Organic Chemistry

474 CHAPTER 12 Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

from compounds that contain acidic groups. The carbon

atom attached to the halogen in the alkyl halide is an elec-

trophile, whereas the carbon atom attached to the metal ion in

the organometallic compound is a nucleophile. The greater

the polarity of the carbon–metal bond, the more reactive the

organometallic compound is as a nucleophile.

New carbon–carbon bonds can be made using transition-

metal organometallic reagents. The reactions are called

coupling reactionsbecause two carbon-containing groups

are joined together. Gilman reagents were the first

organometallic compounds used in coupling reactions. The

Heck,Stille, and Suzuki reactionsare coupling reactions.

Summary of Reactions

1. Conversion of an alcoholto an alkyl halide(Sections 12.1 and 12.3).


2. Conversion of an alcohol to a sulfonate ester(Section 12.4).


3. Conversion of an activated alcohol(an alkyl halide or a sulfonate ester) to a compound with a new group bonded to the carbon
   (Section 12.4).


4. Dehydration of alcohols (Section 12.5).


5. Cleavage of ethers (Section 12.6).

HX = HBr or HI

ROR′ + HX ROH + R′X

∆

H

C

OH

CCC

CC

H 2 O

∆

H 2 SO 4

+

H

C

OH

CH 2 O

POCl 3

relative rate: tertiary > secondary > primary

pyridine, 0 °C +

RY S

O

O

RO S R′

O

O

R′ + Y− + −O

RBr + Y− RY + Br−

sp^3

ROH R′ S

O

O

Cl RO S

O

O

+ pyridine R′ + HCl

ROH + HBr RBr

ROH + HI RI

ROH + HCl RCl

ZnCl 2

ROH + PBr 3 RBr

∆

ROH + PCl 3 RCl

ROH + SOCl 2 RCl

pyridine

pyridine

pyridine

∆

∆

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