Hideki Kurokawa

Solid base-catalyzed reaction of nitriles with methanol to form α,β-unsaturated nitriles. II, Surface base property and reaction mechanism

Abstract Solid acid and base properties of magnesium oxides activated by transition metal ions, Mue5f8MgO, which are effective catalysts for the reaction of nitriles with methanol to form corresponding α,β-unsaturated nitriles, were studied by temperature-programmed desorption of CO2 and the reaction of isopropyl alcohol, and the reaction mechanism was studied by isotopic tracer methods. The surface base property of magnesium oxide was modified by the addition of a metal ion; the addition of a metal ion with larger ionic radius than Mg2+ increases the amount of surface base site, whereas the addition of a metal ion with an ionic radius smaller than that of Mg2+ induces surface acid sites without any appreciable changes in the amount of surface base site. Active catalysts were formed in the latter case but not in the former case. It was thought that a surface acid property as well as a surface base property played an important role in the course of the reaction. Reaction of deuterium-substituted acetonitrile and methanol revealed that the exchange reaction between hydroxyl hydrogen of methanol and methyl hydrogen of acetonitrile took place readily under the conditions of acrylonitrile synthesis and the isotopic distribution in acetonitrile after the reaction was very close to that of isotopic equilibrium. No exchange reaction between methyl hydrogen of methanol and that of acetonitrile was observed. It was found, on the other hand, that the isotopic exchange reaction between methyl hydrogen of deuterated methanol and light methanol can occur under the same conditions. The reaction mechanism appears to be dehydrogenation of methanol to adsorbed formaldehyde which then reacts with the acetonitrile anion and, after dehydration, yields acrylonitrile.

Solid base-catalyzed reaction of nitriles with methanol to form α,β-unsaturated nitriles I. Conversion and selectivity

Abstract The synthesis of α,β-unsaturated nitriles from saturated nitriles and methanol was achieved with basic metal oxide catalysts activated by transition metal ions. The methyl or methylene groups at the α-position of saturated nitriles are converted to a vinyl group. The reaction proceeds via dehydrogenation of methanol, cross coupling, and dehydration. Magnesium oxide, activated by manganese ion or chromium ion, has been found to give the most effective catalytic performance. In the conversion of acetonitrile, the selectivity to acrylonitrile was more than 95%. This method was also useful for the conversion of propionitrile to methacrylonitrile.

Selective Catalytic C-C Bond Formation on Magnesium Oxide to Produce α, β-Unsaturated Compounds

Abstract A new mode of C-C bond formation has been developed by using methanol as a methylenylating agent in order to prepare α, β-unsaturated compounds. Methyl or methylene groups at α-position of saturated ketones, esters or nitriles are converted to vinyl groupsby addition of methanol accompanied by both dehydro-genation and dehydration. The reaction is effectively promoted by magnesium oxide catalysts activated by transition metal cations.

Dehydrogenation of n-Butane to Butenes and 1,3-Butadiene over PtAg/Al 2 O 3 Catalysts in the Presence of H 2

The Al2O3-supported PtAg catalysts were prepared and evaluated for the dehydrogenation of n-butane at 550°C in the presence of H2. The PtAg/Al2O3 catalyst prepared by an impregnation method using the Cl- removing Pt/Al2O3 and AgNO3 showed a higher activity and selectivity to butenes and 1,3-butadiene compared to the Pt/Al2O3 catalyst, but a large amount of coke (about 30 wt% versus the catalyst weight) was formed during the dehydrogenation. The free Ag metal on the prepared catalyst dramatically promoted the coke formation, because the dehydrogenation of 1-butene over the Ag/Al2O3 catalyst produced a large amount of coke. The Cl- addition to the Cl- free Pt/Al2O3 catalyst decreased the coke formation by the reaction of the free Ag particles and Cl to form AgCl which was inactive for the coke formation. The highest initial conversion (50.3%) was obtained with the selectivity to butenes and 1,3-butadiene (butenes = 80.2% and 1,3-butadiene = 5.9%) when the PtAg/Al2O3 catalyst modified with Cl- was used.

Solid base-catalysed rearrangement of methacrylonitrile to crotononitrile

MgO and CaO catalysts have shown high activity for the formation of crotononitrile (cis/trans= 6/4) in the rearrangement of methacrylonitrile.