Acrolein dimethyl acetal

Research reports that zinc-modified Hβ zeolite is catalytically active in the gas-phase aza-heterocyclic aromatization of acrolein dimethyl acetal with aniline for the synthesis of quinoline. The findings revealed that the Zn/Hβ catalyst displayed a higher selectivity to quinoline in comparison with the parent Hβ zeolite. Moreover, a possible reaction pathway for the formation of quinoline from acrolein dimethyl acetal and aniline in this gas-phase reaction system was also proposed.

Fig. 1 Zn-promoted Hβ zeolite catalyzed acrolein dimethyl acetal and aniline to quionlines. (An Li.; et al. 2020)

3-Picoline is a chemical intermediate that has application as a building block for pesticides, fodder, and pharmaceuticals. The classical method of synthesizing 3‑methylpyridine from formaldehyde, acetaldehyde, and ammonia results in only very low yields. In contrast, the reaction between acrolein and ammonia significantly increases the yield to 30–60%. However, the equipment rapidly becomes clogged, and therefore, the reaction must be terminated soon after initiation. In addition, the materials are inherently unstable and toxic. To overcome these disadvantages, the synthesis of 3‑methylpyridine was performed via acrolein dimethyl acetal or acrolein diethyl acetal with ammonia. Acrolein dimethyl acetal or acrolein diethyl acetal, in the presence of acid catalysts, undergoes facile hydrolysis to acrolein and methanol or ethanol. This averts the polymerization which had previously occurred.

Fig. 2 The formation of 3-picoline from acrolein dimethyl acetal and ammonia. (Luo, Cai-Wu.; et al. 2015)