Chemistry Reference
In-Depth Information
Sulfonate surfactants contain a sulfur atom which is directly attached to the carbon
atom of the alkyl group, giving the molecule stability against hydrolysis compared
with the sulfate surfactants. There are three methods to introduce the sulfonate group
into rosin and its derivatives: the first one is to sulfonate the hydroxyl groups directly
with sulfonating agent such as concentrated sulfuric acid, the second is to add sulfate
salt to the double bonds of rosin derivatives and the third one is to react the rosin
derivative with a functional group containing a sulfonate group. DAA has an aromatic
ring, which provides another group for preparing sulfonate anionic surfactants. Chen
and co-workers reported a new unsymmetrical bora form surfactant, (disodium
sulfodehydroabietate [A06]) which was synthesised by sulfonation of dehydroabietic
acid followed by neutralisation (
Scheme 5.18
) [35].
Scheme 5.18
Synthesis of bora form sulfonate surfactant (A06)
The most widely studied of rosin-based anionic surfactants are sulfonate salts, which
are usually prepared by reacting rosin acid or rosin amine with alcohol. The terminal
hydroxyl group is then esterified with maleic anhydride (MA), followed by the
addition of sulfate to the double bond to form the corresponding sulfonate anionic
surfactants (
Scheme 5.19
). Rosin, rosin amine or dehydroabietylamine, rosin hydroxyl
ethyl amide and acrylic rosin can be ethoxylated by epoxy and the terminal hydroxyl
group can be esterified by MA, after addition of sulfate to the double bond to form
corresponding sulfonate anionic surfactants (A07-A11) [36, 37].
