ANALYTICAL EDITION
July, 1944
reagent. Allow the solution to stand 30 minutes and then measure the color by any of the usual means. (MLasurement can be made the fist half hour after color development, provided the time of measurement is controlled within - 5 minutes.) Visual comparison may be made with standards prepared with known amountsof phosphorus, or with a series of permanent s&,ndards (9). Filter photometric measurement should be made with a red filter. For spectrophotometric measurement in the visual region a wave length between 600 and 700 mp seems preferable. Measurement may be made beyond the color range if a suitable spectroradiometer is available. Thus, Fontaine (4) shows a peak in the absorption band near 820 mp for solutions reduced with chlorostannous acid. The writers' solutions did not show this band, but one much Rharper was found with R minimum near 340 mu.
489 LITERATURE CITED
(1) Assoc. Otficial Am. Chem., Oficial and Tentative Methods of (2)Be,l Analysis, and Daisy, SectionBioi. XII,Chem,, Subsections 44, 55 31, (1920). 32,33 (1940). J ,
66, 375 (1925). (4) Fontsine, I N D - ENQ.CHEM.9 ANAL.ED., 14, 77 (1942). ( 5 ) Jandcr and WitZmann, 2.Qn'JW.&7m. C h a . , 215,310(1933). (6) IND* ED.* 14* 855 (1942)* J. Education* 19* 415 (1942). (7) ED.9 14@ 636 (1942) (') Sto'offt IND. (') 13* (lg41).
(3) Fiske and Subbarrow* J a
ABBTBACT~D from B thesis presented by R.E. Kitson to the Graduste school of Purdue University in partial fulfillment of the requiremente for the degree of dootor of philosophy, February, 1944.
Quantitative Determination of Mixtures of Methyl Vinyl Ketone and Diacetyl A Dropping Mercury Electrode Method ELLIS 1. FULMER, JOHN J. KOLFENBACH, AND L. A. UNDERKOFLER Chemistry Department, Iowa State College, Ames, Iowa
A dropping mercury electrode method has been described for determination of (1) methyl vinyl ketone alone and in mixtures with methyl vinyl carbinol and methyl ethyl ketone and (2) diacetyl alone and in mixtures with methyl vinyl ketone and methyl ethyl ketone.
9
UDIES are in progress in these laboratories on the catslytic vapor-phase oxidation of methyl vinyl carbinol and of 2,a-butylene glycol. I n the course of this work it became necessary to devise methods for determining methyl vinyl ketone in the presence of methyl vinyl carbinol and methyl ethyl ketone, and diacetyl in the presence of methyl vinyl ketone and methyl ethyl ketone. The present communication presents such meth& using the dropping mercury electrode. The methods are based on the fact that methyl vinyl ketone and diacetyl are reduced a t the dropping mercury electrode while methyl vinyl carbinol and methyl ethyl ketone are not so reduced.
The equipment employed was manually operated and was similar to that described by Kolthoff and Lingane (8)and Lingane and Kolthoff ( 3 ) . The voltage was measured against an external saturated calomel electrode. The current, in microamperes, was calculated from the IR drop across a resistance of 7000 ohms. The pressure on the mercury was maintained a t 80 cm. of mercury; the dro -time was 3.4 seconds. The value of m,in weight of mercury lowing from the capillary per second, wan 0.00134. Dissolved air was removed from the solutions by meanh of gaseoue nitrogen and all determinations were made a t 25" C
I. Current-Voltage Data" for Methyl Vinyl Ketone Solutions
--
(Molarity X 102)
-4.494-
Current Microampmcr 0.56 0.57 1.31 2.21 2.46 2.46 2.36 2.36 2.36
1.23-
SOURCE OF MATERIALS
The methyl vinyl ketone was made by the catalytic vaporphase oxidation of methyl vinyl carbinol; the details of the method will be made available at a later date. The highly purified methyl vinyl ketone had the following characteristics: b.p. = 19-80" C. a t 760 mm., nL0 = 1.4081, and d:' = 0.862. The diarervl, purchased from the Eastman Kodak Company, was f u r t l i & purified and had the foflowing characteristics: b.p. = 86.5-S7.5'C. at75Omm.,ny 1.3910,,and di8 = 0.980. These constants, for both chemicals, agreed with the best data available in the literature. The methyl vinyl carbinol was purchased from the Shell Chemical Company and the methyl ethyl ketone from the Eastman Kodak Company. I n each case the stock solutions consisted of 1 ml. of the chemical made up to 100 ml. with 0.10 A' potassium chloride. These solutions were diluted with 0.10 .\'
-
Table
APPARATUS AND PROCEDURE
Table
in an atmosphere of nitrogen. Potassium chloride, 0.1 .V, was used as the indifferent electrolyte.
-2.47------
Volts
Current Microamperes
Volts
Current Microamperes
Volts
1.245 1.338 1.412 1.478 1.545 1.615 1.680 1.745 1.820
0.53 0.71 1.71 3.43 4.71 5.20 4.96 4.99 4.99
1.250 1.330 1,400 1.454 1.515 1.581 1.650 1.718 1,800
0.57 0.57 0.90 4.93 7.74 9.07 9.50 9.57 9.57
1.080 1.215 1.290 1.407 1.462 1.527 1.577 1.640 1.720
0 Potential difference between dropping electrode and saturated calomel electrode.
II. Diffusion Currents and Half-Wave Potentials for Methyl Vinyl Ketone
Molarity X 10: ExperiCalcu!ated mental Equation 2 0.494 1.234 2.468
mental
1.43 1.42 1.41
1.80 4.43 9.01
I -
0.493 1.213 2.469
Diffusion Current Calculated Equation 1
Expen-
El/,
1.79 4.50 9.01
Table 111. Current-Volta e Datao for Mixtures of Methyl Vinyl Ketone, Methyl Ethy! Ketone, and Methyl Vinyl Carbinol
---
MVK 0.494 MEK 0.'448 MVC 0.469 Current Microamperea Vob 0.50 0.53 1.57 2.33 2.33 2.33 2.33
...
... ...
1.265 1.314 1.422 1.506 1.580 1.653 1.714
... ... ...
...
--
(Alolnrity X 103) MVK 1.23 MEK = 1.12 MVC 1.17 Current Microampere8 Volts 0.40 0.46 0.89 2.79 4.36 5.04 4.93 4.94 4.93
*.. ...
1.200 1.283 1.352 1.433 1.490 1.557 1.621 1.695 1.760
... ...
---
MVK 1.87 MEK 0.224 MVC 0.234 Current Microamperea Volts 0.53 0.57 1.06 2.86 5.14 6.71 7.07 7.71 7.43 7.37 7.37
1.220 1.270 1.346 1.418 1.470 1.530 1.594 1.655 1.725 1.789 1.850 ... ~
Potential difference between dropping electrode and saturated calomel electrode.
INDUSTRIAL AND ENGINEERING CHEMISTRY
470
from which, log ( M X 10') = 1.1411 log (dc)
Table IV. Diffusion Currents for Mixtures of Meth I Vinyl Ketone, Methyl Vinyl Carbinol, and Methyl Ethyr Ketone Concentration of MVK M.X IO:. Concentrations of MEK and MVC aa in Table 111) Molarity X 108 Diffusion Current
-
Expenmental
0.494 1.23 1.87
-1.13Current Microamperes
0.53 0.56 0.57 0.60
1.39 2.29 3.57 3.97 3.97 a
Yolta 0.459 0.517 0.626 0.690 0.788 0.824 0.875 0.963 1.053
Vol.
IS, No. 7
+ 0.4526
(4)
Calculations, using the above equations, presented in Table VI, show the method to be satisfactory for the analysis of diacetyl Calculated ErperiCalculated alone. The fact that the hyperbolic function is also characterisEquation 2 mental Equation 1 tic of adsorption reactions indicates that adsorption phenomena 0.499 1.82 1.80 1.22 4.47 4.49 may be operating in the case of diacetyl. 1.91 6.80 6.83 Current-voltage data for four mixturw of diacetyl (DA), methyl vinyl ketone (MVK), and methyl ethyl ketone (MEK) Table V. Current-Voltegc DataJ for Diacetyl (Molarity X 101) are given in Table VII. Diffusion currente -0.909d . 5 6 h d.4644.379for the mixtures, together with data calcuCurrent Current Current Current MicroMicroMicroMicrolated by Equations 3 and 4, are given in ampsrw Volts ampere* Volt8 amperw Volb amperw Vdtr Table ~111. It is evident that the proce0.46 0.47 0.49 0.69 1.69
3.00 3.23 3.24
...
0.621 0.633 0.675 0.735 0.822 0.905 0.~91 1.080
...
0.51 0.51 0.54 0.71 1.97 2.36 2.40 2.41
0.484 0.693 0.673 0.774 0.860
0.946 1.036 1.120
...
...
0.39 0.40 0.43 0.67 1.34 1.94 1.97
...
...
0.507 0.615 0.688 0.790 0.834 0.824 1.013
..* ...
0.39 0.40 0.69 1.17 1.61 1.67 1.69
...
...
0.675 0.680 0.786 0.840 0.928 1,020 1.120 ...
dure is applicable to mixtures of diacetyl and ketone in the presence Of methyl ethyl ketone, as well as to the diacetyl or methyl vinyl ketone alone.
,..
Potential difference between dropping electrode and aaturated d o m a l eleatrode.
LITERATURE CITED
H., and Cox, F. W., J . Am. C k m SO^., 60,1151-9 (1938). (2) Kolthoff, I. M.,and Lingme. J..J., C h m . Reo., 24, 1-94 (1939). (3) Lingane, J. J., and Kolthoff, I. M., J . Am. Chem. Soc., 61, 8%34 (1939). ( 1 ) .4dkins,
potassium chloride to give the concentrations used in the experiments. ANALYSIS OF MIXTURES
METHYLVINYL KETONE,METHYLVINYL CARBINOL,AND KETONE. Current-voltage data for three concentrations of methyl vinyl ketone are given in Table I. The diffusion currents, dc, and half-wave potentials, El / * , are given in Table 11. In this, and in subsequent tables, the diffusion current is obtained by subtracting the residual current from the limiting current. The diffusion current is a linear function of the molar concentration, the equation being:
dc from which,
=
3.65 M X 10'
(1)
M X lo8 = 0.274 X dc
WORK W@ supported by a graut from the Industrial Science Research Institute of The Iowa State College, for research on elastomer..
Table
VI. Diffusion Currents and Half-Wave Potentials for Dircetyl Molarity X 10' Calculated Equation 4
%E:,1.136 0.909 0.568 0.454 0.379
Diffusion Current ErperiCalculated mental Equation 3
E%
1.133 0.902 0.575 0.454 0.379
0.824 0.830 0.821 0.825 0.826
3.37 2.76 1.86
3.38 2.78 1.84
1.51 1.29
1.61
1.29
(2)
Table V I . Current-Voltage Drtaa for Mixtures of Diacetyl, Methyl Calculations, using the above equations, given in Table 11, Vinyl Ketone, and Methyl Ethyl Ketone show that the method is entirely satisfactory for the analy(Molarity X IO:) sis of methyl vinyl ketone alone. Current-voltage data for mixtures of methyl vinyl ketone, $$K :;$; MEK 0.834 MEK = 0.501 MEK 0.750 MEK 0.260 methyl vinyl carbinol, and methyl ethyl ketoneare presented Current Current Current Current in Table 111. The calculated values show that the methyl MicroMicroMicroAf icrovinyl carbinol and methyl ethyl ketone are not reduced and ampere# volts amperes voira amperes volts omperer voirB do not interfere with the determination of the methyl vinyl 0.37 0.480 0.31 0,526 0.47 0.459 0.39 0.476 0.39 0.36 0.633 0.53 0.576 0.41 0.680 0.690 ketone. 0.41 0.695 0.43 0.700 0.60 0.680 0.44 0.686 1.36 0.807 0.89 0.792 0.50 0.738 DIACETYL,METHYLVINYL KETONE,AND METHYLETHYL 0.67 0.791 KETONE. Adkins and Cox (1)presenteddataonthe reduction j:;: ~:~~~ of several aldehydes and ketones a t the dropping mercury j::! electrode. Using 0.10 N ammonium chloride as the indiffer1.77 1.200 1.94 1.225 2.14 1.240 3.14 1.108 ent electrolyte, in unbuffered solution, they found two half1.77 1.335 1"81 2.71 2'oo 1.369 1'290 2.43 "le 1.400 3.13 3'13 1.277 1'193 wave potentials for diacetyl a t 0.93 and 1.68 volts. These 3.86 1.600 3.77 1.577 4.81 1.600 values, recalculated on the basis of the use of an external 4.56 1.633 4.73 1.590 3.77 4.81 1.705 3.97 1.673 esturated calomel electrode, are 0.84 and 1.59 volts. The 4.74 1.668 .. , 1.649 ... ... ... 3.97 1.642 ... ... ... ... authors emphasized the necessity for determining the effect 4.74 1.735 ele;E;epl difference between droppiw electrode and saturated calomel on the height of the reducible compounds. of other Current-voltage data for five concentrations of diacetyl are given in Table V. The diffusion currents, dc, and halfmwave are shown in Table VI, The halfTable VIII. Diffusion Currents Of Mixtures Of Dircetyl, Methyl Vinyl Ketone, and Methyl Ethyl Ketone wave potential is 0.83 volt which is identical, within exMethyl Vinyl Ketone Diacet 1 Molarity x 10: biffuion Current Molarity x 108 Diffuaion Currend perimental error, with the 0.84 volt calculated from the results of A&ns and Cox (1). The diffusioncurrent is EX&Calcd. ExptriCdCd. EmirCaId ExPriC d d mental Eq. 4 mental Eq. 3 mental Eq, 2 mental Eq. 1 not a linear function of the concentration of the diacetyl o.385 o,402 o,834 o.814 2,97 but ia given by the hyperbolic relation: 0.462 0.462 1.63 1.63 0.601 0.501 1.88 1.83
: - :::::
:::;
:::::: g%K : -
::E; i::! ::::I
::::
:::E i:
i:;! i:::
::;; !:i
-
!:%: i:;
i:g: :::I y::::
:::$:
i:;;
:::::
...
log
(ac) = 0.8766
log (M x 10')
-
0.462 0.923
0.39137
(a)
0.463 0.879
1.54 2.70
1.53 2.81
0.750 0.250
0.732 0.250
2.67 0.84
2.74
0.01
