Structure Cha ra cte riza tio n by Micro hyd roge na tio n SIR: The development in our laboratories of equipment and techniques to permit the application of Sabatier's (2) classical discoveries in vapor-phase hydrogenation to micro samples was accomplished five years ago. Since then many improvements in the procedure have been made and identifications (1, 3, 5 ) of sulfur compounds in petroleum, previously thought impossible with the quantities of materials available, are now being made routinely. The equipment and general procedure for the microhydrogenation of liquid samples and of trapped, gas liquid chromatographic samples have been adequately described in previous publications (4-7). These publications contain, among other things, tables of representative sulfur, oxygen, halogen, and nitrogen compounds that have been successfully investigated. Techniques and equipment for the hydrogenolysis of solid samples have been developed through recent studies. The method has been applied successfully to unusual types of solids, including metalcontaining compounds. These newly developed techniques and data illustrating their use are presented. EXPERIMENTAL
Solids Charging System. I n t h e hydrogenolysis procedure ( 5 ) ,solids that are sufficiently soluble in simple solvents can be handled by the charging syringe. However, in this technique the solvent introduces an extraneous peak (or peaks) into the chromatogram which
Figure 1 .
Solids charging system for a microhydrogenation unit
sometimes interferes in its interpretation. Another troublesome factor is the low solubility of many solids in any solvent. A more serious difficulty is encountered in introducing solutions, via the hypodermic syringe, by the evaporation of the solvent from the solution during its course through the hot part of the needle, causing stoppage of the injector. All of these and other difficulties are circumvented by the
Thiaadamantane and Bicycle( 3,3,l)nonane
c-c-c cc-c-cc c
Table I. Miscellaneous Compounds and the Hydrocarbon Products of Their Hydrogen01ysis" Product expected Reactant
(1) H z N - o - N O 2
(2) O ~ N - S - S - N ~ O
5
Obtained
c-c
solid-sample injector developed for this purpose and illustrated in Figure 1. I n operation, part C is attached to the catalyst-charged reactor E , and closed by cap D, allowing hydrogen to flush through the heated catalyst. Parts A and B are assembled with the glass sample capsule resting in the right end of B in a position such that it is ready to be thrust forward by the movement of the plunger. When the furnace and
I
-
,
J \
i
Products of Desulfurization
of Thiaadamantane
0-0
F-GcF
c-c-c F c F c-c-c
E.s+?-c-c
I
Note Absence of Thioodamantane
I
CI 0
c1- ,
(7) C l - & C c'o
0:;
CI 0 a Item ( 6 ) donated by British Petroleum C o . ; all others are commercial products. ~~
1042
~
ANALYTICAL CHEMISTRY
40
30
20
IO
0
TIME, minufes Figure 2. Chromatograms of reference compounds and of products of desulfurization of thiaadamantane
Light products
I
II
Heavy products of hydrogenolysis of
II Solvent
c5
I
IO
0
I
I
30
IO
20
0
TI ME,minutes
Figure 3.
Chromatogrums showing the hydrogenolysis of diethyl p-aminobenzylphosphonate
reactor are prepared to receive the sample, the closure D is removed and replaced by B and all its auxiliary fittings. Thus assembled, the left end of tube b projects slightly into the catalyst bed in the enlarged portion of the reactor bore. The plunger can now be pushed forward, moving the glass ampoule against the catalyst; a brisk blow on the end of the plunger shatters the ampoule and the sample is deposited on the heated catalyst. RESULTS A N D DISCUSSION
Figure 2 shows data obtained by the charging of solid thiaadamantane by the solids-charging method described. The solvent methylcyclohexane (indicated in the bottom panel) was used to dissolve the evolved product of the reaction from the trap in which it was collected. The solvent toluene (indicated in the top panel) was used to inject the solid reference compounds into the chromatograph. Table I lists a few of the solid compounds that have been successfully handled in the charging device. Some of these compounds (varying in melting point from 90" to 175" C. and in molecular weight from 138 to 332) are of unusual structure, but all gave the anticipated fragments of hydrogenolysis. Elimination of Other Hetero Atoms. The application of hydrogenolysis is
not limited to sulfur, oxygen, nitrogen, and the halides. Hydrogenolysis may also be applied to the removal of other hetero atoms such as metals and nonmetals in organic molecules. The
successful handling of solid materials by the device described in the preceding section facilitates the study of such compounds. In Figure 3 are reproduced data
Table II. Some M e t a l and Nonmetal Organic Compounds and their Products of Hydrogenolysis Reocta nt
Product
0 - C, HJ
H , N - ~-cH,-
bI = o
Reactant
Product
- 0
-ctc,
O-CZHJ
VOL. 37, NO. 8, JULY 1965
1043
obtained in the hydrogenolysis of diethyl p-aminobenzylphosphonate; it can be seen that phosphorus as well as oxygen and nitrogen are readily removed from this compound to yield the expected hydrocarbons, methyl cyclohexane and ethane. There is no evidence in this experiment of extraneous fragmentation. Table I1 lists additional compounds from which hetero atoms were successfully eliminated. The elements removed from their respective compounds in this series of experiments were antimony, arsenic, bismuth, iron, nickel, phosphorus, and tin.
LITERATURE CITED
( 6 ) Ibid., 34, 151 (1962). (7) Ibid., p. 154.
(1) Rall, H. T., Thompson, C. J., Coleman, H. J., Hopkins, R. L., Proc. Am. Petrol Znst., Sect. VZZZ 42, 81 (1962).
(2) Sabatier, Paul, “Catalysis in Organic Chemistry,’, (translated by E. E. Reid), Van Nostrand, New York, 1923. (3) Thompson, C. J., Coleman, H. J., Hopkins, R. L., Rall, H. T., U.S . Bur. Mines, Rept. Invest. 6096, (1962). (4) Thompson, C. J., Coleman, H. J., Hopkins, R. L., Ward, C. C., Rall, H. T., ANAL.CHEM. 32. 1762 (1960). (5) Thom son, C.’ J., Coleman, H. J., Ward, C., Rall, H. T., Ibid., 32, 424 (1960).
8.
C. J. THOMPSON H. J. COLEMAN R. L. HOPKINS H. T. RALL Bartlesville Petroleum Research Center Bureau of Mines U. S. Department of the Interior Bartlesville, Okla. Presented before the Petroleum Division, 149th Meeting, ACS, Detroit, Mich., April 4-9, 1965. Investigation performed as part of the work of American Petroleum Institute Research Project 48.
Separation of Aromatic Amines by Reversed-Phase Chromatography SIR: The separation of aromatic amines by partition chromatography has been investigated by Roberts and who use a kieselguhr column Selby (4, on which is sorbed a stationary phase consisting of 6N acid. The amines are eluted from the column using chloroform as the mobile phase. Partition chromatography is also used by Clayton and Strong ( 8 ) to separate a homologous series of primary amines. The amine mixture is eluted from a Celite column packed with 18:3 methanol-water. Petroleum ether is used as the mobile phase, and the progress of the separation is followed using phenolphthalein indicator. Amin (1) uses reversedphase chromatography to separate amines as the p-(p-nitropheny1azo)benzoyl derivatives. A column of silanized kieselguhr is packed with a stationary phase consisting of carbon tetrachloride saturated with 65% aqueous formamide, and the aqueous formamide layer is used as the mobile phase. I n this work, mixtures of 1 to 50 mg. of aromatic amines are quanti-
tatively separated by reversed-phase chromatography, using cyclohexane as the stationary phase supported on 70to 80-mesh Teflon-6, a polyfluorocarbon polymer, with water or methanol-water mixtures as the mobile phase. The methanol-cyclohexaneTeflon-6 system has also been useful for separating phenols by reversed-phase chromatography (3). EXPERIMENTAL
Apparatus a n d Reagents. A Photovolt Model 43 recorder was used with a Uviscan-I single channel ultraviolet flow monitor to record the elution curves. The LTviscan-I was purchased from Buchler Instruments, Inc., Fort Lee, N. J. A Beckman Model D B spectrophotometer and a Beckman Expandomatic p H meter was used to obtain quantitative analyses by spectrophotometry and by potentiometric acidbase titration, respectively, A Hamilton 10-p1. syringe was used to inject some samples directly onto chromatographic columns. Columns were prepared by cutting
B :m- Toluldiw
c :p- Toidoh
D: 0- Methoxpnilim E:AnHin F: m-MMaxyanllinr G:p- Metbxyanilinr
50-ml. burets to the required length. A large 2.1- X 50-cm. column was prepared by fusing a stopcock to a length of borosilicate glass tubing. Teflon-6 (DuPont, 70- to 80-mesh) was obtained from Analytical Engineering Laboratories, Hamden, Conn. Amines were Eastman White Label grade. Stock solutions were prepared by weighing approximately 100 to 200 mg. of solute into a 100-ml. volumetric flask, adding 10 ml. of methanol and diluting to volume with water. Procedure. The distribution ratio of each amine is determined as a function of the concentration of methanol in water by a batch distribution technique. A carefully weighed quantity of the amine is added to 25 ml. of equilibrated cyclohexane and 25 ml. of equilibrated polar phase in a 125-ml. separatory funnel. The total quantity of the amine is calculated using data from a previous measurement of the volume of 0,lM hydrochloric acid necessary to titrate a given weight of the amine. A solvent blank correction is applied for each of these measurements. After equilibration of the phases for approximately 1 minute, the volume of each phase is
A:N,N-Dimthyhilhu B:N- Elhybnilim C :Z,6-DlmothyMline 0 I- NOpMhlylamin E:o Ethylaniline G:2pF:N- Methylaniline and 2,S-DinethylonOhe
-
Volume X mrlhyl oleohot
Figure 1 . Distribution ratios of derivatives of aniline as a function of methanol concentration in water
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ANALYTICAL CHEMISTRY
Figure 2. Distribution ratios of aromatic amines as a function of increasing methanol concentration in water
