Esterification of Mixed Carboxylic-fatty Anhydrides Using Amberlyst-15 as Heterogeneous Catalyst.
The article deals with the use of mixed anhydrides for the synthesis of fatty esters. Both aliphatic and aromatic acids are involved, indicating different behaviors according to the chain length of the aliphatic acid. We describe a novel and efficient method for the synthesis of fatty esters by the esterification reaction of primary, secondary and tertiary alcohols with mixed carboxylic-palmitic anhydrides using resin Amberlyst-15 as heterogeneous acid catalyst. Influence of various reaction parameters such as molar ratio (anhydride/alcohol), catalyst amount, type of alcohol and type of mixed anhydride were studied to optimize the conditions for maximum yield. Among tested anhydrides we quote mainly the 4-chlorobenzoic palmitic anhydride because it was both reactive and selective for the preparation of palmitic acid ester. This anhydride gave a good yield of palmitic ester.
Synthesis of Biosurfactants: Enzymatic Esterification of Diglycerol and Oleic Acid. 1. Kinetic Modeling
The growing application of environmentally friendly products raised in the last few years has increased the interest in biodegradable nonionic surfactant products. As an example of these, polyglycerol fatty acid esters have a wide field of application in many industries as additives of cosmetics, food, photography, inks, etc. Also, the huge range of possible raw materials for these products increases cited interest. The esterification of diglycerol with oleic acid using an enzyme (NOVOZYM-435) as catalyst was studied in this work. Several experiments were carried out at different temperatures, catalyst concentrations, and acid/alcohol molar ratios. A pseudo-second-order kinetic model, including Langmuir adsorption factors for the acid, was developed. The results show that this proposed kinetic model reproduces the experimental data with a maximum 10% error.
Phloroglucinol derivatives from Hypericum japonicum.
The isolation and identification of a new phloroglucinol derivative (2), a diterpenol (4), together with the known compounds flavesone (1) and sarothralen B (3), from the aerial parts of Hypericum japonicum are reported. Their structures were established by extensive spectral analysis and the structure of (3) has also been confirmed by a single crystal X-ray determination.