Columns fatty-ester synthesis

The slow water removal is obvious within the synthesis of, for example, myristyl myristate determining the total reaction time. In a stirred-tank reactor it takes 24 h to reach a conversion of 99.6% and in a fixed-bed reactor 14 h. Therefore, a new synthesis platform (Figure 4.11) which also enables conversion of highly viscous polyols and fatty acids from renewable resources to ester-based surfactants was designed. It is used by Evonik on a pilot scale, outperforming conventional methods, such as stirred-tank or fixed-bed reactors. In contrast to the setups introduced before, conversion of >99.6% is already obtained after 5.5 h in the bubble column reactor [44-47]. 

New acid chloride-based preparation of picolinyl esters. A solution of HMP in CH2CI2 (20 mg/mL) is prepared and stored over anhydrous sodium sulfate. The solution is stable in a refrigerator for 1 mo. The stoek solution of HMP in CH2CI2 (0.5 mL) is added to the freshly prepared acid chloride (synthesis of the fatty aeid ehloride, see procedure for DMOX derivatives), eooled in an iee bath, and the mixture is then left to warm up to room temperature for 1 h (a white preeipitate may form). The solvent is added in a stream of nitrogen isohexane (5 mL) is added, followed by 0.5% aqueous sodium bicarbonate. The mixture is shaken thoroughly and then the solvent layer is removed by Pasteur pipette. It is dried via a small sodium sulfate column and concentrated under nitrogen. If necessary, the product can be purified by Florisil chromatography as described above. 

In a more demanding application, the synthesis of various fatty acid alkanolamides was followed by quantitative HPLC using a reversed-phase column and a THF/acetoni-trile/water, pH 2.6, mobile phase. Refractive index detection was used. The methyl ester starting materials were resolved, as were free fatty acids mono-, di-, and triglycerides dialkanolamides and amine esters (154). As a mle, GC or TLC methods provide a more complete characterization of reaction products than does HPLC. 

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