No abstract

No abstract

Catalytic oxidation of isoquinoline yields phthalimide (major product) and smaller amounts of pyridine and hydrogen cyanide. The reaction mechanism is discussed. IntroductionDuring the carbonisation of coal, part of its nitrogen appears in the tar which contains about 2% of nitrogen heterocycles. Of these, pyridine and its derivatives constitute less than one-tenth, while quinoline, isoquinoline and its alkyl derivatives account1 for more than half. The production of large quantities of quinolines and isoquinolines is therefore inherent in any process for the recovery of pyridine and its derivatives from coal carbonisation by-products, and in view of the limited demand for the former and the short supply of the latter, possible conversion of the higher tar bases into the low-boiling picolines or the corresponding carboxylic acids seemed a profitable line of investigation.This communication reports the catalytic vapour-phase transformation of isoquinoline to phthalimide.

The catalytic vapour phase isomerisation of m-xylene into u-and p-xylenes was studied in a flow system i n the temperature range 460-700 "C, and over a wide range of space velocities on a silica-alumina catalyst. The isomeric distribution of the products, as determined by a combination of spectroscopic and chrornatographic methods, was found to be consistent with calculated equilibrium values. Reduced pressures tended to suppress undesirable side reactions such as disproportionation and favoured the isomerisation. First order kinetics appeared to be applicable and the overall activation energy for both isomerisation reactions (i.e. meta-to para-, and meta-to ortho-) was found to be close to 25 kcal/mol, being of the same order of magnitude in both cases. Isomerisation of u-, m-and p-xylenes failed to occur even at 600 "C under non-catalytic thermal treatment, although formation of polynuclear ring systems ("coke") in small quantities was observed. The results appear to indicate that the mechanism of isomerisation of xylenes over acidic catalysts involves essentially ionic intermediates. Based on the evidence obtained, it is concluded that the vapour phase isomerisation of xylenes apparently proceeds via the formation of a localised r-complex, leading to a 1,2-intramolecular shift of the methyl group.

Im Temperaturbereich von 460 ‐ 700°C isomerisiert m‐Xylol (I) in der Dampfphase an einem Siliciumdioxid‐Aluminiumoxid‐Katalysator zu o‐Xylol (II) und p‐Xylol (III).