Red B compound contains 2 bismuth ions to 1dye anion (curve b ) , as does the bismuth--4lizarin Cyanine Green G compound (curve d). The bismuthOrange I1 compound contains 1 bismuth ion t o 1 dye anion (curve f ) . The anions of Amaranth, Acid Alizarin Red B, Alizarin Cyanine Green G, and Orange I1 contain 3, 2, 2, and 1 sulfonate group, respectively. Amaranth, Acid Alizarin Red B, and Orange I1 are azo dyes, while Alizarin Cyanine Green G is a hydroxyanthraquinone dye. The results obtained from these four dyes were selected from those obtained with metal systems of 18 dyes of various types to illustrate the salt-type formation through the strongly ionized sulfonate groups. 4 similar study has shown that thorium combines with the above four dyes in the same ratios ( I ) . A study of the infrared spectra of the bismuth-Amaranth compound indicated no involvement of the azo linkage and the adjacent hydroxy group
on the Amaranth anion in a chelate structure. T o produce a charge balance, the bismuth ions involved must be the bismuthyl, BiO+, ion or its polymers. Souchay and Peschanski (3) have concluded from conductometric measurements that the bismuth ion species present in dilute acid solutions is predominately the bismuthyl tetramer
+
+
+
t
HO-l3i-O-Bi-O-B~-O-Bi-OH
From the molar absorptivity of the Amaranth anion (22,000) and the absorbance a t the stoichiometric point of curve a, Figure 1, the solubility product constant of the bismuth-Amaranth compound was calculated to be 1.0 X 1 0 - 2 2 a t 26" C. Release of the dye from the bismuth-Amaranth compound is effected by the formation of a bismuth-phosphate salt or complex less dissociated than the bismuth-Amaranth compound, LITERATURE CITED
and that the monomer does not exist. The bismuth-Amaranth compound is probably a n extensive polymer involving principally the tetrameric bismuthyl ion and the trivalent Amaranth anion.
(I) Lambert, J. L., Grotheer, M. P., J.Am. Chem. SOC. 77,1386-9 (1955). (2) . . Lambert. J. L., Moore, T. E., Arthur, P., ANAL.C:HEM.'23, 1193 ( m i ) . (3) Souchay, P., Peschanski, D., BulE. SOC. chzm. France 1948, 439-46.
RECEIVED for review March 15, 1958. Accepted June 30, 1958. Taken in part from a dissertation submitted by Morris P. Grotheer to the Graduate School of Kansas State College in partial fulfillment of the requirements for the degree of doctor of philosophy.
Separation of Saturated Hydrocarbons from Petroleum Residues R. D. SCHWARTZ and D. J. BRASSEAUX Exploration and Production Research Division, Shell Development Co., Houston, Tex.
F A chromatographic adsorption procedure which does not require preliminary removal of asphaltenes and resins has been developed for the isolation of the saturated hydrocarbons from crude oil residues, Cyclohexane is used as a solvent for the entire residue, and a chromatographic column packed with a bed of Davison grade 70 silica gel, above a bed of Davison grade 9 1 2 silica gel is employed. The grade 70 adsorbent has large pores (1 40-A. average diameter) and adsorbs asphaltic and resinous materials, while the grade 9 12 adsorbent with smaller pores (22-A. average diameter) adsorbs the simpler aromatic hydrocarbons. Cyclohexane is a suitable eluent for the saturated hydrocarbons. Ultraviolet analysis of typical saturates, prepared by this technique, indicates that their aromatic The results content is less than 5%. obtained in this investigation, indicate that the pore-size distribution of adsorbents is a very important factor in adsorption separations of heavy petroleum fractions.
A
chromatography has developed into a versatile and efficient method of separation. Many applications of this technique to the separation and analysis of petroleum may be found in the literature. I n some respects, the theoretical developments in adsorption chromatography have not kept pace with the practical aspects. There is no comprehensive theory to explain many of the results obtained. Further, in most cases, evaluation of adsorbents is more or less empirical, until one suitable for a given purpose has been selected. Results were obtained in this investigation, originally directed toward the development of methods for the routine analysis of oil residues, boiling above 325" C., which indicate that the pore-size distribution of the adsorbent is a more important factor in adsorption chromatography than has generally been realized. DSORPTION
METHODS
FOR ANALYSIS RESIDUES
OF
PETROLEUM
Several years ago, O'Donnell ( 2 ) published a comprehensive report on the
separation and analysis of Santa Maria asphalt. I n his work, a total of nine separation techniques was described. A complete analysis, such as that of O'Donnell, for many oil residues, would be too time-consuming and expensire for present purposes. The applicability of individual separation techniques to routine analytical problems can be evaluated by noting the efficiency (number of stages), the equipment necessary, and the time required. The most useful techniques are those which are rapid and efficient, and n-hich require simple laboratory equipment. Adsorption chromatography meets these requirements, and this investigation was started in order to develop a chromatographic separation technique for the analysis of crude oil residues. I n addition to O'Donnell (Z), KleinSchmidt ( I ) emplq-ed chromatography for the separation of asphalts. I n each case, however, the chromatographic separation into saturated and aromatic hydrocarbons was preceded by other separation techniques such as distillation, asphaltene precipitation, and resin removal. VOL. 30, NO. 12, DECEMBER 1958
1999
Table I.
Physical Properties of Davison Silica Gel Calcd. Av. Surface Pore Pore $rea, Volume, Diameter, Type or Grade Sq. PII./G. Cc./G. -4. Mesh Size 912 832 0 45 22 28-200 022 832 0 45 22 \lay 22, 1958. -1ccepted July 29, 1958. Presented in part before Division of Analytical Chemistry, 131th Meeting, -ICs,,Chicago, Ill., September 1958. Publication No. 170, Shell Development Co., Exploration and Production Research Division, Houston, Tex
Determination of Dioctyldiphenylarnine in Hydraulic Fluids S. W. NICKSIC and S. H. JUDD California Research Corp., Richmond, Calif.
b The estimation of p,p’-dioctyldiphenylamine is required for manufacturing control and oxidation studies on hightemperature, silicon-based hydraulic fluids A method has been developed based on the reaction of the amine with furfural in the presence of strong sulfuric acid. Degradation products of the amine and the fluid d o not interfere. The reaction with furfural i s apparently a general one for primary and secondary aryl amines, as shown b y the reaction with 15 selected compounds. Similar procedures may b e developed for other aryl amines individually and in the presence of nonaryl amines.
G
performance is a n important prerequisite for certain aircraft hydraulic fluids. A OOD, HIGH-TEMPERATURE
2002
ANALYTICAL CHEMISTRY
composition of growing commercial interest consists of a specific disiloxane derivative with a silicon thickener and p,p’-dioctyldiphenylamine (DODA) as an oxidation inhibitor. The determination of this inhibitor is desirable for manufacturing control and for correlation with the degree of degradation of used hydraulic fluid. Total nitrogen can be determined only with difficulty, because at low levels the blank values approach those for the samples. Further, the nitrogen test does not distinguish the inhibitor from its degradation products. Laboratory oxidation studies have been used, but they are not rapid or sufficiently specific. This paper describes a colorimetric test for determining DODA either in hydrocarbons or in material containing derivatives of silicon. Degradation products of
the fluid and of the inhibitor do not interfere. The reaction of furfural with amines !vas considered in early exploratory studies. With most primary amines the reaction forms Schiff’s bases, RC=XR’;but when the amine is aromatic, more complex reactions can take place ( 3 ) . Aromatic amines, both primary and secondary, give highly colored products in the presence of strong sulfuric acid. Table I illustrates the colors produced with a number of amines. These colors are obtained by treating 35 ml. of a 2-propanol solution of amine successively with 10 ml. of 18S sulfuric acid and 5 ml. of 10% furfural in 2-propanol. Colors of various hues are obtained whenever a primary or secondary amino group is attached directly to an aromatic ring. The only tertiary amine
