Modified Aluminate Chloride Preparation Of Ionic Liquids And Their Catalytic Alkylation Reaction

2,6-Dimethylnaphthalene (2,6-DMN) is a raw material for2,6-naphthalene dicarboxylic acid, which is used in the synthesis of polyethylene naphthalate (PEN). But the complex production technology of2,6-DMN and the high cost limited the use of PEN. In the industry, use multi-step to prepare2,6-DMN, but the complex production technology and the high cost limited the development of2,6-DMN. So, development of a highly efficient and environmentally friendly catalytic system for the highly selective synthesis of2,6-DMN remains challenging.In this paper, pyridinium aluminum chloride ionic liquids (PyHC1-AlCl3),1-butyl-3-methylimidazolium aluminum chloride ionic liquids ([BMIM]C1-AlCl3), Acetamide chlorid aluminum chloride ionic liquids (Acet-AlCl3) were prepared, and modified the ILs with HC1. The acidic properties of ionic liquids were characterized by Py-IR;27Al NMR spectrums of ILs were employed to explore the existing form of the anionic species; protonation degree of alkylation agents were evaluated by using UV-Vis absorption spectroscopy, analysis effect of the ILs acidity and alkylation agents on the transalkylation.We studied the effect of reaction temperature, reaction time, dosage of ILs, and ILs acidity on the catalytic activity to synthesis2,6-DMN by using PyHC1-AlCl3as catalyst. Modified the PyHC1-AlCl3with HC1to highly selective synthesis of2,6-DMN. The optimized reaction conditions were obtained:the molar fraction of AICI3is0.67, amount of ionic liquid is12mmol, molar ratio of TeMB to2-MN is1, reaction temperature is35℃, and reaction time is2h; Under the optimum reaction conditions,14.8%conversion of2-MN,100%selectivity of2,6-DMN in DMN were obtained.By using [BMIM]Cl-xAlCl3as catalyst, we compared the two change the ILs acid methods on the transalkylation, found that the HC1modification were significant improved the catalytic activity, and also investigated the effect of alkylation agents on the transalkylation.The coordinated ionic liquid Acet-AlCl3also can catalyze the transalkylation of2-MN with TeMB, the optimized reaction conditions were obtained:Ace-0.60AlCl3as the catalyst, reaction temperature is30℃, and reaction time is3h; Under the optimum reaction conditions, conversion of2-MN is3.6%, the selectivity of2,6-DMN in DMN is100%. After Acet-0.60AlCl3modified by HC1, the catalytic activity was significant improved, and use the ILs3times, the conversion of2-MN was also unchanged.