Research On Additives-assisted Rupe Rearrangement Reaction In Near-Critical Water

The high ionization constant and low dielectric constant of near-critical water (NCW), making it has self-acid/base catalysis function and owning special solubility of both organic and inorganic compounds, NCW may play roles as reactant in organic synthesis reactions as well as catalyst and solvent, which can replace the use of toxic and hazardous solvents and traditional acids or bases, reduce the pollution to environment. Therefore, NCW has the potential application in organic synthesis reactions, waste recycling and other areas.The literature review section gave a brief introduction to the physical properties of NCW, such as water density, dielectric, ionic product, viscosity and so on. It summarized systematically the application of NCW, using as reactant、solvent or catalyst, in different types of organic reactions.The literature researched Rupe rearrangement of1-ethynylcyclohexan-l-ol and3-methyl-l-pentyn-3-ol in NCW, using one type of stainless steel batch reactor, to investigate the new ways and technology in green chemical processes.1. Research on Rupe rearrangement of1-ethynylcyclohexan-l-ol in NCWWe performed the Rupe rearrangement of1-ethynylcyclohexan-l-ol in NCW to study the reaction under high temperature conditions. The influences of reaction time, temperature, additives and initial reactant-to-water ratio on the yield of1-cyclohexen-1-ylethanone were examined. The yield of1-cyclohexen-1-ylethanone was49.3%in pure water at260℃for a reaction time of60min. However, when additives such as ZnSO4, FeCl3, and NaHSO4, respectively, were introduced to the water to investigate the effect of salts on the Rupe rearrangement reaction, the yield increased markedly to as much as87.7%in5mol.%NaHSO4aqueous solution under the same conditions. The catalytic ability of the additives decreased in order: NaHSO4, FeCl3, ZnSO4. On the basis of these results, a possible reaction mechanism of the Rupe rearrangement of1-ethynylcyclohexan-1-ol in NCW was proposed 2. Research on Rupe rearrangement of3-methyl-1-pentyn-3-ol in NCWWe performed the Rupe rearrangement of3-methyl-1-pentyn-3-ol with additives in NCW. The influences of reaction time, temperature, additives and initial reactant-to-water ratio on the yield of3-methyl-3-penten-2-one were examined. The experiment showed that the yield of3-methyl-3-penten-2-one was51.5%in pure water at240℃for a reaction time of150min. However, when additives such as FeCl3, CuCl2, ZnCl2, and NaHSO4respectively, were introduced to the water to investigate the effect of salts on the Rupe rearrangement reaction, the yield increased to60.3%in5mol.%NaHSO4aqueous solution at240℃for a reaction time of90min. The catalytic ability of the additives decreased in order:FeCl3, CuCl2, ZnCl2, NaHSO4. On the basis of these results, a possible reaction mechanism of the Rupe rearrangement of3-methyl-1-pentyn-3-ol in NCW was proposed.