In this contribution, we provide a comprehensive overview on the CÀ H activation/functionalization reactions of 1-aryl-5-pyrazolones, in particular, 1-aryl-3-methyl-1H-pyrazol-5(4H)-ones (edaravones) and their N-methyl analogues i. e., antipyrines covering the literature since 2013 (the year of the first report). This review summarizes the recent progress in CÀ H functionalization reactions of 1-aryl-5-pyrazolones including edaravone and antipyrine derivatives under transition-metal-catalyzed/free conditions and discusses the related mechanism according to the role of the catalytic species.

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A simple and efficient strategy for N-chlorosuccinimide mediated regioselective CÀ H sulfenylation and halogenation of 4Hpyrido[1,2-a]pyrimidin-4-ones has been established at room temperature using aryl thiols and phenyliodine(III) diacetate (PIDA) respectively. This methodology tolerated a broad variety of functional groups to obtain structurally diverse sulfenyl and halogenated 4H-pyrido[1,2-a]pyrimidin-4-one derivatives under mild conditions. It delivered a range of products which can serve as the key precursors for the synthesis of complex products relevant to pharmaceutical applications.

In this paper, we analyzed the muffler acoustic performance by the finite element method and Virtual.lab. We changed the simple expansion chamber muffler size and expansion ratio related, expansion cavity length, and the number of expansion chambers effectively to improve the muffler. Through muffler design complexity and numerical simulation we analyzed the impact of external factors such as temperature, flow rate, etc. for muffler performance.