Methyl vinyl ketone

About: Methyl vinyl ketone is a research topic. Over the lifetime, 1510 publications have been published within this topic receiving 26839 citations. The topic is also known as: 3-buten-2-one & gamma-oxo-alpha-butylene.

A Nearly Planar Stannene with a Reactive Tin–Carbon Double Bond

Abstract: Bis(2,4,6-triisopropylphenyl)-2,7-di-tert-butylfluorenylidenestannane, Tip2Sn=CR2, an isolable stannene that displays a deep-purple colour, was synthesized by dehydrofluorination of the corresponding fluorostannane by tert-butyllithium. It exhibits the shortest Sn=C distance [2.003(5) A] and the slightest twisting around this unsaturation (10°) among the known stannenes. Its reaction with benzaldehyde according to a [2+2] cycloaddition and that with α-ethylenic aldehydes and ketones such as crotonaldehyde and methyl vinyl ketone by a [2+4] cycloaddition proceeded in near-quantitative yield. With acetone, an ene reaction occurred. The four-membered ring 1,2-oxastannacyclobutane obtained with benzaldehyde underwent a ring expansion with a second molecule of benzaldehyde to afford the six-membered ring dioxastannacyclohexane.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Aldol condensation reactions of acetone and formaldehyde over vanadium phosphate catalysts: Comments on the acid–base properties

Abstract: The acid–base properties of vanadium phosphate catalysts are investigated using the aldol condensation of acetone and the reactions of 2-methylbut-3-yn-2-ol (MBOH). Three well characterised samples of VOHPO4·0.5H2O were prepared using the reaction of V2O5 and H3PO4 with aqueous hydrochloric acid or isobutanol as reducing agents, or from the reaction of VOPO4.2H2O with isobutanol. (VO)2P2O7, prepared by heating VOHPO4·0.5H2O in He (8 h, 750 °C), before and following partial oxidation in air or butane/air, and αI-VOPO4 were also investigated. The reaction of MBOH was used to probe the nature of the acid–base properties of the vanadium phosphates. The V4+ phases (VOHPO4·0.5H2O and (VO)2P2O7) exhibited only acidic active sites, whereas the V5+ phases (αI-VOPO4 and oxidised (VO)2P2O7) exhibited some basic sites in addition to the acid sites. For the aldol condensation reactions of acetone, the V4+ phases were found to be selective for the formation of isophorone from acetone alone and methyl vinyl ketone from the reaction of acetone and formaldehyde. In contrast, vanadium phosphate catalysts containing V5+ phases are not selective to these products and only form hydrocarbons (typically isobutane and isobutene). For all these reactions, the catalyst activity is short lived and the deactivation that is observed is due to the surface becoming fouled by the adsorption of products of polymerisation of the reaction products. However, the catalyst reactivity can be restored by a simple oxidation treatment. The nature of active sites in n-butane oxidation to maleic anhydride is also discussed and it is concluded that basic sites are required in addition to acidic surface sites for the selective formation of maleic anhydride. For the reaction of MBOH, the data are found to give a linear relationship for a Cremer–Constable plot and this is discussed in terms of the enthalpy of adsorption of MBOH.