General
Organic ChemistryTwo credits
Second Semester 2009
King Saud bin Abdulaziz University for Health Science
Reference Book: Organic Chemistry: A Brief Course, by Robert C. Atkins and Francis A. CareyThird Edition
Instructor: Rabih O. Al-Kaysi, PhD.
Chapter 10Chapter 10
Alcohols, Ethers and PhenolsAlcohols, Ethers and Phenols
Lecture 16
Sources of AlcoholsSources of Alcohols
MethanolMethanol is an industrial chemical is an industrial chemical
end uses: solvent, antifreeze, fuelend uses: solvent, antifreeze, fuel
principal use: preparation of formaldehydeprincipal use: preparation of formaldehyde
MethanolMethanolMethanolMethanol
MethanolMethanol is an industrial chemical is an industrial chemical
end uses: solvent, antifreeze, fuelend uses: solvent, antifreeze, fuel
principal use: preparation of formaldehydeprincipal use: preparation of formaldehyde
prepared by hydrogenation of carbon prepared by hydrogenation of carbon monoxidemonoxide
CO + 2HCO + 2H22 CH CH33OHOHCO + 2HCO + 2H22 CH CH33OHOH
MethanolMethanolMethanolMethanol
EthanolEthanol is an industrial chemical is an industrial chemical
Most ethanol comes from fermentationMost ethanol comes from fermentation
Synthetic ethanol is produced by hydrationSynthetic ethanol is produced by hydrationof ethyleneof ethylene
Synthetic ethanol is denatured (madeSynthetic ethanol is denatured (madeunfit for drinking) by adding methanol, benzene,unfit for drinking) by adding methanol, benzene,pyridine, castor oil, gasoline, etc.pyridine, castor oil, gasoline, etc.
EthanolEthanolEthanolEthanol
Isopropyl alcohol is Isopropyl alcohol is prepared by hydration of prepared by hydration of propene.propene.
All alcohols with four carbons or fewer are All alcohols with four carbons or fewer are readily available.readily available.
Most alcohols with five or six carbons are Most alcohols with five or six carbons are readily available.readily available.
Other alcoholsOther alcoholsOther alcoholsOther alcohols
Hydration of alkenesHydration of alkenes
Hydroboration-oxidation of alkenesHydroboration-oxidation of alkenes
Hydrolysis of alkyl halidesHydrolysis of alkyl halides
Syntheses using Syntheses using Grignard reagentsGrignard reagentsorganolithium reagentsorganolithium reagents
Sources of alcoholsSources of alcoholsSources of alcoholsSources of alcohols
Reactions discussed in earlier chaptersReactions discussed in earlier chapters
Reduction of aldehydes and ketonesReduction of aldehydes and ketones
Reduction of carboxylic acidsReduction of carboxylic acids
Reduction of estersReduction of esters
Reaction of Grignard reagents with epoxidesReaction of Grignard reagents with epoxides
Diols by hydroxylation of alkenesDiols by hydroxylation of alkenes
Sources of alcoholsSources of alcoholsSources of alcoholsSources of alcohols
New methods in ChapterNew methods in Chapter
Preparation of AlcoholsPreparation of Alcoholsbyby
Reduction of Aldehydes and KetonesReduction of Aldehydes and Ketones
CC
RR
HH OHOH
HH
CC
RR
HH
OO
Reduction of Aldehydes Gives Primary AlcoholsReduction of Aldehydes Gives Primary AlcoholsReduction of Aldehydes Gives Primary AlcoholsReduction of Aldehydes Gives Primary Alcohols
Pt, ethanolPt, ethanol
(92%)(92%)
Example: Catalytic HydrogenationExample: Catalytic HydrogenationExample: Catalytic HydrogenationExample: Catalytic Hydrogenation
CHCH33OO CHCH22OHOH
OO
CHCH33OO CHCH ++ HH22
CC
RR
HH OHOH
R'R'
CC
RR
R'R'
OO
Reduction of Ketones Gives Secondary AlcoholsReduction of Ketones Gives Secondary AlcoholsReduction of Ketones Gives Secondary AlcoholsReduction of Ketones Gives Secondary Alcohols
(93-95%)(93-95%)
Example: Catalytic HydrogenationExample: Catalytic HydrogenationExample: Catalytic HydrogenationExample: Catalytic Hydrogenation
++ HH22
OO PtPt
ethanolethanol
HH OHOH
SodiumSodiumborohydrideborohydride
LithiumLithiumaluminum hydridealuminum hydride
LiLi++
NaNa++ ––
BB
HH
HH
HHHH––
AlAl
HH
HH
HHHH
Metal Hydride Reducing AgentsMetal Hydride Reducing AgentsMetal Hydride Reducing AgentsMetal Hydride Reducing Agents
act as hydride donorsact as hydride donors
NaBHNaBH44
(82%)(82%)
Examples: Sodium BorohydrideExamples: Sodium BorohydrideExamples: Sodium BorohydrideExamples: Sodium Borohydride
CHCH22OHOH
OO
CHCH
OO22NN methanolmethanol
OO22NN OO
HH OHOH
(84%)(84%)
NaBHNaBH44
ethanolethanol
AldehydeAldehyde
KetoneKetone
Lithium aluminum hydrideLithium aluminum hydrideLithium aluminum hydrideLithium aluminum hydride
more reactive than sodium borohydridemore reactive than sodium borohydride
cannot use water, ethanol, methanol etc.cannot use water, ethanol, methanol etc.as solventsas solvents
diethyl ether is most commonly used solventdiethyl ether is most commonly used solvent
Examples: Lithium Aluminum HydrideExamples: Lithium Aluminum HydrideExamples: Lithium Aluminum HydrideExamples: Lithium Aluminum Hydride
(84%)(84%)
AldehydeAldehyde
KetoneKetone
OO
CHCH33(CH(CH22))55CHCH CHCH33(CH(CH22))55CHCH22OHOH
1. LiAlH1. LiAlH44
diethyl etherdiethyl ether
2. H2. H22OO
OO
(C(C66HH55))22CHCCHCHCCH33
1. LiAlH1. LiAlH44
diethyl etherdiethyl ether
2. H2. H22OO
(86%)(86%)
OHOH
(C(C66HH55))22CHCHCHCHCHCH33
Preparation of DiolsPreparation of Diols
Diols are prepared by...Diols are prepared by...Diols are prepared by...Diols are prepared by...
reactions used to prepare alcoholsreactions used to prepare alcohols
hydroxylation of alkeneshydroxylation of alkenes
OO OO
HCHCCHCH22CHCHCHCH22CH CH
CHCH33
HH22 (100 atm) (100 atm)
Ni, 125°CNi, 125°C
HOCHHOCH22CHCH22CHCHCHCH22CHCH22OHOH
CHCH33
3-Methyl-1,5-pentanediol3-Methyl-1,5-pentanediol
(81-83%)(81-83%)
Example: reduction of a dialdehydeExample: reduction of a dialdehydeExample: reduction of a dialdehydeExample: reduction of a dialdehyde
vicinal diols have hydroxyl groups on adjacent vicinal diols have hydroxyl groups on adjacent carbonscarbons
ethylene glycol (HOCHethylene glycol (HOCH22CHCH22OH) is most familiar OH) is most familiar
exampleexample
Hydroxylation of AlkenesHydroxylation of AlkenesGives Vicinal DiolsGives Vicinal Diols
Hydroxylation of AlkenesHydroxylation of AlkenesGives Vicinal DiolsGives Vicinal Diols
Just for general knowledge, will not be tested on
syn addition of —OH groups to each carbonsyn addition of —OH groups to each carbonof double bondof double bond
Osmium Tetraoxide is Key ReagentOsmium Tetraoxide is Key ReagentOsmium Tetraoxide is Key ReagentOsmium Tetraoxide is Key Reagent
CC CCHHOO OOHH
CC CC
OO OO
OsOs
OOOO
CCCC
Just for general knowledge, will not be tested on
(CH(CH33))33COOHCOOHOsOOsO44 (cat) (cat)
tert-tert-Butyl alcoholButyl alcoholHOHO––
Example Example Example Example
(73%)(73%)
CHCH22CHCH33(CH(CH22))77CHCH
CHCH33(CH(CH22))77CHCHCHCH22OHOH
OHOH
Just for general knowledge, will not be tested on
Reactions of Alcohols
Review of Reactions of AlcoholsReview of Reactions of AlcoholsReview of Reactions of AlcoholsReview of Reactions of Alcohols
reaction with hydrogen halides reaction with hydrogen halides
acid-catalyzed dehydrationacid-catalyzed dehydration
New Reactions of Alcohols in This ChapterNew Reactions of Alcohols in This ChapterNew Reactions of Alcohols in This ChapterNew Reactions of Alcohols in This Chapter
conversion to ethersconversion to ethers
esterificationesterification
esters of inorganic acidsesters of inorganic acids
oxidationoxidation
cleavage of vicinal diolscleavage of vicinal diols
Conversion of Alcohols to Ethers
RCHRCH22OO
HH
CHCH22RR
OHOH
HH++
RCHRCH22OO CHCH22RR HH OHOH++
Conversion of Alcohols to EthersConversion of Alcohols to EthersConversion of Alcohols to EthersConversion of Alcohols to Ethers
acid-catalyzedacid-catalyzed
referred to as a "condensation"referred to as a "condensation"
equilibrium; most favorable for primary alcoholsequilibrium; most favorable for primary alcohols
ExampleExampleExampleExample
2CH2CH33CHCH22CHCH22CHCH22OHOH
HH22SOSO44, 130°C, 130°C
CHCH33CHCH22CHCH22CHCH22OCHOCH22CHCH22CHCH22CHCH33
(60%)(60%)
Mechanism of Formation of Diethyl EtherMechanism of Formation of Diethyl Ether Mechanism of Formation of Diethyl EtherMechanism of Formation of Diethyl Ether
Step 1:Step 1:Step 1:Step 1:
CHCH33CHCH22OO•••• ••••
HH
HH OSOOSO22OHOH
CHCH33CHCH22OO ••••
HH
OSOOSO22OHOHHH
++––++
Just for general knowledge, will not be tested on
Mechanism of Formation of Diethyl EtherMechanism of Formation of Diethyl Ether Mechanism of Formation of Diethyl EtherMechanism of Formation of Diethyl Ether
Step 2:Step 2:Step 2:Step 2:
CHCH33CHCH22••••
HH
HH
++OO
CHCH33CHCH22OO•••• ••••
HH
++++
CHCH33CHCH22
CHCH33CHCH22OO ••••
HH
••••
HH
HH
OO••••
Just for general knowledge, will not be tested on
Mechanism of Formation of Diethyl EtherMechanism of Formation of Diethyl Ether Mechanism of Formation of Diethyl EtherMechanism of Formation of Diethyl Ether
Step 3:Step 3:Step 3:Step 3:
++++
CHCH33CHCH22
CHCH33CHCH22OO ••••
HH
OSOOSO22OHOH–– ••••••••
••••
HH OSOOSO22OHOH
••••
••••
CHCH33CHCH22
CHCH33CHCH22OO ••••••••
Just for general knowledge, will not be tested on
Ethers
Nomenclature of Ethers, Epoxides
name the groups attached to oxygen in name the groups attached to oxygen in alphabetical order as separate words; "ether" is alphabetical order as separate words; "ether" is last wordlast word
CHCH33OOCHCH2 2 CHCH33
ethylethyl methylmethyl ether ether
CHCH33CHCH22OOCHCH2 2 CHCH33
didiethylethyl ether ether
CHCH33CHCH22OOCHCH22CHCH22CHCH22ClCl
3-chloropropyl3-chloropropyl ethylethyl ether ether
Functional Class IUPAC Names of EthersFunctional Class IUPAC Names of EthersFunctional Class IUPAC Names of EthersFunctional Class IUPAC Names of Ethers
cyclopentyl cyclopentyl methylmethyl sulfide sulfide
analogous to ethers, but replace “ether” as lastanalogous to ethers, but replace “ether” as lastword in the name by “sulfide.”word in the name by “sulfide.”
CHCH33SSCHCH2 2 CHCH33
ethylethyl methyl sulfide methyl sulfide
CHCH33CHCH22SSCHCH2 2 CHCH33
didiethylethyl sulfide sulfide
Functional Class IUPAC Names of SulfidesFunctional Class IUPAC Names of SulfidesFunctional Class IUPAC Names of SulfidesFunctional Class IUPAC Names of Sulfides
SSCHCH33
OxiraneOxirane(Ethylene oxide)(Ethylene oxide)
OxetaneOxetane OxolaneOxolane(tetrahydrofuran)(tetrahydrofuran)
OxaneOxane(tetrahydropyran)(tetrahydropyran)
1,4-Dioxane1,4-Dioxane
Names of Cyclic EthersNames of Cyclic EthersNames of Cyclic EthersNames of Cyclic Ethers OO OO OO
OO
OO
OO
Just for general knowledge, will not be tested on
ThiiraneThiirane ThietaneThietane ThiolaneThiolane
ThianeThiane
Names of Cyclic SulfidesNames of Cyclic SulfidesNames of Cyclic SulfidesNames of Cyclic Sulfides SS SS SS
SS
Just for general knowledge, will not be tested on
bent geometry at oxygen bent geometry at oxygen analogousanalogous
to water and alcohols, to water and alcohols, i.e.i.e. sp sp3 3 hybidizationhybidization
Structure and Bondingin
Ethers and Epoxides
112°112°
HHOO
HH
105°105° 108.5°108.5°
(CH(CH33))33CCOO
C(CHC(CH33))33
132°132°
HHOO
CHCH33
CHCH33
OOCHCH33
Bond angles at oxygen are sensitiveBond angles at oxygen are sensitiveto steric effectsto steric effects
Bond angles at oxygen are sensitiveBond angles at oxygen are sensitiveto steric effectsto steric effects
most stable conformation of diethyl ethermost stable conformation of diethyl etherresembles pentaneresembles pentane
An oxygen atom affects geometry in much theAn oxygen atom affects geometry in much thesame way as a CHsame way as a CH22 group group
An oxygen atom affects geometry in much theAn oxygen atom affects geometry in much thesame way as a CHsame way as a CH22 group group
Physical Properties of Ethers
boiling pointboiling point
36°C36°C
35°C35°C
117°C117°C
Ethers resemble alkanes more than alcoholsEthers resemble alkanes more than alcoholswith respect to boiling pointwith respect to boiling point
Ethers resemble alkanes more than alcoholsEthers resemble alkanes more than alcoholswith respect to boiling pointwith respect to boiling point
OO OHOH
Intermolecular hydrogenIntermolecular hydrogenbonding possible in bonding possible in alcohols; not possible alcohols; not possible in alkanes or ethers.in alkanes or ethers.
solubility in water (g/100 mL)solubility in water (g/100 mL)
very smallvery small
99
7.57.5
Ethers resemble alcohols more than alkanesEthers resemble alcohols more than alkaneswith respect to solubility in waterwith respect to solubility in water
Ethers resemble alcohols more than alkanesEthers resemble alcohols more than alkaneswith respect to solubility in waterwith respect to solubility in water OO
OHOH
Hydrogen bonding toHydrogen bonding towater possible for etherswater possible for ethersand alcohols; not and alcohols; not possible for alkanes.possible for alkanes.
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