38
Chapter 3 · The Basics of Oleochemistry - Basic Oleochemicals
3
no longer chemically converted, but used
directly by the consumer as cleaning and
washing agents.
5 The fourth method, which has not (yet)
been technically implemented, is the directhydrogenation of fats and oils into glycerol
and fatty alcohols. Fatty alcohols can also be
formed indirectly by hydrogenation of either
fatty acids or fatty esters, respectively.
Fatty acids, fatty esters and fatty alcohols as well
as the coproduct glycerol can be regarded as
basic oleochemicals in analogy to basic petrochemicals. As we will see in this and the following chapters, these basic chemicals can be
converted into numerous important derivatives.
. Figure 3.1 gives us an overview of the routes
leading to the oleochemical basic products.
3.1.1 Fat Splitting
When one mole of triglyceride is split with three
moles of water, three moles of fatty acids and
one mole of glycerol are formed. Looking at the
quantities, depending on the type of fatty acids,
approx. 950 kg of fatty acids and 100 kg of glycerol are formed from one ton of fat. According to
the equilibrium equation in . Fig. 2.1, it is obvious that good space–time yields are obtained
especially if
5 water is in large surplus,
5 one product is constantly removed from the
equilibrium,
5 the reaction rate is accelerated by the process
conditions or by a catalyst.
There are several industrial processes for fat splitting that consider these three effects:
5 The Twitchell process was developed as early
as 1890: At ambient pressure, fats were heated
in the presence of an aqueous sulfuric acid
solution with the addition of organic sulfonic acids as catalysts. Mixing was carried
out with superheated steam. However, this
batch process, which was carried out in tanks
coated with lead due to the sulfuric acid, has
the major disadvantage of a very long reaction time of up to 24 h. Nevertheless, it is still
occasionally carried out in small companies.
5 The Twitchell process makes good use of the
possibilities of influencing the equilibrium:
Chapter Timetable
5 You will learn several methods for
splitting triglycerides into the basic
chemicals fatty acids (or fatty acid esters,
respectively) and glycerol.
5 We will discuss the chemistry of the
carboxy group of fatty acids, which leads
us to fatty alcohols and fatty amines,
among others.
This chapter describes the basic reactions of
the chemistry of fats and oils, the so-called oleochemistry. They have been known for over a
century and have long been used in industry. On
the other hand, a great deal of research has been
carried out in this field in recent years, and new
types of reactions have been developed. We will
get to know these in 7 Chap. 4.
3.1 Production of Basic
Oleochemicals
In the petrochemical industry, petroleum hydrocarbons are used to produce a large variety of
chemical intermediates and end products. This
process involves splitting the mixture of aliphatic
and aromatic compounds contained in crude oil
into smaller units in the steam cracker and the
reformer before producing specific secondary
chemicals. These smaller units are, for instance,
ethene, propene, butadiene, benzene, toluene
and xylenes. These are called “petrochemical
basic chemicals”.
In oleochemistry, too, only little chemistry is
carried out directly with fats and oils, but triglycerides are often broken down into glycerol and
fatty acids or their derivatives. There are several
variants:
5 As already described in . Fig. 2.1, triglycerides can be broken down into free fatty acids
and glycerol by hydrolysis, i.e. by reaction
with water. This process is called fat splitting.
5 Triglycerides can also be split into fatty acid
(methyl) esters and glycerol by transesterification, e.g. with methanol.
5 The third way is saponification of fats with
bases, e.g. sodium hydroxide, resulting in
glycerol and in the sodium salts of fatty acids,
i.e. soaps, respectively. Soaps are usually
Chapter 3 · The Basics of Oleochemistry - Basic Oleochemicals
3
no longer chemically converted, but used
directly by the consumer as cleaning and
washing agents.
5 The fourth method, which has not (yet)
been technically implemented, is the directhydrogenation of fats and oils into glycerol
and fatty alcohols. Fatty alcohols can also be
formed indirectly by hydrogenation of either
fatty acids or fatty esters, respectively.
Fatty acids, fatty esters and fatty alcohols as well
as the coproduct glycerol can be regarded as
basic oleochemicals in analogy to basic petrochemicals. As we will see in this and the following chapters, these basic chemicals can be
converted into numerous important derivatives.
. Figure 3.1 gives us an overview of the routes
leading to the oleochemical basic products.
3.1.1 Fat Splitting
When one mole of triglyceride is split with three
moles of water, three moles of fatty acids and
one mole of glycerol are formed. Looking at the
quantities, depending on the type of fatty acids,
approx. 950 kg of fatty acids and 100 kg of glycerol are formed from one ton of fat. According to
the equilibrium equation in . Fig. 2.1, it is obvious that good space–time yields are obtained
especially if
5 water is in large surplus,
5 one product is constantly removed from the
equilibrium,
5 the reaction rate is accelerated by the process
conditions or by a catalyst.
There are several industrial processes for fat splitting that consider these three effects:
5 The Twitchell process was developed as early
as 1890: At ambient pressure, fats were heated
in the presence of an aqueous sulfuric acid
solution with the addition of organic sulfonic acids as catalysts. Mixing was carried
out with superheated steam. However, this
batch process, which was carried out in tanks
coated with lead due to the sulfuric acid, has
the major disadvantage of a very long reaction time of up to 24 h. Nevertheless, it is still
occasionally carried out in small companies.
5 The Twitchell process makes good use of the
possibilities of influencing the equilibrium:
Chapter Timetable
5 You will learn several methods for
splitting triglycerides into the basic
chemicals fatty acids (or fatty acid esters,
respectively) and glycerol.
5 We will discuss the chemistry of the
carboxy group of fatty acids, which leads
us to fatty alcohols and fatty amines,
among others.
This chapter describes the basic reactions of
the chemistry of fats and oils, the so-called oleochemistry. They have been known for over a
century and have long been used in industry. On
the other hand, a great deal of research has been
carried out in this field in recent years, and new
types of reactions have been developed. We will
get to know these in 7 Chap. 4.
3.1 Production of Basic
Oleochemicals
In the petrochemical industry, petroleum hydrocarbons are used to produce a large variety of
chemical intermediates and end products. This
process involves splitting the mixture of aliphatic
and aromatic compounds contained in crude oil
into smaller units in the steam cracker and the
reformer before producing specific secondary
chemicals. These smaller units are, for instance,
ethene, propene, butadiene, benzene, toluene
and xylenes. These are called “petrochemical
basic chemicals”.
In oleochemistry, too, only little chemistry is
carried out directly with fats and oils, but triglycerides are often broken down into glycerol and
fatty acids or their derivatives. There are several
variants:
5 As already described in . Fig. 2.1, triglycerides can be broken down into free fatty acids
and glycerol by hydrolysis, i.e. by reaction
with water. This process is called fat splitting.
5 Triglycerides can also be split into fatty acid
(methyl) esters and glycerol by transesterification, e.g. with methanol.
5 The third way is saponification of fats with
bases, e.g. sodium hydroxide, resulting in
glycerol and in the sodium salts of fatty acids,
i.e. soaps, respectively. Soaps are usually