Hydrogenation propyne

Selectivity Control in 1-Phenyl-1-Propyne Hydrogenation Effect of Modifiers... 

Figure 1. Reaction profile for 1-phenyl-l-propyne hydrogenation.

Analysis of the gas phase after reaction, both by GC and infra-red spectroscopy, confirms that propene is the sole hydrogenation product no propane was detected. This has important implications in terms of interpreting the infra-red spectra of the retained species. The species retained during propyne hydrogenation, and that... 

The kinetics of propyne hydrogenation using pumice-supported nickel, palladium and platinum were invariably first order in hydrogen and... 

Vaska s complex, [Ir(CO)(PPh3)2Cl] immobilized onto phosphine-modified silica showed very low activity in Uquid-phase hydrogenations. In gas-phase hydrogenations of propylene at about 70 °C, significant product yield and some weak PHIP effects were observed. In contrast, gas-phase propyne hydrogenation at about 110 C provided very little product but the signal enhancement for... 

Brandao L, Madeira L M and Mendes A M (2007), Propyne hydrogenation in a continuous polymeric catalytic membrane reactor , Chem Eng Sci, 62, 6768-6776. 

Brandao L,Fritsch D, Mendes A M and Madeira L M (2007), Propyne hydrogenation kinetics over surfactant-stabilized palladium nanoclusters , Ind Eng Chem Res,46,311-384. 

A mixture of 0.10 mol of 1-ethylthio-l-propyne (see IV, Exp. 23 and Ref. 1) and 100 ml of glacial acetic acid was heated at 95°C, then 35 ml of 33% hydrogen peroxide were added in 15 min with occasional cooling. After this addition the mixture was kept for 1 h at 100°C, then cooled to 20°C and 200 ml of water were added. Ten extractions with 20-ml portions of chloroform were carried out and the combined extracts were dried over magnesium sulfate (without previous washing)... 

A line structure (introduced in Section C) represents a chain of carbon atoms as a zigzag line. The end of each short line in the zigzag represents a carbon atom. Because carbon nearly always has a valence of 4 in organic compounds, we do not need to show the C—H bonds. We just fill in the correct number of hydrogen atoms mentally, as we see for methylbutane (6), isoprene (7), and propyne (8). As explained in Section 2.7, a benzene ring is represented by a circle inside a hexagon, and we need to remember that one hydrogen atom is attached to each carbon atom. 

In contrast to the work of Peterson (38) with 3-hexyne in trifluoroacetic acid (vide supra), no trimeric adducts were observed in the hydrogen halide additions to propyne (48). 

Diphenylacetylene and 1-phenyl-1-propyne were hydrogenated to the corresponding 1,2-disubstituted alkenes in aqueous organic biphasic media using [ RuCl2(wtppms)2 2] and an excess of wtppms (80 °C, 1 bar H2, TOFs up to 25 h-1). The stereoselectivity of the reaction depended heavily on the pH of the catalyst-containing aqueous phase (Fig. 38.1) and, under acidic conditions, Z-al-kenes could be obtained with a selectivity close to 100% [71]. 

Z)-Methyl styrene was easily obtained by hydrogenation of 1-phenyl-1-propyne using Lindlar s catalyst (5% palladium on calcium carbonate, poisoned with lead) in //-hexane under an atmospheric pressure of hydrogen. The mixture, containing 90% of (Z)-methyl styrene and 10% of the overreduced alkane, was used without further purification. 

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