Description
Dibenzo-18-crown-6 (DB18C6) is the first crown ether synthesized by Pedersen in 1967 and has the strongest binding affinity to a potassium cation (K+) among alkali metal cations. With the similarity of the sizes between K+ and the cavity of crown ether, it had long been believed that the binding selectivity comes from the size relationship between the metal cation and the cavity. However, it was reported that under identical experimental conditions, K+ bound strongly to all crown ethers (12-crown-4 to 24-crown-8) irrespective of the ring size among other cations such as Na+, Ca2+, and NH4+. Moreover, in the gas phase, 18-crown-6 (18C6) and dibenzo18-crown-6 (DB18C6) form preferential complexation in the order Li+ > Na+ > K+ > Rb+ > Cs+, while in the aqueous solution both of them show highest complexion capacity for K+ rather than Li+[1-2].
Chemical Properties
white to slightly beige fluffy powder
Uses
Dibenzo-18-crown-6, is used as an important raw material and intermediate used in organic Synthesis, pharmaceuticals, agrochemicals and dyestuff. It is an important organic intermediate.
Definition
ChEBI:Dibenzo-18-crown-6 is a crown ether that is 18-crown-6 ortho-fused to two benzene rings at positions 8-9 and 17-18. It has a role as a phase-transfer catalyst. It is a member of benzenes and a crown ether.
Purification Methods
Crystallise it from *benzene, n-heptane or toluene and dry it under vacuum at room temperature for several days. [Szezygiel J Phys Chem 91 1252 1987, V.gtle ed. Top Corr Chem (Host Guest Complex Chemistry) 98 1981.]
References
[1] Pooja Sahu, Jayant K. Singh, Sk. M. Ali. “Structural and dynamical properties of Li+-dibenzo-18-crown-6(DB18C6) complex in pure solvents and at the aqueous-organic interface.” Journal of Molecular Modeling 20 9 (2014).
[2] Chang Min Choi, Nam Joon Kim, Jiyoung Heo. “Binding selectivity of dibenzo-18-crown-6 for alkali metal cations in aqueous solution: A density functional theory study using a continuum solvation model.” Chemistry Central Journal 6 1 (2012): 84.
