engleski

Synthesis and Basicity Studies of Quinolino[7,8‑h]quinoline Derivatives

Quinolino[7, 8-h]quinoline is a superbasic compound, with a pKaH in acetonitrile greater than that of 1, 8-bis(dimethylaminonaphthalene) (DMAN), although its synthesis and the synthesis of its derivatives can be problematic. The use of halogen derivatives 4, 9-dichloroquinolino[7, 8-h]quinoline (16) and 4, 9-dibromoquinolino[7, 8-h]quinoline (17) as precursors has granted the formation of a range of substituted quinolinoquinolines. The basicity and other properties of quinolinoquinolines can be modified by the inclusion of suitable functionalities. The experimentally obtained pKaH values of quinolino[7, 8-h]quinoline derivatives show that N4, N4, N9, N9-tetraethylquinolino[7, 8- h]quinoline-4, 9-diamine (26) is more superbasic than quinolino[7, 8-h]quinoline. Computationally derived pKaH values of quinolinoquinolines functionalized with dimethylamino (NMe2), 1, 1, 3, 3- tetramethylguanidino (N=C(NMe2)2) or N, N, N′, N′, N ″, N″-hexamethylphosphorimidic triamido (N=P(NMe2)3) groups are significantly greater than those of quinolino[7, 8-h]quinoline. Overall, electron-donating functionalities are observed to increase the basicity of the quinolinoquinoline moiety, while the substitution of electron- withdrawing groups lowers the basicity.

Superbases

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