Preparation Of Solid Acid/Base And Their Catalytic Performance In Organic Synthesis

Solid acids and solid bases developed recently have become new catalyst materials which overcome many disadvantages of the conventional liquid-acid/base catalysts. They have been given more and more attention and been one of the topic research fields because of their good activities and selectivities in alkylation, nitration, hydrogenation, polymerization, condensation and so on.Solid acids SO₄^2-/M_xO_y perform not only simple for preparation, non-polluting, non-corroding, but also high catalysis activities, good selectivities in most acid-catalyzed reactions. They are recovered easily and maintain activity in recycling. Hydrotalcite-like compounds are a solid base with double-layer structure. They perform excellent basic catalysis because of their particular structure, high specific surface and free energy.It was studied to prepare and characterize SO₄^2-/M_xO_y and to applied which in nitronation of toluene. Solid base of Mg/Al hydrotalcite-like was prepared and been used in aldol condensation of acetone.（1）SO₄^2-/ZrO₂ and SO₄^2-/TiO₂ prepared by different methods are all superacid. Zr（OH）₄ immersed in 0.7 mol / L H₂SO₄ solution then calcinated at 600℃leads to SO₄^2-/TiO₂ with 7.53-9.59 nm crystallite size and mostly at the metastable tetragonal phase of ZrO₂. It shows good catalysis in nitronation of toluene and the yield of nitrotoluene is about 94.5 %.（2）SO₄^2-/ TiO₂ was prepared by the sol-gel method : n（butyl titanate）: n（anhydrous alcohol）:n（acetic acid）:n（H₂O）=1:28:7:24, immersed with 0.7 mol / L H₂SO₄ solution and calcinated at 500℃. Obtained SO₄^2-/TiO₂, with about 8.5 nm crystallite and mostly at the anatase of tetragonal phase of TiO₂, shows good catalysis in nitronation of toluene and the yield of nitrotoluene was about 96.9 %.（3）SO₄^2-/ZrO₂ and SO₄^2-/TiO₂ were easy to preparation and separation in recovery and remain high activity and selectivity in recycles as well as scale-up experiment of nitration of toluene respectively.（4）There are obviously layer structure for the Mg/Al hydrotalcite -like （ HT ） solid base prepared by different methods. HT was appliedto liquid-phase aldol condensations of acetone, which exhibits a high catalytic activity and about 100 % selectivity of diacetone alcohol （DAA）. Furthermore, the HT performs a steady activity in recycles .