Studies On Synthesis Of Calix[4]pyrroles And Its Anions Recognition

Calix [4] pyrroles are macro cyclic compounds which are composed of pyrroles and SP3 hybridize carbons byα–position pyrroles. Because of its special structure and functions, Calix [4] pyrroles have become a new special type of macro cyclic compounds. It can complex with anions and neutral molecules, which is applied in microchemistry. In this article, we researched a serial of Calix [4] pyrroles compounds in their synthetic methods and anions recognition.1 Six Calix [4] pyrroles (1–7) were synthesized by pyrrole and relevant ketone. In this procedure, condense chlorhydric acid was used as catalyst. At the same time, its reaction mechanism and synthetic conditions were discussed. And then, considering all kinds of factors, the best synthetic method and the best suitable conditions were choosed. Towards purification, recrystallize way were always used, which simplified the steps of purification. In this method, pure compounds were obtained, and compound 7 was not be reported by the others.2 Butanone and Ethyl formate were used to synthesis 2-methyl-3-oxo-1-oxide sodium salt (Compound 8). Through oxidation, diethyl oximidomalonate (Compound 9) was synthesis by diethyl malonate. And then, the two compounds which were concerned above, take the reactions of closing ring in HAc/NaOAc conditions.The compound of 2-(ethoxycarboayl)-3, 4-dimethylpyrrole were produced. In the existence of p-TsOH, Compound 10 was condensed with methylal, compound 11a and 11b were obtained. In the process of synthesis, the productivity and purity of compound 10 would be improved through changing the order of putting compound 8,compound 9 and prolonging the reaction times. Towards condensation, reaction time was shorttening by refluence. And then, obtained the pure 11a and 11b by recrystallized.3 The five calix [4] pyrroles (1–5) were applied in recognising anion research. Firstly, the UV absorption of calix [4] pyrroles was set out. And then, adding the TBA salts of F-, Cl-, Br-, I-, AcO-, HSO4-, NO3-, and observed the changes of aborption. Lastly, changing the anion concentration in the responsed substances, and setting out the UV absorption. Through experiments we firstly found out that NO3- anion have recognised on calix [4] pyrroles which were synthesized.4 The different concentration of methanol was added to the solvent which anions were 50 times more than calix [4] pyrroles. And then, set out the UV absorption. Observing the change of absorption, phenomenons were found that methanol competed with anion in NH combining point, when they existed in the same solvent.