Determination of Alkyl and Aryl Halogen In the Presence of Each Other WILLIAM H. RAUSCHER, Rensselaer Polytechnic Institute, Troy, N. Y.
T""
for the determination of the total halogen present. I n those cases where mutual solubility was low, or boiling points widely different, small amounts of the two substances were weighed out in the glass-stoppered vials of Method I or the bomb tubes of Method I1 (1). The entire weighed mixture or solution was analyzed so that only the alkyl or total halogen content of the sample could be determined. The kerosene solutions were made up in small glass-stoppered bottles by weighing all the ingredients.
P use of monoethanolamine in the determination of halogens in organic combination has been previously reported (1). Experience gained in the use of this reagent suggested that it might be used to advantage in the determination of alkyl and aryl halogen in the presence of each other. Monoethanolamine has proved to be capable of quantitatively converting the alkyl or reactive halogen in a number of compounds, solutions, and mixtures, which contain both alkyl and aryl halogen, to the ionic form without affecting the aryl halogen present. The reaction is also quantitative when the halogenated compounds are present in dilute kerosene solution, thus making the reagent useful in the analysis of certain types of insecticides. The aryl halogen in such cases may be found by determining the total halogen by the procedure of Method I as outlined elsewhere ( I ) , and then subtracting the alkyl halogen found. The compounds, solutions, and mixtures listed in Table I were chosen to establish the range of usefulness of the method. The kerosene solutions of carbon tetrachloride and p-dichlorobenzene were chosen to simulate an insecticide. Where the alkyl and aryl substances used as pairs had sufficient mutual solubility and fairly close boiling points, known solutions of the two were made up in small glass-stoppered bottles and portions of the solutions used immediately for analysis. Two or more portions were used for determining the alkyl halogen present and two or more portions
Determination of Alkyl Halogen i n the Presence of Aryl Halogen The apparatus, materials, method of weighing samples, and the general procedure are the same as in Method 11. Micro- and semimicrosamples of the kerosene solutions are weighed, but macrosamples may be measured with a Mohr pipet. One milliliter of the amine is used for microsamples contained in the small bomb tubes, and 3 to 4 ml. are used for macrosamples contained in the large bomb tubes. The kerosene solutions float on the amine, so that care must be used in sealing the bomb in order to avoid loss of the more volatile constituent. Microsamples are heated at the boiling point of diethanolamine for 0.5 hour and the macrosamples for 1 hour. After opening the bombs the procedure of Method I1 is followed exactly. Insoluble aromatic substances are brought into solution by the use of alcohol or dioxane.
TABLEI. RESULTS Total HalogenWeight of Sample
% Aryl Halogen % Alkyl Halogen
Mu.
fo=? A g halide
Mu.
0.444
..... .....
12.215 18.026 1.000
36.34 25.52 57.50 31.15
0.440
50.25 34.95 42.35 38.40 38.98 21.68 46.02 20.60 83.68 64.27 16.42 30.40 Solution.
-Alkyl Weight of Ag halide
Found
Calcd.
%
%
Me.
%
%
28.83 28.85
28.76
p-Bromophenacyl Bromide 57.52 4.912 5.138 5$:51 57.59 p-Chlorobenayl Bromide 12.225 ... 14.937
..... .....
21.146 15.21,5 12.371 10.031
15.346 19,s9f, 13.868 8.677
Calcd.
...
7.250 7.578 6.415 4.509 13.343 16.359 7.584 11.164
Found
2.253
-.--
0 .v100
._
15.87
...
.....
... ...
..... o-Chlorobenayl Chloride 44.06 18.883 13.590
.....
...
22.070 17.870
44: i 3 44.07
..... ..... 92.70
... ...
50.32
... ...
..... .....
p-Bromobensenesulfonyl Chloride 8.848 ... 11.098
.....
17.877 11,199 0.641
...
..... .....
69.29 62.90
..... .....
91.40 40.86
...
o-Chlorobenayt Bromide 33.32 23.36
...
.....
.....
...
... ...
..... .....
... ...
38.99 38.86
22.09 22.10
... ... 40.52 ...
40.41
49. 16
49; i 3
49.07
20.002 39.50
"* S L . *lnV J L 14
... ...
32 22 I
..... .....
76.23 42.35
..... .....
6.450 4.970
..... .....
"-.
(Continued on next papa)
503
38.90
22.03
38.90
... ...
13.67 13.80
... ...
24.69
i:ii ... ...
...
28.76
2i:i.r 28.75 .
I
.
... 22:04 21,97
....
.
.
I
... 3i:ia 31.29
... 15:$3 15.78
...
....
31.28
15.83 0.77
0:is
....
0.72
....
30:i9 30.23
....
17.26
17.30
io: iia
..,.
22.03
17:22
.... .... ....
17.26
1i:il 17.31
.... ....
....
. I . .
1.91
%
....
48.39
...
1.91
....
....
6,381
...
48.'38 48.32
.... ....
4b: OS 21.79 13.88
%
Mu.
5.276 7.812
... ...
39.02 38.95
Aryl Halogen (by Difference) Weight of Ag halide Found Calcd.
.... ...
... ...
AB'-Dichlorodiethyl Ether and Chlorobenzene" 40:52 60.27 24.75 34.95 24.74
.....
.....
..... .....
Halogen-
...
30.31
INDUSTRIAL AND ENGINEERING CHEMISTRY
504
VOL. 9, NO. 10
TABLE I. RESULTS(Continued) Weight of Sample M_a_ . . . 7.121 396.45 21.635 61.754
% Aryl Halogen % Alkyl Halogen 0.0114 51.25 0.0498 41.68
7Total Weight of Ag halide
.
MQ
.....
io:240
75.860
HalogenFound
%
Calcd.
%
-Alkyl Weight of Ag halide
Mg
.
HalogenFound
Calcd.
%
%
Acetylene Tetrachloride and Bromobenseneb ... 23.853 82.86 ,.. 15,738 0.98
...
... ...
, . .
...
Hexachloroethane and Iodobenzeneb ... ... 164.55 76.40 ... ... 170.40 24.13
73.24 64.95 16.246 17.959 16.162 15.620 33.126 18.192 7.848 8.515 13.405 107.10 141.55 19.94 51.52 861.4 (1ml.) 851.4 425.7 425.7 b Mixture.
0.122 1.880 34,73 0.164 11.75 5.918 0.0275 3.035 0.0228 0.0067 0.0074 0.0300 1.769
.....
.....
47.17 116.OB
...
...
... ...
.....
.....
... ...
Carbon Tetrachloride and a-Dichlorobenaeneb ... 50.13 ..... 11.820 3.99 . . . . ... 51.83 19,644 7.48 ..... 90.00 57.584 87.62 54:04 54.72 ..... ... 39.675 90.50 90.53 . . . . ... 59.020 91.66 57.873 91.65 , . ... 122.65 91.59 91.59 ..... , . . 89.85 89.82 ..... , . . 66.080 Carbon Tetrachloride and o-Dichlorobenzene (in Kerosene) 8.03 0 924 2.91 .,. 0,970 2.82 ..... ... 1.460 2.69 ..... ... 12.497 2.88 ..... . . ... 16.786 2.93 8.10 6.491 ..... ... 8.08 16.840 ..... ... ... 98.55 2.86 ..... 98,96 2.88 137.30 8 01 137.65 8 04
.....
...
.....
KO attempt is made to bring the kerosene into solution. Spinning coagulation of the silver halide is the more convenient and rapid method of coagulation. For compounds of the type p-chlorobenzyl bromide and combinations of the type P,P’-dichlorodiethyl ether-chlorobenzene, it suffices to reflux the sample with monoethanolamine alone in the open test tube-cold finger procedure of Method I (1). For the first type of compound 10 minutes’ refluxing is sufficient to convert the alkyl halogen to the ionic form. I n other cases the time allowed should be extended. Determination of Aryl Halogen in the Presence of Alkyl Halogen To determine the percentage of aryl halogen the percentage of total halogen present is found and from this is subtracted the percentage of alkyl halogen found, provided that both halogens present are the same. When the two halogens present are not the same the calculation of aryl halogen must be handled differently. I n this case the weight of mixed silver halides from the total halogen present in the sample is first determined. From this weight is subtracted the weight of
XU.
....
82.94 0.98 78.05 1.20
72.854
76.37 24.13 1.76 72.63
44 I37 8.17
~~
53.28 174.70 39.361 36.746
Aryl Halogen (by Difference) Weight of Ag halide Found Calcd.
3.93 7.49 87.58 13.56 88.51 91.03 90.92 87.20 2.90
i :$is
....
....
.... .... .... .... .... ....
....
%
%
...
0.94 50.33 3.89 50.20
,..
3.89 50.20
... 60194 12.02
9.34 46.48 61.00 11.93
4i:b8 1,99 0.68 0.67 2.65
46.20 44.34 2.42 41.16 2.02 0.62 0.67 2.62
.... ....
6.13
.... .... ....
....
, . .
5.20 5.18
... , . .
5.11 5.14
the silver halide from the alkyl halogen present to get the weight of silver halide from the aryl halogen. The weight of %lkyl” silver halide is obtained by multiplying the sample weight by the percentage of alkyl halogen and dividing by the proper gravimetric factor. I n either case the total halogen is converted to the ionic form by the use of sodium, monoethanolamine, and dioxane exactly as in Method I. Summary A simple and rapid method for the determination of alkyl and aryl halogen in the presence of each other has been developed. It appears to be applicable to a variety of problems and may be used on a micro, semimicro, or macro scale. The procedure may, of course, be used qualitatively. Literature Cited (1) Rauscher, IND.ENG. CHEM.,Anal. Ed.,9, 296 (1937). RECBIVED July 27, 1937. Abstract of part of the Ph.D. dissertation of William H. Rauscher in the Graduate School of Rensselaer Polytechnic Institute.
