Download Chapter 10 for 301

Chapter 10
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Classification
o Alcohols are classified much like alkyl halides - 1°, 2°, and 3°
Nomenclature
o Alcohols have precedence over alkenes and alkynes
 Get to the hydroxyl first!
 You do have to say “1” with straight-chain alcohols
(S,E) 4-bromohex-2-en-1-ol
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When the alcohol is the highest-priority group on a cyclic
molecule, then the “1” is implied so you leave it off.
Don’t worry about the sections naming diols and phenols
 You do need to name diols as “diol,” you just don’t need to call
them glycols or anything else weird.
 When you name a cyclic diol, you do need to say the “1”
2-chlorocyclohexan-1,3-diol
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Physical Properties
o Hydrogen bonding causes higher boiling points
o Solubility – small alcohols are miscible with water; larger alcohols are not terribly
soluble
Solubility
o Smaller alcohols are miscible with water
o The larger the nonpolar piece, the less soluble the alcohol is in water
o You know this!
Acidity
o pka – 15-18
o phenol - pka – 10
 Why? The conjugate base, phenoxide, is resonance stabilized
-
H+
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Formation of Alkoxides
o Acid/base
 Alcohol + very strong base (NaH, NaNH2) → Alkoxide
 If you just use hydroxide or an alkoxide, you will get an
equilibrium mixture.
 The hydroxide or alkoxide is not strong enough to quantitatively
deprotonate an alcohol (unless it’s a phenol)
o Redox
 Alcohol + alkali metal → Alkoxide
 This is one of the few times when you see Na or K and it’s significant.
Synthesis Review
o SN2
 -OH added to primary or methyl alkyl halides
 See Chapter 6 Review
o SN1
 Water added to secondary or tertiary alkyl halides
 See Chapter 6 Review
o Acid-catalyzed hydration of alkenes
 Markovnikov addition of water with rearrangement
 See Chapter 8 Review
o Oxymercuration-demercuration
 Markovnikov addition of water without rearrangement
 See Chapter 8 Review
o Hydroboration-oxidation
 Anti-Markovnikov addition of water
 See Chapter 8 Review
o Addition of OsO4 or KMnO4 to alkenes
 Syn addition of two hydroxyls
 See Chapter 8 Review
o Acid-catalyzed ring-opening of epoxides
 Results in two hydroxyls added anti to one another
 See Chapter 8 Review
o Addition of acetylide ions to carbonyls
 See Chapter 9 Review
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Grignards/Organometallics
o Formation of Grignards and alkyl lithiums
 Magnesium inserts between carbon and halogens
 Lithium replaces the halogen
 This is one time where an sp3-hybridized carbon acts the same as an sp2hybridized carbon.
 This means that this works on any carbon-halogen bond
 Solvent
 There cannot be any acidic protons in the solvent, as the Grignard
is such a strong base.
 There cannot be any pi bonds in the solvent as those are sites of
reactivity that the Grignard will attack.
 From here on, I will use Grignard to refer to both Grignard reagents and
organolithiums, as they do the same things
 The carbon-metal bond is so strongly polar that it’s fine to think of it as
ionic.
 Because of this, it’s often easiest to cross out the Li or MgBr and
call the R-group an RCH3CH2MgBr
Ex. CH3CH2MgBr
o Grignards as nucleophiles in SN2 reactions
 Grignards are strong bases/nucleophiles, so they will participate in both
SN2 and E2 reactions
 SN2 with methyl and primary alkyl halides
-

CH3MgBr
CH3
E2 with secondary and tertiary alkyl halides – no point in using
this strong of a base
o Grignards attacking carbonyls
 The negatively charged carbon of the Grignard is attracted to the partially
positive carbon of the carbonyl
 In the following schemes, A and B are just the alkyl pieces attached to the
carbonyl-containing molecules and C is the Grignard or other strong
nucleophile (such as an acetylide ion)
 Addition of to ketones and aldehydes
1) C 2) H+
A
C
A
B
B
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Addition to esters
1) C 2) H+
A
C
A
OB
C
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Addition to Acid Chlorides
1) C 2) H+
A
C
A
Cl
C
o Addition of Grignards to epoxides
 Grignards (and other strong bases) attack the less substituted side of
epoxides in an SN2-like mechanism
R-
R
R