Derivatization And Synthesis Of Nitrogen Heterocyclic Compounds Catalyzed By Solid Acid In Aqueous System

In traditional organic reactions,organic solvents are usually used as reaction media.After the reaction,it is necessary to separate and purify the products by column chromatography and recrystallization.Usually,these operations need to use organic solvents heavily,resulting in environmental pollution.Therefore,how to reduce the use of organic solvents has been always a challenging in organic synthesis.In order to avoid column chromatography,simplify product separation steps,and reduce the use of organic solvents,a strategy includes exploring synthetic routes and controls the solubility of organic products is proposed in this paper.In this method,solid acid is used as catalyst,and water-containing system as reaction medium,the constituents and ratio of water-containing system are controled to easily isolate the products by different solubility of organic material.The feasibility and versatility of this strategy in the derivation of indole compounds and the synthesis of benzothiazole compounds were also explored.The main work is as follows:1.Preparation of polydivinylbenzene supported trifluoromethyl sulfimide solid acid?H-PDVB-SSFMI?.The acid content was tested as 0.77 mmol/g.The structure and surface properties were characterized by FT-IR,TG,TEM,N₂ adsorption-desorption and contact angle measurement.TG showed that the material could be used safely at 200 ^oC.The water contact angle and ethanol contact angle of the catalyst were 140.6 ^o and<20 ^o respectively,demonstrating its excellent hydrophobic properties.Moreover,the specific surface area of solid acid material is 297 m²/g,which is rich in mesopores and micropores.2.The catalytic activity of solid acid H-PDVB-SSFMI in aqueous phase for the reaction of indole with 1,4-addition of?,?-unsaturated ketone was investigated.The optimum experimental conditions were as follows:under 50 ^oC,with 2.0 mL 40%ethanol-water solution as solvent,the reactants were fed with stoichiometric ratio,the amount of catalyst was 10 mol%.Intriguingly,the yield of the addition reaction of indole with vinyl ketone was up to 92%,and the product could be purified without column chromatography,simple washing,filtration and drying.Compared with other solid acid catalysts,H-PDVB-SSFMI has excellent catalytic performance and can effectively reduce the use of organic reagents.3.In aqueous phase,H-PDVB-SSFMI catalyzed the synthesis of Bisindole alkyl compounds.It was found that the yield of target products could reach 99%at 50 ^oC with 5mol%catalyst dosage and 2.0 mL 50%ethanol-water solution as solvent.Similarly,the product did not need to be separated by column chromatography,and pure products can be obtained through simple washing,filtration and drying.Additionally,the yield ranges from 41%to 90%at 30 ^oC in ethanol.However,traditional column chromatography is still needed for the purification of products.4.In aqueous phase,H-PDVB-SSFMI catalyzed the synthesis of benzothiazoles.It was found that the yield of target products could reach 84%at 50 ^oC with 3.0 mL 30%ethanol-water solution as solvent and 10 mol%catalyst.Similarly,the product does not need to be separated by column chromatography,and pure products can be obtained through simple washing,filtration and drying.