Theoretical Study On The Catalytic Mechanism Of ?-cyclodextrin And Its Derivatives

The quantum chemistry method is employed to study the catalysis of?-cyclodextrin(?-CD)and its derivatives in organic rections.Density functional theory(DFT)and Hartree-Fock(HF)methods is employed for studying styrene and thiophenol as substrates synthesis of 1-phenyl-2-(phenylsulfanyl)-1-ethanol in the presence of ?-cyclodextrin.The results of energy analysis indicate that styrene and thiophenol enter from the secondary and primary hydroxyl ends of ?-CD and forming the stable structures(MB and MC),respectively,and hydrogen bonding interactions contribute to the stability of the inclusion complex.An investigation of the charges from electrostatic potentials using a grid-based method(CHELPG)highlighted the distribution of atomic charges upon complexation.The reaction sites of styrene and thiophenol were determined based on electrostatic potentials(ESPs)and condensed dual descriptor(CDD).The calculated 1H nuclear magnetic resonance(1H NMR)spectrum of ?-CD implied that the chemical shifts of its protons(H3 and H5)decreased and move to high fields upon complexation,while the calculated 13C nuclear magnetic resonance(13C NMR)spectrum of styrene suggested that this molecule is electrophilic and styrene more easily reacts with thiophenol in the presence of P-CD.The experimental results showed that per-6-amino-?-cyclodextrin(per-6-ABCD)is employed in Michael addition reaction which had good selectivity and catalysis.The reaction is calculated by using the DFT and HF methods.The stable structures of inclusion complexes(trans-chalcone-per-6-ABCD and nitromethane-per-6-ABCD)and solvent effect are investigated by energy analysis.Meanwhile,the solvent effect reveals that water as solvent in the Michael addition reaction is profitable.Condensed dual descriptor analyzes the reactive site of isolated trans-chalcone preliminarily.Interaction between guest and host is investigated by natural bond orbital(NBO),and non-covalent interaction(NCI)descriptor is used to study non-covalent interaction.Frontier molecular orbital and Mulliken charge are employed for revealing the electrophilicity,molecular orbital and charge distribution of trans-chalcone.13C NMR spectrum shows that carbon atoms of trans-chalcone are apparently activated by per-6-ABCD,and this reaction is facilitated for the electrophilicity of C28 is increased.All calculated results illustrate that per-6-ABCD as a catalyst plays a significant role in synthesis of 4-nitro-1,3-diphenylbutan-1-one.The experimental date indicated that ketone and substituted 2-aminobenzamides for synthesis 2,3-dihydroquinazolinone derivatives with high reaction rate and yield in the presence of ?-cyclodextrin-SO3H(?-CD-SO3H).DFT is used to study the catalysis of.?-CD-SO3H for synthesis of 2-ethyl-2-methyl-2,3-dihydroquinazolin-4(1H)-one,and speculating the possible reaction mechanisms.Energy analysis results show that 2-butanone enters the cavity from the sulfonic acid edge of ?-CD-SO3H to form a stable inclusion complex,and 2-aminobenzamide enters P-CD-SO3H cavity from the secondary hydroxyl edge.Condensed dual descriptor is used to analyze the reaction sites of 2-butanone and 2-aminobenzamide,preliminarily.Combining the analysis of Mulliken charge,hydrogen bonding,non-covalent interactions,and NMR spectroscopy,revealing that charge distribution and interaction of host-guest inclusion complexes,and then speculating the reaction mechanism of P-CD-SO3H catalyzed 2-butanone and 2-aminobenzamide.