8 Oleochemistry Products
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8.2.4 Synthesis of Surfactants
Biosurfactants are generally categorized by their microbial origin or chemical composition. Starting from renewable raw materials there are several chemical reactions to
obtain surfactants or surfactant precursors. In particular, it is possible to use standard
oleochemical transformations (transesterification, hydrogenation, hydrolysis, etc.) or
more specific reaction to produce surfactants (reduction, sulfonation, chlorination,
etc.).
Considering oleochemical raw materials, some chemical transformations to obtain
surfactants or surfactant precursors are reported in Fig. 8.2. Esterification, ethoxylation, neutralization or condensation reaction are considered to obtain, starting from
fats and oils, the corresponding surfactants such as soaps, mono- and diglycerides,
sugar esters, polyglycol esters, fatty amines, fatty alcohols.
Fatty acid methyl esters
First of all, it is possible to consider as starting materials fatty acid methyl esters that
can be produced by transesterification of triglycerides [56, 188].
Fatty acids (FAs)
Fatty acids (FAs) and their derivatives could act like a surfactant as they contain a
lipophilic ‘hydrophobic’ part (the alkyl chain) and a hydrophilic ‘lipophobic’ (head
group) which could be amino acids, polyglycerides, polysaccharides and the carboxylate groups on fatty acid chains. So, FAs could exist comfortably at an oil–water
interface and can reduce the surface tension at such interfaces. This property is fundamental in all living systems and also in many foods and other manmade systems,
where aqueous and fatty phases must coexist. FAs as surfactants confers surface
activity that allows appropriate compounds to act as emulsifying agents, detergents,
lubricants, etc. [2, 185]. The FAs composition of oils from vegetable sources varies
depending on plant origin and sort. Commercially exploited seeds such as soya, rape,
sunflower and linseed have been the subject of many years of breeding programmes
to obtain oils with particular fatty acid patterns. In addition to breeding efforts on
traditional oil crops, work is being done to domesticate alternative oil-rich plants, that
may yield new potentially useful fatty acids [99]. Oleochemical surfactants including
soaps are mainly made from fatty acids, fatty alcohols or fatty amines using tallow,
palm oil, palm kernel oil or coconut oil as feedstock. Saponins are kind of natural
soaps, which have antifungal and antibacterial activity and are produced by many
plants to form part of the plant’s protection against disease [184].
Unsaturated fatty acid methyl esters obtained from plant oils were converted to
terminally unsaturated esters and α-olefins by metathesis with ethylene using heterogeneous rhenium or homogeneous ruthenium catalysts in the purpose of preparation
of special surfactant. These esters were directly copolymerized with ethylene by
an insertion-type palladium-catalyzed polymerization to functionalized polyolefins.
Polyesters were synthesized by metathetical dimerization of x-unsaturated esters and
subsequent polycondensation of the produced internally unsaturated dicarboxylic
esters or by acidic transesterification with petrochemical diols and additional acyclic
211
8.2.4 Synthesis of Surfactants
Biosurfactants are generally categorized by their microbial origin or chemical composition. Starting from renewable raw materials there are several chemical reactions to
obtain surfactants or surfactant precursors. In particular, it is possible to use standard
oleochemical transformations (transesterification, hydrogenation, hydrolysis, etc.) or
more specific reaction to produce surfactants (reduction, sulfonation, chlorination,
etc.).
Considering oleochemical raw materials, some chemical transformations to obtain
surfactants or surfactant precursors are reported in Fig. 8.2. Esterification, ethoxylation, neutralization or condensation reaction are considered to obtain, starting from
fats and oils, the corresponding surfactants such as soaps, mono- and diglycerides,
sugar esters, polyglycol esters, fatty amines, fatty alcohols.
Fatty acid methyl esters
First of all, it is possible to consider as starting materials fatty acid methyl esters that
can be produced by transesterification of triglycerides [56, 188].
Fatty acids (FAs)
Fatty acids (FAs) and their derivatives could act like a surfactant as they contain a
lipophilic ‘hydrophobic’ part (the alkyl chain) and a hydrophilic ‘lipophobic’ (head
group) which could be amino acids, polyglycerides, polysaccharides and the carboxylate groups on fatty acid chains. So, FAs could exist comfortably at an oil–water
interface and can reduce the surface tension at such interfaces. This property is fundamental in all living systems and also in many foods and other manmade systems,
where aqueous and fatty phases must coexist. FAs as surfactants confers surface
activity that allows appropriate compounds to act as emulsifying agents, detergents,
lubricants, etc. [2, 185]. The FAs composition of oils from vegetable sources varies
depending on plant origin and sort. Commercially exploited seeds such as soya, rape,
sunflower and linseed have been the subject of many years of breeding programmes
to obtain oils with particular fatty acid patterns. In addition to breeding efforts on
traditional oil crops, work is being done to domesticate alternative oil-rich plants, that
may yield new potentially useful fatty acids [99]. Oleochemical surfactants including
soaps are mainly made from fatty acids, fatty alcohols or fatty amines using tallow,
palm oil, palm kernel oil or coconut oil as feedstock. Saponins are kind of natural
soaps, which have antifungal and antibacterial activity and are produced by many
plants to form part of the plant’s protection against disease [184].
Unsaturated fatty acid methyl esters obtained from plant oils were converted to
terminally unsaturated esters and α-olefins by metathesis with ethylene using heterogeneous rhenium or homogeneous ruthenium catalysts in the purpose of preparation
of special surfactant. These esters were directly copolymerized with ethylene by
an insertion-type palladium-catalyzed polymerization to functionalized polyolefins.
Polyesters were synthesized by metathetical dimerization of x-unsaturated esters and
subsequent polycondensation of the produced internally unsaturated dicarboxylic
esters or by acidic transesterification with petrochemical diols and additional acyclic