N
N
OH
N
N
NR 2
N NHSO 4
+
_
Ph-OH
Ph-NR 2
Synthesis of sulpha drugs from aniline
Antimicrobial sulpha drugs, e.g. sulphanilamide, are the amide of sulphanilic acid, and certain related substituted amides. Sulphanilamide, the first of
the sulpha drugs, acts by inhibiting the bacterial enzyme that incorporates
para-aminobenzoic acid into folic acid. Sulphanilamide is a bacteriostatic
drug, i.e. inhibits the further growth of the bacteria.
N
H 2
SO 2 NH 2
Sulphanilamide
(para-aminobenzenesulphonamide)
Multistep synthesis, starting from aniline, as depicted in the following
scheme, can achieve the product, sulpha drug.
NH 2
NHCOCH 3
NHCOCH 3
SO 2 Cl
NHCOCH 3
SO 2 NHR
NHCOCH 3
SO 2 NH 2
NH 2
SO 2 NH 2
NH 2
SO 2 NHR
C
H 3
CH 3
O
+
Acetanilide
para-Acetamidobenzene-sulphonylchloride
NH 3
H 2 O
H +
Sulphanilamide
RNH 2
Substituted sulphanilamide
H 2 O
H +
Separation of aniline and a neutral compound from a mixture by solvent
extraction
If a mixture contains aniline and a neutral compound, both the constituents
can easily be separated and purified by the solvent extraction method. To
purify these compounds, the mixture is dissolved in diethylether, HCl and
water are added and the solution is shaken in a separating funnel. Once two
140
CH4 ORGANIC FUNCTIONAL GROUPS
N
OH
N
N
NR 2
N NHSO 4
+
_
Ph-OH
Ph-NR 2
Synthesis of sulpha drugs from aniline
Antimicrobial sulpha drugs, e.g. sulphanilamide, are the amide of sulphanilic acid, and certain related substituted amides. Sulphanilamide, the first of
the sulpha drugs, acts by inhibiting the bacterial enzyme that incorporates
para-aminobenzoic acid into folic acid. Sulphanilamide is a bacteriostatic
drug, i.e. inhibits the further growth of the bacteria.
N
H 2
SO 2 NH 2
Sulphanilamide
(para-aminobenzenesulphonamide)
Multistep synthesis, starting from aniline, as depicted in the following
scheme, can achieve the product, sulpha drug.
NH 2
NHCOCH 3
NHCOCH 3
SO 2 Cl
NHCOCH 3
SO 2 NHR
NHCOCH 3
SO 2 NH 2
NH 2
SO 2 NH 2
NH 2
SO 2 NHR
C
H 3
CH 3
O
+
Acetanilide
para-Acetamidobenzene-sulphonylchloride
NH 3
H 2 O
H +
Sulphanilamide
RNH 2
Substituted sulphanilamide
H 2 O
H +
Separation of aniline and a neutral compound from a mixture by solvent
extraction
If a mixture contains aniline and a neutral compound, both the constituents
can easily be separated and purified by the solvent extraction method. To
purify these compounds, the mixture is dissolved in diethylether, HCl and
water are added and the solution is shaken in a separating funnel. Once two
140
CH4 ORGANIC FUNCTIONAL GROUPS