Oleochemistry

In concepts for new products the performance, product safety, and product economy criteria are equally important. They are taken into account already when the raw material base for a new industrial product development is defined. Here, renewable resources have often been shown to have advantages compared with fossil feedstock. Over the years it has been demonstrated that the use of vegetable fats and oils in oleochemistry allows the development of competitive, powerful products that are both consumer- and environmentally-friendly. Products from recent developments fit with this requirement profile. 

Biomass feedstocks are already used in some processes, such as in oleochemistry (Chapter 4). In addition, biopolymers are somewhat well established, although their use and production still needs to increase and new improved (catalytic) methods for their production are required. Fine chemicals from renewables (Chapter 5) is another area in which various examples already exist, demonstrat-... 

In Europe, approximately 69 million tons of oil was used as the raw material for the chemical industry in 2008 [1], The total oil demand in Europe was 703 million tons in that year [2], In contrast, only approximately 5% of all industry feedstock is of renewable origin [3], Most of this reflects direct use of natural products like cotton for textiles, wood pulp for papermaking, or different oils for special applications and for oleochemistry in general (detergents, lubricants, etc.) [3],... 

In the past, glycerol was produced mainly from propene via allyl chloride and epi-chlorohydrin, a process developed by I. G. Farben and in operation since 1943. Today, glycerol is obtained almost completely as a coproduct in oleochemistry (fat splitting) and biodiesel production (transesterification) with 110 kg crude glycerol or 100 kg pure glycerol per ton of biodiesel [37]. With the rise in biodiesel production, the availability increased while the price decreased drastically by approximately 66% within 15 years in the United States [38]. 

G. Dieckelmann and H. J. Heinz, The Basics of Industrial Oleochemistry, Oleochemicals Consulting International, D-4330 MuUieim (Ruhr)-Saam, 1988. 

Coconut oil is one of the most important raw materials for the oleochemical industry. The whole range of its fatty acid composition is used as the starting material for a wide variety of oleochemical products. Fatty acids are the building blocks that, with proper selection and application of oleochemistry, are converted to higher valued products. 

Fats and oils are renewable products of nature. One can aptly call them oil from the sun where the sun s energy is biochemically converted to valuable oleochemicals via oleochemistry. Natural oleochemicals derived from natural fats and oils by splitting or tran -esterification, such as fatty acids, methyl esters, and glycerine are termed basic oleochemicals. Fatty alcohols and fatty amines may also be counted as basic oleochemicals, because of their importance in the manufacture of derivatives (8). Further processing of the basic oleochemicals by different routes, such as esterification, ethoxylation, sulfation, and amidation (Figure 1), produces other oleochemical products, which are termed oleochemical derivatives. 

Rendered fats have many other industrial uses. In these other uses, more than 70% require such processes as refining, bleaching, filtration, hydrogenation, traMi-esterification, and winterization before they can be converted to more useful products. All of these products and processes fall under the general category of oleochemistry. 

In the industrial oleochemistry, oxidations of unsaturated fatty substances are limited to epoxidation and — to a much lower degree — to ozonolysis yielding mono- and dicarboxylic acids [1]. Up till now, metal-complex catalysed oxidations have not been applied. 

An example of fundionalization is hydrogenation, in which hydrogen is added to the C-C double bond with the view to obtaining saturated fatty compounds. This process, which is called hardening in oleochemistry, is very well known, for example, in the production of margarine liquid unsaturated oils are mainly converted into solid saturated fats using heterogeneous Raney nickel catalysts. 

Metathesis has been applied in oleochemistry for many years, but only fairly recently technical realization comes within reach [33, 34]. As typical catalysts, ruthenium carbene complexes of the Grubbs type are applied because of their very high activity (turnover numbers up to 200 000). In principle, oleochemical metathesis can be divided into two different types in self-metathesis the same fatty substrate reacts with itself and in cross-metathesis a fatty substrate reacts with, for example, a petrochemical alkene. The simplest case, the self-metathesis of methyl oleate forms 9-octadecene and dimethyl 9-octadecenedioate. The resulting diester can be used along with diols for the production of special, comparatively hydrophobic, polyesters. An interesting example of cross-metathesis is the reaction of methyl oleate with an excess of ethene, so-called ethenolysis. This provides two produds, each with a terminal double bond, 1-decene and methyl 9-decenoate (Scheme 3.3). 

The use of cationic surfactants also makes it possible to apply the concept of biphasic catalysis in oleochemistry. For instance, the Johnson-Matthey company has reported that oleic acid methyl ester or linoleic acid methyl ester can be hydroformylated in micellar media using a water-soluble rhodium complex of monocar-... 

In fat chemistry ( oleochemistry ) no considerable application of homogeneous catalysis and of industrial importance is known so far [1], One reason for this is the modest reactivity of the starting chemicals. Oleochemicals are molecules with a long carbon chain. The double bonds of unsaturated fatty compounds are always in internal positions. Hence, the steric hindrance of oleochemicals is often very high, and the coordination to metal complexes is made difficult. In addition all fatty compounds contain a substituent with a heteroatom such as carboxyl, ester, aldehyde, alcohol, or amine groups. These substituents often react with organome-tallic compounds and can inactivate the catalyst. 

The most typical examples in oleochemistry are the hydrogenation, the carbon monoxide reactions hydroformylation and hydrocarboxylation, and the oxidation reaction. 

One important aim in oleochemistry hydrogenations is the selective hydrogenation of multiply unsaturated fatty compounds to singly unsaturated products. A typical example is the selective hydrogenation of linoleic acid (C18 2) to oleic acid (C181) without significant formation of stearic acid (D18 0) as shown in Eq. (1). This... 

In recent years some work has been done to link oleochemicals with petrochemicals via oligomerization. One possibility is the Dids-Alder reaction of linoleic acid esters with dienophiles, for instance with quinones or ,/Tun saturated aldehydes and ketones [80]. Using scandium or copper triflates as catalysts the reaction can be carried out at very mild temperature conditions (25-40°C) with good yields (< 94%). For the first time in oleochemistry it was possible to carry out Diels-Alder cycloadditions with low catalyst concentrations instead of stoichiometric amounts of Lewis acids. The most successful way to recycle the catalyst was the successive extraction of the triflates with water. After removing the water and drying in vacuum the catalyst was used three times without any loss of yield. 

Soaps, the sodium salts of long-chain alkanoic (or carboxylic, or fatty) acids, are the oldest surfactants that were recognized at ancient times, presumably in Egypt. The bar soap was invented later, in the Middle Ages. Now twenty percent of the ca. 90 million tons of oils and fats produced worldwide in 1996 are for technical use in the oleochemistry and feedstuff industry [86]. The target-oriented part of them is cultivated and the other part is used as a byproduct of oil and meat industry. The Japanese gather and process extensively discarded cooking oil into soap flakes [87]. 

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