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10.1 Structure and Nomenclature 1. Nom encature ofalcohols CH 3 OH M ethanol ( m ethylalcohol ) CH 3 CH 2 OH Ethanol ( ethylalcohol ) a 1 o alcohol Ò»¼¶´¼ CH 3 CHOHCH 3 2-Propanol (Isopropylalcohol) a 2 o alcohol ¶þ¼¶´¼ (CH 3 ) 3 COH 2-Methyl-2-propanol (tert-butylalcohol) a 3 o alcohol Èý¼¶´¼ A hydroxylgroup attached to a saturated carbon atom CH 2 OH Benzylalcohol Üлù´¼ H 2 C CHCH 2 OH 1 2 3 2-Propenol (ally alcohol) 2-±ûÏ©´¼ or Ï©±û´¼ HC CCH 2 OH 2-Propynol 2-±ûȲ´¼ 1 2 3
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Page 1: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.1 Structure and Nomenclature

1. Nomencature of alcohols

CH3OH

Methanol(methyl alcohol)

CH3CH2OH

Ethanol

(ethyl alcohol)

a 1o alcohol Ò»¼¶´¼

CH3CHOHCH3

2-Propanol

(Isopropyl alcohol)

a 2o alcohol ¶þ¼¶́¼

(CH3)3COH

2-Methyl-2-propanol

(tert-butyl alcohol)

a 3o alcoholÈý¼¶´¼

A hydroxyl group attached to a saturated carbon atom

CH2OH

Benzyl alcoholÜлù´¼

H2C CHCH2OH123

2-Propenol(ally alcohol)2-±ûÏ©´¼ or Ï©±û´¼

HC CCH2OH

2-Propynol2-±ûȲ´¼

123

Page 2: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

CH3CHCH2CHCH3

4-Phenyl-2-pentanol4-±½»ù-2-Îì´¼

OH C6H5

1 2 3 4 5

2,4-Dimethyl-1-pentanol2£¬4-¶þ¼×»ù-1-Îì´¼

H2C CHCH2CHCH3

4-Penten-2-ol4-ÎìÏ©-2-´¼

CH3CHCH2CHCH2OH

CH3 CH3

5 4 3 2 1

OH

5 4 3 2 1

Page 3: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

2. Nomenclature of ether

CH3CH2OCH2CH3 CH2=CHCH2OCH3 CH2=CHOCH2=CH2

Diethyl etherÒÒÃÑ

Allyl methyl etherÏ©±û»ù¼×ÃÑ

Divinyl etherÒÒÏ©»ùÃÑ

CH3O CH3CH2O CH31

2 3

4

Methyl phenyl ether±½¼×ÃÑ

1-Ethoxy-4- methyl benzene1-ÒÒÑõ»ù-4-¼×»ù±½

Page 4: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

C6H5OC(CH3)3

CH3CHCH2CH2CH3

OCH3

CH3OCH2CH2OCH3

OO

O

tert-Butyl phenyl etherÊå-¶¡»ù±½ÃÑ

2-Methoxypentane2-¼×Ñõ»ùÎìÍé

1,2-Dimethoxyethane1£¬2-¶þ¼×Ñõ»ùÒÒÍé

Tetrahydrofuran(oxacyclopentane)ËÄÇâ߻ૠTHF

1,4-Dioxane(1,4-dioxacyclohexane)1,4-¶þÑõÁù»·

Page 5: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.2 Physical properties of alcohols and ethers

Alcohols have much higher boiling points than comparable ether or

hydrocarbons.R

:O:

H

H O

R

Hydrogen bonding betweenmolecules of an alcohols

R

O

R

R

O

R

No hydrogen bonding

CH3CH2OH

bp. 78oC

CH3OCH3

bp. -25oC

Page 6: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.3 Important alcohols and ethers

Methanol is highly toxic.

Ingestion of even small quantities of

methanol can cause blindness; large quantities cause death. Methanol

poisoning can also occur by inhalation of the vapors or by prolonged exposure to

the skin.

10.3A Methanol CH3OH

CO + 2 H2

300-400oC

200-300atmZnO-Cr2O3

CH3OH

Page 7: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.3B Ethanol

Ethanol can be made by the fermentation of sugars

YeastCH3CH2OHC6H12O6 + CO2

Sugar

Ethanol

½Íĸ

95%

CH3CH2OHCH2=CH2

Ethanol

+ H2OH+

acid

Page 8: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.3C Ethylene glycol

Ethylene glycol (HOCH2CH2OH) has a low molecular weight and a high-

boiling point is miscible with water. It is an ideal automobile antifreeze.

HOCH2CH2OH

Ethylene glycol

+ H2OH+

acidO

Page 9: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.3D Diethyl EtherDiethyl ether is a very low-boiling, highly flammable liquid. Care should always be taken when diethyl ether is used in the

laboratory, because open flames or sparks from light switches can cause explosive

combustion of mixtures of diethyl ether and air.

CH3CH2OCH2CH3

O2CH3CH2OCHCH3

O OH

explosive

a hydroperoxide

autoxidationYou have to add FeSO4 to remove a hydroperoxide

Page 10: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.4 Synthesis of alcohols from alkenes

10.4A Hydration of alkenes

+ H2OH+

H OH

+ H2OH2PO4 OH

or H2SO4

Page 11: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.5 Alcohols from alkenes through oxymercuration-Demercu

ration

+ H2O( 1 ) Hg(OAc)2 / THF

OH HgOCOCH3

Oxymercuration

( 2 ) NaBH4 / H2O

OH H

Demercuration (ÍÑHg)

Page 12: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

H2O( 1 ) Hg(OAc)2 / THF

( 2 ) NaBH4 / H2O+

CH3

CH3

OH

H

1-Methylcyclohexanol

H2O( 1 ) Hg(OAc)2 / THF

HC CH2

OH HgOCOCH3

OxymercurationCH3(CH2)2CH=CH2 + CH3(CH2)2

( 2 ) NaBH4 / H2O

Demercuration (ÍÑHg)CH3(CH2)2CHCH2

OH H

Page 13: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

A mechanism of addition of Hg(OAc)2

( 2 ) NaBH4 / H2OH2O (CH3)3CHC CH2

HgOAcOH

(CH3)3C CH=CH2 + Hg+OAc

(CH3)3CH2C CH2

HgOAc

(CH3)3CHC CH2

HOH

3,3-Dimethyl-2-butanol (94%)

Page 14: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.6 Hydroboration ( 硼氢化反应 ): Synthesis of organoboran

es( 有机硼的合成)

+ H BHydroboration

C C

H B

OrganoboraneBoron hydrideAlkene

THF

Page 15: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

B2H6 + :O

THF

O: BH3

+ -

DiboraneÒÒÅðÍé THF:BH3

BH3 is a Lewis acid (because the boron has only six electrons in its

valence shell). It accepts an electron pair from the oxygen atom of THF

Page 16: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.6A Mechanism of hydroboration

H3C C

H

C H

H

H B H

HFour centertransition state

H3C C

H

C H

H

H B H

H

H3CHC CH2 + H B

H

H

Hydroboration

Boron hydridePropene

THF

More substituted Less substituted

H3CHC CH2

BH

H

H

Complex

CH3CH=CH2

(CH3CH2CH2)2BHCH3CH=CH2

(CH3CH2CH2)3B

TripropylboraneÈý±û»ùÅð

Hydroboration Hydroboration

Page 17: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.6B The stereochemistry of hydroboration

+ H B

H

HHydroboration

Boron hydride

THF

More substituted

Less substituted

CH3 CH3

H

H

BH H

Syn addition

anti-Markovnikov

硼氢化反应的特点; 1. 顺式加成。 2. 反马加成

Page 18: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.7 Alcohols from alkenes through hydroboration-oxidation

(CH3CH2CH2)3B

TripropylboraneÈý±û»ùÅð

Hydroboration3 CH3CH=CH2

BH3 / THF H2O2, NaOHCH3CH2CH2OH

1-Propanol

+ H B

H

HHydroboration

Boron hydride

THF

More substituted

Less substituted

CH3

CH3

H

H

BH H

Syn addition

anti-Markovnikov

H

CH3

OH

H

H2O2, NaOH

Page 19: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

2. H2O2, NaOHCH3CH2CH2CH2CH=CH2

1. BH3 / THFCH3CH2CH2CH2CH2CH2OH

1-Hexanol1-HexeneAnti-Mar's Rule

CH3CH2CH2CH2CH=CH2H2O, H2SO4 CH3CH2CH2CH2CHCH3

2-Hexanol1-Hexene

OH

Follow Mar's Rule

2. H2O2, NaOHCH3C=CHCH3

1. BH3 / THF

3-Methyl-2-butanol

2-Methyl-2-butene

Anti-Mar's Rule

CH3

CH3CHCHCH3

CH3

OH

Page 20: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.8 Reaction of alcohols

C

O

H

C-O bondO-H bond are polarized

it is replaced by sodium (Na) and potassium (K)

The hydroxyl group is replaced by other groups.

ROH + Na RONa + H2

ROH + K ROK + H2

Page 21: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

The Hydroxyl group (OH) is replaced by other groups (N

u:-)

C O H + H A

Strong acidAlcohol

C O H

H

+

Protonated alcoholÖÊ×Ó»¯µÄ´¼

+ A-

C O H

H

+

Protonated alcoholÖÊ×Ó»¯µÄ´¼

Nu:-

SN2

Nu C + H2O

Page 22: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

H C

H

CH3

O H

H

+

Protonated alcoholÖÊ×Ó»¯µÄÒÒ´¼

SN2

+ H2O

CH3CH2OCH2CH3

Diethyl ether

CH3CH2OH CH3CH2OCH2CH3H

+

-H+

2CH3CH2OH140oC

conc H2SO4 CH3CH2OCH2CH3 + H2O

Diethyl ether

Page 23: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.10 Conversion of alcohols into mesylates (甲基磺酸

酯) and tosylates (苯磺酸酯)

CH3S

O

O

Cl

MethanesulfonylChloride¼×»ù»Çõ£ÂÈ

+ HOCH2CH3-HCl

CH3S

O

O

OCH2CH3

Ethyl methanesulfonate(ethyl mesylate)¼×»ÇËáÒÒõ¥

Page 24: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

S

O

O

Cl

p-Toluenesulfonyl Chloride¶Ô¼×±½»Çõ£ÂÈ

+ HOCH2CH3-HCl

H3Cbase

S

O

O

Cl

p-Toluenesulfonyl Chloride¶Ô-¼×±½»Çõ£ÂÈ

H3CS

O

O

OH

p-Toluenesulfonic acid¶Ô-¼×±½»ÇËá

H3CPCl5

S

O

O

OCH2CH3

Ethyl p-toluenesulfonate(ethyl tosylate)¶Ô¼×±½»ÇËáÒÒõ¥

H3C

Page 25: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

S

O

O

p-Tosyl group¶Ô-¼×±½»Çõ£»ù

H3C Ts-

CH3 S

O

O

Ms

The mesyl group¼×»Çõ£»ù

CH3 S

O

O

OR

An alkyl mesylate¼×»ÇËáÍé»ùõ¥

or MsOR

S

O

O

OR

An alkyl tosylate¶Ô-¼×±½»ÇËáÍé»ùõ¥

H3C or TsOR

Page 26: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.11 Mesylates and tosylates in SN2 reaction

O S

O

O

R

An alkyl mesylateÍé»ù»ÇËáÍé»ùõ¥

RCH2Nu:- + NuCH2R + -O S

O

O

RSN2

a good leaving group

Page 27: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.12 Alkyl phosphates ( 烷基磷酸酯)

Alcohols (ROH) react with phosphoric acid (H3PO4) to yield alkyl phosphates

HO P

OH

O

OH+ P

OH

O

OH

Ethyl dihydrogen phosphateÁ×Ëá¶þÇâÒÒõ¥

CH3CH2OH

Phosphoric acid

CH3CH2O

CH3CH2OHP

OH

O

OCH2CH3

Diethyl hydrogen phosphateÁ×ËáÇâ¶þÒÒõ¥

CH3CH2OCH3CH2OH

P

OCH2CH3

O

OCH2CH3CH3CH2O

Triethyl phosphateÁ×ËáÈýÒÒõ¥

Page 28: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.13 Conversion of alcohols into alkyl halides

Alcohols react with a variety of reagents to yield alkyl halides. The most commonly used reagents are hydrogen halides (HCl, HBr, or HI), Phosporous tribromide (PBr3), and thionly chl

oride (SOCl2).

R OH +

HCl

HBr

HI

PBr3

SOCl2

RCl + H2O

RBr + H2O

RI + H2O

RBr + H3PO3

RCl + SO2 + HCl

Page 29: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

H3C

CH3

CH3

OH + HCl (cond) H3C

CH3

CH3

Cl + H2O

HBr (cond)

PBr3

CH3CH2CH2CH2OH + CH3CH2CH2CH2Br + H2O

95%

3CH3CH2CH2CH2OH + CH3CH2CH2CH2Br + H3PO3

SOCl2

CH2OH

OCH3

¼ä-¼×Ñõ»ù±½¼×´¼

+

CH2Cl

OCH3

1-Âȼ׻ù-3-¼×Ñõ»ù±½

+ SO2 + HCl

(3-Methoxy-phenyl)-methanol 1-Chloromethyl-3-methoxy-benzene

Page 30: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.14 Alkyl halides from the reactions of alcohols with

hydrogen halides

R OH HX+ R X + H2O

(NaX + H2SO4)

The order of reactivity of the hydrogen halides is: HI HBr HCl

The order of reactivity of alcohol is: R3COH 3o R2CHOH 2o ROH 1o

Page 31: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.14A Mechanisms of the reactions of alcohols with

HXH3C

CH3

CH3

OH + HCl (cond) H3C

CH3

CH3

OHH

+Step 1

fastCl-+

SN1 type reaction

Step 2 H3C

CH3

CH3

OHH

+ slowH3C

CH3

CH3

+ + H2O

SN1 type reaction

Step 3 H3C

CH3

CH3

+ + Cl- H3C

CH3

CH3

Clfast

酸 (H+) 和 Lewis acid (ZnCl2) 促进此反应。

Page 32: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.15 Alkyl halides from the reactions of alcohols with PBr3

or SOCl2

3R OH

(1o or 2o)

+ PBr3 3 RBr + H3PO3

RCH2OH + Br P

Br

Br RCH2O

H

+P Br

Br

+ Br-

O

H

+P Br

Br

Br- +

Step 1

Step 2 RCH2 RCH2Br + HOPBr2

SN2 reaction

A good leaving group

Page 33: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

3R OH

(1o or 2o)

+ SOCl2 3 RCl + SO2 + HCl

thionyl chloride

refluxadd R3N or Pyridine to the mixture to promote the reaction by reacting with the HCl

Step 2 RCH2O

H

+S Cl

O-

Cl

RCH2O S Cl

O

+ HCl

Alkyl chlorosulfite

RCH2OH + Cl S

O

Cl RCH2O

H

+S Cl

O-

Step 1

Cl

O S Cl

O

Cl- + RCH2 RCH2Cl + O=S=O + Cl-SN2 reaction

A good leaving group

Step 3

Alkyl chloride

Page 34: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.16 Synthesis of ether 醚的合成

10.16A Ethers by intermolecular dehydration of alcohols ( 醇的分子间脱水制醚)

ROH + HORH+

ROR + H2O

CH3CH2OH

CH2=CH2 + H2O

CH3CH2OCH2CH3 + H2O

Ethene

Diethyl ether

H2SO4

180oC

H2SO4

140oC

Page 35: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.16B The Williamson synthesis of ethers ( 醚的威廉姆孙合

成)An important route to unsymmetrical ethers is a nucleophilic substitution reaction

known as the Williamson synthesis.

RONa + R' L

L = Br, I, OSO2R'', or OSO2OR''

SN2 reactionROR' + NaL

Sodium alkoxide

Page 36: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

How to synthesis of ethyl propyl ether (CH3CH2CH2OCH2CH3)

CH3CH2CH2OH + Na

Propyl alcohol

CH3CH2CH2ONa

Sodium propoxide

+ 1/2 H2

CH3CH2CH2ONa + CH3CH2 ISN2 reaction

CH3CH2CH2OCH2CH3 + NaI

The Williamson synthesis

Page 37: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.16C tert-Butyl ethers by alkylation of alcohols

HOCH2CH2CH2Br + NaC

3-Bromo-1-propanol

NaOCH2CH2CH2Br + HCCH CH

HOCH2CH2CH2C CH HOCH2CH2CH2Br + NaC

3-Bromo-1-propanol

CH

3-Bromo-1-propanol

HOCH2CH2CH2Br+CH2=C(CH3)2 (CH3)3COCH2CH2CH2Br

Éú³ÉÃѱ£»¤´¼ôÇ»ù

NaC CH

SN2 reaction(CH3)3COCH2CH2CH2 C CH

H+, H2OHOCH2CH2CH2C CH

È¥±£»¤»ù

Page 38: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.16D Trimethylsilyl ethers. Silylation

(三甲硅醚 --- 甲硅烷基化作用)

A hydroxyl group can also be protected in neutral or basic solutions by converting it a trimethylsily ether group, -OSi(CH3)3. This reaction, called silylation, is done by allowing the alcohol to react with chlorotrimethylsilane in the prese

nce of a tertiary amineROH + (CH3)3SiCl ROSi(CH3)3

ChlorotrimethylsilaneÂÈ»¯Èý¼×»ù¹è

Éú³É¹èÃѱ£»¤´¼ôÇ»ù

+ HCl(CH3CH2)3N

Page 39: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

ROH + (CH3)3SiCl ROSi(CH3)3

ChlorotrimethylsilaneÂÈ»¯Èý¼×»ù¹è

Éú³É¹èÃѱ£»¤´¼ôÇ»ù

+ HCl(CH3CH2)2N

È¥±£»¤»ùROSi(CH3)3

H+ , H2O ROH + (CH3)3SiOH

Synthesis of HOCH2CH2CH2C CH

3-Bromo-1-propanol

HOCH2CH2CH2Br+(CH3)SiCl (CH3)3SiOCH2CH2CH2Br

Éú³É¹èÃѱ£»¤´¼ôÇ»ùNaC CH

SN2 reaction(CH3)3SiOCH2CH2CH2C CH

H+, H2OHOCH2CH2CH2C CH

È¥±£»¤»ù

(CH3CH2)3N

Page 40: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.17 Reactions of ethers

Heating dialkyl ethers with very strong acids (HI, HBr, and H2SO4) cause them to undergo reactions in which the carbon-oxygen bond breaks. Diethyl ether, for example, react with hot concentrated hydrobromic acid to give two molar equivalents of

ethyl bromideCH3CH2OCH2CH3+ HBr CH3CH2OCH2CH3

H

+

An oxonium salt

Br-

HIH2SO4

2 CH3CH2Br + H2O

Page 41: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

The mechanism for this reaction

CH3CH2OH + CH3CH2Br

HBr

CH3CH2OHH

+ Br-

CH3CH2BrSN2

CH3CH2OCH2CH3 + HBr CH3CH2O

H

+CH2CH3 + Br-

SN2

An oxonium salt(ÑðÑΣ©

Page 42: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.18 Epoxides 环氧化物

Epoxides (Oxirane) are cyclic ethers with three-membered rings.

C C

O

An epoxide

O

IUPAC; OxiraneCommon: Ethylene oxide »·ÑõÒÒÍé

Page 43: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

Synthesis of epoxides

O

RCH=CHR + RC

O

O OH

A peroxy acid¹ýÑõËá

R R

An epoxide»·Ñõ»¯Îï

Alkenes

RC

O

O OH

A peroxy acid¹ýÑõËá

CH3COOH

O

C

O

OOH

Peroxyacetic acid¹ýÑõ»¯ÒÒËá

peroxybenzoic acid¹ý Ñõ»¯±½¼×Ëá

Page 44: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

C

O

OOH

peroxybenzoic acid¹ý Ñõ»¯±½¼×Ëá

cyclohexene

+CH2Cl2 O

H

H

1,2-Epoxycyclohexane

(100%)

(1,2-Ñõ´ú»·¼ºÍ飩

CH3COOH

OPeroxyacetic acid¹ýÑõ»¯ÒÒËá

H3CH

H3C H

+ O

H3C

H3C

H

H

Cis-2,3-Dimethyloxirane˳-2£¬3-¶þ¼×»ù»·ÒÒÍé( a meso compound)

Cis-2-Butene

CH3COOH

OPeroxyacetic acid¹ýÑõ»¯ÒÒËá

H3CH

H CH3

+ O

H3C

H

CH3

H

trans-2,3-Dimethyloxirane·´-2£¬3-¶þ¼×»ù»·ÒÒÍé

+ O

CH3H

CH3

H

(Enantiomer)

trans-2-butene

Page 45: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.19 Reactions of epoxides

The highly strained three-membered ring in molecules of epoxides makes them much more reactive toward nucleophilic substi

tution than other ethers.

Acid-Catalyzed Ring Opening;

C C

O

H+

C C

OH

+

H2OC C

OH +OH2

- H+

C C

OH OH

1,2-Diols

Page 46: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

Based-Catalyzed Ring Opening;

C C

O

RO C C O-RO-

An alkoxide ion

RO C C OHROH

+ RO-

Page 47: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

If the epoxide is unsymmetrical, in base-catalyzed ring opening attack by the alkoxide ion occurs primarily at the less substituted

carbon atom.

H2CHC CH3

O

CH3CH2O-

An alkoxide ion

CH3CH2OCH2CHCH3

O-

Less substituted ring-openingLess hindered

Methyloxirane

CH3CH2OHCH3CH2OCH2CHCH3

OH

+ CH3CH2O-

1-Ethoxy-2-propanol£¨1-ÒÒÑõ»ù-2-±û´¼£©

Page 48: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

In the acid-catalyzed ring opening of an unsymmetrical epoxide the nucleophile attacks primarily

at the more substituted carbon atom.

H2C C CH3

O

CH3CH2OH

More substituted ring-opening3o C+

CH3

H

+

HOCH2C CH3

OCH2CH3

CH3

H+

Protonated epoxide

HOCH2CH(CH3)2

OCH2CH3

+ H+

2-Ethoxy-2-Methyl-1-propanol£¨2-ÒÒÑõ»ù-1-¼×»ù-1-±û´¼£©

Page 49: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.20 Anti hydroxylation of alkenes via epoxides

( 烯烃经环氧化物的反式 - 羟基化)

+ CH3COOH

O

O

H

H

H+ , H2OOH

OH

H

H

trans-1,2-Cyclopentanediol

£¨·´Ê½-1£¬2-»·Îì¶þ´¼£©£¨1,2-»·ÑõÎìÍ飩1,2-Epoxycyclopentane

Cyclopenteneperoxyacetic acid

Page 50: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

Mechanism of this reaction;

+ CH3COOH

O

O

H

H

H+

OH

H

H

+

£¨1,2-»·ÑõÎìÍ飩1,2-Epoxycyclopentane

Cyclopenteneperoxyacetic acid

protonated epoxideÖÊ×Ó»¯»·Ñõ»¯Îï

OH

H

H

+

H2O

OH

OH2

H

H

+- H+

OH

OH

H

H

trans-1,2-Cyclopentanediol

£¨·´Ê½-1£¬2-»·Îì¶þ´¼£©

Page 51: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

H3CH

OH

H3CH

Cis-2,3-Dimethyloxirane

H2O +

a

b

CH3

H

HHO

OHH3C

(2R, 3R)-

H

CH3

OH

HO

H

CH3

(2S, 3S)-2,3-Butanediol

a

b

CH3COOH

O H+ , H2O

H3CH

O

H3CH

CH3H

CH3H

Cis-2-butene Cis-2,3-Dimethyloxirane

H

CH3

OH

HO

H

CH3

+

CH3

H

HHO

OHH3C

(2S, 3S)-2,3-Butanediol(2R, 3R)-

Enantiomers

Page 52: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

CH3COOH

O H+ , H2O

H3CH

O

HH3C

CH3H

HH3C

trans-2-butene trans-2,3-Dimethyloxirane

H

CH3

OH

HO

CH3

H

+

CH3

CH3

HHO

OHH

(2S, 3R)-2,3-Butanediol(2R, 3S)-

Same compounds

R

S

S

R

(the meso compundes)

H3CH

OH

HH3C

trans-2,3-Dimethyloxirane

H2O +

a

b

CH3

CH3

HHO

OHH

(2R, 3S)-

H

CH3

OH

HO

CH3

H

(2S, 3R)-2,3-Butanediol

a

b

identical (Ïàͬ£©(meso compoundes)

Page 53: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.22 Crown Ethers; (冠醚)

1. Phase-Transfer catalysis (PTC) ( 相转移催化)

RX + NaCNQ+X- (¼¾ì¢ÑΣ©

RCN + NaXSN2 reaction

No catalyst, needed long time to finish this reaction.Add Q+X- (PTC) to speed up reaction.

Page 54: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

Fig. Phase-transfer catalysis of the SN2 reaction between

sodium cyanide and an alkyl halide.

RX + NaCNQ+X- (¼¾ì¢ÑΣ©

RCN + NaXSN2 reaction

RX

NaCN

aqueous phase

Organic phase(CH2Cl2)

(Ë®Ïࣩ add Q+X- (¼¾ì¢ÑΣ©

Q+X-

+ RCN

Q+CN+ RX

NaCN+ Q+X-

NaX+

Q+CN

Q+X- (CH3(CH2)3)4N+X-

(CH3(CH2)3)4N+Cl- (ÂÈ»¯Ëļ×泥©

Page 55: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

CH3(CH2)6CH2Cl + NaCN(CH3(CH2)3)4N+Cl- (ÂÈ»¯Ëļװ·£©

CH3(CH2)6CH2CN(95%)

+ NaClSN2 reaction

CH3(CH2)5CH=CH2 + KMnO4

(CH3(CH2)3)4N+Cl-

CH3(CH2)5COOH(ÂÈ»¯Ëļװ·£©

Benzene

Page 56: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

10.22A Crown ethersCompounds called crown ethers are also phase-transfer catalysts and are able to

transport ionic compounds into an organic phase.

O

O

O

OO

O

18-Crown-618-¹Ú-6

K+MnO4-

18-Crown-618-¹Ú-6

K+CN-

Ñõ»¯¼Á

Ç׺ËÊÔ¼Á

O

O

O

OO

O

K+

提高了 KMnO4 的氧化能力和提高了亲核试剂 KCN 的亲核能力。

Page 57: 10.1 Structure and Nomenclature 2. Nomenclature of ether.

RX + KCN RCN + KClSN2 reaction

18-Crown-6

C6H5CH2Cl + KFSN2 reaction

18-Crown-6C6H5CH2F + KCl

100%

C6H5CH2Cl + KCNSN2 reaction

18-Crown-6C6H5CH2CN + KCl

CH3(CH2)5CH=CH2 + KMnO4 CH3(CH2)5COOH18-Crown-6

CH=CH2 + KMnO4 COOH18-Crown-6