Oleochemicals oxidation

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 oldest surfactant is soap, which may be traced back to the ancient Egyptians and beyond. Synthetic surfactants had been produced in the first half of the 20th century but it was only after World War II, with the development of the modern petrochemical industry, that alternative feedstocks to oleochemicals became readily available. Hence chloroparaf-fins and/or alphaolefins and benzene were used to produce alkylbenzene (or alkylate ), processes were developed to produce a range of synthetic fatty alcohols and alkylene oxide chemistry resulted in ethylene oxide and propylene oxide building blocks becoming readily available. 

The fatty acid alkyl chain is susceptible to oxidation both at double bonds and adjacent allylic carbons. Eree-radical and photooxidation at aUylic carbons are responsible for deterioration of unsaturated oils and fats, resulting in rancid flavors and reduced nutritional quality, but they are also used deliberately to polymerize drying oils. Oxidation of double bonds is used in oleochemical production either to cleave the alkyl chain or to introduce additional functionality along the chain. Enzyme catalyzed oxidation is the initial step in the production of eicosanoids and jasmonates (biologically active metabolites in animals and plants respectively) but is not discussed further here. 

Fatty Amines. Fatty amines are the most important nitrogen derivatives of fatty acids. They are produced by the reaction of fatty acids with ammonia and hydrogen. They are the bases for the manufacture of quaternary ammonium compounds used as fabric softeners and biocides. Fatty amine oxides are mild to the skin with good cleaning and foaming properties and find application as a shampoo ingredient. The above mentioned products are but some of the oleochemical derivatives from coconut fatty acids (5). 

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. 

Oxidation of unsaturated oleochemicals can proceed in different ways, and yields numerous products. Typical oxidations of fatty acids are, for instance, ketoniza-tions yielding keto acids [72, 73], hydroxylations to bishydroxy acids [74], epoxida-tions to epoxy acids [75-78] and oxidative splitting reactions [72, 74] yielding mixtures of mono- and dicarboxylic acids. However, not only the double bond but also the functional group of the fatty compound, can be oxidized. One example is the ruthenium-catalyzed oxidation of fatty alcohols to fatty aldehydes or fatty acids... 

Animal edible tallow is normally obtained from beef but also from sheep and goats, processed from suet. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation. It is used in animal feed, to make soap, for cooking, as bird feed, and was used for making candles. It can be used as a raw material for the production of biodiesel and other oleochemicals. ... 

The basic petrochemical feedstocks are ethylene and benzene which are converted to the surfactant intermediates ethylene oxide, linear alkyl benzene (LAB), and detergent alcohols. Oleochemical or natural surfactants are commonly derived from plant oils (coconut and pahn oils), from plant carbohydrates such as sorbitol, sucrose, and glucose or from animal fats such as tallow. 

Trade Name Synonyms Incromine Oxide B t[Croda Inc http //www.croda.com] Croda Oleochems.] Incromine Oxide B-30P [Croda Inc http //www.croda.com]] Incromine Oxide B50 t[Croda Inc http //www.croda.com] Croda Oleochems.]... 

Croda Oleochems.] Incromine Oxide C-35 t[Croda Oleochems.] Jeechem 1770 [Jeen Int l. http //www.Jeen.com], Karox AO-30 t[Clark4] Mackamine CAO [McIntyre http //www.mcintyregroup.com] M ackamIne CAO-35H [McIntyre... 

Genaminox MY [Clariant/Functional Chems.] Incromine Oxide M [Croda Inc http //www.croda.com Croda Oleochems.] ... 

After the oxidation and hydrolysis steps, the alcohols from this process are highly linear, nearly 100%, resembling oleochemical alcohols since they contain an even number of carbon atoms. 

L. Rebrovic and F.D. Gunstone, Oxidative cleavage of unsaturated fatty acids, Lipid Technology, 1996, 8, 135-137. M. Schwitzer, Oleochemicals from ricinoleic acid. Lipid Technology, 1991, 3, 117-121. 

The high consumption figure of ethylene oxide-derived surfactants is due to several factors the surfactants are relatively easy to manufacture, they are relatively inexpensive, and they can be derived from a variety of hydrophobic feedstocks, including oleochemical- and petrochemical-based alcohols, and petrochemical-based alkylphenols and alkylamines. Because their hydrophobe and hydrophile chain lengths can be varied significantly, they fit a wide range of applications. 

The natural oleochemicals are obtained from natural oils with the least change in the structure 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 oleo-chemistry. Natural oleochemicals derived from natural fats and oils by splitting or trans-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 (6). Further processing of the basic oleochemicals by different routes, such as esterification, ethoxylation, sulfation, and amidation (Fig. 12.1), produces other oleochemical products, which are termed oleochemical derivatives. 

Of the enzymes listed in Table 10.1, Upases are the woikhorses. The employment of Upases in non-aqueous media is an estabUshed art, with over 25 years of research serving as a foundation. Lipases are abundant and relatively inexpensive enzymes that require no co-factors and are easily immobilized. Lipases from several thermophiUc organisms have been isolated, cloned, and mass produced via recombinant DNA technology in common vectors such as Escherichia coli. Some of the examples in Table 10.1 are surfactants formed from enzymatic hydrolysis of oleochemical feedstocks, such as MAG formed from lipase-catalyzed hydrolysis of TAG, and lysophospholipids via hydrolysis by Upases or phosphoUpase A. Ui the foUowing sections some specific examples from the literature are given of enzyme-catalyzed synthesis of bio-based surfactants. Other examples not described, such as the oxidation of fatty alcohols to aldehydes (OrUch et al., 2000) and the covalent attachment of fatty alcohols and bio-based diethyl carbonate (Banno et al., 2007, 2010 Matsumura 2002 Lee et al., 2010) are covered in the references provided. 

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