Date of Award

8-1953

Document Type

Thesis

Abstract

Part I -The objects of this part of the work were (1) to study the effectiveness of the hydrogen as an oxidant for the conversion of nitroso compounds in general to nitro compounds (2) to study the effects of possible variations in the conditions upon the progress of such oxidations. Previous work of this sort has consisted of a limited number of isolated experiments, the reports of which gave little information suitable for the selection of optimum conditions for the reactions they described.

Five aromatic compounds (four phenols and one anime) were studied, with most attention being given to p-nitroso phenol. One aliphatic nitroso compound received a similar study. It was found that hydrogen peroxide was generally satisfactory as an oxidant for the aromatics studied, (presumably for aromatic nitroso compounds in general) and apparently superior to other oxidate, as far as the letter have been examined. In the case of the single aliphatic nitroso compound studied, hydrogen per-oxide was found to be inferior to chromic acid.

In the study of p-nitrosophenol, it was observed that a maximum conversion to p-nitrophenol approaching 90% could be attained. Extension of the time of the exposure of reaction mixtures to the hydrogen peroxide led in every case to a progressive loss of some of the nitro compound initially formed.

It was also observed that as the concentration of the peroxide, and/or the temperature was increased, the time required to reach the maximum yields was shortened, but within the ranges covered in this study, the amounts of such maximum yields did not vary greatly.

Examination of the other aromatic nitroso compounds was less thorough but as far as it went, the results were similar to those obtained with p-nitroso phenol.

When nitropropane was oxidized with hydrogen peroxide, much smaller yields, ranging from 0 to 35%, were obtained; the maximum yield being obtained only under narrow conditions of the temperature and concentration.

Part II – The objects of this part of the work were (1) to study the chromatographic and spectrophotometric characteristics of some selected nitro, nitroso, amino, ago, and azoxy compounds; (2) to develop (and to study the effectiveness of) chromatographic and spectrophotometric estimation of these compounds in the solutions containing one or more of them. The relative rates of movement of these compounds on standard chromatographic columns were determined. By varying the adsorbents, the solvents, and the developing solutions, sufficient data were obtained to make possible the separations.

For those compounds which gave a colorless zone, methods for locating the zone on the column were developed. The sensitivities, or the minimum concentrations necessary to give some zones which could be discerned, were ascertained for several of them.

Solutions of the known concentrations of the individual compounds in absolute ethyl alcohol were made up and the absorption curves of these solutions were obtained on a Beckman Model D.U. Quartz Spectrophotometer.

Solutions of known concentrations of the individual compounds, and mixtures of two or more of the compounds, were made up in the proper solvents, and separated on a chromatographic column. The zones were cut out, dried, eluted, and the solutions were determined, using the Bookman Spectrophotometer and the standard curves which had been obtained as described.

From the results obtained, it was concluded that chromatographic and spectrophotometric techniques could be used as an efficient method for the separation, partial identification, and estimation (with a range of error of approximately (-2%) of these compounds in mixtures.

Part III – The objects of this work were (1) to study the interactions, is any, of nitro compounds with nitroso compounds; (2) to study any influences (exerted by interaction or otherwise) of nitro compounds upon the thermal and/or photochemical decomposition of nitroso compounds.

The nitroso compounds studied in this part of the work were p-nitroso phenol and p-nitrosodimethylaniline. The nitro compounds used included nitrobenzene, p-chloronitrobenzene, p-nitrophenol and p-nitrobenzoic acid.

In the case of the amine, it was found that there was some evidence of interaction, but that it was usually small compared to the spontaneous decomposition of the nitroso compound, the extent of the interaction varied with conditions, being negligible or nearly so under mild conditions but more conspicuous under severe conditions of light or temperature. The oxidation of the nitroso compound to the analogous nitro compound, presumably by the oxidation action of the nitro compound initially present, was observed in several instances but was at best small compared to other changes in the nitroso compound.

When p-nitroso phenol was decomposed thermally or photochemically in the presence of a nitro compound, it responded in a manner which contrasted sharply with the behavior of the p-nitroso dimethylaniline. In the case of the phenol, the nitro compound exerted a decided inhibiting action upon such decomposition. This was studied in a variety of ways, and while a complete and assured explanation of it remains to be found, some light has been shed on it by the present work. Indications are that the inhibiting effect is not catalytic in nature, and that it is not to be escribed to the absorption of ultraviolet radiations by the nitro compound. A partial and tentative explanation of this phenomena has been offered.

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