The Foundations of Chemistry

Indeed, this is a better view. The structure of water was discussed in Section 8-9. The
hydroxyl group in an alcohol or a phenol is covalently bonded to a carbon atom, but the
OXH bond is quite polar. The oxygen atom has two unshared electron pairs, and the
CXOXH bond angle is nearly 104.5°.
The presence of a bonded alkyl or aryl group changes the properties of the XOH
group. Alcoholsare so very weakly acidic that they are thought of as neutral compounds.
Phenolsare weakly acidic.
Many properties of alcohols depend on whether the hydroxyl group is attached to a
carbon that is bonded to one, two,or threeother carbon atoms.

Primary alcoholscontain one R group; secondary alcoholscontain two R groups;

and tertiary alcoholscontain three R groups bonded to the carbon atom to which

the XOH group is attached.

TABLE 27-7 (continued)

Normal
Formula Structural Formula bp (°C) IUPAC Name Common Name

(CH 3 ) 2 CHI 89.5 2-iodopropane isopropyl iodide

CH 3 ClCUCHCH 2 CH 2 Cl 40 2,5-dichloro-cis-2-—
pentene; trans
isomer is also
possible

C 5 H 7 Cl 25 3-chlorocyclopenteneis —
shown; other isomers
are also possible

C 6 H 5 I 118 iodobenzene phenyl iodide

C 6 H 4 ClBr 204 1-bromo-2-chloro- o-bromochlorobenzene
benzeneis shown;
other isomers are
also possible

C 14 H 9 Cl 5 1,1,1-trichloro-2,2- DDT
bis(p-chlorophenyl)–
ethane

HH

IH

H C C

H

H

C H

Cl

CH 3 CH 2 C Cl

H

H

H

CC

Cl

2

1

54

3

I

Cl

Br

Cl Cl

Cl

Cl Cl

C

C

H