The phenyl-, naphthyl-, and p m e t h oxyphenylurethans were the least satisfactory as they required the tetracyanoethylene spray for location of spots. The limit of sensitivity with the spray was rather high, ranging between 10 and 20 pg. The C1 to Ce alcohol derivatives of these groups were cleanly separated on propylene glycol impregnated papers; however, the C6 to Clz alcohol derivatives produced oblong spots when chromatographed on vaseline impregnated papers, and consequently adjacent homologs did not separate well. R, values were influenced by the concentration of the dip solutions, particularly in the case of the papers dipped in vaseline. The less vaseline used, the higher were the R, values. They m-ere also influenced by the ratio of methanol to water in the developing solvent. Generally, the more water used the greater the spread of individual R, values, but the spots were longer and tended to run together. The best methanol-water ratio was determined b y experimentation in each particular case. It was found in all cases tested that diethylene glycol and formamide could be successfully substituted for propylene glycol; also, mineral oil for vaseline. CONCLUSIONS
Of seven groups of urethans tested, the o-nitrophenylderivatives were the
Table IV. R, Values of Some p-Phenylazophenylurethans"
Parent Urethan, Alcohol Rf Methyl 0.39 Ethyl 0.61 Propyl 0.73 Butvl 0.82 Am;d 0.88 Hegyl 0.91 Heptyl 0.93 Papers dipped in methanol-propylene glycol (io-30 v./v.) developed with methanol saturated heptane. Table V. R, Values of Some p-Phenylazophenylurethans"
Parent Urethan, Alcohol Rr Hexyl 0 77 Heptyl 0 73 Octyl 0.68 0 65 Konyl 0 56 Decyl Undecyl 0 45 Dodecyl 0 38 See footnote on Table IJ.
most effective for the separation of c6 to CIZalcohol urethans. The p-phenylazophenyl derivatives were also satisfactory and detectable in very small quantities. The m- and p-nitrophenylderivatives were best for separating the short chain
alcohol urethans, with the nitrophenylderivatives producing the best spots. The p-phenylazophenyl derivatives were also satisfactory. The small quantities of the nitrophenyl and phenylazophenyl derivatives which were detected on psper chromatograms made them quite satisfactory for use in conjunction with gas chromatography. The phenyl, naphthyl, and o-methoxyphenyl derivatives were less desirable. LITERATURE CITED
Attaway, J. A,, Wolford, R. IT., Edwards, G. J., J . Agr. Food Chem. 10, 102 (1962). (2) Bosvik, ' R., Iinutsen, K. V., von Sydou-, C. F. Erik, ANAL. CHEM.33, (1)
1162 .- i\l-w - -l -l ',i.
(3) EXis, R., Gaddis, -4.M., Currie, G. T., Ibid., 30,475 (19%). (4)Peurifoy, P. V., Slaymaker. S. C., Naner. M..Ibid.. 31. 1740 (1959). ( 5 ) S h n e r , 'R. L:, Fuson, 'R. C!., "The Systematic Identification of Organic Compounds," 3rd ed., p. 163, Wiley, Yew York, 1948. ( 6 ) Kolford, R. IT., iilberding, G . E., Attaway, J. A , , bbstracte, p. 23A, 140th Meeting, ACS, Chicago. Ill., September 1961. RECEIVED for review December 11, 1961. Accepted February 23, 1962. ACS Joint Southeast-Southwest Regional lIeeting, ?;en. Orleans, La., December 7-9, 1961. Cooperative research by the Florida Citrus Commission and the Florida Citrus Experiment Station. Florida Agricultural Experiment Station Journal Series, S o . 1413.
Simultaneous Microdetermination of Carbon, Hydrogen, and Boron in Organoboranes ROBERT C. RITTNER and ROBERT CULM0 Olin Mathieson Chemical Corp., New Haven, Conn.
b Samples containing 1 to 4 mg. of boron are combusted by the standard Pregl-type procedure, using the Brinkman-Heraeus microcombustion assembly. Carbon and hydrogen values are obtained in the normal fashion. The residue which remains behind in the boat (essentially a mixture of the oxides of boron, vanadium, and chromium) i s transferred to a beaker, dissolved in water, and the boric acid i s titrated b y the identical pH method, using 7.10 as the critical pH. The time required for a complete analysis i s approximately 40 minutes.
T
rapidity, simplicity, and accuracy of the carbon-hydrogen determination by the use of the BrinkmanHeraeus microcombustion assembly, coupled with the work of Arthur and HE
Donahoo ( I ) on the microdetermination of boron through a Pregl-type combustion procedure, led us to investigate the possibility of developing a micro method for the simultaneous determination of carbon-hydrogen and boron by means of a rapid combustion technique. EXPERIMENTAL
The microcombustion assembly is the standard BrinkmanHeraeus instrument. The quartz combustion tube filling is described in detail in Figure 1 , A . The rest of t h e combustion train is similar to that described by Siederl and Siederl (3). The p H meter used for the titrations is a Beckman Model H-2 equipped with the standard glass and calomel electrodes. The stirrer-hot plate used was a Teinco Stir Plate Model SP-1025B. Apparatus.
The sonic vibrator was tkle Sonblaster, Ultrasonic Generator Series 600, manufactured bv the Xarda Ultrasonics Corp. Special Reagents. VAXADIUM PENTOXIDE. Fisher certified reagent. This may be used as received wit?h n o further purification. POTASSIUM DICHROMATE. G . Frederick Smith Chemical Co. The dichromate is melted in a crucible by heating a t 400" C. The melt is cooled, powdered, and dried in an oven at 120" C. for a short while. It is stored in a glassstoppered bottle. The materials used in the combustion and absorption tubes, as well as the oxygen supply, were all stated by the manufacturer to be suitable for use in quantitative organic analysis. Procedure. A sample containing 1 to 4 mg. of boron is weighed into a platinum boat and intimately mixed with -40 mg. of a 1 t o 1 mixVOL. 34, NO. 6, MAY 1962
* 673
ture of V Z O and ~ KzCrzOT. It is then placed inside a platinum cylinder (Figure 1,B). The cylinder is plugged a t both ends with quartz wool and inserted into the quartz combustion tube 6.0 cm. from the long burner. The oxygen flow rate is adjusted to approximately 30 cc. per minute, and the drive mechanism controlling the movement of the short burner (8.0 cm. from long burner) is turned on. The temperature of the short burner is between 850" and 900" C. After 7 minutes, the short burner reaches the long burner, which is a t a temperature of 900' to 950" C. and remains over the sample for an additional 5 minutes. The combustion is now complete, and the total elapsed time is 12 minutes. A check of the oxygen flow rate may be made by observing the Mariotte flask, where -360 cc. of water should have been displaced. The Anhydrone and Ascarite absorption tubes are immediately removed and weighed, and the carbon-hydrogen values are determined. The residue in the platinum cylinder, which consists essentially of the oxides of boron, vanadium, and chromium, is removed from the combustion tube; the quartz wool plugs and boat are removed from the cylinder, and all components are placed in a 150-ml. beaker. The beaker is of ordinary laboratory glassware, since it has been found that under the conditions of this procedure, the boron blanks are insignillcant. Approximately 70 to 80 ml. of distilled water are added to the beaker, and the contents are stirred in a sonic vibrator for -10 minutes. The beaker is then transferred to a stirrerhot plate, where the contents are
Table 1.
OUARTZ W O O L
8 m m ID l O m m OD
ImmlDn
3mmOD
Figure 1. A.
E.
Experimental apparatus
Carbon hydrogen combustion tube packing Platinum cylinder
stirred and heated a t approximately 100' C. for an additional 10 minutes. The solution is then cooled to room temperature in a beaker of cold water, the boat and cylinder are removed (with rinsing) to facilitate stirring, and the solution is ready to be titrated. The pH of the solution is adjusted to 7.10, using -0.01N NaOH (need not be standardized), and excess mannitol (10 t o 12 grams) is added until the pH remains relatively stable. The pH a t this point is usually between 3.5 and 4.0. The tip of a 10.0-ml. microburet (graduated in 0.05-ml. intervals) is placed below the surface of the solution, and standard 0.01 to 0.02X NaOH is added
until the pH is brought back to 7.10. The S a O H used in the titration is stored in a polyethylene bottle and restandardized every 3 or 4 days to eliminate any error due to possible absorption of COZ from the air. RESULTS AND DISCUSSION
In our early work, low carbon values were obtained if the organoborane being analyzed was not mixed with an oxidizing agent before combustion. This was probably due to the formation of refractory boron carbide. Mixing the sample with a 1 to 1 mixture of
Experimental Results for Microdetermination of Carbon, Hydrogen, and Boron
Compound Di henylphosphinedecarborane, & 2 ~ 2 3 ~ 1 0 ~
Bis(aminodipheny1phosphine)decaborane, CZ~H~~BIONZPZ Bis( ethoxydipheny1phosphine)decaborane, C28H42B1002P2 Bis(methylaminodipheny1phosphine)decaborane, CZ~H~OBION~PZ Bis(hydrox dipheny1phosphine)deca borane, ~ N H ~ ~ B ~ o O Z P Z Bis(hydroxydipheny1phosphine)deca borane, CY8H48B10N202P2, bisdimethylamine salt Bis(triethy1ammonium)perhydrodecaborane, C12HdIBloN2
Carbon, % CalcuMean value lated Found and precision 47.02 46.99 46.92 47.00 55.14 55.11 55.30 55.14 57.90 58.10 57.82 57.90 56.70 56.90 56.58 56.82 54.93 54.77 54.60 54.69 55.08 55.14
7.56
55.18 f 0.04 6.94 57.94 f 0.06
7.29
56.77 f 0 . 0 7
7.32
54.69 f 0.06
6.53
55.11 f 0.02
7.87
Boron, yo CalcuMean value lated Found and precision
7.40 7.52 f 0 . 0 7 35.30 35.38 35.36 f 0.02 7.70 35.32 7.45 35.38 7.00 7.04 f 0 . 0 1 20.70 20.84 20.76 f 0.06 7.05 20.83 7.06 20.60 7.40 7.35 f 0.04 18.63 18.88 18.71 f 0 . 0 7 7.24 18.56 7.40 18.68 7.40 7.38 f 0.03 19.65 19.40 19.54 f 0.06 7.45 19.71 7.30 19.51 6 . 6 7 6.68 f 0 . 0 1 20.63 20.98 20.85 Z!Z 0.09 6.70 20.72 8.26 8.32 f 0 04 17.60 17.98 17.82 f 0.11 8.37 17.66
44.70 44.80 f 0.03 13.08 44.89 44.78 44.82 Trimethylamine-dimethylphenylphos- 41.60 41.65 41.73 f 0.03 10.16 10.23 10.18 f 0.06 34.07 34.10 34.10 f 0.06 10.30 34.25 phine decaborane, CIlH32BloNP 41.81 10.01 33.94 41.72 Trimethylamineborane, CaHIZBN 49.45 49.30 49.33 f 0.02 16.48 16.18 16.19 f 0.01 14.84 14.95 14.84 f 0.08 16.20 14.72 49.35
674
ANALYTICAL CHEMISTRY
44.90
46.97 f 0.02
Hydrogen, % 'CalcuMean value lated Found and precision
vanadium pentoxide and potassium dichromate or with conditioned tungstic oxide seemed to alleviate this problem. The use of tungstic oxide was discontinued, however, because it was found that if the sample contained phosphorus, the boron values were always low. I n the absence of phosphorus, the tungstic oxide works as well as the V206 and KZCr2O7mixture. Most of the samples involved in this study could be analyzed satisfactorily without use of the protective cylinder described in the procedure; but occasionally, xve have noticed some spattering of the residual boric oxide. To obviate this possibility, the protective cylinder should be used a t all times. I n the combustion procedure for boron described by rlrthur and Donahoo ( I ) , the boric oxide residue is deposited on a platinum tube which has been inserted into the regular combustion tube. These authors found it necessary to reflux the tube with HzO for 21/2 hours to remove the boric oxide quantitatively. In our method, the boric oxide is all contained in the protective cylinder, which
is then placed in a beaker of water. In approximately 20 minutes, the solution is ready to be titrated. The titration method used is essentially that of Foote (d), who advocated a pH of 7.6. Taylor ( 5 ) ) who named the method the identical p H method, used a pH of 6.3. We have found a pH of 7.10 most satisfactory. The big advantage of this titration procedure over others is that only materials reacting with mannitol to yield acid will interfere. It is stated by Taylor (5) that phosphoric acid is the only common material besides boric acid which will do this, but to a much smaller degree. Although most of the organoboranes that n-e have analyzed contain phosphorus, we have not experienced any interference. We have analyzed the residue after combustion and solution in water and have not found any phosphate. However, analysis of the residue by emission spectrography does indicate the presence of phosphorus. Therefore, the noninterference of phosphorus in this method can be explained by the formation, after combustion, of an insoluble form of phosphorus which
does not complex with mannitol to interfere in the subsequent titration. The results obtained for carbon, hydrogen, and boron are tabulated in Table I. ACKNOWLEDGMENT
The authors acknowledge the efforts of H. 9. Schroeder and T. L. Heying in the preparation of the compounds listed in Table I, as well as for their cooperation in publishing the paper. LITERATURE CITED
(1) Arthur, P., Donahoo, W. P., U. S. Atomic Energy Comm. Rept. CCC1024-TR-221, January 18, 1957. (2) Foote, F. J., IND. ENG.CHEM.,ANAL.
ED.4, 39 (1932). (3) Xederl, T. B., Niederl, V., “Micromethods of Quantitative Organic Analysis,” 2nd ed., pp. 129-30, Wiley, New York, 1942. (4) Schroeder, H., Reiner, J., Heying, T. L., Inorganic Chemistry, to be published. ( 5 ) Taylor, D. S., J . Assoc. Oflc. Agr. Chemists 33, 132 (1950).
RECEIVED for review December 1.5, 1961. Bccepted March 12, 1962.
Laboratory Evaluation of Sulfur Dioxide Methods and the Influence of Ozone-Oxides of Nitrogen Mixtures FRANK P. TERRAGLIO and RAYMOND M. MANGANELLI Deparfment of Sanitafion, Rotgers, the State University, New Brunswick, N. J.
b A laboratory evaluation of three wet chemical methods used to measure atmospheric sulfur dioxide concentrations showed that the acidimetric and spectrophotometric methods gave comparable average recoveries over the concentration range of 0.3 to 3.78 mg. of SO2 per cubic meter. Recoveries b y the iodimetric method over the same concentration range were lower than the spectrophotometric method. The presence of ozone-oxides of nitrogen mixtures interfered with all three methods.
A
including wet chemical procedures and instrumental detectors, may be used to determine the concentration of sulfur dioxide in the atmosphere. The instrumental devices are usually calibrated on synthetic atmospheres t h a t have been standardized by one of the wet chemical methods. The three wet chemical methods which were evaluated for deviations, comparative recoveries, and response to mixtures of sulfur dioxide with ozone NUMBER OF METHODS,
and oxides of nitrogen are: K e s t and Gaeke spectrophotometric method (9), in which sulfur dixoide is trapped in a sodium tetrachloromercurate solution and estimated by formation of a purple color with pararosaniline and formaldehyde; iodimetric method ( 4 ) , in which sulfur dioxide is trapped in dilute sodium hydroxide and titrated with standard iodine solution; and acidimetric method (4),in which sulfur dioxide is trapped in a solution of hydrogen peroxide and dilute sulfuric acid, and the resulting sulfuric acid is titrated with standard sodium hydroxide solution. Greenburg and Jacobs ( 1 ) in a comparative study of atmospheric samples containing 0.10 to 0.79 mg. of SO,per cubic meter found that the acidimetric method gave results 20Yo higher than the values obtained by the iodimetric and spectrophotometric methods. The authors attributed the higher values to the presence in the atmosphere of acidproducing substances other than sulfur dixoide. Jacobs ( 3 )has emphasized that the spectrophotometric method depends upon the quality of the pararosaniline so
that each batch of dye requires testing to ensure suitability for sulfur dioxide analysis. Kelch and Terry (8) reported that values obtained by the acidimetric method were lower (approximately 70%) than values found by the spectrophotometric method for concentrations up to 1.70 mg. of SOz per cubic meter. In this paper, all air concentrations have been converted to weight per unit volume (7’). PROCEDURE
Test atmospheres were produced in a darkened 200-cubic foot continuouspass-through chamber. The influent air was passed through a countercurrent water scrubbing tower which removed water-soluble airborne materials and over 99% of the sulfur dioxide that existed in the laboratory air. Dilutions of sulfur dioxide in nitrogen were prepared in cylinders and metered to the chamber. Temperature was controlled between 22’ C. and 26’ C., and humidity was maintained between 50 and 70%. Complete mixing of the gases was ensured by two fans located in the test chamber. VOL. 34, NO. 6, MAY 1962
675
