Understanding and Optimizing the Behavior of Al- and Ru-Based Catalysts for the Synthesis of Polyisobutenyl Succinic Anhydrides

Abstract

Polyisobutenyl succinic anhydrides (PIBSAs) are an important class of chemicals in the automotive industry due to their wide use in lubricant and fuel formulations. However, the synthesis of these molecules takes place at elevated temperatures through the ene reaction between maleic anhydride (MAA) and polyisobutylene (PIB). Lewis acid catalysts (e.g., AlCl 3 ) have been shown to facilitate PIBSA synthesis by lowering the activation energy of the reaction; however, the desorption of the final product (PIBSA) from the catalyst can be highly endergonic. Herein, we demonstrate ligand engineering strategies to optimize the performance of Aland Ru-based catalysts by combining first-principles calculations with kinetic modeling. We discover that alkyl chlorides such as the EtAlCl 2 retain relatively low activation barriers like AlCl 3 , while lowering the desorption energy of the final product (PIBSA). In addition, we address metal oxidation state and ligand effects on the ene reaction performance of Ru-based catalysts. We demonstrate that depending on the metal oxidation state and type of ligands there is a competition between concerted and stepwise mechanisms. We uncover a Ru(II) catalyst, RuCl 2 •2H 2 O, exhibiting enhanced activity but suffering from low stability. Overall, our work identifies catalysts of industrial importance that can reduce the energy input required for intensified processes and highlights challenges associated with catalyst performance.

Characterization of Polyisobutylene Succinic Anhydride (PIBSA) and Its PIBSI Products from the Reaction of PIBSA with Hexamethylene Diamine

“…PIBSA molecules are an essential component in the preparation of PIBSI dispersants used as engine oil additives. Since the properties of PIBSI dispersants are a result of their chemical architecture, which is itself a direct consequence of the chemical composition of the PIBSA starting material, the characterization of PIBSA samples has been the focus of intense research [ 8 , 23 , 24 , 37 , 38 , 39 , 40 , 41 , 42 ]. Despite the numerous challenges complicating the characterization of PIBSA samples [ 19 ], this study provides a protocol that can be implemented to determine the weight fraction w PIB of unmaleated PIB chains in a PIBSA sample by analyzing the GPC traces obtained with a DRI detector of PIBSA–H( X ) reaction mixtures obtained from the reaction between different amounts of PIBSA and HMDA.…”

Polyisobutylenes with Controlled Molecular Weight and Chain-End Structure: Synthesis and Actual Applications

“…Given the clear calculated drivers for Lewis acid acceleration and the fact that this is a successful strategy in other Alder-ene reactions [ 139 ], the authors of [ 132 ] proposed that the minor by-products formed during the reaction between MA and HRPIB are also strong sequestering agents for AlCl 3 . More recently, Mpourmpakis et al proposed the use of EtAlCl 2 instead of AlCl 3 , which showed that alkylaluminum chloride retained relatively low activation barriers like AlCl 3 but formed less stable complexes with PIB-SA [ 140 ].…”

“…Lewis acid acceleration and the fact that this is a successful strategy in other Alder-ene reactions [139], the authors of [132] proposed that the minor by-products formed during the reaction between MA and HRPIB are also strong sequestering agents for AlCl3. More recently, Mpourmpakis et al proposed the use of EtAlCl2 instead of AlCl3, which showed that alkylaluminum chloride retained relatively low activation barriers like AlCl3 but formed less stable complexes with PIB-SA [140]. From a practical point of view, the use of excess MA in an ene reaction with HRPIB, that results in the formation of 'SA-excessive' adducts like PIB-BSA, entails substantial improvement in the characteristics of the corresponding PIB-SI [141,142].…”

Mechanical Properties of Aramid Fiber Fabrics and Composites Enhanced by Phthalic Anhydride Catalyzed with Anhydrous Aluminum Chloride

“…However, there is currently no research on the use of anhydrous AlCl3 for the reaction between phthalic anhydride and PPTA fiber. The catalytic mechanism of anhydrous AlCl3 for acylation reactions involves the carbon of the acyl group (-CONH-) on the benzene ring of PPTA fiber becoming a carbocation under the action of anhydrous AlCl3, promoting the occurrence of aromatic electrophilic substitution reactions, effectively increasing the reaction rate and yield, thereby shortening the modification time, and introducing more polar oxygen-containing functional groups on the fiber surface, increasing the number of active sites on the fiber surface [45,46]. This article investigates the effects of different concentrations of phthalic anhydride on etching plain-woven aramid fiber fabrics.…”