Abstract: A preparation method of zaleplon is provided and belongs to the technical field of pharmaceutical chemistry. The preparation method adopts simple and cheap m-nitrobenzaldehyde and triethylamine as raw materials, and constructs a core structure of zaleplon with high efficiency and high selectivity through a one-pot series reaction without transition metal catalysis, thereby avoiding the formation of isomers, reducing the generation of by-products, increasing the yield of target products and reducing the synthesis cost; and after simple nitro reduction modification, zaleplon is prepared. The method has the advantages of short preparation route, mild reaction conditions and simple operation, so the method is suitable for industrial production.

Abstract: The present invention discloses a large-flow plunger pump, comprising a box, a crank-link mechanism, a plunger, a suction valve and a discharge valve. On the basis of the conventional multi-cylinder plunger pumps, assemblies such as a detachable upper crosshead guide, an intelligent plunger packing lubrication system, a damping valve, crankshaft support roller assemblies, and a suction-pressure stabilizer having a cooling water coil therein are invented. Both the service life and the reliability of the large-flow plunger pumps are overall improved.

Abstract: The present invention discloses a large-flow plunger pump, comprising a box, a crank-link mechanism, a plunger, a suction valve and a discharge valve. On the basis of the conventional multi-cylinder plunger pumps, assemblies such as a detachable upper crosshead guide, an intelligent plunger packing lubrication system, a damping valve, crankshaft support roller assemblies, and a suction-pressure stabilizer having a cooling water coil therein are invented. Both the service life and the reliability of the large-flow plunger pumps are overall improved.