Chem357_Alcohols____Final_Students_

Chem357_Alcohols____Final_Students_ - Alcohols, Ethers and...

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1 Alcohols, Alcohols, Ethers and Their Ethers and Their Sulfur Analogues Sulfur Analogues Paula Y. Bruice , , Chapter 10 Chapter 10 2 Learning Summary: 1. Alcohols as Electrophiles (making OH a better leaving group) a) Protonation of the OH b) Conversion to Halide c) Conversion to Tosylate 2. Substitution and Elimination Reactions 3. Thiols and Sulfides 4. Overview of Oxidation/Reduction 5. Biological Relevance 6. Using Alcohols/Epoxides in Multi-step Synthesis a) Alcohols b) Amines c) Ethers a) Polyols and Sugars (D & L) b) Amines and Amino Acids c) Thiols and Sulfides Learning Summary
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3 -OH, -OR and -NH -OH, -OR and -NH 2 as LG as LG B. Leaving Group LG H H H + Nuc H H H LG + Nuc Relative Reactivity: -OH -NH 2 -OR R e c a l CH 2 H 3 C CH 3 4 Converting OH to Halide LG CH 3 OH NaI NO RXN HI However. .. So. ... CH 3 OH CH 3 I + H 2 O Mechanism: H-I CH 3 OH CH 3 O H H I CH 3 I H 2 O is a weak base
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5 CH 3 O H H NH 3 N O T E : NH 3 , RNH 2 , OR won't work here. Why? CH 3 OH NH 4 + H 2 N O H H OH H 3 N + Acid-Base Chemistry ONLY Converting OH to Halide LG Converting OH to Halide LG 6 Examples: CH 3 CH 2 CH 2 OH HI CH 3 CH 2 CH 2 I CH 3 CHCH 2 OH HBr CH 3 CHCH 2 Br OH HI I CH 3 C CH 3 CH 2 CH 3 OH HBr CH 3 C CH 3 CH 2 CH 3 Br CH 3 CH 3 Converting OH to Halide LG
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7 CH 3 C CH 3 CH 2 CH 3 OH HBr CH 3 C CH 3 CH 2 CH 3 Br MECHANISM: H--Br CH 3 C CH 3 CH 2 CH 3 O H H CH 3 C CH 3 CH 2 CH 3 Br CH 3 C CH 3 CH 2 CH 3 Br S N 1 Br CH 3 C CH 3 CH CH 3 E1 HBr Converting OH to Halide LG Converting OH to Halide LG 8 CH CH 3 CH CH 3 OH HBr CH 3 In-Class Exercise: ? Converting OH to Halide LG
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9 CH CH 3 CH CH 3 OH HBr CH 2 CH 3 C CH 3 CH 3 Br CH CH 3 CH CH 3 Br CH 3 MAJOR + MINOR In-Class Exercise: CH 3 Converting OH to Halide LG Converting OH to Halide LG 10 CH CH 3 CH CH 3 OH PBr 3 CH 3 Treating alcohols with Phosphorous Trihalides N pyridine CH CH 3 CH CH 3 Br CH 3 N pyridinium salt of bromophosphite H OPBr 2 + Mechanism: Br P Br Br CH CH 3 CH CH 3 O CH 3 H P Br Br N CH CH 3 CH CH 3 O CH 3 P Br Br Br CH CH 3 CH CH 3 Br CH 3 N H Br OPBr 2 Converting OH into Halides using PX Converting OH into Halides using PX 3
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11 Converting OH into Halides using PX Converting OH into Halides using PX 3 PCl 3 Treating alcohols with Phosphorous Trihalides N N H OPBr 2 + OH OH Cl PCl 3 N N H OPBr 2 + Cl Primary and Secondary Alcohols work well but. .. 12 Converting OH into Halides using PX Converting OH into Halides using PX 3 PCl 3 N OH PCl 3 N Tertiary Alcohols D O N O T give poor yield of expected halide. OH Why? POOR YIELD POOR YIELD
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13 Converting OH into Halides using PX Converting OH into Halides using PX 3 C R R O P Br Br Br R C R R R Br 14 CH CH 3 CH CH 3 OH SOCl 2 CH 3 Treating alcohols with Thionyl Chloride N pyridine CH CH 3 CH CH 3 Cl CH 3 N pyridinium chloride H SO 2 + Mechanism: Cl S Cl O CH CH 3 CH CH 3 O CH 3 H S O Cl N CH CH 3 CH CH 3 O CH 3 S O Cl Cl CH CH 3 CH CH 3 Cl CH 3 N H Cl Cl + O S O Converting OH into Chlorides using SOCl 2
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15 Converting -OH into Converting -OH into Sulfonate Sulfonate Esters Esters C CH 3 CH 2 CH 3 OH Tosyl Cl
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This note was uploaded on 03/29/2009 for the course CHEM 3570 taught by Professor Ganem, b during the Fall '06 term at Cornell University (Engineering School).

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Chem357_Alcohols____Final_Students_ - Alcohols, Ethers and...

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