ANALYTICAL CHEMISTRY
1250
Figure 1. %Methylnaphthalene (50 X) hfc.
Right.
Cmstals obtained by careful maoraublimation Thin crystalline film from fusion
OPTICALPROPERTIES (deterzined by W. McCrone). Refractive Indices (5893 A,; 25" C.), CL = 1.494 * 0.001, 0 = 1.640 0.004. y = 1.77 0.01. Optic Axid Angles (5893 b.; 25" C.). 2V, = 81"; 2Er = 108". f
f
Dispersion. v > II (on centered obtuse hisedrix figure). Optic A.xidalPlrtne. L!OO. Sign of Double Refraction. ( Acute Bisectrix. In the 100 p
form hrientatia& orientation. These cryst& crystals, ne& never show angles ,eit,her either growing or in mixed fusion. 2. All crystals from the melt show a centered obtuse hisectrix interference figure with isogyres just included by N . A . = 1.25; 2 H y = 108'; v > r on this view and the sign is negative. A mixed fusion with Citrgille index liquid, 1.414,oauses the crystals cryst,als t o distlppear in the position showing alpha at 2C"
-
I CITED
uramiscne nnsrauographie." Vol. Engelmann, 1910. (2) Neuhaus, Z. R ~ i s t .101, , 177-92 (1939).
(1) CTrocn,
0,
p.
*LA,
~ieiyuig.
meter Analysis SIR: The reoent article on "Mass Spectrometer Analysis" by Brown et al. [ANAL.CHEM.,20, 5 (19481 contains mme excellent work on the application of this technique to liquid samples. The d s h presented in Tablea XI a i d XI1 introduce into the literature for the first time the conclusion that 3-ethylpentane and other ethylparaffins are present in oonsiderable quantities in cracked naphthas. The data. submitted on this point should, therefore, be examined oritioally. The following data are presented in Table XI: NaBtha. B, Vol. % Naphtha A, Vol. % Fraotion No. 2 3 4 2 3 4 3-Methylhersne 6.06 1.78 2.94 4.74 3.57 1.10 3-Ethyl~enthne %-Heptane
.. .,
0.26 1.62
ii.92
.. ..
0.822.26 li.78
In distillation outs of the type being analyzed here. the abundanoe ratio 01 the compounds found on analyzing successive fractions has been ioun'd to follow a regular pattern determined by boiling points. I n the case of naphtha A, for example, if 3-ethylpentane were present to the reported extent between 3-methylhenme and n-heptane in fraction 3, it would normally be found in much IcLrger amount in fraction 4, where both the adjacently boiling oompounds are increased. In the oorresponding cuts from naphtha. B a similar situation appears, and the amount of 3-ethylpentme would be expected to be roughly the same in fraotions 3 and 4. Accordingly, the total amounts of this compound in the original samples are probably much larger ,than those reported here if the No. 3 cut analyses &re reliable. or much less if the No. 4 cut analyses are correct. In previous naphtha analyses by fractional distillation, infrared, or Raman spectroscopy, it has usually been impossble to demonstrate that the ethylparaffins'me present in more than trace amounts. Specific statements hcwe been made with regard to the apparent absence of 3-ethylpentane.in the seven virgin naphthas examined by A.P.I. Project 6 (I), and the absence of the methylethylpentams in alkylates and hydropolymers (2). I n view of the data previously reported and the internalinconsistency of the present data, it Seems that 8 further study of these samples may be in order. The above situation suggests t h t a major defioiency of the method
a8 described may be the uncertainty of the qualitative analysis of thr samples. In Table XII, for example, it is not clear why 2,2.3-trimethylbutane was included in the analysis and 2,Z-dimethylpentane left out. The authors report that these compounds have very similar maas spectra, and previous data indicate that the 2.2-dimethylpentane is .a likely and 2,2,3-trimethylbutane an unlikely constituent. The vduelues reported for the trimethylpentanes in.Ta,ble XI1 and 3,3-dimethylpentane in Table XI &re also interesting in this oonneotion. It would appear that further experiments are warranted to determine whether or not these compounds are as rare in naphtha samples 88 has commonly been supposed. Hohma J. HAIL Esso Laboratories, Standard Oil Development Co., Elisabeth, N. J.
LITERATURE CITED
(1) Foruiati, A. F., Willingham. C. B., Mair. B. J.. and Rossini, F. D., J . Resewch Nail. Bur. Standards, 32,31 (1944). (2) Glasgow, A. R., Streiff. A. J., Willingham, C. B., and Rossini, F. D., Proc. Am. Petrolwm Inst., 26.111. 169 (1946). SIR: It is well recognized that the ability of the mass speotrometer aoourately to resolve an isomeric mixture is largely dependent on both the nature of the mixture and the relative concentrations of individual components therein. To verify independently the presenoe of 3-ethylpenhne in naphtha BI cut 3 was analyeed by an infrared spectrometer subsequent to the receipt of Hall's communication. At the wave length 01 11.13 microns, 3-ethylpentane exhibits a unique absorption relative to other hydrooabons present in the 92' to 96O C. distillate cut. The data show positive infrared confirmation of the maas spectrometer analysis, thereby establishing beyond reasonable doubt the presence of 3-ethylpentane in the cut in question. In out 4,*however,the total volume of the sample was oonsiderably larger, with the oonoentration of heptanes present in excess of 75%. thereby rendering the
1251
V O L U M E 20, NO. 1 2 , D E C E M B E R 1 9 4 8 resolution of 3-ethylpentane uncertain. Although it is probable that this cut may also contain some 3-ethylpentane, no check was made o n this point by means of infrared. Concerning the analysis shown in Table XII, Hall is correct in his contention that, 2,2-dimethylpentane should have been included with 2,2,3-triniethylbutane. Owing to an oversight by the abthors the usual grouping of these two compounds was omitted from the table. The reported presence of 2,2,3-trirnethylpentane in Table XII, on the other hand. is strongly indicated by the data, making grouping with other compounds unnecessary. I t would perhaps have been expedient to group in the same table 2,2-dimethylhexane with 2,2.4-trimethylpentane. The chief limitation of the mass spectrometer method is its inability to resolve isomers having similar spectra. There conditions permit a satisfactory resolution to be made, however, experience has shown few cases in which a reliable qualitative analysis could not be established. IT.P. YOUNG At,lantic liefining Company, Philadelphia 1, Pa.
API Symposium on Rapid Methods of Analysis of the annual meeting of the iimerican Petroleum A Institute, held Soveniber 8 t o 11 a t the Stevens Hotel, FE.iTcRE
Chicago, Ill., was a Symposium on Rapid Methods of Analysis, hponsored by the Committee on -4nalytical Research. J. B. Rather, Jr., Socony-Vacuum Oil Co., Brooklyn, S. T.,preqided over the sessions. The following program was presented.
Quantitative Determination of Sulfur in Hydrocarbons by XKay Absorption. \ l r L. ~ KEHL ~A X D~JOHN ~ c. ~ HhRT, ~Gulf~ Research and Development Co., Pittsburgh, Pa. Rapid Method of Stack-Gas Analysis for Total Sulfur and Sulfur Dioxide. C. W. KEY, Richfield Oil Corp., Wilmington, Calif. Carbon Dioxide Scrubbing Nethod for Determining Stripper Efficiency. L. A. KEBBER, Phillips Petroleum Co., Borger, Tex Continuous Determination of Carbon Monoxide and Carbon Dioxide in Pilot Plant and Refinery Operations Using a n Infrared AND F. P. HOCHGESAW, SoconyGas Analyzer. H. SOBCOV Vacuum Laboratories, Paulsboro, S . J. Determination of Dissolved Oxygen in Hydrocarbon Oils. J. H . D. HOOPER, Anglo-Iranian Oil Co., Ltd., Sunbury-onThames, Middlesex, England. Use of the Viscorator for Plant Viscosity Control. A. E. F R 4 N Z E N , Standard Oil Co. (Indiana), Whiting, Ind Determination of Inhibitors in Gasoline. P ~ U R. L THOMAS ASD HARRYC. BECKER, The Texas Co., Beacon, X. Y.; ASD LEONDONS,Jefferson Chemical Co., Yew York, X. 1‘. Modified Burners for Elemental Analysis by Lamp Combustion and Their Application t o Special Problems. G. E. C. WEAR A K D E. R. QUIRAM, Standard Oil Development Co., Elizabeth, S . J. Determination of Inorganic Chlorides in Crude Oils by Direct ASD L. V. SORG. StandElectrometric Titration. R. E . DICKEY ard Oil Co. (Indiana), Sugar Creek, Mo. Deterniination of Sitrogen in Volatile Organic Compounds by a Semimicro-Dumas Method. €3. B. BUCHANSN, M. D. GRIMES, D. E. SMITH,AND B. J. HEINRICH,Phillips Petroleum Co., Bartlrsville, Okla. Determination of Water in Gaseous Propane by Mean% of Infrared Spectroscopy. \\’. S.GALL~TTAY, Universal o i l Products Co., Riverside, I11 Continuous Infrared Determination of Ethylene Oxide in Pilot Plant Facilitates Process Development. I. HASEGAWA ASD R . G. SmfARD, Atlantic Refining Co., Philadelphia, Pa. Determination of Naphthalene, Rlethvlnaphthalenes, and Total Xaphthalenes in Admixture IT ith Other Hydrocarbons by Cltraviolet Absorption. J. -4.ANDERSOS, JR.,Humble Oil and Refining Co., Raytonn, Tea. Applications of X-Ray Diffraction Methods to Rapid Analyses in the Petroleum Industry. H ~ R O L K. D HUGHES,JOHNW. WILCZEWSXI, AND J. B. RATHER,JR., Socony-Vacuum Laboratories, Brooklyn, S . Y . Determination of Total Olefin and Total Aromatics in Hydrocarbon Mixtures by Raman Spectrometry. J . J. HEIGL, J. F. BLACK,A N D R. F. DUDENBOSTEL, JR.,Standard Oil Development Co., Elizabeth, S. J.
Fourth Annual Analytical Symposium Fourth Annual Analytical Symposium, sponsored by the T Analytical Division, Pittsburgh Section, CHEMICAL SOCIETY, \Till be held a t the Hotel William Penn, Pittsburgh, Pa., HE
.%AIERICAS
,January 20 and 21,1949. I n addition to a talk by I. 11. liolthoff on “The Role of Reaction Kinetics in dnalytical Chemistry,” the folloxing preliminary program has been arranged. Method for Volumetric Determination of Unsaturated and BALL. Aromatics in ilnalysis of Gases. EDMCND J. R. dtmosphere Studies in Emlssion Spectroscopy. CHURCHILL. Statistical Methods in Analytical Chemistry. B. L. CLARKE Ultraviolet Absorption Analysis for Saphthalenes. NORMAN D. COGGESH.4LL AND ALVIS s. GLESSNER, JR. Comparative Study of hIethods for Determination of Kickel. M.D. COOPER. Organic Polarography. PHILIP J. ELVING. Analrsis of Molybdenum-Tungsten and Cobalt-llolybdenumL. EMERSON. Tungstkn High Speed Steels. ‘CTALDO Isoquinoline as a Reagent in Inorganic Analysis. Zinc. HENRYFREISER AND ADOLPH E. SPAKOTVSKI. Determination of Nitrogen in Steel. JOHK L. HAGUE. Operational Experiences with Infrared Gas Analysis. WILLIAM J. HAPPEL AKD S O R J f A N D. COGGESHALL. Improved Method for Determination of Phosphorus in Alloys. J A M E S L. KdSSNER. Electrolytic Separations in the Platinum Group with Controlled Cathode Potential. Seuaration of Rhodium and Iridium. iJrILLIAM R I A C S E V I K . * Purity Determinations as Ascertained by Phase Subjects. IT.J. MADER.4ND H. A. FREDIANI. Vacuum Fusion Analysis. W.PEIFFER. Determination of Tin in Plain Carbon Steel by Sulfide Separation and Iodate Titration. IT7. R SAYRE. Separation of Cesium from Other Alkalies, and Preparation of Cesium Bromide. V. A . STENGER. Discussion periods will follow the scheduled addresses. Walter J. Murphy, editor of Industrial and Engineering Chemistry and ~ N A L Y T I C A LCHEMISTRY, d l act as toastmaster for the banquet to be held January 20, sponsored jointly by the Analytical Division and the Pittsburgh Section. Dean Burke, Xational Cancer Institute, will speak on “Cobalt and Iron Chelation in. Biochemical Function and Antibiosis.” The following companies will be among those exhibiting new analytical tools: A. S. Aloe Co., American Optical Co., H . Reeve Angel and Co., Bausch B: Lomb Optical Co., Boder Scientific Co., Burrell Technical Supply Co., Central Scientific Co., Coleman Electric Co., Eimer & .%mend, Fisher Scientific Co., Harshaw Scientific Co., Research .%ppliance Corp., and Arthur H. Thomas Co. Hotel reservations should be made directly with the Hotel iYilliam Penn. Those interested in obtaining copies of the complete program and abstracts, t o be ready early in January, should write to Dwight L. Deardorff, Rlellon Institute, Pittsburgh 13, Pa. Fourth Annual Analytical Symposium. Hotel William Penn, Pittsburgh, Pa., January 20 and 21, 1949. Second Symposium on Analytical Chemistry. Louisiana State University, Baton Rouge, La., March 2 to 5 , 1949. Second Annual Summer Symposium on Analytical Chemistry. Wesleyan University, Middletown, Conn., June 1949. Fourth Instrument Conference and Exhibit, Municipal ludltorium, St. Louis, Mo., September 12 to 16, 1949.
