A Solvent-free Synthesis of Polyhydroquinolines via Hantzsch Multicomponent Condensation Catalyzed by Nanomagnetic-supported Sulfonic Acid

A simple and efficient procedure for the synthesis of polyhydroquinolines was developed, involving a one-pot four-component Hantzsch condensation of aromatic aldehydes, 1,3-cyclohexanediones, alkyl acetoacetate and ammonium acetate in the presence of a catalytic amount of nanomagnetic-supported sulfonic acid under solvent-free conditions. The method offers several advantages including high yields, short reaction times, a simple work-up procedure and catalyst reusability for several runs. Furthermore, easy isolation of the catalyst from the reaction mixture was enabled by use of an external magnet.KEYWORDS Nanomagnetic-supported sulfonic acid, multicomponent reaction, solvent-free conditions, heterocyclic compound, Hantzsch reaction

The role of zirconium in microalloyed steels

Recently there has been a renewed interest in the addition of zirconium to microalloyed steels. It has been used since the early 1920's, but has never been universally employed, as have niobium, titanium or vanadium. The functions of zirconium in steelmaking are associated with a strong chemical affinity, in decreasing order, for oxygen, nitrogen, sulphur and carbon. Historically, the main use of additions of zirconium to steel was for combination preferentially with sulphur and so avoid the formation of manganese sulphide, known to have a deleterious influence of the impact toughness of wrought and welded steel. Modern steelmaking techniques have also raised the possibility that zirconium additions can reduce the austenite grain size and increase dispersion strengthening, due to precipitation of zirconium carbonitrides, or in high nitrogen vanadium-zirconium steels, vanadium nitride. This review gathers information on the compounds of zirconium identified in steels together with crystallographic data and solubility equations. Also brief accounts of the role of sulphides and particles in general on austenite grain size control and toughness are included