How do functional groups affect organic molecules?

1 Answer
Sep 24, 2015

Answer:

Functional groups determine the identity of organic molecules

Explanation:

Functional groups are very important in organic chemistry since they determine the identity of these molecules and therefore, depict the chemical and physical properties of them.

For example, hydroxy groups #OH# is specific for alcohols. the general structure for alcohols is #R-OH#.

In a similar way, #COOH# is the functional group for carboxylic acids of a general structure #R-COOH#.

For esters, the functional group is #COOR'#, where esters have the general structure #R-COOR'#.

And so on.

with different functional groups, alcohols, carboxylic acids, and esters have different chemical and physical properties and therefore, different identity.

Let us take a specific example; Propane #CH_3CH_2CH_3#. Propane is a gaseous molecule at room temperature. Adding a hydroxy group to its structure we get #CH_3CH_2CH_2-OH# which is the propanol. Propanol is liquid at room temperature ( change on physical property ). Propanol can react thanks to the presence of the oxygen atom in its backbone, however, propane has very limited reactivity ( change on chemical property ).

There are many other functional groups such as:
Sulfides: #R-S-R'#
Thiols: #R-SH#
Ethers: #R-O-R'#
Anhydrides: #R-CO-O-CO-R'#
Ketones: #R-CO-R'#
Aldehydes: #R-CO-H#
Amides: #R-CO-N(R')_2# or #R-CO-NH_2# or #R-CO-NHR'#
Amines: #R-NH_2# or #R-NHR'# or #R-N(R')_2#
Nitriles: #R-CN#
Alkyl halides: #R-X# where #X# is an element from group 17.
Alkenes: #R-CH=CH-R'#
Alkynes: #R-C-=C-R'#
etc.