Chapter 11 Alcohols, phenols,
thiols, ethers, and sulfides
乙二醇，甘醇: 一种醇类总称。在一个甘醇分子中,
有两个羟基(OH)连接于不同的碳原子。
Alcohols
• contain the hydroxyl –OH functional group
• primary / secondary / tertiary
• monofunctional / polyfunctional
• naming: -ol (or alkyl alcohol)
-diol (or alkyl glycol)
–triol,...
• -OH attached directly to the benzene ring
→ phenols (= group name)
If the hydroxyl group is not the principle one:
hydroxy-
Alcohols - properties
• low MW alcohols: colourless liquids, specific
odour (unpleasant from C4), narcotic effect(麻醉效
应） , toxic
[nɑr'kɑtɪk]
• polyfunctional alcohols: sweet taste
• higher alcohols (from C12): solid compounds
• H-bonds → solubility in water, higher boiling
points than alkanes
• structure:
polar functional group
nonpolar hydrocarbon chain
 hydrophobic properties increase with MW
印地安赛车500
熄灭
排放物
辛烷值表示汽化器式发动机燃料的抗爆性能好坏的一项重要指标，列于车用汽油规格的
首项。汽油的辛烷值越高，抗爆性就越好，发动机就可以用更高的压缩比
发酵
酵母
烈酒
共沸混合物
变性的
度
氧化还原反应
羟汞化
Alcohols – important reactions
1. with alkali metals → alkoxide (strong base!)
2 Na + 2 CH3OH → H2(g) + 2 CH3O- + 2 Na+
(sodium methoxide)
2. substitution
CH3CH2CH2OH + HCl → CH3CH2CH2Cl + H2O
3. dehydration !
CH3-CH2-OH → CH2=CH2 + H2O
Alcohols – important reactions
4. oxidation (burning) !
* primary alcohols → aldehydes
* secondary alcohols → ketones
* tertiary alcohols → no reaction
5. esterification !
alcohol + acid → ester + H20
* organic acid esters
* inorganic acid esters (with H2SO4, H3PO4, HNO3)
Alcohols – important examples
• methanol = methyl alcohol
• ethanol = ethyl alcohol
• ethane-1,2-diol = ethylene glycol
• propane-1,2,3-triol = glycerol
• cyclohexanol, inositols（环己六醇 ，肌醇 ）
• cholesterol
肌醇（inositol ）是一种水溶性维生素；维生素B族中的一种
，肌醇和胆碱一样是亲脂肪性的维生素，又称为环己六醇，
白色晶体粉末（无结晶水），风化性结晶（含二分子结晶水）
。有9种立体异构体，其中有医用价值的内消旋体，可促进细
胞新陈代谢、助长发育、增进食欲，用于治疗肝脂肪过多症、
肝硬化症。
Cholesterol（胆固醇）
胆固醇主要存在于动物性食物之中 。
胆固醇分为高密度胆固醇和低密度胆固醇，
高密度胆固醇， “好胆固醇”，对心血管
有保护作用，低密度胆固醇，“坏胆固醇”
偏高，冠心病的危险性就会增加。
人体中胆固醇的总量大约占体重的0.2%
Alcohols - toxicity
Ethylene glycol
• toxic: 50 mL, lethal（致命的 ） 100 mL
Methanol
• 5-10 mL toxic, 30 mL lethal
• loss of eyesight, metabolic acidosis（代谢性酸
中毒，酸碱平衡紊乱 ）
Ethanol
酒度在40度—50度之间
• lethal: 6-8 g/kg ( 1 L of vodka伏特加酒)
• degradation: oxidation of 0,15 g/kg/hour
降解
法国白兰地
玉米制成的烈性酒
威士忌酒
波兰鸡蛋
利口酒
0,5 L of beer (4%)  20 mL of ethanol = 16 g
70 kg man: 0,7 x 70 = 49 kg (L) water
i.e. 16 g etOH / 49 L = 0,33 g / L = 0,33 ‰
Color Atlas of Biochemistry / J. Koolman, K.H.Röhm. Thieme 1996. ISBN 0-86577-584-2
肝硬化
戒酒
29,4 kJ/g of ethanol
Obrázek převzat z: Color Atlas of Biochemistry / J. Koolman, K.H.Röhm. Thieme 1996. ISBN 0-86577-584-2
Aromatic alcohols = PHENOLS
• -OH group is bonded directly to the benzene
ring (instead of 1 or more hydrogens)
• aromatic alcohols with –OH group attached to
a side chain are not phenols! (benzyl alcohol)
• phenols are stronger acids than alcohols
(but weaker than organic acids)
 soluble in basic solutions
Ka: acetic acid (10-5), phenol (10-10), ethanol (10-17)
• phenols also react with active metals
Ethers
• 2 alkyl or aryl groups bonded to oxygen:
 R1-O-R2
/ R-O-Ar / Ar1-O-Ar2
• lower boiling points than alcohols (no H-bonds)
 dimethyl ether is a gas, higher ethers: liquids
• not miscible with water
• soluble in organic solvents
• basic properties
• inflammable, volatile
• narcotic effect
diethyl ether (l) = general anesthetics: depressant on the CNS
Ethers – naming:
radical functional names
CH3-O-CH2-CH3 = ethyl methyl ether
(alphabetical order of alkyl names)
• higher MW ethers: alkoxy group
(= the smaller alkyl)
 2-methoxypentane / 1,2-dimethoxyethane
• cyclic ethers = EPOXIDES
 oxygen is bound to neighbouring carbons
 prefix: epoxy- (2,3-epoxybutane)
 epoxyethane (= ethylene oxide or oxirane) is a toxic gas,
used as a sterilant or in organic synthesis
Sulfur ethers - SULFIDES
• sulfur analogs of ethers
• more reactive than ethers
• name: alkyl alkyl sulfide or alkyl thioalkane
 CH3-S-CH2-CH3
= ethyl methyl sulfide or methyl thioethane
 CH3-S-CH3
= dimethyl sulfide or methyl thiomethane
Introduction
• Formula R-O-R where R is alkyl or aryl.
• Symmetrical or unsymmetrical
• Examples:
CH3
O
O CH3
O CH3
=>
Structure and Polarity
• Bent molecular geometry
• Oxygen is sp3 hybridized
• Tetrahedral angle
=>
Boiling Points
Similar to alkanes of comparable molecular weight.
Hydrogen Bond Acceptor
• Ethers cannot H-bond
to each other.
• In the presence of
-OH or -NH (donor),
the lone pair of
electrons from ether
forms a hydrogen
bond with the -OH or
-NH.
=>
Solvent Properties
• Nonpolar solutes
dissolve better in ether
than in alcohol.
• Ether has large dipole
moment, so polar
solutes also dissolve.
• Ethers solvate cations.
• Ethers do not react with
strong bases.
=>
Ether Complexes
• Grignard reagents
• Electrophiles
H
+ _
O B H
H
BH3 THF
• Crown ethers
=>
Common Names of Ethers
•
•
•
•
•
Alkyl alkyl ether
Current rule: alphabetical order
Old rule: order of increasing complexity
Symmetrical: use dialkyl, or just alkyl.
Examples:
CH3
CH3CH2
O CH2CH3
diethyl ether or
ethyl ether
CH3
O C CH3
CH3
t-butyl methyl ether or
methyl t-butyl ether =>
IUPAC Names
• Alkoxy alkane
• Examples:
CH3
CH3
O CH3
O C CH3
CH3
2-methyl-2-methoxypropane
Methoxycyclohexane
=>
Cyclic Ethers
• Heterocyclic: oxygen is in ring.
• Epoxides (oxiranes)
H2C CH2
O
• Oxetanes
• Furans
O
O
• Pyrans
(Oxolanes
O
(Oxanes
O
)
O
O
•Dioxanes
=>
O
)
Naming Epoxides
• Alkene oxide, from usual synthesis method
H
peroxybenzoic acid
O
cyclohexene oxide
H
• Epoxy attachment to parent compound,
1,2-epoxy-cyclohexane
• Oxirane as parent, oxygen number 1
H
CH3CH2
O
CH3
H
trans-2-ethyl-3-methyloxirane
=>
Spectroscopy of Ethers
• IR: Compound contains oxygen, but
O-H and C=O stretches are absent.
• MS: -cleavage to form oxonium ion, or
loss of either alkyl group.
• NMR: 13C-O signal between 65-90,
1H-C-O signal between 3.5-4.
=>
Williamson Synthesis
• Alkoxide ion + 1 alkyl bromide (or tosylate)
• Example:
CH3
CH3
O H
+
K
CH3
CH3
CH3
CH3
_
O
+ CH3CH2
CH3
CH3
H
C
H
CH3
_ +
O K
CH3
Br
CH3
_
O CH2CH2CH3 + Br
CH3
=>
Phenyl Ethers
• Phenoxide ions are easily produced for
use in the Williamson synthesis.
• Phenyl halides or tosylates cannot be
used in this synthesis method.
_
O H
+ NaOH
O Na+
+
HOH
=>
AlkoxymercurationDemercuration
Use mercuric acetate with an alcohol to add
RO-H to a double bond and form the
Markovnikov product.
CH3CH2CH CH2
1) Hg(OAc)2, CH3OH
2) NaBH4
H
CH3CH2CH CH2
OCH3
=>
Bimolecular Dehydration
of Alcohols
• Industrial method, not good lab synthesis.
• If temperature is too high, alkene forms.
CH3CH2
O H + H O CH2CH3
H2SO4
CH3CH2 O CH2CH3
140°C
=>
Cleavage of Ethers
• Ethers are unreactive toward base, but
protonated ethers can undergo
substitution reactions with strong acids.
• Alcohol leaving group is replaced by a
halide.
• Reactivity: HI > HBr >> HCl
=>
Mechanism for Cleavage
• Ether is protonated.
CH3
O CH3
H Br
CH3
H
+
O CH3
_
_
+ Br
• Alcohol leaves as halide attacks.
_
Br
CH3
H
+
O CH3
Br CH3 + H O CH3
• Alcohol is protonated, halide attacks,
and another molecule of alkyl bromide is
formed.
=>
Phenyl Ether Cleavage
• Phenol cannot react further to become
halide.
• Example:
OH
O CH2CH3
HBr
+ CH3CH2
Br
=>