predicted. why elimination? First, look at what bonds formed and broke. In the discussion on basecatalyzed epoxide opening, the mechanism is essentially SN2. Since there are an equal number of atoms of each element on both sides, the equation is balanced. If you see a tertiary or secondary alcohol with H2SO4, TsOH, or H3PO4 (and especially if you see heat)think: carbocation formation followed by elimination reaction (E1). What type of reaction is this? Opening Epoxides With Aqueous Acid. why. The nucleophile itself is potent: a deprotonated, negatively charged methoxide ion. The result is anti-hydroxylation of the double bond, in contrast to the syn-stereoselectivity of the earlier method. Both substitution and elimination reactions of alcohols can be catalyzed by acid. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. CH3OH + H2SO4 = (CH3)2SO4 + H2O might be a redox reaction. However, if one of the epoxide carbons is tertiary, the halogen anion will primarily attack the tertiary carbon in an SN1 like reaction. The Third Most Important Question to Ask When Learning A New Reaction, 7 Factors that stabilize negative charge in organic chemistry, 7 Factors That Stabilize Positive Charge in Organic Chemistry, Common Mistakes: Formal Charges Can Mislead, Curved Arrows (2): Initial Tails and Final Heads, Three Factors that Destabilize Carbocations, Learning Organic Chemistry Reactions: A Checklist (PDF), Introduction to Free Radical Substitution Reactions, Introduction to Oxidative Cleavage Reactions, Bond Dissociation Energies = Homolytic Cleavage. Show all steps and all resonance forms for intermediates. Is it an example of kinetic vs thermodynamic control? Since it requires deprotonation to create a better leaving group, I would think not but Im not sure. Note: Please keep in mind that for the reaction that involves carbocation intermediate, the rearrangement of carbocation is always an option. write an equation to illustrate the cleavage of an epoxide ring by a base. Label each compound (reactant or product) in the equation with a variable . If Kw = 1.0 x 10^-14 then shouldnt the formation of H3O+ be very unfavorable? Step 2: Methanol reacts with the carbocation. c. 57. Label Each Compound With a Variable. Monochlorination Products Of Propane, Pentane, And Other Alkanes, Selectivity in Free Radical Reactions: Bromination vs. Chlorination, Types of Isomers: Constitutional Isomers, Stereoisomers, Enantiomers, and Diastereomers, Introduction to Assigning (R) and (S): The Cahn-Ingold-Prelog Rules, Assigning Cahn-Ingold-Prelog (CIP) Priorities (2) - The Method of Dots, Enantiomers vs Diastereomers vs The Same? explain why epoxides are susceptible to cleavage by bases, whereas other cyclic ethers are not. WOULD YOU MIND TELLING ME THE MECHANISM OF ALCOHOL and Me2C(OMe)2 and p-TsOH(CATALYST)?Thanks in advance, Its a way of forming a cyclic acetonide from a diol. The ions from the acids H2SO4 and HNO3 are SO42, NO3. Then the carbon-oxygen bond begins to break (step 2) and positive charge begins to build up on the more substituted carbon. Legal. However, if the epoxide is symmetrical, each epoxide carbon has roughly the same ability to accept the incoming nucleophile. HO Na2Cr207 H2SO4 /H20. Give the likely products of these reactions, and indicate whether methanol is acting in each as an acid or base. Some Practice Problems, Antiaromatic Compounds and Antiaromaticity, The Pi Molecular Orbitals of Cyclobutadiene, Electrophilic Aromatic Substitution: Introduction, Activating and Deactivating Groups In Electrophilic Aromatic Substitution, Electrophilic Aromatic Substitution - The Mechanism, Ortho-, Para- and Meta- Directors in Electrophilic Aromatic Substitution, Understanding Ortho, Para, and Meta Directors, Disubstituted Benzenes: The Strongest Electron-Donor "Wins", Electrophilic Aromatic Substitutions (1) - Halogenation of Benzene, Electrophilic Aromatic Substitutions (2) - Nitration and Sulfonation, EAS Reactions (3) - Friedel-Crafts Acylation and Friedel-Crafts Alkylation, Nucleophilic Aromatic Substitution (2) - The Benzyne Mechanism, Reactions on the "Benzylic" Carbon: Bromination And Oxidation, The Wolff-Kishner, Clemmensen, And Other Carbonyl Reductions, More Reactions on the Aromatic Sidechain: Reduction of Nitro Groups and the Baeyer Villiger, Aromatic Synthesis (1) - "Order Of Operations", Synthesis of Benzene Derivatives (2) - Polarity Reversal, Aromatic Synthesis (3) - Sulfonyl Blocking Groups, Synthesis (7): Reaction Map of Benzene and Related Aromatic Compounds, Aromatic Reactions and Synthesis Practice, Electrophilic Aromatic Substitution Practice Problems.