1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralo...1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.展开更多
Six novel chiral dinuclear Salen complexes[Cu 2 L 1 ·H 2 O(3a),Cu 2 L 2 (3b),Ni 2 L 1 ·2H 2 O(4a),Ni 2 L 2 (4b),Mn 2 Cl 2 L 1 ·H 2 O(5a),Mn 2 Cl 2 L 2 (5b)]have been synthesized(L 1 and L 2 are chiral d...Six novel chiral dinuclear Salen complexes[Cu 2 L 1 ·H 2 O(3a),Cu 2 L 2 (3b),Ni 2 L 1 ·2H 2 O(4a),Ni 2 L 2 (4b),Mn 2 Cl 2 L 1 ·H 2 O(5a),Mn 2 Cl 2 L 2 (5b)]have been synthesized(L 1 and L 2 are chiral dimeric Salen ligands with different chain length which were synthesized from(R,R) - diaminocyclohexane,salicylaldehyde,4,4 ’- (1,10 - decaneoxy)sali - cylaldehyde,4,4 ’- (1,6 - hexyloxy)salicylaldehyde).These compounds were charactered by elemental analysis,1 H NMR,FT - IR,UV - Vis and CD spectra.The FT - IR,UV - Vis and CD spectra were discussed and compared with those of monomeric ligand and complex in detail.It was found that the spectra properties of compounds of differ - ent chain length were almost alike,and the properties of dimeric and monomeric compound were similar too.Furthermore Cotton effect and Cotton split of CD spectra of these chiral compounds were explained by the exciton interaction theory.It seemed that the direction of Cotton split depend on the configuration of diaminohexane.(R,R) - diaminohexane determine the chirality of Salen compounds as negative,and the positive and negative compo - nent of Cotton split lie at higher and lower energy respectively.展开更多
SalenMX has drawn much attention recently,because it is nonsensitive to moisture and effective for copolymerization of CO2 and epoxides.However,usually expensive organic metal compounds were used.A low cost procedure ...SalenMX has drawn much attention recently,because it is nonsensitive to moisture and effective for copolymerization of CO2 and epoxides.However,usually expensive organic metal compounds were used.A low cost procedure of SalenMX preparation is described that SalenAl（OPr） can be obtained by using aluminium iso-propoxide reacted with SalenH2 in tetrahydrofuran at room temperature overnight.The catalyst precursor Schiff-base SalenH2 （N,N′-Bis（salicylidene）-1,2-phenylenediamine） was synthesized by refluxing 2 equiv salicylaldehyde and 1 equiv of 1,2-phenylendiamine in methnol for a period of time.SalenH2 and SalenAl（OPr） were characterized by FT-IR,mass Spectroscopy,UV-Vis and 1H-NMR.The copolymerization of carbon dioxide and cyclohexene oxide（CHO） was carried out at 80℃ for a certain period time using 50 mg SalenAl（OPr） as catalyst.SalenAl（OPr） had been shown to be an effective catalyst for the copolymerization of CO2 and CHO along with a small quantity of byproduct cyclic carbonate.The addition of various cocatalysts,including DMAP,N-MeIm,DBU and Bu4NCl or Bu4NBr salts can greatly enhance the rate of copolymerization.The copolymers were produced with >95% carbonate linkages and <5% cyclic carbonates.The highest catalytic efficiency is 190 g copolymer per g catalyst.展开更多
文摘1-Tetralone, a useful synthetic intermediate in the manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin to 1-tetralone is still a big challenge with low-temperature processes using environmentally friendly routes even after decades of research. Herein, we demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was characterized by powder X-ray diffraction, Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse reflectance spectra, scanning electron microscopy (SEM) and elemental analysis. The theoretical calculations of free sulphonato-salen-nickel(II) complex using Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were also used to determine the orientation of the Ni-salen compound within the layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an effective reusable catalyst for the oxidation of tetralin to 1-tetralone using a combination of trimethylacetaldehyde and molecular oxygen (14.5 psi) and at 25°C. At 45.5% conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration experiment showed that oxidation proceeded through Ni(II) sites in LDH-[Ni-salen]. The catalysts were reused several times without losing their catalytic activity and selectivity. The present results may provide a convenient strategy for the preparation of 1-tetralone using layered double hydroxide-based heterogeneous catalyst at ambient temperature for industrial application in near future.
文摘Six novel chiral dinuclear Salen complexes[Cu 2 L 1 ·H 2 O(3a),Cu 2 L 2 (3b),Ni 2 L 1 ·2H 2 O(4a),Ni 2 L 2 (4b),Mn 2 Cl 2 L 1 ·H 2 O(5a),Mn 2 Cl 2 L 2 (5b)]have been synthesized(L 1 and L 2 are chiral dimeric Salen ligands with different chain length which were synthesized from(R,R) - diaminocyclohexane,salicylaldehyde,4,4 ’- (1,10 - decaneoxy)sali - cylaldehyde,4,4 ’- (1,6 - hexyloxy)salicylaldehyde).These compounds were charactered by elemental analysis,1 H NMR,FT - IR,UV - Vis and CD spectra.The FT - IR,UV - Vis and CD spectra were discussed and compared with those of monomeric ligand and complex in detail.It was found that the spectra properties of compounds of differ - ent chain length were almost alike,and the properties of dimeric and monomeric compound were similar too.Furthermore Cotton effect and Cotton split of CD spectra of these chiral compounds were explained by the exciton interaction theory.It seemed that the direction of Cotton split depend on the configuration of diaminohexane.(R,R) - diaminohexane determine the chirality of Salen compounds as negative,and the positive and negative compo - nent of Cotton split lie at higher and lower energy respectively.
文摘SalenMX has drawn much attention recently,because it is nonsensitive to moisture and effective for copolymerization of CO2 and epoxides.However,usually expensive organic metal compounds were used.A low cost procedure of SalenMX preparation is described that SalenAl（OPr） can be obtained by using aluminium iso-propoxide reacted with SalenH2 in tetrahydrofuran at room temperature overnight.The catalyst precursor Schiff-base SalenH2 （N,N′-Bis（salicylidene）-1,2-phenylenediamine） was synthesized by refluxing 2 equiv salicylaldehyde and 1 equiv of 1,2-phenylendiamine in methnol for a period of time.SalenH2 and SalenAl（OPr） were characterized by FT-IR,mass Spectroscopy,UV-Vis and 1H-NMR.The copolymerization of carbon dioxide and cyclohexene oxide（CHO） was carried out at 80℃ for a certain period time using 50 mg SalenAl（OPr） as catalyst.SalenAl（OPr） had been shown to be an effective catalyst for the copolymerization of CO2 and CHO along with a small quantity of byproduct cyclic carbonate.The addition of various cocatalysts,including DMAP,N-MeIm,DBU and Bu4NCl or Bu4NBr salts can greatly enhance the rate of copolymerization.The copolymers were produced with >95% carbonate linkages and <5% cyclic carbonates.The highest catalytic efficiency is 190 g copolymer per g catalyst.
