Synthesis Of PVDC Supported L-proline Catalyst And Their Catalytic Properties For Asymmetric Aldol Reactions

Organic asymmetric catalytic reactions is one of the hotspots in the field of asymmetric synthesis.Catalyst design and synthesis of small organic molecules is the focus of the field. ongoing of the researchon organocatalysts such as L-proline and its derivatives, the preparation of organocatalysts possessingincreased activity and selectivity is becoming more and more challenging. In recent years, as a branch ofthe field, the research of polymer supported organic catalyst’s design, synthesis and catalytic properties hasbeen got more concern. Supported organic catalysts can not only compensate for the shortcomings of smallorganic molecules which can not be reused, but also indirectly affect the catalytic performance for itsunique spatial structure. Polyvinylidene chloride resin as the carrier, L-proline as the catalyst unit, usingthree kinds of combination, and synthesis of the organic catalyst of the three types catalyst. In this thesis,the main content and study are as follows:1. Performance study of polyvinylidene chloride (PVDC) supported of the L-prolinamide catalyst and itscatalytic performance for asymmetric Aldol reactionDifferent polyamines were selected as the connection arm, polyvinylidene chloride was modified bypolyethylene polyamine, Then the protected L-proline reacted with PVDC-polyethylene polyamine,deprotected and the PVDC supported prolinamide catalyst was got. The catalysts were used for catalyzingdirect asymmetric aldol reaction of aldehydes and ketones, and investigated the catalytic performance.Studies showed that three kinds of catalysts can effectively catalyze the direct asymmetric Aldol reaction.When water was used as the solvent, the activity of the catalyst is higher(yield>98%), under solvent-freeconditions, the selectivity of the catalyst is higher(e.e.>89%); By changing the reaction conditions,screened out the optimum reaction conditions. activity and selectivity of the catalyst achieved to thebest(yield99%; d.r.16:84, e.e.92.3%). The catalyst use water as solvent, and can be recycled to be reusedfor four times, the catalyst activity and selectivity are no major changes.2. No-covalent catalyst system——preparation of polyvinylidene dichloride supported polyethylenepolyamine/L-proline catalyst and the performance for asymmetric Aldol reactionA series of PVDC loaded polyethylene polyamine resins were synthesized by a simple chemical reaction, and by acid-base ion pairs in the form of L-proline to be loaded on PVDC branches. This series ofcatalysts can catalyze aldol reaction of a range of different substrate. Studies have shown that the catalystshave higher activity and lower selectivity in the water, but the applicability of the general substrate in theseries of catalysts, selectivity and activity is not higher except nitrobenzaldehyde. This series of catalystscan be recycled and reused, the activity does’t decrease obviously.3. Prepareration of polyvinylidene dichloride loaded ionic liquid/of L-proline catalysts and theperformance for asymmetric Aldol reactionPolyvinylidene chloride as the carrier, combined with L-proline, a new type of polymer loadedtwo-phase organic catalyst was formed. It Showed excellent catalytic performance in asymmetric Aldolreaction of aldehyde and ketone, further examined the its applicability of the substrate and recyclingperformance. Studies have shown that regardless of the substituent groups are strong electron withdrawingor weak, the catalyst system showed high activity and high selectivity(yield74-99%; e.e.69-98%); Theapplicability of the substrate is better than the aforementioned two types of polymer supported catalysts.The catalyst recycling is also quite excellent. The catalytic system can be reused at least six times theactivity and selectivity are no major changes.