Esters hydroxycarboxylic fatty acid

An essentially neutral process for C-acylation relies on the reaction of imidazolides (542) with the magnesium salt (543) of a malonic acid half thiol ester (Scheme 119) (79AG(E)72>. The method requires slight modification when applied to an w-hydroxycarboxylic acid since a primary hydroxyl reacts with carbonyldiimidazole. The use of malonic acid half thiol esters in this fashion patterns the scheme proposed for carbon-carbon bond formation in the biosynthesis of fatty acids. 

Hydroxycarboxylic and fatty acid esters are produced by esterifying organic acids to monoglycerides. This increases their hydrophilic properties. Organic acids used are ace-... 

Camauba wax (also called Brazil wax or palm wax) is isolated from the leaves of the palm Copernicia prunifera (camauba palm), a plant native to northeastern part of Brazil. It has an appearance of yellow flakes. Camauba consists mostly of aliphatic esters (40.0 wt%), diesters of 4-hydroxycinnamic acid (21.0 wt%), ra-hydroxycarboxylic acids (13.0 wt%), and fatty acid alcohols (12.0 wt%). These compounds are mainly derived from acids and alcohols in the C26-C30 range. Distinctive for camauba wax is the high content of methoxycinnamic acid as well as diesters. This type of wax is one of the hardest natural waxes with the highest melting point between 78°C and 86°C, but most often the melting-point range is 82°C-85°C. Like all other waxes, it is insoluble in water, but soluble on heating in ethyl acetate and in xylene, and practically insoluble in ethyl alcohol (European Pharmacopeia 6.0). 

Hydroxycarboxylic acids and 5-hydroxycarboxylic acids occur in the form of corresponding y- and 5-lactones in many fruits, especially apricots and peaches. Many other hydroxy fatty acids are also found in seed oils of plants. For example, (S)-jalapinolic acid (3-28) occurs in lipophilic ester-type dimers of acylated pentasaccharides derived from L-rhamnose in sweet potato Ipomoea batatas, Convolvulaceae), which are known as batatins. (9Z,12S)-12-Hydroxyoctadec-9-enoic (ricinoleic) acid (3-29) occurs in castor oil, where it represents about 90% of the total fatty acids. So-called castor oil is extracted from the seeds of the castor oil plant Ricinus communis) of the Euphorbiaceae family, and is used only for technical purposes as it has purgative properties. 

Fatty adds may also be directly esterified by hydroxycarboxylic adds, the most common of which are lactic acid and (2S,3S)-tartaric (D-tartaric) acid. Lactic acid gives rise to esters called lactylates, at first a monoester (11-75), which reacts with another molecule of lactic add yielding the ester of a dimeric add (11-76), which may arise also by reaction of a fatty acid with lactides. Other reactions can produce emulsifiers in which one molecule of a fatty add accounts for a greater number of molecules of lactic add (11-77). Stearoyl tartrate, also known as stearoylpalmitoyl tartrate (E483), is approved in the EU as an emulsifier. The main components of this product are distearoyl tartrate, dipahnitoyl tartrate and stearoylpalmitoyl tartrate. 

A final class of sulfated alkyl surfactants is that of the sulfated fats and oils in which the sulfate esters are obtained by the treatment of a variety of hydroxylated or unsaturated natural fats and oils with sulfuric or chlorosulfonic acids. These materials represent the oldest types of commercial synthetic surfactants, dating back to the original turkey red oils. Because of the nature of the starting materials and preparation processes, the sulfated fats and oils are chemically heterogeneous materials whose properties are very sensitive to their history. In fact, the preparation of such materials may correctly be considered to be more art than science. They will contain not only sulfated glycerides similar to those discussed above but also sulfated carboxylic acids and hydroxycarboxylic acids produced by hydrolysis of the starting materials. With the increased availability of more chemically pure surfactant materials, the use of the sulfated fatty oils has decreased considerably. They do still have their uses, however, especially where purity is not a major concern and cost is important. 

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