Determination of Olefinic Unsaturation

D E C E M B E R 1947

analysis or titrimetry, colorimetry is a close second, and if com- bined 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 spec- trography, instrumental titrimetry (volumetric analysis), and polarography. Statistically outstanding steps preliminary to 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.

971

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) . (6) Hallett , L. T., ANAL. CHEM., 19, No. 1, 17 ;i (1947). (7) Harris, R. L . , J . Chem. Education, 24, 392 (1947). (8) Kolthoff, J . SI., and Ssndell, E. B., “Textbook of Quantitative

Inorganic Analysis,” New 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) Ib id . , KO. 1, 23 A (1947). RECEIYED October 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

URIXC: the war, Subcommittee XXV \vas organized under D 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 con- flicting reactions associated with halogen titration procedures, and two general procedures utilizing nitrogen tetroxide were out- lined Tvhich were proposed as possible replacements for, or supple- ments 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 cooper- ated 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

1 70mm.O.D.

Figure 1. Treating-Dis- tilling Flask

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 Volu- metric Procedure. Gaseous nitrogen tetroxide is passed into the chilled sample to react with the olefins. The

-

nitrosates formed react with 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 content of the sample is required.

972 V O L U M E 19, NO. 1 2

separatory funnel for collecting the steam-distilled product, and a dry ice aftercondenser to minimize loss of product by vaporization. Type 2 receiver (Figure 4) was essentially the same design as that described in a previous publication (3).

REAGENTS. Urea or sulfamic acid solution was recommended for destroy- ing the excess nitrogen tetroxide after treatment of the sample. Urea solution was used by most of the cooperators.

Most of the cooperative work was obtained with ethanol solutions of reagents, but more recent work has indicated that methanol is more suitable, since the ethanol solutions of sodium hydroxide or potassium hydroxide darken on standing.

PROCEDURE. With the use of Type 1 product receiver, the steam-distillation procedure was as follows:

The flask containing the treated sam-

L4LCOHOLIC SOLUTIONS OF REAGENTS.

Table I. Composition of Synthetic Blends of Olefins for Cooperative Testing in A.S.T.RI. D-2 XXV-B

B-5 B-6 B-7 B-8 Components Vol. % Vit. % Vol, % Wt. 70 Vol. 'Z Wt. % Vol. % Wt. 74

Hexene-3 Octene-1 Decene-1 Diirobutylene Nonenes (mixed) Cvelohexene 2-"Methylpentadiene a-Methylstyrene Oklahoma City

naphtha, straight- run

Totals Total olefins Total olefins, a v .

mol. wt.

1 .o 6 . 9 3 . 0

, . . . . . , . . . . .

0 . 9 6 . 7 2 9

1 . 0 8 . 0 4 . 0

. . i : 0 2 . 0 2.0

0 . 9 7 . 6 4 .0

2 . 2 1 . 9 2 . 4

. . .

. . .

0 . 5 14.0 5 . 0

6 . 5 1.5 1.5

. . .

. . .

0 . 5 13.4 5 . 0

7 . 0 1 .4 1 . 8

. . .

. . .

. . . , . . . . . 1 2 . 0 6 . 0

. . . , . . , . .

. . .

. . .

. . . 11.6 6 . 0

. . .

. . .

89.1 8 9 . 5 8 1 . 0 8 1 . 0 71 .0 70.9 8 2 . 0 82.4

1 0 . 9 1 0 , 5 1 9 . 0 1 9 . 0 2 0 . 0 29 .1 1 8 . 0 17 .6 1oo.o 1oo.o 1oo.o 100.0 im 1oo.o 1oo.o 1oo.o

115 107 104 116

Table 11.

Sample Hexene-3

2-hI e thyl- pentsdiene

a-Nethylstyrene Diisobutylene Decene-1 Octene-1 Cyclohexene Mixed nonenes

Properties of Olefins Used in A.S.T.31. Cooperative Samples B-5 to B-8

Literature Values Refractive Refrac- Bromine Theo-

tive Xo, by Specific retical Density, Index* >lethod Disper- Bromine Density index, Refer-

d2a ngo ES-45, slon N o . d 20 nY ence 0.6890 1.3986 174 133.2 189.8 cis-0.6796 1.3934 ( 1 )

trans-0.6779 1.3938 (1)

0,7183 1.4469 234 226.8 388 .8 0.719 1.446 (1 ) 0,9092 1.5381 13: 135.2 0.9106 1.5386 (1)

0.7413 1.4214 110 113.6 118 .9 0.!396 1.4220 (4) 0.7158 1.4083 139 117.1 142.4 0 . t 1 6 0 1.4088 ( 1 ) 0.8106 1.4463 182 119.0 194.4 0.8108 1.4467 14) 0.7302 1.4251 123 116.5 126.5 . . . . , . . . . .

0.7177 1,4100 149 12i :Z 142.4 . . . . . . . .

ple vas connected to ;he assemhled condenser and product receiver Type 1 (Figure 3). The separatory funnel containing a few milliliters of water was surrounded with an ice water bath, the nitrosate trap filled with water, and the aftercondenser filled with dry ice. The steam-distillation was carried out by im- mersing the distilling-treating flask in boiling water and introducing steam 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, 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).

h

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 dif- fermce. This apparatus, constructed of glass, inrluded a treating-distilling flask (Figure l), an adapter for connecting the flask to 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

F B 0

n( I n 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, F

I.B.P.

56.2

192 5%

10% 20% 30%

60% 70% 80% 90% E.P. Recovery, To Residue, % Loss,, 5%

gq

Refractive index, ng0 Density, d'o Reid vapor pressure. Ib./s Bromine No. (ER-45,) Fperific disperLion Total acid absorption, vol. Sulfur. ! x - t . %

~ . _ 222 231 241 250 259 266 274 284 29.5 310 3 58

99.0 0 .9 0 1 1.4194 0 7489 1 2 0 . 1

108 0 1 1 . 5 0.009

U Figure 4. Product Receiver Assembly,

Type 2 -458)

@ Oklahoma City straight-ruu naphtha.

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

redure given in a previous

Table IV. Summary of Determination of Olefin Content of A.S.T.>\Z. Cooperative Samples by Nitrogen Tetroxide Methods '

Deviation from Volume % Volume % Olefins0 Deviation from Average Olefins Blended

pressure in the separatory RIethod A Xethod A Method .4 Funnel receiver. The pro- Product Product Method Pioduct Product Method Product Product Method

Laboratory receiver 1 recelx er 2 B r e r u l er 1 receiver 2 R receiver 1 receiver 2 B publication f3) is considered equally satisfactory.

In the cooperative work only the alcoholic sodium hydroxide and water washes were ap- D

E F

H

plied to the hydrocarbon distillate. The procedure given G in the previous publication in- dudes a wash with alcoholic * I potassium sulfide solution.

Method B. APPARATUS. No specialized ap aratus was

determination being carried C out in a modified Babcock bottle ( 2 ) . F

REAGESTS. The coopera- G

r tive work was carried out with ethanol solutions of reagcnts, but more recent work indi- cates methanol to be more

.A B

D E

H

required for Metiod B, the

!$.? 11.4 12.0 0 . 8 0 . 8 1 1 . 8 0 . 5

1 2 . 0 1 . 6 1 . 6 1 3 . 0 0 . 6 0 . 3 1 2 . 0 0 . 4 I .o 1 4 . 0 0 . 3 0 . 2 1 1 . 3 0 . 8 2 . 0 15 .0 3 . 7 b 1 . 5

1 1 . 5 0 . 3 0 . 0

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 . 4 6

0 , 5

2 . 9 1 . 6 0 . 3 1 . 5 0 . 7 2 . 8

1',3

1.1 0.Y 0 . 6 1 . 1 2 . 1 1.1 3.1 0 .4 4 .1

L 1 . l 11.3 12:2 13 .2 13 .8 1 1 . 0 1 2 . 5 1 1 . 2 11 .2 11 .9 12 .4 1 0 . 8 10 .2 15.3'. 13.7

1" (11.6) (12 .2) 112.5) (0.7) ( 0 . 9 )

Samule B-6 21.3 20.0 19.5 20.4 19.7 19.4 1 9 . 6 1 9 . 9 1 9 . 7 1 9 . 3 1 9 . 1 1 9 . 0 31.2b 18 .9 1 9 . 1 2 0 . 5 19.7

A b . (19.8) (19.6)

20 .0 20.0 2 1 . 5 1 9 . 5 1 9 . 5 19 5 22 .0 1 9 . 3 21 .5

1 . 5 0 . 2 0 . 6 0 . 4 0 . 1 0 . 5 0 . 8 0 . 9 0 . 7

0 . 4

0 . 1 0 . 0 0 . 1 0 . 5

11.66 0 . .5

. .

0 . 1

0 .3 0 . 3 1 . 2 0 . 8 0 . 8 0 .8 1 . 7 1 . o 1 . 2

2 . 3 0 . 6 1 . 4 0 . 4 0 . 9 0 . 3 0 . 0 0 . 1 1 . 5

L.0

0:i 0 . 6 0 . 7 0 . 1

12 .2b 0 . 1 0 . 7

1 . u 1 . 0 2 . 5 0 . 5 0 . 5 0 . 5 3 . 0 0 . 3 2 . 5

(20.3) (0 .8) ( 0 . 2 )

Snmple B-7 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

.A B C D E F G H I

3 0 . 0 3 1 . 2 29 .9 30 0 2916 29 .0 29.2 27 0 28.7 29 .1 29 .3 27 .0 3 1 . 0 28 .6 30 2 3 2 . 2 29.5

3 0 . 7 0 . 8 1 4 30.4 0 . 7 31 .0 0 . 8 0 . 2 2 8 . 8 0 . 2 0 . 6 30 .1 2 . 2 1 . 1 29 .5 0 . 1 0 . 5 28 .0 2 . 2 1 . 2 2 8 . 0 0 . 6 0 . 4 32.0 2 . 0 0 . 3

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

0 . 6 0 . 2 0 . 3 0 . 3 2 . 0 1 . 2 0 . 5

1 1 . 4 2 . 0 0 . 2 1 . 1 0 . 5 1 .o 3 . 0 0 . 0

i v . (29 .2) (29.8) :29 ,9) ( 1 . 1 ) ( 0 7 )

Painple B-8 .\ B C 1) E F G

16.9 1 8 . 3 1 6 . 0 0 . 9 2 . 1 1 4 . 5 0 . 3 1 7 . 0 1 . 6 1 . 3 1 5 . 0 1 . 2 0 . 7 1 6 , 5 1 . 2 0 . 9 1 3 . 0 0 . 6 0 . 7 1 6 . 0 6 . 3 t 0 . 8 1 5 . 0 1 . 5 1 . 2 1 9 . 0 2 . 0 1 . 1

0 .0 * 1 . 1 1 . 5 1 . i 1.0 0 . 4 1.0 3 . 2 0 . 5 3 . 2 1 . 0 2 . 6 0 . 0 8 . 3 b 1 . 0 3 . 5 3 . 0 0 . 0

0.3,

O . i 2 . 5 2 .7 2 . 5 2 . 6 3.0 0 . 7

1. I! 3 . 5 1 . 0 3 . 0 1 . 5 3 . 0 2 . 0 3 . 0 1 . o

1 6 . 3

14 .8 15 3 1 4 . 8 1 5 . 3 1 5 . 4 1 5 . 5 9 . 7 h 15 .4

1 4 . 5 15 .0 18 .0 1 7 . 3

17.6 1 7 : 5

[I I mhute. "After cooling, 11 to

12 ml. of water were added. followed by the addition of sufficient alcohol-water solu- Volume Yo olefins listed are averages reported from each laboratory tion (1 to 1) to bring the 6 S o t included in averages. unreacted portion of test ~ _ _

(16.0) (1 .2) (1.1) Av. (16.0) (16.2)

974 V O L U M E 19, NO. 1 2

Table V. Summary of Standard Deviations Found in Determinations of Olefin Content of Cooperative Samples B-5 to B-8 by Nitrogen Tetroxide Rlethods

Sample Blended

Olefins, Volume % Average Found0

Method A Product Product receiver receiver

1 2 Method B

Standard Deviation No. of From Blended From Av. Found Determinations

Method A Method 4 Method A Product Product Product Product Product Product receiver receiver receiver receiver receiver receiver

1 2 Method B 1 2 Method B 1 2 MethodB B-5 10.9 1 1 . 6 1 2 . 2 1 2 . 3 1 . 2 1 . 8 1 . 8 1 . 0 1 . 3 1 . 2 16 15 21 B-6 1 9 . 0 19.8 1 9 . 6 2 0 . 3 1 . 3 0 . 7 1 . 6 1 . 1 0 . 5 1 0 17 14 21 B-7 29 0 2 8 . 9 30 .0 3 0 . 0 1 . 3 1 . 5 1 . 7 1 . 4 1 . 1 1 . 2 17 17 27 B-8 1 8 . 0 1 6 . 0 1 6 . 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.

B-5 10.9 1 1 . 6 1 2 . 2 1 2 . 3 1 . 2 1 . 8 1 . 8 1 . 0 1 . 3 1 . 2 16 15 21 B-6 1 9 . 0 19.8 1 9 . 6 2 0 . 3 1 . 3 0 . 7 1 . 6 1 . 1 0 . 5 1 0 17 14 21 B-7 2 9 . 0 2 8 . 9 30 .0 3 0 . 0 1 . 3 1 . 5 1 . 7 1 . 4 1 . 1 1 . 2 17 17 27 B-8 1 8 . 0 1 6 . 0 1 6 . 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. In general, the samples were made up t o contain the following types of olefins:

Qarnple No. Trpes of Olefins B-5 liormal olefins 3 - 6 B-7 B-8 Highly branched olefins

Sormal cyclic and aromatic olefins and a diolefin h'orrnal: cyclic: and aromatic olefins and a diolefin

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 agree- ment 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.

DISCUSSION

A sthtistical analysis of the data obtained in this evaluation of the nitrogen tetroxide methods for olefins gave the following standard deviations:

Standard Deviation (Based on Total Sample)

From % From av. '36 olefin blended olefin found

Method A (product receiver Type 1) All samples B-5 to E-7, inclusive B-8

Method B

1 . 6 1 . 2 1 . 3 1 . 1 2 . 4 1 . 4

All samples 1.9 B-5 t o B-7, inclusive 1 . 7 B-8 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 com- pares 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.

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.

THRtE BRACLS

I \ ROTATL 90' ro BACK,

1 li U n

R€C€/VER STOPPER S.J. 28/15 SOLID

Figure 5, Apparatus for Nitrogen Tetroxide Method of Olefin Determination

D E C E M B E R 1 9 4 7 975

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

Product Receiver Type 1 Product Receiver Type 2 4 x - Acid

Refractive Density, index;

Lab. d*O n g

0.7489 1 4194

A B C D E F G H I

1.4198 1.4184 1.4197 1.4196 1.4198 1.4196 1 ,4202 1.4199 1 ,4202

AY. (0.7504) (1.4197)

A 0.7502 1.4198 B 0 .7485 1.4189 C 0.7505 1.4197 D 0.7507 1.4196 E . . . . . . . . . . . F 0.7481 1 4196 G 0 .7545 1 4204 H 0.7613 1.4199 I 0.7501 1 ,4202

4v . ( 0 , 7 5 0 5 ) (1.4198)

A 0.7506 1.4199 B 0 .7485 1.4177 c 0.7505 1 .4195 D 0.7499 1.4191 E 0,7529 1 ,4203 F 0.7491 1 .4197 G O.761ga 1.4214 H 0.7510 1 .4198 I 0.7500 1.4198

Av. (0.7503) (1.4197)

.4 0 7528 1.4194 B 0 .7486 1.4183 C 0.7514 1.4197 D 0 .7513 1.4192 E 0.7557 1 .4193 F 0.7505 1.4195 G 0 . 7680a 1 , 4 2 2 0 H 0 ,7559 1 ,4200 I 0.7582 1 ,4204

Av. (0 .7527) (1.4198) a N o t included in averages.

Bromine abs-&tion No. by by method Refractive method ES-ljn&. Density, index. ES-45, vol. ,O d'n 20

Straight-Run Base Stock

0.1

0 . 0 0 . 2 0 .05 0 1 0 , s 0 . 0 0 . 2 3

0 : 3 (0.17)

0 . 0 0 . 1 0.05 0 . 1

0 . 0 0 . 1 8

. , .

0 : 3 ( 0 , l O )

0 . 0 0 . 1 0 .10 0 . 7 0 . 5 0 . 0 0 . 0 9

0 : 3 (0 .22)

0 . 2 0 . 6 0.18 1 . 4 0 . 5 1 . 0 0 . 4 6

0 : 3 ( 0 . 5 8 )

1 1 . 5

Sample B-5

10.5 1 1 . 0 1 1 . 4 11 .2 1 1 . 5 1 2 . 0 11.3

i i : o (11.2)

Sample B-6

1 0 . 0 11.0 12 .3 1 1 . 7

1 2 . 2 12:o

i i : o (11.5)

Sainplp B-7

10 5 1 0 . 0 12 .0 1 1 . 2 1 2 . 0 1 2 . 5 16 3 a

lo .@ ( 1 1 . 2 )

Sample B-8

1 2 . 0 10 .5 1 2 . 8 13 .2 1 2 . 5 1 4 . 0 20 .1n

13:5 (12.6)

0 .7489

0.7504

0.7512 0 . 7 5 1 2

0.7481 0 ,7822 0.7507 0.7506

(0 .7506)

. . . .

. . . .

0,7308

0.7511 0.7506 0 . 7 5 2 8 0,7489 0 . 7 5 0 8 0,7506 0.7505

( 0 . 7 5 0 7 )

. . . . .

0 . 7514

0.7517 0.7509

0.7493 0 ,7618 0.7509 0.7512

(0.7510)

. . . .

. . . .

0.7523

0 : 7k38 0.7335

0.7605 0,7583 0 ,7564 0.7513

. . . .

(0.7537)

1.4194

1.4194

1 .4201 1.4201

1.4196 1.4203 1.4199 1 ,4204

(1,4200)

. . . .

. . . .

1,4193

1 ,4200 t .4196 1.4206 1 .419z 1 . 4 1 9 s 1.4199 1 ,4203

(1.4199)

. . . .

1.4201

1 : 4202 1 .4194

1.4198 1.4195 1 .4202 1 4203

(1.4199)

. . . .

1.4199

1 .4198 1 .4194

1 .4196 1 ,4203 1.4200 1.4202

(1.4200)

. . . .

. . . .

Bromine No. by method ES-45,

0 . 1

0 . 0

0 . 1

0 .13

0:05

0 : 0

0 : i to . IO)

0 . 0

0 : 0 8 0.1 0 . 5 0 . 0 0 . 1 4

0:3 10.16)

0 . 0

0:08 0 . 2

0 . 0 6

0 : 3 (0.11)

0:0

0 . 1

1 . 3

117 0 . 1 5

0 : i o

0 : 3 (0.61)

absorption by method

ES-45a, vol. YC

1 1 . 5

9 . 0

1 1 . 4

12 .5

12: 5

12:o

10:s (11.3)

11.0

11:3 1 1 . 2 11 .o 11.0 10 .8

i i . 5 (11 .3)

1 1 . 5

l2:8 1 1 . 2

12 .0 1 1 . 3

i i : o (11.6)

9 . 5

1 3 . 2 13:5

1 4 . 0

12.0

1 4 . 3

(12.8)

The average values for handling loss, as obtained by "blank" determinations on the samples, were 0.45 ml. with product receiver Type 1 and 0.55 ml. with product receiver Type 2. The Type 1 receiver is preferred for the more volatile samples.

Since the same straight-run base stock was used in the four 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 of olefin removal and absence of undesirable side reactions. This comparison is shown in Table VI, which gives the average of determined properties such as density, refractive index, bromine number, and acid absorption on the unreacted portions of samples B-5 to B-8. Except in the case of sample 13-8, these properties are fairly close to those of the original base stock, indicating practically complete removal of olefins without substantial change in the other hydrocarbon types. Density and nitrogen determinations, ho\wver, indicate nitrogen tetroxide reaction products, in amounts of the order of 0.05 to 0.25% by nxight, remaining in the unreacted portion.

Since the reaction of olefins with nitrogen tetroxide is carried out in a temperature range of 80" to 100" F., the procedures given are limited to mixtures containing hexanes or higher boiling hydrocarbons, and therefore should find application in analysis of

ide has been left in contact

depentanized gasolines. I t is probable that suitable modi- fications of apparatus and procedure can be developed to handle samples containing appreciable amounts of pen- tanes and lighter hydrocarbons.

A recent design of apparatus for Method A, submitted by tk.e Shell Development Com- pany laboratory, is shown in Figure 5 . While this apparatus has not been cooperatively tested, it has been used by several laboratories and appears to have certain ad- vantage?, such as saving in laboratory space and in time required to make a determination.

Tno possible hazards exist in the handling of nitrogen tetrolide in combination with olefins-namely, the degree of stability of the reaction products and the toxicity of nitro- g m tetroxide. While several references have been made to the fact that reaction products of light olefins and di- olefins n ith nitrogen tetroxide are unstable, an investigation of the products from representative samples, such as thermal and catalytic gasoline and pentenes, show them to be nonexplosive, even by the use of detonators (6). How- ever, olefin-nitrogen tetroxide compounds are thermally unstable and subject to rapid decomposition if heated di- rectly much above 250" to 300'F. Violent reactions have occurred where nitrogen tetrox-

with hydrocarbons for long peri- ods of time. The presence of oil in pipes, valves, etc., used for nitrogen tetroxide should be avoided.

The nitrogen tetroxide reaction should be carried out under a hood, and observance of safe laboratory practice in handling toxic gases i* recommended (5).

LITERATURE CITED

(11 . h i . Petroleum Inst., Research Project 44, "Selected 1-alues of Properties of Hydrocarbons," Tables Sa, loa, l l a , 13a, Natl. Bur. Standards, June 30. 1945.

(2 , A m Soc. Testing Materials. Emergency Method E9-45a, "AS.- T.M. Standards on Petroleum Products and Lubricants," 1945. This niethod has been redesignated -1,S.T.M. Method DS75- 46T.

( 3 ) Bond. G. R., Jr., ISD. ENG. CHEM., AS.\L. ED., 18, 692-6 (1946). (4 ) Doss, M. P., "Physical Constants of the Principal Hydro-

carbons," 4th ed., New York, The Texas Co., 1943. ( 5 , Jacobs, Ai. B., "Analytical ChemistrJ- of Industrial Poisons,

Hazards. and Solvents," p. 280, New York, Interscience Pub- lishers, 1941.

( G i Uahley, H. S., unpublished results obtained by two cooperators with assistance from an explosives manufacturing company.

RECEIVED February 15, 1947.

Documents

Determination of Olefinic Unsaturation