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In this paper, a dual-functional Brønsted acidic ionic liquid (BAIL) catalyst, namely 1,3-(4,4'-dipyridinium disulfonic acid)propane dimethanesulfonate (DPDSPDM), was produced, and its structure was identified using TGA, FT-IR, 13C NMR, 1H NMR, and mass spectrometry techniques. Then, it was utilized as a versatile, homogeneous, and recyclable catalyst in preparing N,N'-Methylene bisamides (1a-14a, 5–13 min, 90–98%, 50 °C, solvent-free), Tetrahydrochromeno-chromenes (1b-12b, 8–20 min, 91–98%, 60 °C, solvent-free), and Pyrido-dipyrimidines (1c-12c, 2–5 min, 93–98%, 25 °C, H2O). In all three synthetic routes, the catalytic activity scope of DPDSPDM was remarkable and general due to having basic (MeSO3ˉ) and acidic (SO3H) sites, and reasonable mechanisms were displayed to support this high performance. The reproducibility of this homogeneous catalyst along with advantages such as appropriate TOF (turnover frequency) and TON (turnover number) values, mild conditions, simplicity of the workup, short reaction times, high yields, non-metallic nature of the catalyst, and the use of cheap and available raw materials in its synthesis; making it a potential candidate for future research. [ABSTRACT FROM AUTHOR]

In this research, a novel Brønsted-acidic ionic liquid 1,3-(4,4′-bipyridinium disulfonic acid)-propane-dihydrogen sulfate (BPDSPDH) was synthesized as a bi-functional catalyst. BPDSPDH was characterized using various analytical techniques such as FTIR, TGA, 13CNMR, 1HNMR, and mass spectrometry. Afterward, the catalytic ability of BPDSPDH was explored in the synthesis of chromeno[4,3-b]chromene and pyrido[2,3-d:6,5-d′]dipyrimidine derivatives. BPDSPDH is an ionic liquid catalyst with advantages such as having a high catalytic activity due to its acidic and basic sites, the use of affordable and easily accessible starting materials for catalyst production, recyclability of the catalyst up to 4 times without significant loss in catalytic activity, short reaction time, high yields and moderate reaction conditions. [ABSTRACT FROM AUTHOR]