Exercise 8: ALCOHOLS Flashcards
which is the
active component of alcoholic
beverages, is just one and most common
among the large family alcohols.
Ethanol (ethyl alcohol)
organic compounds composed of an aliphatic carbon atom with a
hydroxyl (-OH) functional group
very common and may exist freely in nature
exhibit some unique set of physicochemical properties mainly due to
the presence of the hydroxyl functional group
Alcohols
the is a functional group of all alcohols, hence the
general formula of ROH, where R is the alkyl group
hydroxyl group
some of the properties of alcohols depend on the
length of the alkyl chain attached to the hydroxyl group
C with the –OH group attached to one other carbon atom
general formula:
primary (1°) alcohol
RCH2OH
C with the –OH group attached to two other carbon atoms
general formula:
secondary (2°) alcohol
R2CHOH
C with the –OH group attached to three other carbon
atoms
general formula:
tertiary (3°) alcohol
R3COH
generally have higher boiling points as compared to hydrocarbons
having the same molecular masses
mainly due to the in between the OH
groups
BOILING POINT
intermolecular H-bonding
boiling point = number of C in the aliphatic chain
boiling point = branching in aliphatic carbon chain
Increase. Increase
Decrease, increase
governed by its ability to perform intermolecular H-bonding with
polar solvents
SOLUBILITY
are usually formed in between the OH group of alcohol
and water (which makes alcohol soluble with H2O)
however, the longer the alkyl chain is, the - alcohol
becomes soluble with water
H-bonds
lesser
acidic in nature because of their ability to react with active metals
(e.g. sodium, potassium,) forming the corresponding
ACIDITY
alkoxide
acidity is due to the
polarity of the hydroxyl bond
acidity = when an electron donating group is attached to the
hydroxyl group as the electron density increases on the oxygen
atom
Decrease
primary alcohols are - than secondary and tertiary
alcohols
more acidic
PROPERTIES OF ALCOHOLS
Boiling point
Solubility
Acidity
alcohols exhibit a
range of
spontaneous
chemical
reactions due to
the cleavage of
C-O and O-H
bonds
JONES TEST (CHROMIC ACID TEST) results
n-butyl alcohol
blue-green solution
changes color much faster
JONES TEST (CHROMIC ACID TEST) results
sec-butyl alcohol
blue-green solution
changes color much slower
JONES TEST (CHROMIC ACID TEST) results
tert-butyl alcohol
orange solution
n/a
used to distinguish primary and
secondary alcohols from tertiary alcohols
positive result: blue-green solution
JONES TEST (CHROMIC ACID TEST)
reagent: Jones reagent ();
chromium oxide CrO3 in sulfuric acid H2SO4