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UH CHEM 3332 - Reactions of Alcohols

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CHEM 3332 1st Edition Lecture 4Outline of Last Lecture Substitution vs. Elimination (Wade summaries: sections 6-16 and 6-22)Exception: 1 halide with a strong, unhindered base – SN2 gives major productExamples: 1.2.3.4.5.Synthesis of AlcoholsI. From Alkyl HalidesII. From Alkenes: Ch. 8A. Hydration (H3O+) = Mark/Inversion/RetentionB. Oxymercuration/ Demercuration: 1. Hg(OAC)2/H2O 2. NaBH4 = Mark /Anti additionC. Hydroboration: 1. BH3THF 2. H2O2/OH- = Non-Mark/Syn additionD. Epoxidation followed by an acidic hydrolysis: 1. MCPBA 2. H3O+ or CH3CO3H/H3O+ = Trans vicinal diolE. Hydroxylation: OsO4/H2O2 or cold, basic KMnO4 = Syn vicinal diolIII.From Acetylide Anion and Carbonyl Compound: Ch.9IV. Organometallic Reagents + Carbonyl Compounds → R-OH: Ch.10A. Preparation of Reagents1.2.B. Mechanism of Grignard Reaction (mechanism of organolithium reaction is similar)1. With aldehydes and ketones:2. With esters or acid halidesV. Reduction of CarbonylsA. Hydride ReductionsReducing AgentsNaBH4: the milder choice: usually chosen for aldehydes and keytones- May use H2O or alcohol as solvents- Very slow reduction or esters; will not reduce acid chlorides or carboxylic acidsLiAlH4: more reactive than NaBH4- Reduced aldehydes, ketones, esters, acid halides and carboxylic acids- CAUTION: reacts violently with H2O and alcohols! Must use esters as solvents1. Reduction of aldehydes and keytones:2. Reduction of esters, acid halides and carboxylic acidsB. Catalytic Hydrogenation of Aldehydes and Ketones: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.- Catalytic reduction of carbonyl is slower than reduction of carbon-carbon double bond- Raney Ni is best catalystOutline of Current LectureReactions of Alcohols I. OxidationsA. Oxidation of 1 alcohols: B. Oxidation of 2 alcohols: C. Oxidation of 3 alcohols [ox] : 1. Chromic acid reagenta) Na2Cr2O7/H2SO4/H2Ob) CrO3/H2SO4/H2O/acetone/ 0 (Jones reagent) 2.Pyridinumchlorochromate / CH2CL2 (written as: PCC/CH2CL2 or CrO3 pyridine HCL/CH2CL2)II. Formation of the tosylate ester (converting the OH group to a better leaving group)III. Conversion of alcohols to alkyl halides – The BEST methodsA. Formation of 3 alcohols: use hydrohalic acids (HBR,HCL) B. Formation of 1 / 2 alkyl halides from 1 / 2 alcohols: 1. Bromides: use PBR32. Chloridesa) PCL3 or PCL5b) SOCL2 – NOTE: The mechanism given on Pg 463 occurs only in solvents like dioxane. The more typical mechanism is SN2 IV. Dehydration of alcohols to alkenes (first discussed in Ch.7)A. For 3 , 2 alcohols use H2SO4 (conc)/heat (Be careful!E1, so may rearrange) B. For 1 (and 3 , 2 that may rearrange) use POCL3/pyridine – E2, so no carbons NOTE: this reagent is given by Wade in a chapter problemV. Formation of EthersWilliamson Ether Synthesis (symm. Or unsymmetrical ethers)Current LectureReactions of Alcohols I. OxidationsA. Oxidation of 1 alcohols: B. Oxidation of 2 alcohols:C. Oxidation of 3 alcohols [ox] : 1. Chromic acid reagenta) Na2Cr2O7/H2SO4/H2Ob) CrO3/H2SO4/H2O/acetone/ 0 (Jones reagent) 2.Pyridinumchlorochromate / CH2CL2 (written as: PCC/CH2CL2 or CrO3 pyridine HCL/CH2CL2)II. Formation of the tosylate ester (converting the OH group to a better leaving group)III. Conversion of alcohols to alkyl halides – The BEST methodsA. Formation of 3 alcohols: use hydrohalic acids (HBR,HCL) B. Formation of 1 / 2 alkyl halides from 1 / 2 alcohols: 1. Bromides: use PBR32. Chloridesa) PCL3 or PCL5b) SOCL2 – NOTE: The mechanism given on Pg 463 occurs only in solvents like dioxane. The more typical mechanism is SN2 IV. Dehydration of alcohols to alkenes (first discussed in Ch.7)A. For 3 , 2 alcohols use H2SO4 (conc)/heat (Be careful!E1, so may rearrange) B. For 1 (and 3 , 2 that may rearrange) use POCL3/pyridine – E2, so no carbons NOTE: this reagent is given by Wade in a chapter problemV. Formation of EthersWilliamson Ether Synthesis (symm. Or unsymmetrical


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