Chem 334 1st Edition Lecture 15Outline of Last Lecture I. Acyl substitution and Fisher esterficationOutline of Current Lecture II. Addition and Elimination ReactionsIII. Addition-Elimination Reactions with WaterIV. Acids as NucleophilesCurrent LectureAddition Mechanism:An addition reaction relies on a nucleophile attack. Aldehydes and ketones undergo addition reactions, as they don’t have a good leaving group. O O-R H nuc R nuc H Addition-elimination Mechanism: O O- OR LG R nuc LG R nucnucElimination reactions: O H2O, pyridine O Cl OHElimination reactions reform a π bond in order to kick out a leaving group. In the example elimination reaction above, Cl- is a very good leaving group, meaning that the reaction is very fast and there is no catalyst needed. The more stable the anion, the better the leaving group, and the weaker the base, the better the leaving group.Examples of good leaving groups (in order):These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Cl-> Carboxylate >-OR >-NR2Addition-elimination reactions with water(Hydrolysis):Anhydrides:Anhydrides are very reactive, meaning that no catalyst is necessary, and no base is needed to take care of HCl in the reaction. O OO- O O- O OO O H2O O OH O OH O H2O H–O+–H Esters: This reaction is the reverse of esterification and can be acid or base catalyzed.Acid catalysis: O H+/H2O O O OH OHMechanism:O OH O–H OH H O H–O+–H O H2O OOH O H–O–H H H–O–H H2O:OH O–H H2O O OH O OH OHOH HO H Base catalyzed: (Even though parts of this reaction are reversible, the reaction overall is not reversible) O NaOH/H2O O O O- OHMechanism: O O- O O O HO O O–H OO OH OHAmides:Amides require harsher conditions for hydrolysisAcid catalysis: O H3O/Δ O NH2 OH Mechanism:O O–H O–H OH H NH2 H–O+–H NH2 H2O NH2OH NH2 H–O–H H H–O–H H2O:OH O–H H2O O OH NH3 OH NH3 OH Base catalyzed: (Even though parts of this reaction are reversible, the reaction overall is not reversible) O NaOH/H2O/Δ O NH O- NH2Mechanism:Make sure to protonate the leaving group AS it leaves O O- H–O–H O O NH HO NH O–H OH- O NH2OHAcids as nucleophiles (to make esters):Acid Chlorides: O Pyridine O Cl OH or Et3N OAnhydrides: O O OH OO O OOEsters: O H+ O O OH O OHAmides:You cannot react an amide with an alcohol nucleophile to get an
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