423
V O L U M E 2 2 , NO. 3, M A R C H 1 9 5 0 If this point falls on the established curve, the atom per cent enrichment corresponding to the ratio obtained for the unknown sample is read directly from the curve. If the ratJioof the standard falls slightly t o one side of the curve, a line is drawn through the new point parallel to the calibration curve. The enrichment corresponding to the ratio obtained for t,he unknown is then read from this corrected segment of curve. Thus, the calibration curve can be used for a considerable period of time, over somewhat changing operating conditions. Csing the method of calibration permits adjusting the instrument itself for maximum shbility, regardless of its effect on the measured value of tlic ratio. Deviation of measured from absolute ratios will t h n i be determined by the accuracy of synthesis of the standards and by the reproducibility of the instrumental measurements. 13y using adequate precautions in preparing standards, therefor(,, this method of calibration results in :tcuuracy approaching instrumental precision. Of particular interest in future comparisons of d a t a obtained by various laboratories is the large difierence between the HD/H? ratio of unenriched tank hydrogen and that obtained from reduct ion of unenriched tiouhly distilled water. Tank hydrogen contains only one h d f to two t,hirds as much deuterium as does the hydrogcn from water. Furthermore, variations in deuterium content of hydrogen and water samples from various sources have been reported (4, 1 4 ) . It is true that any arbitrary standard can be chosen for one laboratory, but obviously the bme isotope concentration must be known and specified if data from different laboratories are to be coinpared. SUMMARY AYD COYCLUSIONS
A satisfactory procedure for determination of deukrium-hydrogen mixtures has bcen developed using the Consolidated-Sier 21-201 mass spectrometer. T h e minimum detectable difference from normal distilled water when frequent standards are run is 0.0004 atom %, or less under favorable conditions. Over the entire range, reproducibilit>- is * 1% of the ratio for periods of several hours and *3y0 of the ratio for longer periods. It was found t h a t instrumental factors, including the set,ting of the source magnet, affect materially t.he value of the ratio of HD/H2 obtained. Hence, t,he instrument was calibrated with synthetic samples of kno\m deuterium enrichments, hydrogen obtaincd from doubly distilled water being used as zero enrichment,. I n preparing thc cdibrnting samples, it was found neces-
sary to collect hydrogen from the entire water sainple placed in the reduction apparatus, as a different ratio was obtained from the first and last half of the reduction. The calibration curve showing known enrichment plotted against measured H D / H H ratio can be used for a range of operating conditions and hence for an estended period of time and has the advantage of yielding results in nearly absolute enrichment. ACKNOWLEDGMEST
This ivork \Y:LS (tone under a grant from tlie Life Insurance Medical Research Foundation to H. J. Deuel, J r . The authors also rvish to thank Stella Alogdelis for her aid in preparing several samples, C. E. Berry of the Consolidated Engineering Corporation and R. J. Kinzler of the University of Southern California for thrir advice and cooperation, the Hancock Foundation for the use of its facilities, H. E. Pearson for his assistance in establishing the l l a s s Spectrometer L:thoratory at the Los Angeles County Hospital, and the Cancer Teaching Fund of the U. S. Public Health Scrviw for its partial support. LITERATURE CITED (1) Alexander, R. W,, and Marx, W., unpublished research. (2) Berry, C. E., private communication. (3) Bleakney, W., Phys. Rev., 41, 32 (1932). (4) Bleakney, W., and Gould, A . , Ibid., 44, 265 (1933). (5) Consolidated Engineering Gorp., “Mass Spectrometer, Model 21-201, Operation and Maintenance Manual,” 1945. (F) Kirshenbaurn, A. D., Hindin, S.G., and Grosse. -4. V.,Nature, 160, 187 (1947). (7) Kier, A. 0.. “Preparation and Measurement of Isotopic Tracers,” p. 11, Ann Arbor, hfich., Edwards Bros.. 1946. (8) Nier, -4. O., Rev. Sci. Instruments, 18, 398 (1947). and Iluutad, B., (9) Nier, A . O., Inghram, M. G., Stevens, C. .4., Manhattan District Declassified Document, M.D.D.C. Rept. 197 (1947). (10) Rittenberg, David, “Preparation and Measurement of Isotopic Tracers,” p. 31, Ann Arbor, Mich., Edwards Bros., 1946. (11) Sprinson, D. B., and Rittenberg, David, U. S.Naval Med. BUZZ.,Supplement, p. 82 (March-April 1948). (12) Swartout, J. A , , and Dole, XI.. J . A m . C h e n . SOC.,61, 2026 (1939). (13) Washburn, H. W.,0’. S.Saval .Ired. Bull., Supplement, p. 60, (March-April 1948).
RECEIVED August 1. 1949. Contribution 226 f r o m t h e Department of Riocheinistry and Xutrition, University of Southern California. The deuterium oxide used i n this investigation was purchased from tho Stuart Oxygen Company on oliocation froin the Isotopes Division. U. 8. Atomic Energy Co:niiiiasion.
Determination of Certain Ortho-Substituted Phenols IIOB.iRT H. WILLARD AND A. L. WOOTEN’, L-nicersily of .VZichigun, / I n n ,Irbor, Mich. A colorimetric method for the determination of o-phenglphenol or o-tertbutylphenol in the presence of their para isomers is based on the formation of their aristols and subsequent extraction with toluene. The optimum amoiin t of o-phenylphenol is about 2.5 mg. and of o-tert-brltylphenol is about 0.5 mg. An accuracy of about 1% is practical.
S
Y N T H E T I C coating rebins are prepared in large volumes from p-te? t-butylphenol and from p-phenylphenol. One of the iiiost objectionable impurities to be found in these p-phenols is the ortho isomer. The o-phenol tends t o cause a yellow color i n the final resin; poor drying characteristics and other undesirable features are also present. The present analytical methods were developed as controls for certain experimental processes, but it, is believed, that they may find application in the routine assay of commercial phenols. In t>hepresence of alkali and iodine, a n o-alkyl or aryl phenol undergoes iodination and subsequent polymerization. Bordeianu
’
Present address. Reichhold Chemic& Inc., Ferndale. Jfich.
( 1 , 2 ) showed that polymerization occurs through the positions para to the hydroxyl groups. H e showed t h a t the action of oxidizing agents on 2,4diiodothymol and 2-iodo--i-bromothyrnol yielded a red polymer through the same diphenoquinone iodide. The results of Poplawski ( 4 ) C31I; CaH7 are in agreement with these. Wollett ( 5 ) found polymers with o = ~ = b = o molecular weights up t o 1400. This necessity for a free para I , LEI3 C H , I position indicates t h a t a di-ophenol would interfere with the present procedure, but that an o,p-dialkvlphenol would not ~
!
ANALYTICAL CHEMISTRY
424
interfere. Emery and Fuller ( 3 )described a gravimetric method based on the same reaction, but it distinguishes only qualitatively between 0- and p-phenols.
Table VIII.
Effect of Volume at Extraction
(Extra water added just before toluene extraction) Volume a t Optical Extraction, hll. Density
REAGENTS
26.0 51.0
Approximately 1.0 iV hydrochloric acid. Approximately 0.1 .V iodine solution. Approximately 0.1 S sodium thiosulfate solution. Starch indicator. Toluene, reagent grade. Buffer, 0.5 molar aqueous sodium carbonate solution.
219 220
Table IX.
PROCEDURE
A weighed sample of the phenol is dissolved in a slight excess of dilute alkali. To an aliquot that contains no more than 10.0 mg of total phenols and no more than 2.5 mg. of o-phenylphenol (or 0.5 mg. of o-tert-butylphenol) are added 5.0 ml. of buffer and 10.0 ml. of 0.1 AViodine. After 1 minute 10.0 ml. of 1 N hydrochloric. acid are added. The excess iodine is destroyed xvith 0.1 ATthiosulfate and starch, 50 ml. of toluene are added, and the flask is stoppered and vigorously shaken for 30 seconds. The two layers separate readily and a portion of the toluene is decanted through a coarse filter paper into a colorimeter tube. The color is read at 490 millimicrons (at 450 millimicrons with o-tert-butylphenol)
Effect of Volume of Toluene
Toluene, MI.
Optical Density
20
472 312 233 188 159.5
an ~. 40 50
60
Table X. o-Phenylphenol, hlg. 0.000 0.500 t.000
Optical Density 0.0
Optical Density X x 10-8
h.11.
9.44 9.36 9.32 9.40 9.30
Standardization Curve o-Phenylphend, Mg.
Optical Density
1 500 2.000 a 500
126 0 168 5 205 8
35.7 79.2
EXPERIRIENTAL R E S U L T S
The results reported in Tables I to X are for o-phenylphenol; very similar results xere obtained for o-tert-hutylphenol and have
been omitted. In each of the experiiiierits a sample containing 2.5 mg. of o-phenylphenol was used and the above procedure was followed except for the concerned variable.
Effect of pH of Buffer
Table I. PH
Optical Densitj
PH
Optical Density
8.4 9.7 10.5
207 211 214
12.0 12. B
219 219
DISCUSSION
-111 the variables in the procedure have been, in PO far as possible, adjusted so that minor changes in technique will not affect the results. Several attempts were made t o anal-yze the color bodies. All results indicated that the product was of varying quinone content. This is in agreement with previous publications as well as the conclusions drawn from experimental data. The reaction is definitely not a stoichiometric one and for this reason details sliould be standardized as much as possible. An examination of the experimental data accumulated in the development of this method allon-s the following conclusions to be drawn: It is permissible for the p H of the buffer to vary in the range of 12.0 to 12.5. Low results i d be obtained on either jide of t,liis range. The procedure allows a twofold excess of buffer over t,he minimum necessary. The volume during iodination must be the same during each detclrmination, for the amount of color body formed decreases as t,he volume increases. The concentration of iodine specified is twice the minimum amount. The iodination time is not a variable within the range of 0.5 to 5.0 minutes. Excess hydrocliloric acid and sodium thiosulfat'e have little effect on the color. This is probably due to the extreme insolubility of these aristols (thymol iodides). This method is not ideal by any means; it requires a skilled technician and close attention to detail. When used as a qualitative test, such care is, of course, not necessary.
Table 11. Effect of Volume of Buffer
.
Buffer, 311.
Optical Density 192 215
1 2
---
01) tic a1 Density
Buffer, 111. 3 5
219 219
Effect of Volume of Iodine
Table 111. Iodine, bll.
Water, hll.
Optical Density
1.0 2.0 3.0 5.0
4.0 3.0 2.0 0.0
139 219 220 219
Table IV.
Effect of Total \-olume during Iodination
(After iodination volumes were adjusted to same figure) Volume during Volume during Optical Iodination, Iodination, Optical Density NI. Ivfl. Density 219 25 11 20 206 216
Table V.
30
Effect of Iodination Time
Time, Zlin.
Optical Density
0.25 0.50 1.00 5.00
202 218 219 218
Table VI.
5.0 10.0
Table VII. MI.
0 .SI 5.0
ACKNOWLEDGMENT
One of the authors wishes t o express thanks t o Reichhold Chemicals, Inc., for the financial assistance that made this work possible.
Effect of Excess Hydrochloric Acid
Excess 1.0 N Acid, M I . 0.0
Excess 0.1 N Thiosulfate,
196
OptiFal Density
__ .~
LITERATURE CITED
219 220 218 .
_
_
Effect of Excess Thiosulfate Optical Density After 0.5 After 10.0 minute minutes 219 218
219 219
_
~
(1) B o r d e i a n u , C. V., Arch. pharm., 272, 8 (1934). (2) B o r d e i a n u , C . V., Ann. sei. Unzu. J a s s y , Pt. I, 23, 240 (1937). (3) E m e r y , W. O., a n d F u l l e r , H. C., IND.ESG. CHEY.,ANAL. ED., 7, 248 (1935). (4) P o p l a w s k i , W., Arch. Chem. Farm. ( W a r s a w ) , 3, 234 (1937). (5) W o l l e t t , G. H., J . Am. Chem. Soc., 43, 553 (1921). RECEIVEDAugust 31, 1949.
From a dissertation submitted b y A. L Wooten t o t h e Graduate School of the University of Michigan in partial fulfillment of the requirements for t h e degree of doctor of philosophy in chemistry.
