Terrence P. Sherlock Burlington County College 2004 CHE 242 Unit V Structure and Reactions of Alcohols, Ethers and Epoxides; Basic Principles of NMR Spectroscopy CHAPTER ELEVEN Terrence P. Sherlock Burlington County College 2004

Types of Alcohol Reactions Dehydration to alkene Oxidation to aldehyde, ketone Substitution to form alkyl halide Reduction to alkane Esterification Tosylation Williamson synthesis of ether => Chapter 11

Summary Table => Chapter 11

1º, 2º, 3º Carbons => Chapter 11

Oxidation of 2° Alcohols 2° alcohol becomes a ketone Reagent is Na2Cr2O7/H2SO4 Active reagent probably H2CrO4 Color change: orange to greenish-blue => Chapter 11

Oxidation of 1° Alcohols 1° alcohol to aldehyde to carboxylic acid Difficult to stop at aldehyde Use pyridinium chlorochromate (PCC) to limit the oxidation. PCC can also be used to oxidize 2° alcohols to ketones. => Chapter 11

3° Alcohols Don’t Oxidize Cannot lose 2 H’s Basis for chromic acid test => Chapter 11

Alcohol as a Nucleophile ROH is weak nucleophile RO- is strong nucleophile New O-C bond forms, O-H bond breaks. => Chapter 11

Alcohol as an Electrophile OH- is not a good leaving group unless it is protonated, but most nucleophiles are strong bases which would remove H+. Convert to tosylate (good leaving group) to react with strong nucleophile (base) =>  + C-Nuc bond forms, C-O bond breaks Chapter 11

Formation of Tosylate Ester p-toluenesulfonyl chloride TsCl, “tosyl chloride” ROTs, a tosylate ester => Chapter 11

SN2 Reactions of Tosylates With hydroxide produces alcohol With cyanide produces nitrile With halide ion produces alkyl halide With alkoxide ion produces ether With ammonia produces amine salt With LiAlH4 produces alkane => Chapter 11

Summary of Tosylate Reactions => Chapter 11

Reduction of Alcohols Dehydrate with conc. H2SO4, then add H2 Tosylate, then reduce with LiAlH4 => Chapter 11

Reaction with HBr -OH of alcohol is protonated -OH2+ is good leaving group 3° and 2° alcohols react with Br- via SN1 1° alcohols react via SN2 => Chapter 11

Mechanism with PBr3 P bonds to -OH as Br- leaves Br- attacks backside (SN2) HOPBr2 leaves => Chapter 11

Reaction with Thionyl Chloride Produces alkyl chloride, SO2, HCl S bonds to -OH, Cl- leaves Cl- abstracts H+ from OH C-O bond breaks as Cl- transferred to C => Chapter 11

Periodic Cleavage of Glycols Same products formed as from ozonolysis of the corresponding alkene. => Chapter 11

Fischer Esterification Acid + Alcohol yields Ester + Water Sulfuric acid is a catalyst. Each step is reversible. => Chapter 11

Tosylate Esters Alcohol + p-Toluenesulfonic acid, TsOH Acid chloride is actually used, TsCl => Chapter 11

Sulfate Esters Alcohol + Sulfuric Acid => Chapter 11

Nitrate Esters => Chapter 11

Phosphate Esters => Chapter 11

Phosphate Esters in DNA => Chapter 11

Alkoxide Ions ROH + Na (or NaH) yields sodium alkoxide RO- + 1° alkyl halide yields ether (Williamson ether synthesis) => Chapter 11

POWER POINT IMAGES FROM “ORGANIC CHEMISTRY, 5TH EDITION” L. G POWER POINT IMAGES FROM “ORGANIC CHEMISTRY, 5TH EDITION” L.G. WADE ALL MATERIALS USED WITH PERMISSION OF AUTHOR PRESENTATION ADAPTED FOR BURLINGTON COUNTY COLLEGE ORGANIC CHEMISTRY COURSE BY: ANNALICIA POEHLER STEFANIE LAYMAN CALY MARTIN Chapter 11