REACTIOS BETWEEK GLUCOSE X S D POTASSIUM PERMASGAKATE I S XCID SOLUTION* BY S. LOUISA RIDGWAT
Purpose The purpose of this investigation has been to work on the reaction between potassium permanganate and glucose in acid solution especially with reference to the following points:The possible formation of gluconic acid at the pH a t which it is formed I. by bromine. Some unpublished work done in the Cornell laboratory suggested this. If gluconic acid were formed by such oxidation by potassium permanganate, this might be a better method of preparing it than by the use of bromine or silver oxide. The change in the amount or rate of oxidation with change in pH. 2. 3 . The possibility of finding conditions a t which the reaction products would be stable and the oxidation could be stopped. If such a set of conditions could be found, this would be a convenient method of determining glucose in solutions known to contain no other oxidizable material. Method The method used was quite simple. The potassium permanganate solution and the acid (sulphuric unless otherwise specified) were put into distilled water in an Erlenmeyer or a Florence flask and brought to the required temperature. Then the glucose solution was added and the reaction time reckoned from that point. When the reaction had proceeded for the desired length of time, an amount of standard sodium oxalate greater than that needed to react with the permanganate was added. If necessary, enough acid was added to bring the total amount u p to I O cc of I : I sulphuric acid and the temperature was brought nearly to the boiling point. Then the excess oxalate n'as titrated back with permanganate quickly. The first relatively permanent pink (lasting 15 see.) was taken as the end-point, for of course unused glucose would continue to reduce any permanganate present. This procedure gave a conrenient method for varying concentrations, rolume, acidity, temperature, reaction time, etc. The only temperatures used were room temperature and boiling (refluxing, using fine carborundum to prevent bumping). The r e d t s obtained were accurate to within about t m percent, (Table I ) . ~
'.4 thesis presented to the Farulty of the Graduate School of Cornell University for the degree of Master of I r t s , 1930.
1986
S . LOUISA RIDGWAP
TABLE I Time I hr. I hr. I hr. I hr. I hr. I hr I hr. I hr. 73 hr.* 78 hr.* j min. I O min. I hr. I hr. 4% hr. o hr.** o hr.**
Arid
cc cc I O cc I O cc 2 cc 2 cc 4 cc 4 cc IO
I :I
IO
I:I 1:i I :I
I:I I:I
I:I 1:I
IO
cc
I:I
2
cc
I:I
0.01394 g 0.01394 g 0.01394 g 0,01394 g 0.01394 g IO IO
cc cc
I :I I :I
Oxalate 40 cc
35 5 CC 3 5 . 6 cc 35 cc 35 cc 3 5 cc 35 cc 45 cc 41 cc 36 cc 40 36 36 36 36
cc cc cc cc
cc Sone Kone
Back KMnOI 9 . 5 cc 3 . 6 cc 5.0
cc
4. j
CC
1 . 8 cc
cc 1.85cc 2 . 5 cc 7 . 1 cc . i cc 2.0
4 . 5 5 cc .6cc
cc 1 . 1 cc I . $ cc 1.1
KMnOp for blank
cc cc 4 . 5 cc 5 . 0 cc 2 . 3 cc 5.1
4.1
2.5
cc
2 . 3 5 cc 2.5
cc
1 . 7 cc 0 . 2 cc 0 . 1 5 cc cc 0 . 6 cc 0 . 6 cc 0 . 9 cc 0.1
0.1
cc
0 . I j cc
*Room temperature. All the other runs were made a t the boiling-polnt. **The volume was I I O c c ; I j o cc in all other runs.
Blanks run in the usual way on the reagents gave practically negative results. Blanks on the reagents refluxed for some time gave low positjve results. Blanks to which had been added a small amount of oxalate previous to standing long periods of time or refluxing (in order to produce a small amount of manganese sulphate which is known to catalyze oxidation by permanganate and which was present in all experimental flasks) gave quite high positive results. As all ordinary precautions were taken to guarantee the purity of the reacting substances, extreme care would be necessary to reduce the positive value of this blank any considerable amount. The data later presented have been corrected on the basis of these blanks, unless i t is otherwise stated. The solutions used were:I . K/zs sodium oxalate made by weighing out the pure reagent. X i 2 5 (approx) potassium permanganate made by dissolving 5 gm in a 2. liter of water, boiling ten minutes, letting stand one day, filtering through a Gooch filter, diluting to 4 liters, and standardizing against oxalate. 3. I : I sulphuric acid made up from c. p. acid and distilled water in a graduated cylinder (as slight change in acidity had no effect). 4. 0 . 2 % anhydrous glucose made up by weighing out Baker's C. P. The moisture content was determined by drying a t 7 in. of mercury and 60" for two hours, and then at 70' until the weight was constant. This treatment drove off water of crystallization. The value obtained was checked by use of the polarimeter.
I987
GLUCOSE AND PERMANGANATE IN ACID SOLUTION
5 . Solutions of potassium permanaganate, sodium oxalate, and glucose were made up approximately 1 2 I / Z times as strong as the preceding; and also solutions of potassium permanganate and glucose about z j times as strong. 0.45 N sodium oxalate is nearly a saturated solution. The mechanism of the reaction was a t first assumed to be 2 K M n 0 4 j glucose 3 H z S 0 4-+ j glucose oxidation product KzSOa (I) zMnS04 3 H 2 0 . 2KMn04 3 M n S 0 4 2 H z 0 -+ jMnOz zHzSO K z S O ~ (2) for the solutions rapidly became colorless with the precipitation of manganese dioxide. The manganese dioxide thus formed would have the same amount of oxygen to give up as the permanganate and would continue the reaction with the glucose. (3) MnOz glucose HzS04+MnS04 glucose oxidation product HzO. Then as is shown later in this paper, the last z / j of the oxygen (corresponding to having all the manganese in the form of manganese dioxide) is given up much less rapidly than the first 3 / j of the oxygen. If manganese dioxide is the oxidizing agent except a t the very start, why should there be this difference in speed? It was suggested that first 2KMn04 3 glucose H z S 0 4-+ 2MnO2 K2S04 HzO 3 glucose oxidation product, and then oxidation was continued more slowly by manganese dioxide. The first equations were finally considered to be the actual ones for these reasons:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
I . With oxalic acid' and glucose, manganese sulphate is a catalyst and increasingly so up to 3 molecules for z of permanganate. The amount of oxidation of j cc of 0.2% glucose in 4 hours a t room temperature in a total volume of I 50 cc with 2 cc of I : I sulphuric acid was 0.29 atoms of oxygen per molecule when no manganese sulphate was added, and 3.77 atoms when 3 molecules of manganese sulphate were added. 2 . At room temperature with glucose, a n initial period is evident before the reaction starts, due presumably to the formation of manganese sulphate. Cf. Figs. 9-11.
3 . Manganese sulphate is shown to have an inhibiting effect on oxidation by manganese dioxide, so when it is no longer removed by action with permanganate the reaction slows up. j cc of o.z% glucose in a total volume of neutral solution refluxed one hour with manganese dioxide equivalent to 35 cc N/25 (approx) permanganate was oxidized to the extent of 5.92 atoms of oxygen per molecule, while in the presence of 15 cc X/z j manganese sulphate, it was oxidized only to 4.78 atoms per molecule. If the action of glucose may be considered analogous to that of oxalic acid, except that it is slower, Skrabal? who assumes the formation of a M n ' * ' ion which is instantaneously reduced, would write the equations in this way:Harcourt and Eeaon: J. Chem. Soc., 20, 460 (1867). (1904).
* Z . anorg. Chem., 42, I
1988
S. LOLiISA RIDGWAT
+
glucose Rhln04 Mn' glucose (2) Mn(OH)? KMnO, hln ' (3) Afn(OH)z Rln(OH)I hln ' ' ' glucose (I)
+
+
+
+
+
Mn' oxidation product hln(OH)2 oxidation product Mn' ' ' -+ hln(0H)z Mn(OH)( --+ M n ' ' ' + ?rln(OH)z oxidation product
-+
-+
-+
+ + +
Formation of Gluconic Acid In attempting to oxidize the glucose to gluconic acid by potassium permanganate a t the pH a t which this oxidation is brought about by bromine, the method of Kiliani and Kleeman,' Ruff,* and Herzfeld and Lenert3 was repeated and the calcium gluconate prepared. Measuring the pH of the reaction mixture itself was impossible. The p H vias too lorn for ordinary indicators aside from the fact that the bromine destroyed all those tried and the color of the bromine masked any indicator change. The hydrogen and quinhydrone electrodes can not be used in the presence of free bromine. The next best procedure was to determine the pH of the mixture after the reaction had been completed and the solution freed from bromine by boiling and repeated shaking with carbon tetrachloride. With the quinhydrone electrode, the pH was found to be very nearly 0.0. In other words, the solution was normal in respect to hydrogen ions. In order to make up a sulphurie acid-permanganate mixture having such a pH, it is necessary to use more than a normal solution of acid as the dissociation is far from complete a t such concentrations. Also a t these concent,rations, a large change in the amount of acid causes a relatively very small change in pH. Sulphuric acid from j-8 normal or from I :4 to I :8 concentration was found to be within the approximate range. Using 1:8 sulphuric acid and solid reagents-Io gm anhydrous glucose and 4 gm potassium permanganate in 50 cc of acid, the reaction was immediate and violent. The permanganate was in slight excess over that needed to furnish one atom of oxygen per molecule of glucose. Enough extra acid was added to neutralize the KOH formed from the permanganate. X clear colorless solution resulted which became yellow on standing. The sulphate was precipitated by barium hydroxide. A dark brown caramelly smelling liquid was obtained on evaporation. This was precipitated as the phenyl-hydrazine compound. It was recrystallized from alcohol and melted at 198"-200°. This , was not the corresponds to gluconic acid phenylhydrazide ( 1 9 5 ~ - 2 o o ~ )but colorless compound described. Besides it could not be converted into calcium gluconate by the method used by Fisher and Passmore.4 It was not considered to be a derivative of gluconic acid. Another point of evidence in favor of this view was that the reaction betxveen the glucose and permanganate was I 2
3 4
Ber., 17, 1298 (1884). Ber., 32, 2273 (1899). Z. Ver. Zuckerind., 1919, Ber., 22, 2 j z 8 ( I 889).
122
I989
GLUCOSE A S D PERMASGAKATE I N ACID SOLCTION
TABLE I1 Effect of Change of Acidity in Dilute Solutions A,'G: Atoms-of oxygen used Glucose: j cc of 0.2% per molecule of glucose KMnOa: 3j cc of S '2 j Time: 3 0 min. for experiments Yolume: I j o cc marked with an asterisk; Temp. : Boiling 60 min. for tlie others I:I
H~SOI cc 0
N of
H?SOa 0
IO
4.7
16.j
2.65
22.7
0.472
20
5.0
2 4 .I
2.9
25.2
0.946
16 16 16
1.18 1.6ij
14
16 16
I . 895
I8
2.13
I8 20 20
24
2.84
24 28 28
3.35
32
3 i9
32
36
11.;.
.8j 1.2
23.8 2j.I
23.8
15
2
'7 .o
15
I.2j
1;
3.3
23.8 26.4
2j.I
2.2
;.
25.3
3.9
27 .o
14
.7
13
24.6 27.3
14
2.6 2.8
I1
2 . j
13 IO IO
I ,2
IO
I
15
8.79*
9.75 9.2j*
10.35
4.5
29.2
10.43*
3.6
30.6 28.2j 28.0 31.6 33.0
'0.93
.o
7
2.Ij
4.74
6 6
2.75 I .o
4
25.7
8.89* 9.01 8.61* 9.05 8.6* 9 0 8 3* 8.7 8.j * 9.0 8.;* 8.96 8.68* 9 ' 43 9.04* 9.64
29.0
4.26
36 40 40
23.45
2.5
15
I
2.37
I.Ij
15
14
IO
14
22.3
20
0.236
A G
cc
22.6 21.6
4
8 8
.9
15
used by glucose
I .2
2
4
cc
KMnO,
15
0
2
Oxalate cc
Back KMnOd
1.4
31.2 33.2
I O .I* 10.0
II.29*
11.79 11.14* 11.8j
uncorrected accompanied by a marked evolution of gas which must have been carbon dioxide formed from the more complete oxidation of some of the glucose. Still another point was the fact that all the permanganate was used, although the amount present was in excess of that needed to convert all the glucose to gluconic acid. It is of interest to note here that calcium gluconate will reduce
I990
6 . LOUISA RIDGWAY
permanganate under the conditions of the experiment. This makes it possible, though it is improbable, that the oxygen available is used to oxidize a part of the glucose more or less completely going through gluconic acid as a n intermediate compound. The result of this experiment was confirmed by the reaction of dilute solutions of permanganate and glucose in a reacting mixture of the same acidity. The glucose was oxidized almost to carbon dioxide and water as shown by the amount of permanganate used. See Table 11. Another method of making gluconic acid was tried. Permanganate and hydrobromic acid were added to a glucose solution. The permanganate of
FIG.I Effect of Change of Acidity
course liberated bromine from the acid. I t was hoped that by keeping the hydrobromic acid in excess, so the ordinary reaction of permanganate in acid would not take place, the nascent bromine (though not in as high concentration as in the methods using liquid bromine) would oxidize the glucose to gluconic acid. I n quite a number of experiments no gluconic acid was isolated as the calcium compound or the phenylhydrazide. A large amount of the bromine escaped as the free gas and the concentration was always low.
Reaction Rate Between Glucose and Potassium Permanganate The study of the change in amount and rate of oxidation with change in pH, and the search for a stable intermediate point in the oxidation of glucose by potassium permanganate was carried on by the titration method outlined above. Table I1 and Fig. I show the effect of change of acid concentration in dilute and Table I11 and Fig. z in concentrated solutions. In dilute solutions, increasing acidity has no accelerating but a slight depressing effect on the oxidation of glucose by permanganate until a normality of about 1 . 7 5 is reached. Then the effect is steady increase up to the maximum. I n concentrated solutions, the amount of oxidation steadily increases from zero acidity to the highest acidity used. It is suggested that possibly the decrease in pH forces back the enolization and therefore the amount of oxidation,' until such high acidity is reached that the products of partial oxidation are themselves rapidly oxidized. Evans found that in the presence of strong acids, oxidation 'Evans: J. Am. Chem. Soc., 50, 2267 (1928);Chem. Reviews, 6,281 (1929).
GLUCOSE AND PERMANGANATE IN ACID BOLUTION
1991
by such a weak reagent as copper acetate practically stops. I n the more concentrated solutions the effect of the concentration overbalances this. However Table IV and Fig. 3 show that by decreasing the volume and thereby increasing the concentration up to three times the original, the oxidation is only slightly if any increased. The change due to concentration must be relatively gradual. This knowledge is of value in interpreting some later results.
$“ 8 8d
I
6
t
cc
I.?
I
OF I I
I
/U
d
I
24
c,50*
FIQ.3 Effect of Chan e of Volume. Ordinates gen per Molecule of are Atoms of G!kxoe.e.
8,
FIG. 2 Concentrated Solutions
TABLE I11 Effect of Change of Acidity in Concentrated (25x) Solutions A/G: Atoms of oxygen used Glucose: 5 cc of 5% K M n 0 4 : 35 cc of N per molecule of glucose Time: 3 0 min. for experiments Volume: 1 5 0 cc Temp. : Boiling marked with an asterisk; 60 min. for the others I:I
H2S0, cc
N of HiSOi
Oxalate cc
0
100.0
0
15.6 13 .os 11.3 9.2 6.4 6.0
4.5
0.550
4 8
0.472 0.946 0.946 I .418 I ,418
8 12
Back KMnO, cc
38.5 0.3 0.85
KMnO, used by glucose cc 25.0
0.8 0.6
27.7 29.5 30.6 31.3 32.5
1.1
0.4
32.5
5.0
0.2j
7.0 5 .O
0.25
A/G 8.74* 9.69 10.38* 10.70 10.96* 11.36 11.36* 11.47 11. IS* 11.54
24
1.805 2.13 2.13 2.37 2.37 2.84
24
2.84
0.2
0.I
32.8 31.9 33.0 34.5 34.3 33.2 34.8 34.9 35.0
28 28
3.35 3.35
0.I
0.05
35.0
12.24*
0.05
35.05
12.25
12
16 16 18
18 20 20
I . 895
0.4
6.0 4.0 4.0
2.4 1.2 0.I
1.4 I .o
0.5
0
0.4
uncorrected
12.06* 12.00
11.96* 12.17
12.20* 12.24
S. LOUISA RIDGWAT
1YY2
TABLE IV Effect of Change of Volume Glucose: j cc of 0 . 2 % A,'G. Atoms of oxygen used K h l n 0 4 : 3 j cc S '2 j per molecule of glucose H2S04:concentration ( I : 2 7 ) Time. 30 min. for experiments marked with an asterisk; or 1.3 N Temp: Boiling 60 min. for the others 5'01. cc
I :I
H?SO,
Back KMn04
Oxalate cr
cr
Total Kh.ln04 used hy glucose
cc
AIG
rc
IjO
I1
11.0
0.5
24.5
150
11
10.0
0.7
25.7
8.8* 9.2
130 13 0
9.5 9' 5
15.2
0,45
23.5
13
0.3
25.I
8.3* 8.j
I IO
8
Ij.?
1.3
21.3
a.i*
IIO
8 6.6 6.6 5.1 5.' 3.7 3.7
I3
1.1
9.0
14.7
1.2
24.9 24.6
'3 '3
5 .6 2.6 .6
2j.j
2 . 1
2.i.9
9.' 8.8' 0.5 i,7* 9.3
90
90 io
70 SO 50
I
'3 11.6 '3
,
24.5
26.4 21,q
S.R*
uncorrected
TABLE V Effect of increasing Amount of Perniangan:ite relative t o that of Glucose -4,G : ;Itoms of osyycn used Glucose: j cc of 0 . 2 7 ~ per molecule of glucose HZSO,: I I cc I . I or 1.3 ?; Time: 30 niin. for esperiments Volume: 1 5 0 cc riiarkcd with an asterisk; Temp. : Boiling 60 niin. for the others E3ai.k
KhlnO+ cc X /2j
Ovalate cc
KAIn04 ('C
Total KAIn04 used by glucose
A G
cc
35 35
11
. _ I
21. j
8.5'
10
' /
25
9.2
40 40 35
20
2
i 26 33
20
2.6j
26.9
2 ?.
I
26.9
9.7 9 . j*
23
I
.6 .o
27.9
10.0
3'
2.1
23.8
IO.
2i
1.5
30.3
45 50 50
55 55
1
I
9 . j"
4* 10.9
35
2.4
29.3
IO.?*
32
3.3
33.1
11.9
corrected
I993
GLUCOSE A S D PERHANGAXATE I X ACID SOLUTIOX
TABLE VI Reaction Velocity in Hot Dilute Solution H280,: z cc I:I A/G : Atoms of oxygen used per molectile of glucose
Glucose: j cc of 0.2% KMnOd: 35 cc S ' 2 j Volume : I 50 cc Temp. : Boiling Time
Oxalate cc
min. min. 30 min. 40 min. jo min. 60 min. 3 hr. s hr. 6 hr. 8 3/14hr. I I hr. IO
32
20
18 16 15 15
15
'5 IO 10
IO IO
Back KMnOI CC
13.7 2.8 1.4 3.4 1.55 2
.oj
4.I '7 2.8 3.4 3.6 corrected
KMn04 used by glucose cc
19.8 21.5
21.9 25.0
23.0
23.5 23.5 26.7 28.8 29.4 29.6
A/G
7.90 8.29 8.31 8.39 8.45 8.50 8.30 9.35 IO.09 10.00
IO.00
TABLE
Reaction Velocity in Hot Dilute Solution Glucose: j cc of KMnOa: 3j cc 3 Volume : I 50 cc Temp. : Boiling Time
5 min. min. 20 min. 30 min. 40 min. 50 min.
hr.
3 / 4 hr. 4 1/3 hr. 7 hr.
2
8
I/Z
II
hr.
H2S04:4 cc I : I
/ 2 5
A/G : Atoms of oxygen used per molecule of glucose
Oxalate cc
IO
I
o.zyo
hr.
Back KMnO, cc
22.1
5.6
20.0
5.0
15.0
' 45 1.4
15.0 15.0
1.2
15.0
1.2
12.5
2.4 .4
8 .o 8.0 6.5 6.0 6.0
.6
.8 1.5
.7 corrected
KMnO, used by glucose
A/C
cc
20.6 21.9 21.9
22.8 22.6 22.6 24.7 27.3 27.5 29.2 30.4 29.6
8.IO 8.57 8.42 8.61 8.39 8.25 7.9' 8.61 8.53 8.82 9.08 9.00
S. LOUISA RIDGWAY
'994
TABLE VI11 Reaction Velocity in Hot Dilute Solution Glucose: j cc of 0.2% K M n 0 4 : 35 cc N/z j Volume: I jo cc
Time j min.
min. 20 min. 30 min. 40 min. jo min. I hr. 2 hr. 4 hr. 7 hr. IO
11
hr.
Oxalate cc 27. I
Temp. : Boiling H2SO4: IO CC 1:I A/G: Atoms of oxygen used per molecule of glucose Back KMn04 cc 10.2
KMnO, used by glucose cc 20.7
17.
I .j
21.1
16. 16.
0.7
21.9
I .6
22.
15.
1.7
23 ' 1
2.3
23.7 26.3 28.2 29.9 34.3 34.0
15. 12. 11.
8. 2. 2 .
3.35 4.25 2.90 1.3 I .o
I
A/G
8.16 8.17 8.24 8.02 8.11
8.0j 7.73 8.20 8.19 9.54 9.54
corrected
TABLE IX Reaction Velocity in Hot Dilute Neutral Solution Glucose: j cc of 0.2% KMn04: 3j cc N/z j Volume : I 50 cc H 2 S 0 4 :0.01394gm Time j min.
min. 20 min. 30 min. 40 min. 60 min. 90 min. 1 2 0 min. 3 hr. 4 hr. 6 hr. IO hr. IO
Temp. : Boiling A/G: Atoms of oxygen used per molecule of glucose KMn04 used by glucose
cc
Back KMnO, cc
25
11.3
21.7
25
12.j
22.9
15 20
2.8
23.0
7.9 3.3 3.8 4.45 4.7 4.65 5.9 3.4 3 .os
23.2
Oxalate
IS
'5 I5 15.1 1.5.
16.0 13.0 13.0
corrected
cc
A/G
25.6
7.89 8.33 8.36 8.38 8.44 8.48 8.79 8.81 8.82 8.86 9.01
25.25
8.8
