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GSU CHEM 3410 - Exam 2 Study Guide
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CHEM 3410 1st Edition Exam 2 Study GuideOutline of CurrentI. All electrophilic Aromatic SubstitutionsII. Mechanism for Misenhymer Complex Reactions (Resonance)/ Nucleophilic Aromatic Substitution. III. Mechanism forAcid Catalyzed DehydrationA. POCl3 dehydrationB. SOCl2 dehydrationIV. Manipulating R,SV. Reactions of BenzeneVI. Alcohols - Key Concepts ReviewVII. Naming& Properties of AlcoholsVIII. Reactions of AlcoholsIX. Review Spectroscopy notes from D2L. You will need to know how those concepts for Exam 2….(bond types, what IR is used for…etc)I. Electrophilic Aromatic Substitution You really just need to know the difference between this mechanism and the nucleophilic aromatic substitution mechanism.These notes represent a detailed interpretation of the professor’s lecture. These notesare best used as a supplement to your own notes, not as a substitute.II. Mechanism for Misenhymer Complex ReactionsParaOrthoMETA WILL NOT WORK WITH THIS MECHANISMIII. Mechanism for Acid Catalyzed DehydrationDehydration with H2SO4 does not work at all on primary alcohols. It does not work well on secondary alcohols, and gives a yield that is garbage and it requires extreme conditions..Dehydration with sulfuric acid only really works well with tertiary alcohols.This is how to dehydrate primary and secondary alcohols:Mechanisms: Secondary:The mechanism for dehydration with SOCl2 is very similar and in the textbook, Chapter 17.Tertiary: (E1)IV. Manipulating R,SControlling Stereochemistry: MECHANISM WILL BE ON EXAM 2V. Reactions of BenzeneOxidizing Side Chains of BenzeneIII. Substituent Effects on Aromatic Rings(1) Substituents affect the reactivity of aromatic rings.- Electron donating groups increase benzene reactivity- Electron withdrawing groups decrease benzene reactivityAll electrons are delocalized, so the withdrawing or donating effects spread to ALL carbons in the ring.(2) Substituents direct the placement of additional groups (location- ortho, meta, para)These groups are deemed “directing groups.”-ortho, para directors-meta directors These ortho, meta, and para placements are named relative to the groups already there. A. Electron Withdrawing vs Electron donatingB. Inductive Effects vs Resonance EffectsInductive effects – bond polarity due to electronegativity differences.Resonance Effects – the group can remove electrons from benzene through resonance Resonance withdrawing groups:NO2 will always acts at an electron withdrawing group (EWG). Cyano groups will always be less reactive than benzene!Resonance DonationResonance donation is far more important than inductive withdrawal because, experimentally, the product is more reactive than Benzene.Bromine is more effective as a resonance donor due to its abundant nonbonding electrons. It can also stabilize itself. Substituent More or less reactive than BenzeneReactivity Directing EffectInductive Effect Resonance EffectH N/A N/A N/A N/A N/ACH3 (or anyR group)Slightly more reactive Activating O,P Donating N/aOH, NH2A lot more reactiveActivating O,P Donating DonorF, Cl, Br, I Slightly less reactiveDeactivating O,P Withdrawing DonorNO2, Cyano A lot less reactiveStrongly DeactivatingM (Strongly) Withdrawing(Strongly) WithdrawingCarbonyls A lot less reactiveStronglyDeactivating M (Strongly) Withdrawing(Strongly) WithdrawingImportant Notes:Activating: more reactive than regular benzeneDeactivating: less reactive than regular benzeneOH, NH2 are activator s because of resonance donation. That is what also makes them ortho, para directors. The inductive effects on halogens makes them deactivating. All carbonyls are strong deactivators because of the resonance withdrawal. VI. Naming and Properties of AlcoholsA. Primary, Secondary, Tertiary Alcohols are polar and organic. They mix well with organic and inorganic materials.B. NamingC. PropertiesHydrogen bondingCompared to other molecules, alcohols will have higher viscosity, melting points, boiling points….alcohols will have higher physical properties than alkenes and other organic molecules because of hydrogen bonding. Charge distribution interaction:This is why alcohols are fully miscible with water.Rule of 88 or more carbons on an alcohol will not mix with water because the charge distribution interaction is disrupted through the addition of 8 or more carbons. Also, remember that the more atoms, the higher the physical properties.Acidity/ BasicityGeneral Rules:Withdrawing groups make alcohol more acidic. Higher substitution causes the molecule to be less acidic.Primary > Secondary > TertiaryPhenols are more acidic than linear alcoholsThe closer the EWD effects to the oxygen of the alcohol, the more acidic it will be. Inductive effects diminish through space.VII. Alcohols - Key Concepts ReviewWe have both acid conditions and E2 conditions for our eliminations. E1 and E2. E1 works bestfor tertiary. If I treat a tertiary alcohol with H2SO4 and a mild amount of heat (30-50 oC), I can dehydrate that tertiary alcohol into the corresponding alkene via an E1 carbocation intermediate pathway. I can also do that with secondary alcohols, but the conditions are far more severe. Concentrated sulfuric acid and a lot of heat (100+ oC). You can do this to the secondary alcohol, but you must remember that this method can destroy some compounds that may be highly sensitive to what you can doing. POCl3 can be used to dehydrate tertiary, secondary, and most primary alcohols. Not all primary alcohols will be dehydrated, you just have to work the problem to see. When doing substitution reactions on the tertiary alcohol, you can never use thionyl chloride (SOCl2) or phosphorous tribromide (PBr3) because you can never preform Sn2 substitution of atertiary substrate. You must use the acidic Sn1 conditions (HCl or HBr or KI/ H2SO4), and you would have to do the reaction with extreme excess of the acid to get more substitution ratherthan elimination products.For a secondary alcohol, you can still do the substitution with HBr or HCl, but you will face two issues. The first is extreme conditions because concentrated acid and extreme heat is required (150oC). The second issue is that you may cause the compound to undergo elimination as well, leaving you with a mix of Sn1 and E1 products.Primary and secondary alcohols will always convert directly to halides if you use the two specialized reagents, thionyl chloride (SOCl2) or phosphorous tribromide (PBr3).You can NEVER dehydrate a primary alcohol


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