FUNCTIONAL GROUPS
HYDROXYL GROUP: --OH
• Polar, since O—H bond is polar covalent
• Makes molecule water-soluble, with –OH forming
hydrogen bonds
• Organic compounds with hydroxyl groups are
called ALCOHOLS.
• Example: ethanol (C-C-OH) in alcoholic drinks
CARBONYL GROUP: --CO
• Functional group with a carbon double-bonded to
an oxygen atom
• Polar group, making molecules water-soluble
• Functional group found in sugars. If carbonyl group
is at the end of the carbon chain, the molecule is a
Aldehyde, otherwise it is an Ketone.
• Ex. Propanol (aldehyde) and acetone (ketone)
CARBOXYL GROUP: --COOH
• Group consists of a carbon atom doublebonded to an oxygen atom, and singlebonded to a hydroxyl group
• Polar group, molecules are water-soluble
• H+ can disassociate, giving the molecule
acidic properties.
• Compounds with group are called
CARBOXYLIC ACIDS.
• Ex. Acetic Acid (in vinegar)
AMINO GROUP: --NH2
• Polar group that is water-soluble.
• Acts as a weak base, accepting
a proton (H+)
• Organic compounds with group
are called AMINES.
• NOTE: Amino acids (monomers of
proteins) have both an amino group
and a carboxyl group
SULFHYDRYL GROUP:--SH
• Help stabilize the structure of proteins
• Organic compounds with this functional group are
THIOLS.
• Ex. Cysteine
• Sulfhydryl groups formed in hair during perms to give curly
form
PHOSPHATE GROUP: --PO4
• Dissociated form of H3PO4
• Has acidic properties since it loses
H+
• Polar group, soluble in water
• Compounds are ORGANIC
PHOSPHATES, important in cellular
energy storage and transfer (ATP).
METHYL GROUP: --CH3
• Nonpolar, hydrophobic (all other
functional groups are hydrophilic)
• Important group in nonpolar
amino acids, contributing to the
tertiary structure of proteins
• Compounds containing a methyl
group are called methylated
compounds