alcohol,phenols,ethers

Topics: Alcohol, Functional groups, Functional group Pages: 14 (1961 words) Published: January 17, 2014
Experiment #8 – properties of Alcohols
and Phenols
Introduction
As has been mentioned before, over 20 million organic compounds have been identified. If each substance had to be studied as an entity completely separate from all the other substances, the study of organic chemistry as a whole would be impossible; that is to say, even more impossible than you currently believe it to be. Fortunately, the subject can be organized and it is often organized around the concept of the functional group. A functional group is an atom or group of atoms, bonded together in a certain way, that, as part of a molecule, will impart certain physical and chemical characteristics to the molecule as a whole. It is the case that the rest of the molecule can modify the characteristics of the functional group. It is also the case that if the rest of the molecule is an alkyl group the modifications may be modest. On the other hand, other functional groups in the molecule, especially if they are close by, are more likely to profoundly modify the characteristics of the functional group in question. The functional group we are considering in this experiment is the hydroxy (or hydroxyl) functional group, -OH. This group shows up in a number of guises in organic compounds. Some of the common ones are shown in the table below. Functional Group Structure

Compound Generic Name

Comments

alcohol

In an alcohol, the -OH is
attached to a tetrahedral
carbon atom. Very weekly
acidic.

enol

Two functional groups
attached to the same
carbon. It’s an alkene and
an alcohol. Usually
unstable.

phenol

-OH directly bonded to an
aromatic ring. Weekly
acidic.

hemiacetal

Two functional groups
attached to the same
carbon. Formed from
reaction between an
alcohol and an aldehyde or
ketone.

carboxylic acid

Two functional groups
attached to the same
carbon. Moderately acidic.

C OH

C

C

OH

OH

C O C OH

C OH
O

Experiment #8

sulfonic acid

O
C

S

Properties of Alcohols and Phenols

Page 2

Very acidic.

OH

O

The functional groups we will consider in this
experiment are alcohols and phenols. In alcohols the
-OH group is attached to a tetrahedral carbon atom. If
the carbon atom is bonded to three hydrogens in
addition to the -OH, the alcohol is methanol. If the
carbon that is bonded to the -OH is bonded to one
o
carbon and two hydrogens, the alcohol is a primary (1 )
alcohol. If the carbon that is bonded to the -OH is
bonded to two carbons and one hydrogen, the alcohol is
o
a secondary (2 ) alcohol. If the carbon that is bonded to
the -OH is bonded to three carbons, the alcohol is a
o
tertiary (3 ) alcohol. All of these alcohols share some
characteristics but other characteristics are different
owing to their different structures.

H

H

H C OH H C OH
H
methanol

C
1o alcohol

H

C

C OH C

C OH

C

C
2 alcohol
o

C
3 alcohol
o

In phenols the -OH group is directly attached to a carbon that is part of an aromatic ring. Alcohols and phenols are similar in some ways, but there are enough differences so that they are considered different functional groups. One major difference is that phenols are typically about a million times more acidic than alcohols. Addition of sufficient aqueous sodium hydroxide to a phenol will cause the -OH group of most of the molecules present to be deprotonated; this will not happen to an alcohol. Physical Properties

The larger an alcohol or phenol the higher the boiling point, usually. As the alcohol size increases
H O H
H
the probability that the H O
O H
O
H
H
alcohol will be a solid
H
H
H
increases. Many
O H Alcohols can
H
O H
phenols are solids.
O H HH
hydrogen bond.
O H
Small alcohols are
O H
C C
H
water soluble because
H
H
HH
the hydroxyl group can
H O
H
hydrogen bond with
H O
H O
H O H O
water molecules. But
H
H
H H
as the size of the alkyl
O H
group increases the...
Continue Reading

Please join StudyMode to read the full document

You May Also Find These Documents Helpful

  • Essay about Alcohols and Phenols
  • Alcohols And Phenols Essay
  • Chapter 17: Alcohols and Phenols Essay
  • Essay about ALCOHOLS
  • phenols Essay
  • alcohol Essay
  • Alcohols Essay
  • Properties of Alcohol Essay

Become a StudyMode Member

Sign Up - It's Free