Isolation of the three xylenes from an Oklahoma petroleum

Abstract

Each of the three xylenes has been isolated in a high state of purity from an Oklahoma petroleum. The relative amounts present are o, 3; m, 3; p, 1, the total xylene content of the crude oil being about 0.3 per cent. The density, refractive index, boiling point, freezing point, and infra-red absorption spectrum have been determined for each xylene. CONTENTS Page I. Introduction 711 II. Preliminary distillation 712 III. Extraction with liquid sulphur dioxide 714 IV. Fractional crystallization of the sulphur dioxide extract 714 V. Systematic distillation of the crystallization fractions 715 VI. Isolation of the three xylenes 716 VII. Properties of the isolated xylenes 717 VIII. Content of the xylenes in the crude oil 720 IX. Conclusion 720 X. Acknowledgment 720 I. INTRODUCTION The presence of xylene in petroleum was first recognized by de La Rue and Muller. 3 Since then many investigators have reported the presence of m-xylene, and two have reported p-xylene in European and Asiatic petroleum, 4 but in no case were the hydrocarbons themselves isolated.. In the first allusion to the occurrence of aromatic hydrocarbons in American petroleum, 5 no reference was made to the presence of xylene. Many years later, Mabery 6 established the presence of m-and^-xylene in the oils of Ohio and Canada and also in those of California 7 by isolating their nitro derivatives from the fraction distilling between 137°and 140°C. Not until recently, however, has o-xylene been detected in any petroleum. Tausz, 8 by oxidizing the xylene fraction of a number of oils (including one from Pennsylvania), succeeded in isolating the three phthalic acids. No one, however, has reported heretofore the separation of each of the xylenes from petroleum. 1 Financial assistance has been received from the research fund of the American Petroleum Institute.

Separation, by distillation with acetic acid, of the aromatic hydrocarbons from the fraction of a midcontinent petroleum boiling between 154 and 162 C

“…This result is analogous to those obtained in previous investigations of aromatic hydrocarbons in t his petroleum [3,4,8] .…”

“…BEHAVIOR WITH SYNTHETIC MIXTURES Acetic acid as an azeotropic agent to separate paraffinic and naphthenic hydrocarbons has been used by Schicktanz [23], who pointed out that it fulfills the requirements of an azeotropic agent in that it does not react with, nor polymerize, the hydrocarbons, is easily and quantitatively removable from the hydrocarbons (by washing with water), and is inexpensive and readily available. Although having a ' See White and Rose [8] (xylenes), Mair and Schicktanz [9] (trimethylbenzenes), Smith and coworkers [1O, 11,12] (tri· and tetramcthy Jbenzenes) , Clarke and Taylor [13] (xylenes), Armstrong and Miller [14] (goneral). low-boiling point (118.1° C), it forms azeotropes with petroleum hydrocarbons over a considerable range and may be used successfully with hydrocarbons boiling from 130° to 175° C [25].…”

“…Many solvents which have been used for this purpose, include liquid sulfur dioxide [8,9,15], liquid sulfur dioxide and petroleum ether [9,16], aniline [4], and many others. However, both the miscible aromatic phase and the immiscible paraffin-naphthene mixture will be contaminated by mutual solution unless an apparatus is used which has reflux and a large number of theoretical plates [17,18,19].…”

Separation of the three methyloctanes from midcontinent petroleum

“…The results of the filtration are shown in table 1. The refractive index of the filtrate is shown in more detail in the graph of shaded lines in the upper part of figure 1. Both refractiveindex graphs show that, whereas each of the half-degree fractions boiling below 100.5° C was filtered separat ely, the fractions boiling between 100.5 and 102° C and between 102 and 103.5° C were mixed before filtering.…”

“…The presence of the methyl octane fraction in an Oldahoma petroleum 3 became apparent when, a few years ago, the material boiling normally between 140 and 145 0 C was redistilled after first removing the aromatic hydrocarbons by extraction [1]. 4 More recently, Tongberg, Fenske, and Nickels [2] have encountered the same fraction in petroleum from the Yates field in Texas.…”