Long-chain esters

Long-chain esters of pentaerythritol have been prepared by a variety of methods. The tetranonanoate is made by treatment of methyl nonanoate [7289-51-2] and pentaerythritol at elevated temperatures using sodium phenoxide alone, or titanium tetrapropoxide in xylene (12). PhenoHc esters having good antioxidant activity have been synthesized by reaction of phenols or long-chain aUphatic acids and pentaerythritol or trimethyl olpropane (13). 

Long-chain esters of pentaerythritol have been used as pour-point depressants for lubricant products, ranging from fuel oils or diesel fuels to the high performance lubricating oils requited for demanding outiets such as aviation, power turbines, and automobiles. These materials requite superior temperature, viscosity, and aging resistance, and must be compatible with the wide variety of metallic surfaces commonly used in the outiets (79—81). 

Figure 10. Infrared spectrum of long-chain ester recovered from gas chromatography after hydrolysis and methylation of pyrethrum concentrate...

Figures 2 through 9 are infrared spectra of fractions collected from partition columns, gas chromatography, thin-layer chromatography, or a combination of these separation techniques. Figure 10 is the infrared spectrum of a compound isolated by gas chromatography after hydrolysis of a pyrethrum concentrate. In this case the compound is a long-chain ester. All the infrared spectra were made with a Perkin-Elmer Model 221 instrument. The following operating parameters were used. A liquid demountable cell with a 0.01-mm path length was employed.

The acute toxicity of ester sulfonates is mainly related to the length of the carbon chain of the fatty acid. The acute fish toxicity of tallow-based ester sulfonates is relatively high (LC0 = 0.4-0.9 mg/L) compared with coconut-based ester sulfonates (LC0 — 46 mg/L) [113]. In spite of this relatively high fish toxicity of the long-chain ester sulfonates both acute and long-term toxic effects can be excluded for normal environmental conditions. For example, the sum of all anionic surfactants in German rivers is stable on a level far below... 

Scheme 2.20 gives some examples of the application of the Julia olefination in synthesis. Entry 1 demonstrates the reductive elimination conditions. This reaction gave a good E.Z ratio under the conditions shown. Entry 2 is an example of the use of the modified reaction that gave a good E.Z ratio in the synthesis of vinyl chlorides. Entry 3 uses the tetrazole version of the reaction in the synthesis of a long-chain ester. Entries 4 to 7 illustrate the use of modified conditions for the synthesis of polyfunctional molecules. 

The oleaginous phases of creams differ composi-tionally from hydrocarbon ointments. Many, but not all, creams are patterned after vanishing cream and contain considerable stearic acid. In lieu of some or all of the stearic acid, creams sometime contain long-chain waxy alcohols (cetyl, Ci6 stearyl, Ci8), long-chain esters (myristates, Ci4 palmitates, Ci6 stearates, Cig), other long-chain acids (palmatic acid), vegetable and animal oils, and assorted other waxes of both animal and mineral origin. 

P. Tulloch, L.L. Hoffman, Canadian beeswax analytical values and composition of hydro carbons, free acids and long chain esters, Journal of the American Oil Chemists Society, 49, 696 699 (1972). 

Generally, alkaline saponification in hydroalcoholic KOH is the most widespread approach [11 13]. This allows us to cleave ester bonds and, if necessary, to separate the saponifiable fraction (acids) and unsaponificable fraction (alcohols, sterols, and hydrocarbons). Generally, 3 h of saponification in 10% KOH in water/methanol (3 1) at 60 °C achieves a quantitative yield for triglycerides. Wax esters are less prone to hydrolysis and generally need stronger conditions. Quantitative hydrolysis of beeswax long chain esters has been obtained using 10% KOH in ethanol assisted by microwaves, for 60 min at 80 °C and at 200 W [21],... 

The long chain esters that characterise beeswax, as well as the low volatile and long chain acids, hydroxyacids and alcohols, require some kind of pretreatment prior to GC/MS... 

Polycondensation of long-chain esters of amino acids containing aromatic rings in the monolayer assemblies. 

The percent conversion of the monomer to the polypeptide can be estimated by the quantity 100 (Aq - At) / Aq, where Aq and At are the integrated intensities of the ester band at the start and time t, respectively. At 40 °C, it tended to saturate at about 30 % for the Y-type films of L-NaphAla-C-i s, and L-PyrAla-G 8, although the conversion for the LB film of long-chain ester of alanine (L-Ala- Ci s) reached to 90 % [52]. This difference is considered to be due to a larger steric hindrance of the aromatic rings. 

Long-chain ester derivatives of phorbol, a tetracyclic diterpene from the seed oil of Croton tiglium L., including its most abundant representative, 12-0-tetradecanoylphorbol-13-acetate (65), are potent activators of protein kinase G (PKG) and are used as standard tumor promoters for the study of experimental carcinogenesis in animal models." ... 

The F, T curve beyond this point is again linear, but the surface pressure decreases rapidly with elevation of the temperature until the point B is reached where an abrupt change in the slope of the curve is noted, in many cases such as in the long chain esters the film is found to be condensed at A and expanded at B, thus AB is the expansion interval of Labrouste and Adam. For acids on the other hand with the exception of stearic, the film is already expanded at the melting point and the portion of the curve AB is missing. 

Conversely, groups of electronegative heteroatoms which should act to decrease electron availability, deactivate neighboring C—H bonds towards attack, even though the resulting radicals should be markedly stabilized by delocalization—e.g., R—CH—COOR, RCH—NQ2. Thus, autoxidation of long chain esters occurs at points remote from the ester function. 

Various /i-oxo esters are fluorinated by perchloryl fluoride in the presence of sodium ethoxide, while the fluoro products 8 are usually converted into a-fluoro esters 9 various saturated and unsaturated long-chain esters, e.g. 10 and 11, can be prepared in high yield.23-24... 

Besides polymerization, another type of polyreaction can be used for stabilizing model membrane systems. Recently, Fukuda et al.28) described polyamide formation via polycondensation in monolayers at the gas/water interface (definition of mono-layers see Sect. 3.2). Long-chain esters of glycine and alanine were polycondensed to yield non-oriented polyamide films of polyglycine and polyalanine. 

Several studies have been made of LB films of esters of naturally occurring polysaccharides. Kawaguchi et al. [242] formed long chain esters of cellulose which, however, could only be formed into multilayers by the horizontal lifting technique. Schoondorp et al. [243] studied LB multilayers of esters of amylose and showed that materials with short alkyl side chains have a helical conformation at the air/water interface and that this structure can be transferred into multilayers. As in the case of the isotactic polymethylmethacrylate, the helical structure appears to lead to an oriented structure in the LB film. These two families of materials are illustrated in Figure 5.9. 

Another investigator reports 46.72 dynes/cm at 81° (Ref 25). A study has been made (Ref 71) of the interfacial tension between waxes and TNT, and its reduction by adding long-chain esters of 2.4,6-trinitrobenzoic acid... 

Some compounds such as long chain esters and polyethers decompose in the inlet system, and the spectrum obtained is not that of the initial substance. Calibration coefficients are required for quantitative analyses. The sample introduced to the instrument cannot usually be recovered. 

Our principal target in P-450 mimics was the selective oxidation of saturated carbons directed by geometric control, not by intrinsic reactivity. In our first study, we examined selective geometrically controlled attack on aliphatic C-H bonds by photo-excited benzophenones [145]. In a process we labeled remote oxidation", photolysis of a long-chain ester 69 of benzophenone-4-carboxylic acid afforded insertion into CH2 groups far into the chain. 

Bianchi, G., Tava, A., Vlahov, G. and Pozzi, N. (1994) Chemical structure long chain esters from sansa olive oil. J. Am. Oil Chem. Soc., 71, 365—369. 

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