Sorbitan, production

Sorhita.n nd Sorbitol Esters. This group of emulsifiers is formed from the reaction of sorbitan and stearic acid. Sorbitan monostearate is often used in combination with polysorbate in ice cream, imitation dairy products, and baking appHcations (36). 

Anhydrosorbitol Esters. Eatty acid esters of anhydrosorbitol (see Alcohols,polyhydric) are the second largest class of carboxyHc ester surfactants. The important commercial products are the mono-, di-, and triesters of sorbitan and fatty acids (Table 18). Sorbitan is a mixture of anhydrosorbitols, principally 1,4-sorbitan (1) and isosorbide (2) ... 

Sorbitan oleate and the monolaurate are pale yeUow Hquids. Palmitates and stearates are light tan soHds. Sorbitan esters are not soluble in water but dissolve in a wide range of mineral and vegetable oils. They are lipophilic emulsifiers, solubiHzers, softeners, and fiber lubricants that find appHcation in synthetic fiber manufacture, textile processing, and cosmetic products. Sorbitan esters have been approved for human ingestion and are widely used as emulsifiers and solubiHzers in foods, beverages, and pharmaceuticals. 

Ethoxylated Anhydrosorbitol Esters. Ethoxylation of sorbitan fatty acid esters leads to a series of more hydrophilic surfactants (Table 19). All hydroxyl groups of sorbitan can react with ethylene oxide. The stmcture of the principal component of a nominal polyoxyethylene (20) sorbitan monostearate illustrates the composition of these products, where w x y z = 20. 

A series of sorbitol-based nonionic surfactants are used ia foods as water-ia-oil emulsifiers and defoamers. They are produced by reaction of fatty acids with sorbitol. During reaction, cycHc dehydration as well as esterification (primary hydroxyl group) occurs so that the hydrophilic portion is not only sorbitol but also its mono- and dianhydride. The product known as sorbitan monostearate [1338-41 -6] for example, is a mixture of partial stearic and palmitic acid esters (sorbitan monopalmitate [26266-57-9]) of sorbitol, 1,5-anhydro-D-glucitol [154-58-8] 1,4-sorbitan [27299-12-3] and isosorbide [652-67-5]. Sorbitan esters, such as the foregoing and also sorbitan monolaurate [1338-39-2] and sorbitan monooleate [1338-43-8], can be further modified by reaction with ethylene oxide to produce ethoxylated sorbitan esters, also nonionic detergents FDA approved for food use. 

The suspension polymerization of 65% acrylamide aqueous solution dispersed in n-hexane (aqueous phase -hexane = 1 5) in the presence of a stabilizer (sorbitan monostearate, 1.4% with respect to -hexane) and an initiator (2,2 -azo-bis-A/, A/ -dimethyleneisobutylamide chloride) carried out at 65°C for 3 h, with subsequent holding at 110°C, yields a powdered product with the granule size of 0.5 mm, while the addition of Na2S04... 

As a result, various non-amine-based products have been introduced to the market that continue to provide appropriate levels of corrosion protection, yet do not exhibit the limitations normally associated with amines. The most promising of these are the sorbitan-based, nonionic surfactant treatments, such as those marketed by ONDEO Nalco under the Tri-Act brand (U.S. patent 5,849,220, December 1998). 

Sorbitan [C6H80(0H)4] products have a particularly low toxicity level, being derived from the hexahydric alcohol sorbitol [CH2OH (CHOH)4 CH2OH], which is, in turn, produced by the reduction of glucose sugar. 

Somewhere in the middle are soy lecithin and sorbitan mono-laurate, which make good foam stabilizers in whipped cream and similar products. 

Sorbitan esters of fatty acids are well known. Similar products can be made from ether carboxylic acids and sorbitol without an acid catalyst with a good color [39]. The advantage of these products is that the hydrophilicity can be adjusted by the polyethylene glycol content in the ether carboxylic acid. 

The reaction product with monoethanolamine acts as a thickening agent [41,101] and with alcohols as an emollient [40]. Also reaction products with amino acids and oligo- or polypeptides for use in cosmetic formulations are known [43]. Sorbitan esters from ether carboxylates are described as emulsifiers or mild surfactants in cosmetic formulations [39] and alkyl ether carboxylic acid taurides as nonirritant anionic surfactants for cosmetic cleaners in particular [44]. Using unsaturated ether carboxylates it is possible to make viscous formulations based on combinations of unsaturated and saturated ether carboxylates [111]. Highly purified alkyl ether carboxylates based on alcohol ethoxylates with low free alcohol content have also been described [112]. 

The stability characteristics of two different antiperspirant lotion systems were compared. Sample 1 represented an aqueous emulsion containing an aluminum salt. The internal phase consisted of stearyl alcohol and ethylene oxide reaction products, polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan tristearate. Methylcellulose was used as a stabilizer and bodying agent. Sample 2 represented a dispersion of magnesium aluminum silicate in an aqueous system containing aluminum ions. Because of its com-... 

Fatty Acid Esters. Defoamers that are more environmentally acceptable than convential products are based on fatty acid esters of hydroxy alcohols, such as sorbitan monooleate [1908] or sorbitan monolaurate in combination with diethylene glycol monobutyl ether as a cosolvent [451]. These defoamer compositions are as effective as conventional materials, for example, those based on acetylenic alcohols are less toxic, especially to marine organisms, and are readily biodegradable. The defoamer compositions are used in water-based hydrocarbon well fluids during oil/gas well drilling, completion, and workover, especially in marine conditions. 

A few other successful 13C 1-NMR determinations should be mentioned. Hunt et al. [28] used 13C NMR to characterise fractions of extracted analytes of PAG and sorbitan ester samples and identified Irganox 1010. H and 13C NMR have been used to identify the main organic components of a breathable diaper back-sheet as LLDPE and pentaerythritol tetra-octyl ester (PETO) [233]. The equally present AOs Irganox 1010 and Irgafos 168 were not detected without extraction. Barendswaard et al. [234] have reported fully assigned 13C solution spectra of these two antioxidants. Chimas-sorb 944 in a polyamide matrix can be determined by H or 13C 1-NMR using solvents such as formic acid, trifluoroacetic acid or trifluoroethanol [235], Both H and 13C NMR have been used to follow the chemistry of a bis-phenoxidemethylaluminum complex (reaction product of BHT and trimethylaluminum) by exposure in air. Pierre and van Bree [216] also used 13C NMR to... 

The HLB of a relatively pure poly(oxyethylene) adduct can be calculated from theoretical data [37]. For these agents the HLB is an indication of percentage by mass of the hydrophilic portion, divided by five to give a conveniently small number. For example, if the hydrophilic portion of a purely hypothetical nonionic agent accounted for 100% of the molecule (such a product cannot, of course, exist), its HLB is 20. Similarly, a more plausible product in which 85% of the molecule is accounted for by the hydrophilic portion has an HLB of 85/5 = 17. The ICI Americas Inc. method of calculating the theoretical HLB of a sorbitan monolaurate nonionic having 20 oxyethylene units per molecule is given in... 

Other nonfood applications of D-sorbitol result from etherification and polycondensation reactions providing biodegradable polyetherpolyols used for soft pol5mrethane foams and melamine/formaldehyde or phenol resins. Sizable amounts of D-sorbitol also enter into the production of the sorbitan ester surfactants (cf. later in this chapter). 

Waxes of melting point 57-60°C are used with an emulsifying agent based on sorbitan monostearate or ethoxylated sorbitan monostearate [2]. The properties of a commercial product are given in Table 4.4 [5]. 

Low-molecular-weight surfactants ( emulsifiers ) are important ingredients in food products. The types of surfactants most commonly studied in food colloids research are phospholipids (lecithin), mono/diglycerides (particularly glycerol monostearate), polysorbates (Tweens), sorbitan monostearate or monooleate (Spans), and sucrose esters. These small lipid-based amphiphiles can typically lower the interfacial tension to a greater extent than the macromolecular amphiphiles such as proteins and certain gums (Bos and van Vliet, 2001). 

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