Furylvinylhalogenide. X [1]. Reaktionen von β-Fur-2-yl-β-chlor-α-cyanacrylsäurederivaten mit Hydrazinen

Furylvinylhalides. X. Reactions of β-Fur-2-yl-β-chloro-α-cyanoacrylic Acid Derivatives with Hydrazines β-Fur-2-yl-β-chloro-α-cyanoacrylic acid derivatives 3 react with hydrazines yielding 3-fur-2-yl-5-aminopyrazoles 5 or 3-fur-2-yl-4-cyanpyrazolin-5-ones 6 . In some cases the β-hydrazino-α-cyanoacrylic acid derivatives 4 , could be isolated.     

β-Fur-2-yl-α-halogenacrylonitrile. V [1] Darstellung von β-(5-Nitro-fur-2-yl)-α-azidoacrylonitril und β-(5-Nitro-fur-2-yl)-α-aminoacrylonitril

β-Fur-2-yl-α-halogenacrylonitriles. V. Preparation of β-(5-Nitro-fur-2-yl)-α-azidoacrylonitrile and β-(5-Nitro-fur-2-yl)-α-aminoacrylonitrile β-(5-Nitro-fur-2-yl)-α-chloroacrylonitrile ( 1 ) reacts with sodium azide to yield β-(5-nitro-fur-2-yl)-α-azidoacrylonitrile ( 2 ). By Staudinger-reaction β-(5-nitro-fur-2-yl)-α-aminoacrylonitrile ( 5 ) is formed. The ¹H- and ¹³C-n.m.r. spectra of E/Z isomers are discussed.     

Oxidation and Ammoxidation of Aromatics

An overview of the state of the art in the direct oxygen or nitrogen insertion to aromatic rings and side‐chains by hydroxylation, acetoxylation, partial oxidation and ammoxidation is presented. The influence of a variety of catalysts and oxidants on the yields of hydroxylated products of aromatic species is discussed in more detail. The survey is also focussed on the usage of H₂O₂ as an effective oxidising agent for hydroxylation reactions. Acetoxylation of methyl‐substituted aromatic compounds to their corresponding esters in a single step is indeed an interesting area from an industrial point of view. Hence, the topics covering benzylic acetoxylation, although they are under a developmental stage for commercial exploitation, are also reviewed. The present contribution also covers the main directions of selective oxidation/ammoxidation of aromatic compounds to useful products, surveys recent developments and provides an updated discussion of the state of the art in the field of oxidation and ammoxidation of aromatics. Additionally, a comparative study of the vapour phase oxidation and ammoxidation of different alkyl aromatics to their corresponding aldehydes and nitriles using various heterogeneous catalysts is presented. Besides, the achievements and limitations of the catalysts/processes are emphasised. Furthermore, the present article includes a discussion of common features and differences in mechanistic steps of oxidation and ammoxidation reactions investigated by in situ FITR spectroscopy. The influence of acid‐base properties of catalyst surfaces in connection with electronic effects of the substituents on the performance of the catalysts is also described.     

Furylvinylhalogenide. IX. Reaktionen von β-Fur-2-yl-β-chlor-α-cyanacrylsäureestern mit Aminen

Furylvinylhalides. IX. Reactions of β-fur-2-yl-β-chloro-α-cyanoacrylates with amines β-Fur-2-yl-β-chloro-α-cyanoacrylates 4 react with amines to yield β-Fur-2-yl-β-amino-α-cyanoacrylates 5 . The ¹H-n.m.r. spectra of 5 are discussed.     

Oxidation of benzene to phenol on supported Pt-VOx and Pd-VOx catalysts

Gas-phase oxidation of benzene using a mixture of oxygen and hydrogen has been carried out on silica-supported vanadium oxide catalysts modified with platinum or palladium. Catalyst activity and phenol selectivity were studied as a function of the precious metal used, the vanadium oxide loading as well as of temperature. The binary catalysts have been characterized by TPR and TEM. Pt-VO_x/SiO₂ catalysts were more active than Pd-VO_x/SiO₂ catalysts. By using platinum catalysts benzene conversion amounted to 1.0% (S_phenol=97%) at 413 K, whereas palladium catalysts reached a conversion of only 0.2% (S_phenol=86%) for the same contact time and temperature. The most active catalyst for the oxidation of benzene to phenol was a low vanadium loaded 0.5 wt.% Pt–3 wt.% V on silica catalyst. At temperatures above 413 K phenol selectivity decreased strongly because of enhanced total oxidation. Active catalysts need both components: a dispersed transition metal oxide such as VO_x as well as small precious metal particles such as platinum. The activity of the catalysts arises from a close interaction between the redox-active compound VO_x and the electron mediator and hydrogen activator platinum as was confirmed by correlation of catalytic results and catalyst properties. Highly dispersed platinum particles are exclusively located on the vanadium oxide covered surface as demonstrated by TEM investigations. TPR studies showed and enhanced reducibility of a part of vanadium(V) oxide indication a close neighborhood of VO_x and platinum.     

β-Fur-2-yl-α-halogenacrylonitrile. IV. Reaktionen von β-Fur-2-yl-α-halogenacrylonitrilen mit Alkoholen und Phenolen

β-Fur-2-yl-α-halogenacrylonitriles. IV. Reactions of β-Fur-2-yl-α-halogenacrylonitriles with Alcohols and Phenols β-Fur-2-yl-α-halogenacrylonitriles 1a – c react with alcohols and phenols to yield β-fur-2-yl-β-alkoxyacrylonitriles and β-fur-2-yl-β-aroxyacrylonitriles 2a – k respectively. With ethylene glycol α-[2-(fur-2-yl)-1, 3-dioxolan-2-yl]acetonitriles 3a, b are formed.     

β-Fur-2-yl-α-halogenacrylonitrile. I. Darstellung von β-Fur-2-yl-ß-aminoacrylonitrilen und β-Fur-2-yl-α-aminoacrylonitrilen

β-Fur-2-yl-α-halogenacrylonitriles. I. Preparation of β-Fur-2-yl-ß-aminoacrylonitriles and β-Fur-2-yl-α-aminoacrylonitriles β-Fur-2-yl-α-halogenacrylonitriles 1 react with secondary amines to yield β-fur-2-yl-ß-aminonitriles 2 and β-fur-2-yl-α-aminoacrylonitriles 3 . The ¹ H-n.m.r. spectra of the E/Z isomers are discussed.