43
3
after salting out with common salt the “soap
core” is finally formed, which is processed into
soap after further washing.
Today, modern industrial processes are predominantly continuous. Low-cost tallow (80%) is
usually used as raw material, but coconut oil and
palm kernel oil are also used. In addition, also
special soaps are made from other raw materials,
such as the “Savon de Marseille”, which is made
from olive oil.
Soaps can also be produced by neutralizing
free fatty acids. . Figure 3.7 schematically shows
the continuous production of fine soaps from fats
or fatty acids and alkali: Saponification produces
a soap brew from which the water is removed in
a dryer. The soap chips formed are mixed with
perfume and color additives. The mixture is then
transferred in an extruder into a soap strand,
which is cut into handy units in the soap bar cutter. After passing through a cooling tunnel, an
imprint is finally punched onto the soap bar.
3.1.4 Direct Hydrogenation
Besides the splitting of fats by hydrolysis,
transesterification or saponification, one can
also try to achieve fat splitting by hydrogenation. . Figure 3.8 shows that the fatty acids of
triglycerides are hydrogenated to fatty alcohols.
In the 1980s, the German Henkel company
carried out extensive work on this reaction.
Unfortunately, it turned out that even with the
best catalysts one problem cannot be solved: If
good yields of fatty alcohols are to be achieved,
drastic reaction conditions must be applied
under which the coproduct glycerol is dehydrated by hydrogenation. 1,2-Propanediol is
formed by cleavage if one water molecule, and
isopropanol by cleavage of a second one, respectively. Since these products are (so far) not as valuable as glycerol and, additionally, would have to
Fatty acid methyl esters have numerous
applications:
5 Direct use, e.g. as “biodiesel” in combustion
engines (7 Chap. 20),
5 By conversions of the ester group, interesting products, e.g. fatty alcohols or fatty acid
alkanolamides are produced (7 Sect. 3.2),
5 Many important derivatives, e.g. sulfofatty
acid esters, epoxides or aldehydes (7 Chap. 4),
are formed by functionalizing the carbon
chain of the fatty esters.
3.1.3 Saponification
Soaps (from lat. sapo) are usually referred
to as the water-soluble sodium or potassium
salts of fatty acids. Solid sodium soaps are also
called hard or curd soaps, the greasy-liquid
potassium soaps are also called soft soaps. The
salts of fatty acids with other metals, such as
calcium or zinc, are called “metal soaps”. Soaps
are produced by reacting fats and oils with the
corresponding bases, e.g. with caustic soda
solution (. Fig. 3.6).
Soap recipes were already recorded on clay
tablets of the Sumerians around 2500 B.C., which
were adopted by the Egyptians. The Romans
used soap from the second century onward
according to our calendar. However, their greater
distribution only began in the nineteenth century, when bases were available in technical
quantities. Soaps belong to the surfactants: Dissolved in water above the critical micelle concentration (CMC), they form micelles in which dirt
particles can dissolve. In this way, soaps can be
used for body cleaning or washing textiles.
In earlier times, soaps were produced by the
discontinuous “soap boiling” process. This first
produces a viscous “soap glue”, which then solidifies into a “glue soap” which, however, still contains a large amount of water and glycerol. Only
. Fig. 3.6 Saponification
of a fat with caustic soda to
curd soap
H 2 C O C
O
HC O C
O
H 2 C O C
O
+ 3 NaOH
H 2 C OH
HC OH
H 2 C OH
+
COONa
COONa
COONa
3.1 · Production of Basic Oleochemicals
3
after salting out with common salt the “soap
core” is finally formed, which is processed into
soap after further washing.
Today, modern industrial processes are predominantly continuous. Low-cost tallow (80%) is
usually used as raw material, but coconut oil and
palm kernel oil are also used. In addition, also
special soaps are made from other raw materials,
such as the “Savon de Marseille”, which is made
from olive oil.
Soaps can also be produced by neutralizing
free fatty acids. . Figure 3.7 schematically shows
the continuous production of fine soaps from fats
or fatty acids and alkali: Saponification produces
a soap brew from which the water is removed in
a dryer. The soap chips formed are mixed with
perfume and color additives. The mixture is then
transferred in an extruder into a soap strand,
which is cut into handy units in the soap bar cutter. After passing through a cooling tunnel, an
imprint is finally punched onto the soap bar.
3.1.4 Direct Hydrogenation
Besides the splitting of fats by hydrolysis,
transesterification or saponification, one can
also try to achieve fat splitting by hydrogenation. . Figure 3.8 shows that the fatty acids of
triglycerides are hydrogenated to fatty alcohols.
In the 1980s, the German Henkel company
carried out extensive work on this reaction.
Unfortunately, it turned out that even with the
best catalysts one problem cannot be solved: If
good yields of fatty alcohols are to be achieved,
drastic reaction conditions must be applied
under which the coproduct glycerol is dehydrated by hydrogenation. 1,2-Propanediol is
formed by cleavage if one water molecule, and
isopropanol by cleavage of a second one, respectively. Since these products are (so far) not as valuable as glycerol and, additionally, would have to
Fatty acid methyl esters have numerous
applications:
5 Direct use, e.g. as “biodiesel” in combustion
engines (7 Chap. 20),
5 By conversions of the ester group, interesting products, e.g. fatty alcohols or fatty acid
alkanolamides are produced (7 Sect. 3.2),
5 Many important derivatives, e.g. sulfofatty
acid esters, epoxides or aldehydes (7 Chap. 4),
are formed by functionalizing the carbon
chain of the fatty esters.
3.1.3 Saponification
Soaps (from lat. sapo) are usually referred
to as the water-soluble sodium or potassium
salts of fatty acids. Solid sodium soaps are also
called hard or curd soaps, the greasy-liquid
potassium soaps are also called soft soaps. The
salts of fatty acids with other metals, such as
calcium or zinc, are called “metal soaps”. Soaps
are produced by reacting fats and oils with the
corresponding bases, e.g. with caustic soda
solution (. Fig. 3.6).
Soap recipes were already recorded on clay
tablets of the Sumerians around 2500 B.C., which
were adopted by the Egyptians. The Romans
used soap from the second century onward
according to our calendar. However, their greater
distribution only began in the nineteenth century, when bases were available in technical
quantities. Soaps belong to the surfactants: Dissolved in water above the critical micelle concentration (CMC), they form micelles in which dirt
particles can dissolve. In this way, soaps can be
used for body cleaning or washing textiles.
In earlier times, soaps were produced by the
discontinuous “soap boiling” process. This first
produces a viscous “soap glue”, which then solidifies into a “glue soap” which, however, still contains a large amount of water and glycerol. Only
. Fig. 3.6 Saponification
of a fat with caustic soda to
curd soap
H 2 C O C
O
HC O C
O
H 2 C O C
O
+ 3 NaOH
H 2 C OH
HC OH
H 2 C OH
+
COONa
COONa
COONa
3.1 · Production of Basic Oleochemicals