Chemistry Reference
In-Depth Information
Raw material Intermediates Final surfactant type
Benzene Linear Linear alkylbenzene
alkylbenzene sulfonates (LABS)
Normal paraffins Secondary alkane
sulfonates
Paraffin waxes Linear α-olefins
α -Olefin sulfonates
Fatty acids Fatty amine oxides
Fatty alkanol amines
Natural fats
Alkyl glyceryl
ether alcohol
sulfates
Detergent-range
linear primary
alcohols Linear alcohol
ethoxylates
Ethylene
Ethylene oxide Alcohol ether sulfates
Figure 2.2. Evolutionary pathways for some of the more important types of commercial
surfactants.
2.2.3.1. The Natural Fatty Acids
One of the major sources of raw materials for the commercial production of surfac-
tants is also the oldest source—agriculture. Fats and oils (oleochemicals), products
of nature's ingenuity and human labor, are triglyceride esters of fatty acids, which
can be readily hydrolyzed to the free fatty acids and glycerol. Naturally occurring
plant or animal fatty acids usually contain an even number of carbon atoms
arranged in a straight chain (no branching), so that groups symbolized by an R
in abbreviated nomenclature will contain an odd number that is one less than
that of the corresponding acid. The carbons are linked together in a straight
chain with a wide range of chain lengths; those with 16 and 18 carbons are the
most common. The chains may be saturated, in which case the R group has the
formula C
n
H
2n
þ
1
, or they may have one or more double bonds along the chain.
Hydroxyl groups along the chain are uncommon, but not unknown, especially in
soaps made using castor oil (recinoleic acid). Other substitutions are rare.
Commercially, the largest surfactant outlet for fatty acids is conversion to soap
by neutralization with alkali. In a strict sense, this may be considered to be a syn-
thetic process, and soap therefore a synthetic surfactant. However, common usage
