Oct., 1937
REACTIONS OF SOME
The final isobutylene fraction (b. P. about -6') solved completely in 63% sulfuric acid solution.
INDICATORS WlTH
dis-
Summary Isobutylene, when decomposed a t 650 to the extent of 0.1-1.041,, gives rise to methane, propyl-
[CONTRIBUTION FROM
THE
1871
HYDROXYL ION
ene and ethylene as the only gaseous reaction products. The fact that ethylene persists even a t 0.1% conversion emphasizes the need for caution in interpreting the "initial products of reaction" by the zero-extrapolation method. RECEIVED JULY 19, 1937
EVANSTON, ILLINOIS
LABORATORY OF PHYSICAL CHEMISTRY O F THE UNIVERSITY O F PENNSYLVANIA]
The Reaction of Brom Phenol Blue, Iodo Phenol Blue and Chlor Phenol Blue with Hydroxyl Ion' BY
FRANKw.PANEPINTO
In the study of the dissociation constants of indicators it has been shown that brom phenol blue reacts with hydroxyl ion to give a colorless solution.2 This paper presents the results of a study of this reaction and the reaction of tetrachloro- and tetraiodophenolsulfonphthaleins with hydroxyl ion. From a study of the kinetic electrolyte effect it will be shown that the reaction is between the bivalent anion and the hydroxyl ion. Experimental Part The indicators used in this study were specially purified products.3 Analysis gave the following: M. p.
'C corr.
Tetrabromophenolsulfonphthalein (Brom phenol 270-271 blue) Tetraiodophenolsulfonphthalein (Iodo phenol blue) 259-260 Tetrachlorophenolsulfonphthalein (Chlor phenol blue) 255
Found,
%
Calcd.,
%
S, 4 . 5 5 4 . 7 7 Br, 47.76 47.73 I, 59.05 59.12 C1, 28.70 28.80
Stock solutions of the indicators were prepared by dissolving the acid in alcohol, adding sufficient carbonatefree sodium hydroxide to form the monosodium salt, evaporating off the alcohol and dissolving the salt in water. All stock solutions were approximately 2 X molar and were diluted tenfold for the experiments. The reaction was followed by measuring the disappearance of the blue color by means of a Duboscq colorimeter. All (1) Abstracted from the dissertation of Frank W. Panepinto presented t o the Faculty of the Grnduate Schcol of the University of Pennsylvania in partial fulfilment of the requirements for the degree of Doctor of Philosophy, April, 1937. (2) Chase and Kilpatrick, THIS JOIJRXAL, 64, 2284 (1932); Kilpatrick, Chem. Rev., 16, 57 (1935). (3) The authors take this opportunity to acknowledge the kindness of Dr. W. C. Harden oi Hynson, Wrstcott and Dunning Co. in supplying these indicators.
AND
MARTINKILPATRICK
solutions were referred to standard solutions which were freshly prepared from stock solutions. The experiments were carried out in a thermostat regulated to *0.005' and the solutions were protected from light except during the transfer of samples for analysis. All salts were c. P. products purified by crystallization.
Preliminary experiments had shown that the rate of disappearance of the blue color followed the moiiomolecular law2 as shown in Table I. TABLE I FADING OF BROMPHENOL BLUEAT 30" Days
k
0.875 1.0 1.167 1.875 2.17 2.83 3.0 3.167
0.590 ,585
3.83 4.0 4.83 5.0 5.21 6.0 6.17 6.83 7.0 7.83 8.0
NaOH (moles per liter) 0.009 0.005
ki
65.5 64.9 ,581 64.5 ,574 63.8 ,578 64.2 ,592 65.6 .583 64.8 ,566 62.8 Average 64.5
k
ki
0.287 ,298 ,290 ,302 ,295 .299 ,285 ,305
57.3 59.6 58.0 60.5 59.0 59.8 57.0 60.9
0.286 .293 ,288 .303 ,290 ,295
57.1 58.7 57.5 60.6 57.9 59.0 59.7 59.3 57.0 60.4
,299
.297 ,285 ,302 ,300 60.0 Average 58.9
The velocity constant k is calculated from the equation k = 2.30/t log a / ( a - x ) where a represents the initial concentration of the bivalent anion, a - x the concentration at time t. The unit of time is the day. From Table I it is seen that the reaction a t constant hydroxyl ion concentration follows the monomolecular law and from
FRANK W. PANEPINTO AND MARTIN KILPATRICK
1872
the value of K I = k / C o H - it is evident that although the rate is approximately proportional to the hydroxyl ion concentration the values of k increase with increasing sodium hydroxide concentration. This is confirmed by the results summarized in Table 11.
in the presence of neutral salts. marizes the experiments.
.002
48.4 47.6 48.0 52.3 52.5
.003
53.7
.004
55.2 55.1 58.9 58.5 58.8 59.0 62.1 63.3 64.6 64.6 65.5
*
005
,006 .007 .008
.009
.OlO
Table I11 sum-
TABLEI11 ELECTROLYTE EFFECT AT 3 0' NaOH, m./L
NaCI, m./L
0,002
0.001 .005 .009 .045 .041 .095 .095 .091 .091 .091 ,145 .141 .195 .191
.002 .001
TABLEI1 EXPERIMENTS WITH BROM PHENOL BLUEAT 30" NaOH, m./L L Av. value k
0.001
VOl. 59
.005 * 009 .005 .005 .009 .009
48.0 52.4 53.7
.009 .005
55.2
.009 .005 .009
58.7
&I
.
53.7 62.0 65.4 94.3 94.8 98.3 106.5 111.0 113.7 115.6 116.1 117.1 130.0 130.1
KBr, m/l.
0.005 .009 .009 ,005 .004 .005 .004
58.9 62.1 63.3 64.6 65.5
0.045 .041 .191 .195 ,001 .002 .006 .OlO .017 .015 .045 .041 ,195
.005
In order to determine whether this was an electrolyte effect, experiments were carried out
*
003
005 .005 ,009 *
.005
94.2 93.7 130.5 130.0 58.0 61.9 65.5 70.1 75.1 75.1 93.7 94.4 129.3
The results summarized in Tables I1 and I11 are presented graphically in Fig. 1 (average values in the graph), log k1 being plotted against fiand brom phenol blue > iodo phenol blue. It is interesting to note that some reactions involving organic halides and hydroxyl ion give the reverse order of stability to that found for the fading reaction. For example, the reaction between alkyl halides and potassium hydroxide studied by Grant and Hinshelwood has the following values for the velocity constants for alkyl chloride k = 0.793 X 1011 f l e - z a , o O o l R T for alkyl bromide k = 1.28 X 1011
