Improved chemoselective hydrogenation of crotonaldehyde over bimetallic AuAg/SBA-15 catalyst

Selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols is important for the synthesis of fine chemicals, yet very challenging. Herein, we reported a metal-free CeO2 nanorods (...

Metal-Free Ceria Catalysis for Selective Hydrogenation of Crotonaldehyde

Matrix isolation studies, combined with infrared spectroscopy, of the twin jet codeposition of ozone into matrices containing either cyclopentadiene or cyclopentene have led to the first observation of several early intermediates in these ozonolysis reactions. Specifically, evidence is presented for the formation, identification, and characterization of the long sought-after Criegee intermediate for each system, as well as the primary and secondary ozonides. These were observed after initial twin jet deposition and grew ∼300% upon annealing to 35 K. Extensive isotopic labeling (2H, 18O and mixtures) experiments provided important supporting data. Detailed theoretical calculations at the B3LYP/6-311++G(d,2p) and B3LYP/6-311++G(3df, 3pd) levels were carried out as well to augment the experimental work. Merged jet (flow reactor) experiments followed by cryogenic trapping in solid argon led to the formation of “late” stable oxidation products of cyclopentadiene and cyclopentene. In contrast, no thermal reacti...

Matrix isolation study of the early intermediates in the ozonolysis of cyclopentene and cyclopentadiene: observation of two Criegee intermediates.

Ultrasonic studies of macromolecules

Étude par spectrométrie photoélectronique d'aldéhydes et de cétones éthyléniques conjugués

Infrared spectra of acraldehyde, crotonaldehyde, methyl vinyl ketone, and ethylideneacetone in solution and vapour states are reported. Band intensity measurements at temperatures between –110° and 200° are interpreted in terms of conformational equilibrium between the s-trans and non-trans forms of the ketones. The additional enthalpy (ΔH) of the non-trans forms are: [graphic omitted] No evidence is found for more than one form of the aldehydes and the rotational structure of vibrational bands of both acraldehyde and crotonaldehyde suggest these exist in the s-trans conformation. Vibrational assignments are provided for the various conformations detected in these compounds.

Conformations of some αβ-unsaturated carbonyl compounds. Part I. Infrared spectra of acraldehyde, crotonaldehyde, methyl vinyl ketone, and ethylideneacetone

W. F. Maddams

Papers

Conformations of some αβ-unsaturated carbonyl compounds. Part I. Infrared spectra of acraldehyde, crotonaldehyde, methyl vinyl ketone, and ethylideneacetone