The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, Formula: C20H24O6
Spectroscopic properties of uranyl crown ether complexes in non-aqueous solvents
The spectroscopic properties of the complexes of uranyl with oxacrowns, azacrowns, thiacrowns of different ring size, polyethyleneglycols (PEG-200, PEG-300, PEG-400), and [2.2.1] and [2.2.2] cryptands were studied in acetonitrile and propylene carbonate solutions by absorption and luminescence spectroscopy. Depending on the ligand, marked differences in the fine structure of the spectra were observed. The crown ethers with six oxygen atoms (18-crown-6, dicyclohexano-18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6 and [2,4]-dibenzo-18-crown-6) form inclusion complexes with the uranyl ion in the central cavity. In the case of 18-crown-6 and dibenzo-18-crown-6, a complex with a high coordination symmetry is formed. Outer-sphere complexes are formed with the crown ethers with small ring size (12-crown-4 and 15-crown-5) and with PEG-200. Only minor changes in the spectra were observed when changing the ligand. The spectra of the large crown ethers ([3,4]-dibenzo-21-crown-7, dibenzo-24-crown-8 and dibenzo-30-crown-10), together with those of PEG-300 and PEG-400 show that these ligands coordinate in the equatorial plane to the uranyl ion. In the presence of competing inorganic ligands like chloride and nitrate ions, the crown ether is replaced in the first coordination sphere. Azacrowns and cryptands coordinate externally to the uranyl ion, and the corresponding spectra do not show fine structure. In the case of the thiacrowns, no coordination of the ligand to the uranyl ion was observed.
Note that a catalyst decreases the activation energy for both the forward and the reverse reactions and hence accelerates both the forward and the reverse reactions.Formula: C20H24O6, you can also check out more blogs about14187-32-7
Reference£º
Chiral Catalysts,
Chiral catalysts – SlideShare