Ionic Liquid In The Acid-catalyzed Organic Reactions And The Synthesis Of Chiral Molecular Sieve

Room temperature ionic liquids are molten salts that being liquids at normal temperature. As a replacer of versatile organic solvents, room temperature ionic liquids are attracting scientist's more attention. In this dissertation, the application of Bransted acidic ionic liquid in some reaction, which normally catalyzed by acid, was investigated. Moreover, several chiral ionic liquids, which were further served as structure directing agent for preparation of chiral sieves, were designed and synthesized.(1) Condensation of aldehydes or ketones with alcohols is one of the most common methods for protecting carbonyls. In this thesis, the condensation of different carbonyls with neopentyl glycol, ethylene glycol and methanol, respectively, was studied with Bransted acidic ionic liquid as recyclable medium as well as acidic catalyst. Using neopentyl glycol as protecting reagents, the results showed that most of the aldehydes or ketones gave almost quantitative conversions in [Hmim]BF4 except for the ketones with big steric hindrance. Satisfactory conversions of 93% ~ 98% for aromatic aldehydes were obtained.Using ethylene glycol as protecting reagents, the reaction rates slightly decreased under the same reaction conditions. Longer reaction time was required to obtain similar conversions and selectivities compared with neopentyl glycol. The steric hindrance and electron-donating effect were unfavorable to the condensation reactions.The protection with methanol was difficult to proceed. Better results only for aliphatic aldehydes and cyclohexanone were obtained while using a higher proportion of methanol (molar ratio 1:6).The water produced in the reactions did not need to be removed during the reaction because [Hmim]BF4 was miscible with water while the acetals or ketals were immiscible with [Hmim]BF4. Hence the product could be separated conveniently bydecanting. The ionic liquid [Hmim]BF4 could be easily recycled. After reaction, [Hmim]BF4 was readily separated and reused after drying in vacuum.(2) The conversion of alcohols to alkyl halides was investigated using acidic ionic liquid [Hmim]X as halogenating agent, acidic catalyst as well as medium. The reactions of primary alcohols gave very satisfactory conversions and selectivities except for the substrates with lower boiling point,such as n-octanol and benzyl alcohol. They obtained the corresponding halides with almost quantitative yields(95%-100%) .The secondary alcohols also gave the corresponding halides with excellent conversions, however, the by-products of dehydration were detected. [Hmim]X was transformed into methylimidazole after the reaction. The methylimidazole was dissolved in the products halide, so the product could not be isolated directly. After the reaction, the insoluble halide could be easily separated by addition of equivalent of halogen acid, and the ionic liquid [Hmim]X could be regenerated conveniently by removal of water. Hence, for the whole process, the reaction consumed equivalent of halogen acid and alcohol to produce halide and water. The procedure is very practive for the preparation of primary halides.(3) Series of chiral ionic liquid, which contained one chiral carbon, was designed and synthesized using L-(-)- a -methylbenzylamine as the starting substrate. The attempts for preparing chiral molecular sieves were made with the chiral ionic liquid L-(-)- a -methylbenzyl-N,N-dimethylbromocetylquaternary ammonium salt as structure directing agent. We got a product which construction as that of MCM-41.