Sorbitol fatty acid esters

Shin and colleagues obtained high yields of sorbitol-fatty acid esters in media with extremely high (4—7 M) substrate concentration [69]. The media were entirely liquid, and contained small amounts of water and organic solvents, but are probably quite similar in composition to the liquid phases of related systems with excess solid substrates. The very high substrate concentrations positively influenced the initial rate of the reactions. 

Chem. Descrip. POE sorbitol fatty acid ester Ionic Nature Nonionic... 

Sorbitol is the most important higher polyol used in direct esterification of fatty acids. Esters of sorbitans and sorbitans modified with ethylene oxide are extensively used as surface-active agents. Interesteritication of fatty acid methyl esters with sucrose yields biodegradable detergents, and with starch yields thermoplastic polymers (36). 

An oral dental riase geaeraHy coasists of water, alcohol, a humectant, an emulsifier, flavor, color, and an active agent. Water is the primary vehicle. The alcohol provides bite and is also a formulation aid. The humectant improves the feel ia the mouth and also prevents locking of the cap to the container between uses glycerin or noncrystaUiziag sorbitol may be satisfactory. The emulsifier is a nonionic type, for example, a polyoxyethylene—polyoxypropylene block copolymer or a polyoxyethylene sorbitan fatty acid ester. Flavors are generally a type of mint or cinnamon. Colors are FD C or D C. 

Polyoxyethylene sorbitan fatty acid esters (polysorbates) are a series of partial fatty acid esters of sorbitol and its anhydrides copolymerized with approximately 20, 5, or 4 moles of ethylene oxide for each mole of sorbitol and its anhydrides. 

If a surface barrier is created based on hydrophilicity rather than molecular size, a different type of exclusion is carried out. This type of sorbent is called a semipermeable surface, or SPS. An example is the coating of a nonionic surfactant, such as Tween (a fatty-acid ester of bis-polyethyleneoxide modified sorbitol), onto a reversed-phase silica (Fig. 12.7). In this case, small... 

The fatty acid esters of sorbitan (which generally are referred to as Spans, an Adas commercial trade name) and their ethoxylated derivatives (generally referred to as Tweens) are perhaps one of the most commonly used nonionics. They were first commercialised in the USA by Atlas (which has since been purchased by ICI). The sorbitan esters are produced by the reaction of sorbitol with a fatty acid at a high temperature (>200 °C). The sorbitol dehydrates to 1,4-sorbitan, after which esterification takes place. If 1 mol of fatty acid is reacted with 1 mol of sorbitol, a monoester is obtained (some diester is also produced as a byproduct). Thus, sorbitan monoester has the following general formula ... 

Common antifogging agents are fatty acid esters such as glycerol and sorbitol stearate, fatty alcohols, and ethyloxylates of nonyl phenols. Antifogging agents are incorporated in the resin in levels ranging from 0.5 to 4%. Factors involved in the selection and use of these additives include polymer type, thickness of the structure... 

FIGURE 17.1 (a) Fatty acid esters (i and ii) of polyol, such as sorbitol, are the class of nonionic surfactants... 

Figure 10.2. Common food emulsifiers Tweens (polyoxyethylene mono fatty aeid esters of sorbitan or sorbitol anhydrides), Spans (partial fatty acid esters and sorbitol anhydrides), lecithin (phosphatidylcholine), monoglycerides (monoaeylglyeerols), propylene glyeol mono fatty aeid esters (1,2-propanediol esters), suerose mono fatty aeid esters, stearyl-2-lactylate. Tween/Span 20, monolaurate Tween/Span 40, monopalmitate Tween/Span 60, monostearate.

The properties of the fatty acid esters of the glycosides of sorbitol, like those of lactitol and maltitol are comparable with those of the known sucrose esters. Sucrose has 8 hydroxyl groups which can be esterified, whereas lactitol and maltitol contain 9 hydroxyl groups. 

Sorbitol is a six-carbon sugar alcohol which contains six hydroxyl groups available for esterification. However, under process conditions that are required for the direct esterification with fatty acids sorbitol undergoes an internal etherification to 1,4-sorbi-tan (anhydro sorbitol), the monoanhydride form of sorbitol, which only contains four hydroxyl groups available for esterification. According to this, the esterification of sorbitol with fatty acids yields sorbitan esters. Sorbitan fatty acid esters can be produced in a one-step process by direct, base-catalyzed reaction of sorbitol with a fatty acid at temperatures of 260 Milder temperature conditions are desirable for more odorless sorbitan esters with lighter color (Figure 4A.43). 

Figure 4A.43 Sorbitol and sorbitan fatty acid esters.

In the second process step the anhydro sorbitol reacts with a fatty acid at a temperature from about 180 to about 215 °C in the presence of a basic catalyst such as NaOH or K2CO3 in order to produce the desired sorbitan fatty acid ester. Depending on the type and amount of fatty acid used, sorbitan mono, sesqui or tri laurate, palmitate, ole-ate, or stearate are produced. Sorbitan esters have originally been introduced by Atlas Powder Co. (later I Cl, now Croda) under the trademark designation Span . 

EMSORB Sorbitan Fatty Acid Esters, or polyol esters, are created by the two basic mechanisms of dehydration and esterification. Sorbitol, with six hydroxyl groups, is dehydrated, undergoing ring closure with the loss of two hydroxyl groups. The cyclic sorbitan moiety is produced. Through the esterification reaction, hydrophobic fatty acids are combined with the sorbitan, thereby decreasing its hydrophilic attributes. The exact degree of hydrophllicity depends on the size and number (mono-, di-, tri-) of acid molecules added to one sorbitan molecule. 

TRYLOX Ethoxylated Sorbitol Esters are relatively low foaming and find wide use as emulsifiers for petroleum oils, vegetable oils, organic solvents and oil based metal lubricants. TRYLOX Ethoxylated Sorbitol functions as a humectant and plasticizer and serves as an intermediate in the synthesis of fatty acid esters and improves the pourability and clarity of high solid "clear concentrate" surfactant solutions. 

Although we have invested only a small amount of time in our study of organic chemistry, we can now identify several important kinds of organic compounds. For example, the shaving cream Edge Gel lists as its contents deionized water, palmitic acid, triethanolamine, pentane, fatty acid esters, sorbitol, and isobutane. 

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