Natural oleochemicals

Surfactant alcohols are linear, primary alcohols with carbon chain lengths in the C12-C14 and the C16-C18 range. Surfactant alcohols can be derived from either petrochemical or oleochemical feedstocks, and thus are referred to either as synthetic alcohols or as natural (oleochemical) alcohols. Petrochemical feedstocks used for surfactant alcohol production are ethylene and, to a lesser degree, paraffins. 

The shift to oleochemicals has been supported by increasing environmental concerns and a preference by some consumers, especially in Europe, for materials based on natural or renewable resources. Although linear alkylbenzenesulfonates (LASs) are petrochemically based, alcohol ethoxylates, alcohol ethoxysulfates, and primary alcohol sulfates are derived from long-chain alcohols that can be either petrochemically or oleochemically sourced. There has been debate over the relative advantages of natural (oleochemical) vs synthetic (petrochemical) based surfactants. However, detailed analyses have shown there is litde objective benefit for one over the other. 

Kayama, M., and Mankura, M. 1998. Natural oleochemicals in marine fishes. INFORM, 9,794-799. 

Oleochemicals, by their very name, may be defined as chemicals from oil. These could be natural fats and oils, or oils of petrochemical origin. To have a clear distinction, oleochemicals derived from natural oils are termed natural oleochemicals, whereas those derived from petrochemicals are termed synthetic oleochemicals (8). 

The natural oleochemicals are obtained from natural oils with the least change in the stmcture of the carbon chain fraction. In contrast, synthetic oleochemicals are built up from ethylene to the desired carbon chain fraction or from oxidation of petroleum waxes. 

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. 

When it comes to the hydrophobic part of a surfactant, the natural oleochemical source predominantly offers straight hydrophobic chains with even amounts of carbon atoms. These structures are not always optimal and it has been shown that some branching that does not destroy the biodegradability is preferable from a performance point of view in many applications like cleaning, wetting, etc. On the hydrophilic side, one of the most interesting structural elements that forms the non-ionic surfactants as well as some of the anionic surfactants is ethylene oxide, which at present is made from petroleum sources, i.e. ethylene. 

For at least the next 25 years enough lauril (natural C12-C14) oil will not be available to replace petrochemical-based surfactants even if this were desired. However, the oleochemical share of the surfactant intermediate market will grow because a large portion of excess lauric oil (coconut and palm kernel) will be designated for the surfactant market and used to supply the fatty alcohol capacity that has been announced for startup in the coming years. 

Surfactants can be produced from both petrochemical resources and/or renewable, mostly oleochemical, feedstocks. Crude oil and natural gas make up the first class while palm oil (+kernel oil), tallow and coconut oil are the most relevant representatives of the group of renewable resources. Though the worldwide supplies of crude oil and natural gas are limited—estimated in 1996 at 131 X 1091 and 77 X 109 m3, respectively [28]—it is not expected that this will cause concern in the coming decades or even until the next century. In this respect it should be stressed that surfactant products only represent 1.5% of all petrochemical uses. Regarding the petrochemically derived raw materials, the main starting products comprise ethylene, n-paraffins and benzene obtained from crude oil by industrial processes such as distillation, cracking and adsorption/desorption. The primary products are subsequently converted to a series of intermediates like a-olefins, oxo-alcohols, primary alcohols, ethylene oxide and alkyl benzenes, which are then further modified to yield the desired surfactants. 

The total world production of natural oils and fats in 1997 amounted to 100 X 106 t, of which 80 X 106 t were of vegetable and 20 X 1061 of animal origin [28]. From these oils and fats, 80% are suitable for human nutrition and 14% end up in so-called oleochemical uses, among them... 

Oleochemical alcohols, sometimes known as natural alcohols, are also identified by the carbon range C12-C14 lauric, Ci6-Ci8 tallow, regardless of the origin of the raw material. C1(-i-C18 alcohols were predominantly produced in the past from tallow, hence their name, although today they are also widely produced from palm oil. Lauric range alcohols are produced from either coconut oil or from palm kernel oil. 

The use of oleochemicals in polymers has a long tradition. One can differentiate between the use as polymer materials, such as linseed oil and soybean oil as drying oils, polymer stabilizers and additives, such as epoxidized soybean oil as plasticizer, and building blocks for polymers, such as dicarboxylic acids for polyesters or polyamides (Table 4.2) [7]. Considering the total market for polymers of ca. 150 million tonnes in 1997 the share of oleochemical based products is relatively small - or, in other terms, the potential for these products is very high. Without doubt there is still a trend in the use of naturally derived materials for polymer applications, especially in niche markets. As an example, the demand for linseed oil for the production of linoleum has increased from 10000 tonnes in 1975 to 50 000 tonnes in 1998 (coming from 120000 tonnes in 1960 ) [8a]. Epoxidized soybean oil (ESO) as a plastic additive has a relatively stable market of ca. 100000 tonnes year-1 [8b]. 

Several years ago research was undertaken to use oleochemicals to build up matrices for natural fiber reinforced plastics [9]. The use of natural fibers, such as flax, hemp, sisal, and yucca is of increasing interest for various applications, among them the automotive and public transportation industries, where the com-... 

Oleochemical based dicarboxylic acids - azelaic, sebacic, and dimer acid (Figs. 4.5 and 4.6) - amount to ca. 100000 tonnes year-1 as components for polymers. This is about 0.5% of the total dicarboxylic acid market for this application, where phthalic and terephthalic acids represent 87%. The chemical nature of these oleochemical derived dicarboxylic acids can alter or modify condensation polymers, and, used as a co-monomer, will remain a special niche market area. Some of these special properties are elasticity, flexibility, high impact strength, hydrolytic... 

The physicochemical nature of the oil phase components in a cosmetic emulsion, the emollients, determines the skin-care effects, such as smoothing, spreading, sensorial appearance. Test methods have been developed to characterize and classify the numerous emollients available on the market, such as silicones, paraffins, and oleochemical-based products. The latter include glycerides, esters, alcohols, ethers, and carbonates with tailor-made structures, depending on the performance needed (Table 4.8). However, especially with regard to additional effects, there is still a demand for new products with unique performance properties. 

Raw materials. The hydrophobe for SME is currently derived exclusively from oleochemical sources, rather than from petrochemicals, as in the case of LAS and AOS. While these two sources can often provide surfactants of equivalent performance, oleochemcials are frequently preferred (especially in personal care applications) because they are derived from natural ingredients. The use of renewable resources is also cited as an additional benefit of oleochemical-based surfactants and this is discussed more fully in Section 4.2.1. 

Fatty alcohols, by which the author means those in the range C and above, are split into two classes, petrochemical and oleochemical, or, as they are more usually referred to, synthetic and natural. The discussion of the relative merits of synthetic vs natural products has been at the forefront of surfactant technology for many years and has produced a wealth of literature. It is beyond the scope of this work to discuss whether oleochemicals have an inherent environmental benefit over petrochemicals. A good deal of scientific study on life cycle analysis and macro environmental impact is available but social and ethical arguments, as well as the perceptions of the end consumer, also play a part. On a strictly scientific basis, the author sees no inherent advantage in either source. The performance of a surfactant based on synthetic materials may differ from a naturally derived one but neither is intrinsically better than the other. In terms of impact on humans and the environment, there is also no clear evidence to suggest a difference between the two sources of hydrophobe. 

Fatty acids with trans or non-methylene-interrupted unsaturation occur naturally or are formed during processing for example, vaccenic acid (18 1 Hr) and the conjugated linoleic acid (CLA) rumenic acid (18 2 9tllc) are found in dairy fats. Hydroxy, epoxy, cyclopropane, cyclopropene acetylenic, and methyl branched fatty acids are known, but only ricinoleic acid (12(/f)-hydroxy-9Z-octadecenoic acid) (2) from castor oil is used for oleochemical production. OUs containing vernolic acid (12(5),13(/ )-epoxy-9Z-octadecenoic acid) (3) have potential for industrial use. 

Fatty acid salts and many polar derivatives of fatty acids are amphiphilic, possessing both hydrophobic and hydrophilic areas within the one molecule. These are surface-active compounds that form monolayers at water/air and water/surface interfaces and micelles in solution. Their surface-active properties are highly dependent on the nature of the polar head group and, to a lesser extent, on the length of the alkyl chain. Most oleochemical processes are modihcations of the carboxyl group to produce specihc surfactants. 

The oleochemical industry is fairly well developed and its future secure because of a reliable supply of raw materials. The world s fats and oils output has been growing rapidly over the past few decades, far beyond the need for human nutrition. The world s production and consumption of natural oils and fats has grown from 79.2 million t in 1990 to 117 million t in 2001. Malaysia, Indonesia, and Argentina are notable excess-supply producers India, the European Union countries, and China are notable high-demand areas that supplement regional production through imports (1). 

Coconut oil and palm kernel oil, a coproduct of pahn oil, comprise less than 5% of the total natural fats and oils, but they are important feedstocks of the oleochemical industry. 

As oleochemicals for the preparation of dicarboxylic acids we did not choose natural C18- or C22-fatty acids with an internal double bond (oleic-, erucic acid),... 

Lipases (triacylglycerol hydrolases, EC 3.1.1.3) are enzymes that catalyze reactions such as hydrolysis, interesterification, esterification, alcoholysis, acidolysis, and aminolysis [1]. There is an increasing interest in the development of lipase applications to oleochemical transformations to obtain esters of long-chain fatty acids, as monoalkyl esters of fatty acids [2]. Utilization of lipase as a catalyst for the production of biodiesel, defined as a mixture of monoalkyl esters, is a clean technology due to its nontoxic and environmental fnendly nature, requiring mild operating conditions compared with chemical method [3]. 

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