971
D E C E M B E R 1947 analysis or titrimetry, colorimetry is a close second, and if combined with those on the very similar method of spectrophotometry, exceeds every other method. Instrumental methods of analysis comprise 56% of all papers, the first five being (in decreasing order) colorimetry, spectrophotometry, emission spectrography, instrumental titrimetry (volumetric analysis), and polarography. Statistically outstanding steps preliminary t o the final determination are (in decreasing order) adsorption (especially chromatography), extraction, precipitation, distillation, sampling, and filtration. Next to English, the language in which most 1946 analytical papers are written is Russian: French, Spanish, and Italian follow in that order. Tabulation of the countries in which the research for papers was done gives, in decreasing order, United St,ates, Great Britain, V.S.S.R., France, Sweden, etc. More than half of the papers (5S%j are on the determination of organic compounds.
ACKNOWLEDGMENT
The author is indebted to Earl J. Serfass for his interest in the progress of this paper and for his helpful advice and criticism. LITERATURE CITED
(1) Conklin, R. B . , J . Chem. Education, 24, 271 (1947). (2) Ibid., p. 272. (3) Crane, E. J . , Chem. Eng. Sews. 24, 3353 (1946). (4) Dunkelberger, T. H . , J.Chem. Education, 24, 383 (1947). (5) Green, J. C . , Chem. Ene. News,25, 1335 (1947). i(1947). (6) Hallett, L. T., ANAL.CHEM.,19, No. 1, 17 ; (7) Harris, R. L . , J . Chem. Education, 24, 392 (1947). (8) Kolthoff, J . SI., and Ssndell, E. B., “Textbook of Quantitative Inorganic Analysis,” N e w York, Macmillan Co., 1936. (9) Lambert, R . H . , J . Chem. Education, 23, 2, 610 (1946). (10) Muller, R. H., Ari.4~.CHEM.,19, No. 1, 24 -1,(1947). (11) Ibid., KO.5, 26 A (1947). (12) I b i d . , KO.1, 23 A (1947). RECEIYEDOctober 6 , 1947.
Determination of Olefinic Unsaturation Cooperative Evaluation of Nitrogen Tetroxide Methods E. T, SC.iFE AKD JOHN HERSI.4N, Research and Development Laborutories, Socony-Vacuum Oil Co., Paulsboro, N.J . G. R. BOND, JR., Houdry Process Corporation of Pennsylvania, W‘Vilmington, Del., AND’ COOPERATORS1
Two standardized procedures for the determination of olefins by reaction w-ith nitrogen tetroxide were cooperatively evaluated by an A.S.T.Rl. group. The results of this work indicate that the methods give a satisfactory value for total olefin content of hydrocarbon mixtures i n the gasoline boiling range which contain other than highly branched olefins. Further work is planned on highly- branched olefins of the
D
URIXC: the war, Subcommittee XXV \vas organized under Committee D-2 of the American Society for Testing
Materials for the purpose of developing methods of analysis of petroleum products for hydrocarbon types. Of particular interest to this group was the reaction of nitrogen tetroxide with olefin hydrocarbons as a possible basis for a procedure for quantitative determination of the olefin content of hydrocarbon mixtures. Previous work by Bond (3) indicated that, under certain prescribed conditions, nitrogen tetroxide was void of the conflicting reactions associated with halogen titration procedures, and two general procedures utilizing nitrogen tetroxide were outlined Tvhich were proposed as possible replacements for, or supplements to, the commonly used bromine number methods for determination of olefins. The evaluation and standardization of these procedures were placed under the jurisdiction of Section B of Subcommittee XXV. The work undertaken by this section involved (1) improvement of the design of apparatus and operating technique, and (2) cooperative evaluation of standardized procedures as test methods for determination of olefins. Sine laboratories cooperated in this phase of the work. The present paper presents in some detail the present statu? of the development work, and the limitations and precisions of the methods as interpreted from the data and contributions of the cooperators. 1
E . L. Baldeschwieler, Standard Oil Development C o . L.31. .Henderson, Pure Oil Co. S.S. Kurtz, Jr., Sun Oil Co. H. Levin, The Texas Co. C. E. Starr, Standard Oil Co. of New Jersey, Louisiana Division E. B. Tucker, Standard Oil Co. of Indiana F. D. Tuemmler, Shell Development Co.
di- and triisobutylene type. The need for estimating olefin molecular weights, required with bromine number methods, is eliminated. Method 4 provides an olefiwfree portion of the test sample which is suitable for additional analysis for other hydrocarbon types. Future work will further improve the precision and accuracy of the methods and extend their applicability to highly branched olefins, OUTLINE OF METHODS
Method A. Steam-Distillation Procedure. Gaseous nitrogen tetroxide is passed into the chilled sample to react with the olefins. At the end of the reaction, an aqueous solution of urea is added to decompose the excess nitrogen tetroxide. The mixture is steam-distilled, the unreacted hydrocarbons being removed as the distillate. The content of total olefins is obtained from the difference in volume of the unreacted hydrocarbons and the volume of the original sample. This procedure, in addition to determining the olefin content, produces an essentially olefin-free portion of the sample, which may be used for determination of other hydrocarbon types. Method B. Direct Volumetric Procedure. Gaseous nitrogen tetroxide is passed into the chilled sample to react with the olefins. The nitrosates formed react with 70mm.O.D. alcoholic potassium sulfide solution, permitting the measurement of the unreacted portion of the test sample. The content of total olefins is obtained from the difference in volume of the unreacted portion of the test sample and the original volume of test Sam le.Tfis method is applicable where only the total olefin Figure 1. Treating-Discontent of the sample is retilling Flask quired.
1
V O L U M E 19, NO. 1 2
972
separatory funnel for collecting the steam-distilled product, and a dry ice aftercondenser t o minimize loss of product by vaporization. Type 2 receiver (Figure B-5 B-6 B-7 B-8 4) was essentially the same design as that Components Vol. % Vit. % Vol, % Wt. 70 Vol. 'Z Wt. % Vol. % Wt. 74 described in a previous publication (3). ... 0.5 ... 0.5 Hexene-3 1.0 0.9 1 .o 0.9 REAGENTS.Urea or sulfamic acid ... 13.4 ,.. 7.6 14.0 6.7 6.9 8.0 Octene-1 solution was recommended for destroy... 5.0 ... 5.0 4.0 4.0 2 9 3.0 Decene-1 11.6 1 2 . 0 . . . . . . . . ... Diirobutylene ing the excess nitrogen tetroxide after ,.. 6.0 6.0 ... ... ... Nonenes (mixed) ... treatment of the sample. Urea solution ... 6.5 7.0 ... i:0 2.2 Cvelohexene ,.. was used by most of the cooperators. 1.5 , . . ... 1.4 ... 2.0 1.9 2-"Methylpentadiene , . . 1 . 8 1.5 2.4 2.0 a-Methylstyrene L4LCOHOLICSOLUTIONS OF REAGENTS. Oklahoma City Most of the cooperative work was obnaphtha, straighttained with ethanol solutions of reagents, 82.0 82.4 71.0 70.9 81.0 89.1 89.5 81.0 run but more recent work has indicated that 1oo.o 1oo.o 1oo.o 100.0 i m 1oo.o 1oo.o 1oo.o Totals 1 7 . 6 2 9 . 1 1 8 . 0 1 9 . 0 2 0 . 0 methanol is more suitable, since the 19.0 10.9 10,5 Total olefins Total olefins, a v . ethanol solutions of sodium hydroxide or 115 107 104 116 mol. wt. potassium hydroxide darken on standing. PROCEDURE.With the use of Type 1 product receiver, the steam-distillation Table 11. Properties of Olefins Used in A.S.T.31.Cooperative Samples procedure was as follows: B-5 to B-8 Literature Values The flask containing the treated samRefrac- Bromine TheoRefractive ple vas connected to ;he assemhled contive Xo, by Specific retical Density, Index* >lethod Disper- Bromine Density index, Referdenser and product receiver Type 1 d2a ngo ES-45, slon No. d 20 nY ence Sample (Figure 3). The separatory funnel con0.6890 1.3986 174 133.2 189.8 cis-0.6796 1.3934 (1) taining a few milliliters of water was Hexene-3 trans-0.6779 1.3938 (1) surrounded with an ice water bath, the 2-hI e thylnitrosate trap filled with water, and the 0,7183 1.4469 234 226.8 388.8 0.719 1.446 (1) pentsdiene 0,9092 1.5381 13: 135.2 0.9106 1.5386 (1) aftercondenser filled with dry ice. The a-Nethylstyrene 0.7177 1,4100 149 12i:Z 142.4 .... .... Diisobutylene steam-distillation was carried out by im0 . 7 4 1 3 1.4214 110 113.6 118.9 0.!396 1.4220 (4) Decene-1 mersing the distilling-treating flask in 0.7158 1.4083 139 117.1 142.4 0.t160 1.4088 (1) Octene-1 boiling water and introducing steam 0.8106 1.4463 182 119.0 194.4 0.8108 1.4467 14) Cyclohexene 0.7302 1.4251 123 116.5 126.5 .... ,... .. Mixed nonenes through the three-way stopcock of the adapter (Figure 2), until the distillate became heavier than water and settled to the bottom of the nitrosate trap The unreacted hydrocarbon, after the water had been drawn off, h was shaken with 10 ml. of alcoholic sodium hydroxide solution. mater was then added. the mixture agitated and allowed to settle, and the aqueous layer drawn off. Measurement of the volume of the hydrocarbon layer was carried out as described (3). Table I.
Composition of Synthetic Blends of Olefins for Cooperative Testing i n A.S.T.RI. D-2 XXV-B
In F
B
0
n(
Figure 2.
Adapter
METHODS USED IN COOPERATIVE WORK
The analytical procedures used in the cooperative work were essentially those described in a previous publication (S), with the following exceptions:
Method A. APPARATUS.The apparatus was designed t o minirnize handling and distillation losses, since Method A requires careful volume measurements to determine olefins by differmce. This apparatus, constructed of glass, inrluded a treating-distilling flask (Figure l), an adapter for connecting the flask t o the steam-distillation setu (Figure 2), an efficient condenser, and a producat receiver assemby. Two tvpes of product receivers were tested cooperatively. Type 1 (Figure 3) consisted of a water trap for nitrosates, a
Figure 3.
Product Receiver Assembly, Type 1
D E C E M B E R 1947
973 sample into the graduated section of the neck of the bottle. After the bottle was shaken and centrifuged, the volume of unreacted sample was measured (3). COOPERATIVE EVALUATION OF METHODS
Cooperative testing of the nitrogen tetroxide procedures W M carried out by nine laboratories, and the results obtained on a set
Table 111. Inspections on Base Stock" Used in Preparing A.S.T.M. Cooperative Samples B-5 to B-8 Gravity, A.P.I. A.S.T hl. Distillation, I.B.P. 5% 10% 20% 30%
56.2
F
192 . _ ~
222 231 241 250 259 266
gq
274
60%
284 29.5 310 3 58 99.0 0.9 0 1 1.4194 0 7489 1 2 0.1 108 0 11.5 0.009
70%
U Figure 4.
Product Receiver Assembly, Type 2 @
In the use of Type 2 product receiver, a Slow &eam of air was passed into the side tube of the adapter, just sufficient to overcome the hydrostatic pressure in the separatory Funnel receiver. The proredure given in a previous publication f3) is considered equally satisfactory. In the cooperative work only the alcoholic sodium hydroxide and water washes were applied to the hydrocarbon distillate. The procedure given in the previous publication indudes a wash with alcoholic potassium sulfide solution. Method B. APPARATUS. No specialized ap aratus was required for Metiod B, the determination being carried out in a modified Babcock bottle ( 2 ) . REAGESTS. The cooperative work was carried out with ethanol solutions of reagcnts, but more recent work indicates methanol to be more sui table. PROCEDURE. I n the cooperative work, the following procedure was used in treating the sample after the reaction with nitrogen tetroxide: Dilute alcoholic sodium hydroxide solution was added with agitation of the bottle, until a light red color of the lowcr layer was obtained. Next, 11 to 12 ml. of alcoholic potassium sulfide solution were addcd gradually, and the bottle mas stoppered and vieorouslv shaken for 0.5 mhute. "After cooling, 11 to 12 ml. of water were added. followed by the addition of sufficient alcohol-water solution (1 to 1) to bring the unreacted portion of test
Table IV.
Summary of Determination of Olefin Content of A.S.T.>\Z. Cooperative ' Samples by Nitrogen Tetroxide Methods Volume % Olefins0 RIethod A Product Product Method receiver 1 recelx er 2 B
Laboratory
!$.?
11.4
L 1 . l
D E F G
*
80% 90% E.P. Recovery, To Residue, % Loss,,5% Refractive index, ng0 Density, d'o Reid vapor pressure. Ib./s Bromine No. (ER-45,) Fperific disperLion Total acid absorption, vol. -458) Sulfur. ! x - t . % Oklahoma City straight-ruu naphtha.
H I 1" .A
B C D
11.3 13.2 11.0 11.2 11.9 10.8 15.3'. (11.6)
12:2 13.8 12.5 11.2 12.4 10.2 13.7 (12.2)
21.3
20.0
19.5
Ab.
20.4 19.4 19.9 19.3 19.0 18.9 20.5 (19.8)
19.7 19.6 19.7 19.1 31.2b 19.1 19.7 (19.6) 31.2
iv.
30.0 29.9 30 0 29.0 27 0 29.1 27.0 28.6 32.2 (29.2)
E
F G H
r
.A
B C
D
E
F G
H
I
2916 29.2 28.7 29.3 31.0 30 2 29.5 (29.8)
12.0
11.8 11.5 12.0 13.0 12.0 14.0 11.3 15.0 112.5)
Deviation from Volume % Deviation from Average Olefins Blended Xethod A Method .4 P i o d u c t P r o d u c t Method Product P r o d u c t Method r e r u l er 1 receiver 2 R receiver 1 receiver 2 B 0.8 0.5 0.3 1.6 0.6 0.4 0.3 0.8 3.7b (0.7)
Samule B-6 1.5 20.0 0.2 21.5 0.6 19.5 0.4 19.5 0.1 0.5 19 5 22.0 0.8 19.3 0.9 21.5 0.7 (20.3) (0.8) 20.0
30.7 30.4 31.0 28.8 30.1 29.5 28.0 28.0 32.0
:29,9)
Snmple B-7 0.8 0.7 0.8 0.2 2.2 0.1 2.2
0.6 2.0 (1.1)
0.8
0.0 1.6 0.3 I .o 0.2 2.0 1.5 (0.9) 0.4
..
0.1 0.0 0.1 0.5 11.66 0 . .5 0.1 (0.2) 1 4 0.2 0.6 1.1 0.5 1.2 0.4 0.3 (07)
Painple B-8 16.0 0.9 2.1 16.9 18.3 B 16.3 14.5 0.3 17.6 17:5 17.0 1.6 1.3 C 1) 15.0 14.8 15 3 1.2 0.7 1 6 ,5 E 1.2 0.9 14.8 15.3 13.0 0.6 0.7 15.4 15.5 F G 16.0 9.7h 15.4 6.3t 0.8 15.0 1.5 1.2 [I 14.5 15.0 19.0 I 2.0 1.1 18.0 17.3 A v . (16.0) (16.2) (16.0) (1.2) (1.1) Volume Yo olefins listed are averages reported from each laboratory 6 S o t included in averages. .\
0.5 0.7 1.0 0.5 0.5 0.5 1.5 1.2 2.5
1.5 0.2 0.4 2.3 0.1 0.3 1.0 0.1 4.46
0 ,5 1',3
2.9 1.6 0.3 1.5 0.7 2.8
1.1
0.Y 0.6 1.1 2.1 1.1 3.1 0.4 4.1
1.u 1.0
2.3
L.0
0.3 1.2 0.8 0.8 0.8 1.7 1. o 1.2
0.6 1.4 0.4 0.9 0.3 0.0 0.1 1.5
0:i 0.6 0.7 0.1 12.2b 0.1 0.7
0.8 0.5 1.1 1.1 0.2 0.4 1.9 0.9 2.1
1.0 0.9 1.0 0.0 2.0 0.1 2.0 0.4 3.2
2.2
1 1.4
0.6 0.2 0.3 0.3 2.0 1.2 0.5
2.0
1.1
0.3,
1.I!
O.i 2.5 2.7 2.5
1.0 3.0 1.5 3.0 2.0 3.0 1 .o
0.3
0.0 1.5 1.0
1.0 0.5 1.0 0.0 1.0 3.0
*
1. i 0.4 3.2 3.2 2.6 8.3b 3.5 0.0
~ _ _
2.6
3.0 0.7
2.5
0.5 0.5 0.5
3.0 0.3 2.5
0.2 1.1 0.5 1 .o 0.0
3.0
3 .5
V O L U M E 19, NO. 1 2
974 Table V.
Summary of Standard Deviations Found in Determinations of Olefin Content of Cooperative Samples B-5to B-8 by Nitrogen Tetroxide Rlethods
Olefins, Volume % Standard Deviation No. of Average Found0 From Blended From Av. Found Determinations Method A Method A Method 4 Method A Product Product Product Product Product Product Product Product receiver receiver receiver receiver receiver receiver receiver receiver Blended 1 2 Method B Sample 1 2 Method B 1 2 Method B 1 2 MethodB 11.6 12.2 12.3 B-5 10.9 1.2 1.8 1.8 1.0 1.3 1.2 16 15 21 19.8 19.6 20.3 B-6 19.0 1.3 0.7 1.6 1.1 0.5 1 0 17 14 21 28.9 30.0 30.0 299 .00 1.3 B-7 2 1.5 1.7 1.4 1.1 1.2 17 17 27 B-8 18.0 16.0 16.2 15.9 2.4 2.2 2.5 1.4 1.3 1.4 15 16 21 All samples .. .. .. .. 1.6 1.7 1.9 1.2 1.0 1.2 65 62 90 B-5 to B-7, inelusive .. .. .. 1.3 1.4 1.7 1.1 1.0 1.1 50 46 69 a Averages based on individual determinations.
..
of synthetic mixtures of olefins are reviewed herein, as offering the best indication of the precision and accuracy of the method as developed and standardized at the present time. Data on the composition of the test samples, designated B-5 to B-8, are given in Table I, and the properties of the olefins and the base stock used in preparation of the samples are given in Tables I1 and 111, respectively. I n general, the samples were made up t o contain the following types of olefins: Qarnple No.
Trpes of Olefins liormal olefins Sormal cyclic and aromatic olefins and a diolefin h'orrnal: cyclic: and aromatic olefins and a diolefin Highly branched olefins
B-5 3-6 B-7 B-8
As indicated by the deviations shown for sample B-8, both procedures give poorer results on highly branched olefins than on mixtures of other types of olefins. In general, the highly branched olefins are more difficult to react completely with nitrogen tetroxide, and the nitrosate reaction products formed are less readily separated from the unreacted hydrocarbons than is the case with othcr types of olefins. A summary of the deviations found on each of the samples cooperativelv tested is given in Table V. With regard to Method -1,the data in this table show no marked difference in precision of results obtained with the two types of product receivers tested.
While the purity of the olefins used has not been definitely established, the data in Table I1 show that the properties of the olefins (with the exception of hexene-3) are in fairly good agreement s i t h the literature values (1, 4 ) . A summary of the results obtained for total olefin content by the nitrogen tetroxide methods is given in Table IV.
li
DISCUSSION
A sthtistical analysis of the data obtained in this evaluation of the nitrogen tetroxide methods for olefins gave the following standard deviations:
Method A (product receiver Type 1) All samples B-5 to E-7, inclusive B-8 Method B All samples B-5 t o B-7,inclusive B-8
Standard Deviation (Based on Total Sample) From % From av. '36 olefin blended olefin found
THRtE BRACLS
1
1.6 1.3 2.4
1.2 1.1 1.4
1.9 1.7 2.5
1.2 1.1 1.4
Comparable data on these samples by a bromine titration procedure (h.S.T.M. ES-45a, 2) show a standard deviation of 1.1 based on the average of all determinations of bromine number. This value is of the same order of magnitude as that indicated by the nitrogen tetroxide procedure. Inasmuch as the bromine number procedure requires an estimation of the molecular weight and. specific gravity of olefins present in the mixture to convert to volume per cent olefins, the direct volumetric determination of olefins by the nitrogen tetroxide procedure is considered fundamentally more reliable. The above data show that Method B compares favorably with Method A, and because of its relative simplicity and rapidity, use of Method B is indicated in cases where only the volume per cent olefins is required.
ROTATL 90'
ro B A C K ,
I\
n
U
R€C€/VER STOPPER S.J. 28/15 SOLID
Figure 5, Apparatus for Nitrogen Tetroxide Method of Olefin Determination
DECEMBER 1947
975
depentanized gasolines. I t is probable that suitable modifications of apparatus and Product Receiver T y p e 2 Product Receiver T y p e 1 procedure can be developed 4 x Acid to handle samples containing Bromine absorption Bromine abs-&tion by method No. b y by method Refractive No. b y Refractive appreciable amounts of penES-45a, method Density, index; method ES-ljn&. Density, index. ES-45, vol. , O d'n 20 ES-45, vol. YC tanes and lighter hydroLab. d*O ng carbons. Straight-Run Base Stock A recent design of apparatus 11.5 1.4194 11.5 0.7489 0.1 0.1 0.7489 1 4194 for Method A, submitted by Sample B-5 tk.e Shell Development Company laboratory, is shown in 10.5 0.7504 1.4194 0.0 9.0 1.4198 0.0 A 11.0 .... .... 0.2 B 1.4184 Figure 5 . While this appa12: 5 11.4 1.4201 0.7512 0:05 0.05 1.4197 C 11.2 1.4201 11.4 ratus has not been coopera0.7512 0.1 0 1 1.4196 D 11.5 .... .... 0,s 1.4198 E tively tested, it has been used 0:0 12:o 12.0 0.7481 1.4196 0.0 1.4196 F 1.4203 11.3 0,7822 0.13 12.5 1,4202 0.23 G by several laboratories and 1.4199 0.7507 H 1.4199 appears to have certain adii:o 1,4204 0:i 10:s 0:3 0.7506 1,4202 I vantage?, such as saving in ( 0 . 7 5 0 6 ) (1,4200) to. IO) (0.17) (11.2) (11.3) AY. (0.7504) (1.4197) laboratory space and in time Sample B-6 required to make a determina10.0 0,7308 1,4193 0.0 11.0 A 0.7502 0.0 1.4198 tion. 11.0 ..... .... 0.1 B 0.7485 1.4189 12.3 0.7511 1,4200 0:08 11:3 0.05 C 0.7505 1.4197 T n o possible hazards exist 0.7506 11.7 t.4196 0.1 11.2 0.1 D 0.7507 1.4196 1.4206 in the handling of nitrogen 0.7528 0.5 .,. 11 .o E ........... 1.419z 12:o 0,7489 0.0 0.0 11.0 F 0.7481 1 4196 tetrolide in combination with 1.419s 12.2 0.7508 0.14 0.18 10.8 G 0.7545 1 4204 1.4199 0,7506 H 0.7613 1.4199 olefins-namely, the degree of ii:o 0.7505 1,4203 0:3 ii.5 0:3 I 0.7501 1 ,4202 stability of the reaction prod(11.5) ( 0 . 7 5 0 7 ) (1.4199) (0,lO) 10.16) (11.3) 4 v . ( 0 , 7 5 0 5 ) (1.4198) ucts and the toxicity of nitroSainplp B-7 g m tetroxide. While several 10 5 0 . 7514 references have been made 1.4201 0.0 0.0 11.5 A 0.7506 1.4199 10.0 .... 0.1 B 0.7485 1.4177 to the fact that reaction prod0.7517 1: 4202 0.10 0:08 l2:8 12.0 c 0.7505 1.4195 11.2 0.7509 1.4194 0.2 D 0.7499 1.4191 0.7 11.2 ucts of light olefins and di.... 0.5 .... 12.0 E 0,7529 1 ,4203 olefins n ith nitrogen tetroxide 12.5 0.7493 1.4198 0:0 0.0 12.0 F 0.7491 1.4197 0,7618 1.4195 16 3 a 0.09 0.06 G O.761ga 1.4214 11.3 are unstable, an investiga1.4202 0.7509 H 0.7510 1.4198 0.7512 lo.@ 1 4203 0:3 0:3 I 0.7500 1.4198 ii:o tion of the products from (0.7510) (1.4199) (0.22) (11.2) (0.11) Av. (0.7503) (1.4197) (11.6) representative samples, such as thermal and catalytic gasoSample B-8 line and pentenes, show them 12.0 0.7523 1.4199 0.1 0.2 1.4194 .4 0 7528 9.5 10.5 0.6 .... to be nonexplosive, even by 1.4183 B 0.7486 0 : 7k38 1.4198 12.8 0.18 0 : io 0.7514 1.4197 13:5 C the use of detonators (6). How1 3 . 2 0.7335 1 . 4 1 9 4 1.4 1.3 0.7513 1.4192 D 13.2 12.5 0.5 .... .... 0.7557 1.4193 E ever, olefin-nitrogen tetrox1 4 . 0 0.7605 1 . 4 1 9 6 1.4195 1.0 117 F 0.7505 14.0 1,4203 ide compounds are thermally 20.1n 0,7583 0.46 0.15 1,4220 G 0 .7680a 14.3 1.4200 0,7564 1 ,4200 H 0,7559 unstable and subject to rapid 0.7513 13:5 1.4202 0:3 0:3 1 ,4204 12.0 I 0.7582 decomposition if heated di(0.7537) ( 0 . 5 8 ) (12.6) (1.4200) (0.61) Av. ( 0 . 7 5 2 7 ) (1.4198) (12.8) rectly much above 250" to a N o t included in averages. 300'F. Violent reactions have occurred where nitrogen tetroxide has been left in contact with hydrocarbons for long periThe average values for handling loss, as obtained by "blank" ods of time. The presence of oil in pipes, valves, etc., used for determinations on the samples, were 0.45 ml. with product renitrogen tetroxide should be avoided. ceiver Type 1 and 0.55 ml. with product receiver Type 2. The The nitrogen tetroxide reaction should be carried out under a Type 1 receiver is preferred for the more volatile samples. hood, and observance of safe laboratory practice in handling toxic Since the same straight-run base stock was used in the four gases i* recommended (5). synthetic mixtures used in the investigation, the properties of the "unreacted portion" of test sample obtained by Method ; i can be compared with those of the base stock to indicate completeness LITERATURE CITED of olefin removal and absence of undesirable side reactions. This (11 . h i . Petroleum Inst., Research Project 44, "Selected 1-alues of comparison is shown in Table VI, which gives the average of Properties of Hydrocarbons," Tables Sa, loa, l l a , 13a, Natl. determined properties such as density, refractive index, bromine Bur. Standards, June 30. 1945. number, and acid absorption on the unreacted portions of samples ( 2 , A m Soc. Testing Materials. Emergency Method E9-45a, "AS.B-5 to B-8. Except in the case of sample 13-8, these properties T.M. Standards on Petroleum Products and Lubricants," 1945. This niethod has been redesignated -1,S.T.M. Method DS75are fairly close t o those of the original base stock, indicating 46T. practically complete removal of olefins without substantial change ( 3 ) Bond. G. R., Jr., ISD. ENG.CHEM.,AS.\L. ED.,18, 692-6 (1946). in the other hydrocarbon types. Density and nitrogen deter( 4 ) Doss, M. P., "Physical Constants of the Principal Hydrominations, ho\wver, indicate nitrogen tetroxide reaction products, carbons," 4th ed., New York, The Texas Co., 1943. ( 5 , Jacobs, Ai. B., "Analytical ChemistrJ- of Industrial Poisons, in amounts of the order of 0.05 to 0.25% by nxight, remaining in Hazards. and Solvents," p. 280, New York, Interscience Pubthe unreacted portion. lishers, 1941. Since the reaction of olefins with nitrogen tetroxide is carried ( G i Uahley, H. S., unpublished results obtained by two cooperators out in a temperature range of 80" to 100" F., the procedures given with assistance from an explosives manufacturing company. are limited to mixtures containing hexanes or higher boiling hydrocarbons, and therefore should find application in analysis of RECEIVED February 15, 1947.
Table VI. Comparison of Properties of Unreacted Portion of Test Sample Obtained by Nitrogen Tetroxide 3Iethod A with Properties of Base Stock Used in Test Samples
