1. 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

2. 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 =>
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3. Summary Table
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4. 1º, 2º, 3º Carbons
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5. Oxidation of 2° Alcohols
2° alcohol becomes a ketone
Reagent is Na2Cr2O7/H2SO4
Active reagent probably H2CrO4
Color change: orange to greenish-blue
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6. 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.
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7. 3° Alcohols Don’t Oxidize
Cannot lose 2 H’s
Basis for chromic acid test
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8. Alcohol as a Nucleophile
ROH is weak nucleophile
RO- is strong nucleophile
New O-C bond forms, O-H bond breaks =>
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9. 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
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10. Formation of Tosylate Ester
p-toluenesulfonyl chloride
TsCl, “tosyl chloride”
ROTs,
a tosylate ester
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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 =>
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12. Summary of Tosylate Reactions
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13. Reduction of Alcohols Dehydrate with conc. H2SO4, then add H2
Tosylate, then reduce with LiAlH4
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14. 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
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15. Mechanism with PBr3 P bonds to -OH as Br- leaves
Br- attacks backside (SN2)
HOPBr2 leaves =>
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16. 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 =>
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17. Periodic Cleavage of Glycols
Same products formed as from ozonolysis of the corresponding alkene.
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18. Fischer Esterification
Acid + Alcohol yields Ester + Water
Sulfuric acid is a catalyst.
Each step is reversible.
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19. Tosylate Esters Alcohol + p-Toluenesulfonic acid, TsOH
Acid chloride is actually used, TsCl
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20. Sulfate Esters
Alcohol + Sulfuric Acid
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21. Nitrate Esters
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22. Phosphate Esters
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23. Phosphate Esters in DNA
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24. Alkoxide Ions ROH + Na (or NaH) yields sodium alkoxide
RO- + 1° alkyl halide yields ether (Williamson ether synthesis)
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25. 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
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