摘要：

The project aims to develop new chemical processes for the modification of the byproducts obtained in the production of biodiesel in order to obtain esters with improved properties as lubricants. The three most important properties that an oil should have to be used as a lubricant are: viscosity, cold properties and oxidative stability. The 1st generation biolubricants show some limitations when compared with their petroleum based counterparts. Due to the operating conditions, lubricants must withstand high temperatures (chemical and oxidative stability), as well as having good cold properties (pour point and turbidity). These properties are inherent to the chemical structure of the fatty acids used in 1st generation biolubricants, where the good cold properties are inferred by the unsaturations while giving low oxidative stability because of their high reactivity. To obtain 2nd generation biolubricants, it requires the unsaturation replacement by branches in order to increase the oxidative stability of the compounds while maintaining good cold properties. In this work we have developed a new synthetic pathway in three steps using the strategy of epoxidation-ring opening of unsaturations, in order to obtain compounds where the unsaturations have been replaced by ester-ester asymmetric branches. We have characterized the new synthesized products (density, viscosity, pour point ...) in order to study the relationship between structure properties. The introduction of branching produces a substantial improvement of the oxidative stability of the compounds while maintaining good cold properties, kinematic viscosity substantially increases due to branching and some properties can be modulated by the length of the branch. The properties of the new compounds have been compared with the properties of other 2nd generation bio-lubricants described in the literature, showing the difference produced by the use of ether or ester bonds and the symmetry or asymmetry of the branches. A computational study using molecular dynamics of different possible types of branching, has allowed the rationalization of the behavior of different types of branching at the molecular level. Finally, we have conducted a study on the possibility of obtaining such products through white biotechnology techniques, namely the esterification of hindered alcohols using lipases. The results have shown that it is possible to obtain compounds with high added value through a process which improves the available processes based on traditional chemistry.

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