Construction Of DMAP-Functionalized Nanoreactors And Their Catalytic Application In Acylation Reaction In Water

The synthesis of dye intermediates is an important part in the field of dye industry.Dye intermediates containing ester groups can be successfully synthesized by4-dimethylaminopyridine(DMAP)catalyzed acylation of alcohols.The process of dye intermediates synthesis in organic phase catalyzed by DMAP is not conducive to the recovery of DMAP.At the same time,DMAP can cause environmental pollution due to the high toxicity,which also harm people's health.Therefore,the problems of high toxicity and poor recovery performance from free DMAP can be effectively solved by anchoring DMAP onto heterogeneous carriers.At present,carriers mainly include inorganic substances and organic polymers.Among them,the self-assembly of amphiphilic polymers in aqueous phase to construct catalytic nanoreactor can not only achieve heterogeneous catalysts,but also achieve highly efficient catalysis in water.In addition,The introduction of temperature sensitive monomers into the polymer makes the polymer temperature responsive.When the temperature is lower than the lower critical solution temperature(LCST),the polymer forms micellar nanoreactor in the aqueous phase.When the temperature rises above the LCST,the polymer is separated from the water phase and can be easily separated from the water by centrifugation and filtration.This thesis focuses on the construction and application of DMAP-functionalized nanoreactors,mainly including the following two parts.1.Small-molecule catalyst 4-(N,N-dimethylamino)pyridine(DMAP)-functionalized nanoreactors were constructed by self-assembly of amphiphilic block copolymers with DMAP moieties in the hydrophobic block,leading to heterogeneous catalysts with excellent dispersity in water.The key preparation route including reversible addition-fragmentation chain transfer(RAFT)polymerization of 2-(N-methyl-N-(4-pyridyl)amino)ethyl methacrylate(MAPMA)and methyl methacrylate(MMA)using poly(oligomeric(ethylene glycol)methyl ether methacrylate)(POEGMA)as a hydrophilic macromoleculer RAFT reagent to afford P(MAPMA-co-MMA)-b-P(OEGMA₇₀).The characterization by dynamic light scattering(DLS)and transmission electron microscopy(TEM)shows that the nanoreactors possess a core-shell nanostructure with the diameter of around 110 nm.The resulting polymeric nanoreactors showed excellent catalytic activity for acylation of alcohols in water.High conversion of a variety of alcohol(>99%)and excellent product selectivity were achieved within 60 min.The high catalytic efficiency of the nanoreactors may be attributed to the enhancement of the interaction between the reactant and the catalyst in the confined hydrophobic space,which simulates how enzymes usually work.Moreover,the catalyst could be easily recovered by thermos-responsive separation and reused with high activity for more than 5 cycles.2.In order to avoid using organic solvent in polymerization,DMAP was introduced to the amphiphilic polymer by polymerization induced self-assembly(PISA)in water.First,macromolecular hydrophilic chain transfer reagent mPEG₁₁₃-CEPA was synthesized from polyethylene glycol monomethyl ether(mPEG)and CEPA.Acrylate monomer of DMAP(MPAEA)which was in the hydrophobic part after polymerization was synthesized from4-chlorine pyridine hydrochloride.Then,Self-assembly of mPEG₁₁₃-P(MPAEA-co-THFA)was prepared directly by PISA in the deionized water using tetrahydrofuran acrylate(THFA)as hydrophobic mononer.Different types of DMAP-functionalized nanoreactors were also successfully fabricated when THFA monomer was replaced with 2-methoxyethyl acrylate(MEA)and hydroxybutyl acrylate(4-HBA).The morphology of the nanoreactors were characterized by DLS and TEM.The nanoreactors have been successfully applied to the acylation of alcohols in water.A variety of acyl compounds were synthesized with low catalyst dosage in the nanoreactor system and excellent yields(>99%)were obtained.The high catalytic efficiency of the nanoreactor may be attibuted to the enhanced interaction between the reactants and the catalyst embedded in the hydrophobic part of the nanoreactor.In addition,the nanoreactor maintains high catalytic activity after multiple recycling.