. The methods described are suitable for preparing the pure compounds in quantities of 1 kg or more. For each of the hydrocarbons and also for n-heptane and 2.2,4-trimethylpentane we have determined accurate values for the boiling point, melting point, densities at 15" and 20" or at 20" and 25", refractive indices and molecular refractions at the same temperatures for the wave lengths 6563. 5876, 4861, 4341 A. W e have also recorded accurate values for the surface tension at 20" and for the parachor. The critical solution temperatures with aniline have also been determined.
A description is given of methods for the preparation of 4‐, 2,4‐ and 3,4‐substituted pyridines, e.g. 4‐aminopyridine. the N‐oxide of pyridine or derivatives of pyridine is used as an intermediate to make e pyridine nucleus accessible for substitution in positions 2 and 4.
. Eine systematische Untersuchung uber die katalytische Hydrierung von mehrkernigen heterocyclischen Verbindungen ist von Bedeutung fur die synthetische Chemie.Wir haben uns die Frage gestellt, ob die Reduktion von Phenylpyridinen nach der katalytischen Methode so durchgefuhrt werden kann, dass entweder nur der Phenylkern oder der Pyridinring reduziert wird. In dtr Gruppe der substituierten Pyrrole hat eine Untersuchung von Meta de Jong2) und dem einen von uns gezeigt, dass bei der Reduktion der Phenylpyrrole nicht nur der Pyrrolring, sondern auch die Phenylkerne durchhydriert werden. W a s das N-Phenylpyrrol betrifft, so wurde dasselbe Resultat unabhangig von uns und zu gleicher Zeit von Craig und Hixon 3 ) beschrieben: diese Forscher erhielten ebenfalls bei der katalytischen Hydrierung des genannten Pyrrols das N-Cyclohexylpyrrolidin.Wir haben die obenerwahnte Fragestellung auch auf die Reduktion der Pyridylpyrrole und der Nikotyrine ausgedehnt und dabei auch das Nikotin in den Kreis unserer Untersuchung einbezogen.Die katalytische Reduktion von Pyridin selbst, entweder in der Gasphase oder in Losung, ist von verschiedenen Forschern untersucht worden. Die Reduktion von 2-Methylpyridin bei 1 60° uber Palladiumasbest wurde von Borrissow 5 ) beschrieben. Skita und Brunner * ) haben die Reduktion der Pikoline und des Kollidins mit kolloidem Platin untersucht. Trotzdem haben auch wir die Reduktion der Methylpyridine ausgefuhrt, um durch Versuche unter vergleichbaren Bedingungen einen Einblick in den Einfluss der Substituenten auf die Geschwindigkeit der Hydrierung zu gewinnen.
The properties of hydrocarbons containing a long aliphatic chain in which aromatic or alicyclic rings occur as, substituents. are of importance for the examination of high-boiling petroleum fractions and products obtained from them, such as lubricating oils. Of the hydrocarbons described in this paper dicetylbenzene has not been described in the literature: the remaining products have already been prepared by other investigators: except for octadecylbenzene and for cetylbenzene, the statements of the earlier authors do not guarantee that the desired hydrocarbon was obtained in the pure state.The degree of purity of the preparations obtained by us is not easy to Idetermine. As these hydrocarbons can only be distilled at a low pressure, a purification of the final product by ver)r sharp fractional distillation is not possible. In some cases the purity could not be checked by determination of a cooling curve, owing to the. very low rate of crystallization. A reasonable degree of purity of the final products could only be guaranteed, therefore, by using pure starting materials and by purifying the synthesized intermediate products as thoroughly as possible.The properties of the cetylbenzene and octadecylbenzene prepared by us are in good agreement with the statements of some earlier authors. Our preparations of the hydrocarbons IV, V I and VII no doubt have a much higher degree of purity than the preparations obtained by earlier authors. In this paper we give the refractive indices for 1 = 5876 and the specifics gravities. In a subsequent paper we intend to publish the refractive indices at other wave lengths and to. discuss the refractometric constants. An attempt to prepare dicetylbenzene by applying the W ii r t z reaction to a mixture of p-dibromobenzene and cetyl iodide was not successful, as dicetyl (C,,H,,) was formed almost exclusively. W e therefore prepared l-cetyl-
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