2269
THEACTIONOF HYDROGEN PEROXIDE ON GLYCOLIC ACID
Nov., 1935
[CONTRIBUTION FROM
THE
DEPARTMENT OF CHEMISTXY, U N I w R S I n OF
CINCINNATI]
The Action of Hydrogen Peroxide upon Simple Carbon Compounds. 111. Glycolic Acid' B Y H. SHIPLEY FRYAND KENNETHL. MIL STEAD^
The action of hydrogen peroxide upon glycolic but maintained, as did others, that glyoxylic acid acid has been studied extensively and a notable was the first intermediate product of oxidation. Wieland' detected glyoxylic, formic and carvariety of apparently contradictory results has been recorded. This is due to the widely different bonic acids and formaldehyde in the reaction experimental conditions under which the action mixtures. He also observed the evolution of has been investigated and to the omission of a hydrogen and naturally assumed that its formastandardized quantitative experimental method tion was due to a secondary reaction between the of procedure whereby the yields of each and every intermediately formed formaldehyde and hydroproduct of the reaction have been checked with gen peroxide. Hatcher and Holden,8 in attempting to clear the quantities of hydrogen peroxide participating up the conflicting opinions of previous investigain the severally occurring reactions. A brief review of the several reactions recorded tors, found neither formaldehyde nor hydrogen by previous investigators is pertinent to the pres- but maintained that glycolic acid is first conent study, the purpose of which is to correlate verted into a peracid, which, in turn, gives glyoxquantitatively the extent of the occurrence of the ylic, formic and ultimately carbonic, acids. most likely reactions with the amounts of the hydroTheoretical gen fieroxide therein participating. From a review of the previous investigations, it Fenton and JonesS reported a quantitative yield follows that the present quantitative study of the of glyoxylic acid when hydrogen peroxide reacted action of hydrogen peroxide upon glycolic acid with glycolic acid in the presence of ferrous salts. should not only explain the formation of the Heimrod and L e ~ e n ewith , ~ 30% hydrogen per- variously reported intermediate products, but oxide in alkaline solution, obtained formic, car- also correlate quantitatively the yields of each of bonic and glyoxylic acids. the recovered products of the reaction, notably Dakin5 reported that glycolic acid in the pres- hydrogen, formic kind carbonic acids, with the ence of ferrous sulfate gave a small amount of amounts of hydrogen peroxide initially used which glyoxylic acid, the main product being formaldefunction in the formation of these products, both hyde which was almost entirely oxidized to formic respectively and totally. acid. It should here be noted that Dakin did not To this end, an explanatory scheme of reactions, mention the formation of hydrogen, which would based upon and serving further to illustrate the be an expected product of the reaction if formalde- previously published perhydrolysis reaction mechhyde is an intermediate product, in conformity anism of Fry and Payne,' is proposed. The with the established equation' 2HCHO HzOz equations for the involved reactions are recorded +2HCOOH Hz. in formulas sufficiently graphic t o illustrate the Spoehr6 found that glycolic acid in alkaline perhydrolysis type of reaction. solution was partly converted into equimolecular The first product of the reaction of hydrogen quantities of formic and carbonic acids, but, in peroxide upon glycolic acid is generally conceded the presence of ferrous sulfate, carbonic acid was to be glyoxylic acid, which, according to Hatcher much in excess. This indicated further oxidation and Holden,8 is preceded by (a) the formation of the intermediately formed formic acid. Spoehr and (b) the decomposition of perglycolic acid, made no mention of the formation of hydrogen thus
+
+
(1) Fry and Payne, THIS JOURNAL, 63, 1973. 1980 (1931); Part Methyl Alcohol, Formaldehyde and Formic Acid; Part 11. The Mechanism of the Reactions. (2) Synopsis of Doctorate Thesis of Kenneth L. Milstead. (3) Fenton and Jones, J . Chcm. Soc., 77, 69 (1900). (4) Heimrod and Levene, Biochcm. Z . , 2% 48 (1900). ( h ) Dakin, J B i d . Chem., 1, 271 (1906); ibid., 4, 91 (1908). ( t i l Spoehr, A m . Chem. J.,43, 248. 263 (1910). 1.
CH20HCOOH
+ HOOH +
CH200HCOOH CHiOOHCOOH +CHOCOOH H20 -
+
+ H20
(a) (b)
(7) Wieland. A n n . . 436, 233 (1924). ( 8 ) Hatcher and Holden, Tvons R o y Soc. Con., 90, 396. 407 (1928).
H. SHIPLEY FRYAND KENNETH
2270
+
Z(a, b) C H Z ~ H C O O H HOOH 4
CHOCOOH
+ 2HzO
(c)
The glyoxylic acid thus formed undergoes perhydrolysis CHOCOOH + HOOH +HCOOH [HOCOOH ---+ HzO Coil (4
+
Z(C,d) CHz0HCOOH
+ + 2H20z + HCOOH -+ COS + 3Hz0
(A)
Thus, glycolic acid, through the intermediate formation of glyoxylic acid, may yield not only formic and carbonic acids, but it may also undergo another concomitant reaction, namely, a direct perhydrolysis to yield formaldehyde and carbonic acid
+ +
CHZOHCOOH HOOH + HCHO HzO [HOCOOH +COz
+
+ HtO]
(e)
Formaldehyde, in turn, reacts with hydrogen peroxide to give formic acid and hydrogen 2CHz0
+ HzOz +DHCOOH + Hz
(f)
VOl. 57
L.MILWEAD
In order to correlate quantitatively the yields of each of the three products of the reaction with the quantities of hydrogen peroxide active in their formation, both respectively and collectively, it was necessary to determine how much of the hydrogen peroxide initially used did not participate in reactions (A), (B) and (C). This is the hydrogen pero5ide which suffered direct decomposition into water and oxygen. The quantity of oxygen liberated in each experimental run would be equivalent to this inactive quantity of hydrogen peroxide. The difference between this and the initially used quantity is the active hydrogen peroxide. Hence, it was necessary in all experimental runs and related calculations to include a fourth equation (D) for the concomitant reaction 2Hz02 42H20
+
0 2
(D)
It is highly probable that the extents of the The summation of equation (e), doubled, and occurrence, or the rates of reactions A, B, C and equation (f) represents the conversion of glycolic D, are different in alkaline solution, in acid soluacid to formic and carbonic acids and hydrogen. tion and in the presence of ferrous salts, as the z(e, f) 2C"zOHCOOH 3H202 4 observations of previous investigators apparently 132 + 2HCOOH 2COa + 4HgO (B) indicate. It should here be noted, however, that This derivation of each of the summation equa- the present study is limited to the determination tions, (A) and (B), for the two principal con- of the extent of the occurrence of the reactions A, comitant reactions, indicates the conversion of B, C, and D in acid solution, with increasing conglycolic acid to the final products, formic and centrations of hydrogen peroxide, as described in carbonic :dds. Equation (B) indicates the for- the experimental part. mation of hydrogen also. Experimental The marked susceptibility of oxidation of formic acid to carbonic acid by hydrogen peroxide exThe train of apparatus and the experimental plains our quantitative observations, subsequently method of procedure employed in this study have recorded, that in all experimental runs, with been previously described in detail by Fry and varied coiicentrations of hydrogen peroxide, the Payne. * yields of carbonic acid (carbon dioxide) were In five successive experimental runs (I-V), each greater than the yields of formic acid. This conducted in duplicate, one-quarter mole of pure secondary reaction of intermediately formed for- glycolic acid was added to successively increased mic acid necessitates the postulation of a third quantities of 30% hydrogen peroxide, free from equation organic preservatives, specially prepared by the HCOOH HOOH +HzO + [HOCOOH --3 Roessler and Hasslacher Chemical Company, HzO Cod (C) namely, (I) one-eighth, (11) one-fourth, (111) oneThe generally reported final products of the half, (IV) three-fourths, and (V) one mole, action of hydrogen peroxide upon glycolic acidrespectively. Each of these mixtures of hydrogen formic and carbonic acids and hydrogen-have peroxide and glycolic acid was further acidified been identified, and their quantitative yields have hy the addition of 2.16 g. of sulfuric acid, diluted been determined in the present investigation. with water to a total volume of 125 cc., and heated Their formation is explained in terms of three continuously for nine hours in a 250-cc. roundreactions represented by the above derived equa- bottomed Pyrex flask submerged in a water-bath tions (A), (B), and (C). The first two will be a t 100'. shown to be concomitant, while the third is a The hydrogen formed (equation B) and the secondary reaction. oxygen evolved (equation D) were collected in
+
+
+
+
THEACTIONOF HYDROGEN PEROXIDE ON GLYCOLIC ACID
Nov., 1935
TABLE I MOLARQUANTITIESOF HYDROGEN PEROXIDE AND GLYCOLIC ACID USEDAND 1 Initial
2
Initial
Run
HzOt mole
CHsOHCOOH, mole
Ia Ib IIa IIb IIIa IIIb IVa I?% Va Vb
0.1250 .1250 .2500 .2500 .5000 .5000 .7500 .7500 1.0000 1.0000
0.2500 .2500 ,2500 .2500 .2500 .2500 .2500 .2500 .2500 .2500
3 HCOOH
4 HzCOa found, mole
Hz found, mole
0.0142 .0141 .0271 .OB6 .0353 ,0339 .0374 .0363 ,0399
0.0267 .0268 ,0566 ,0563 .loo0 .0979 .1530 .l540 .194 .208
0.0024 .0023 .0055 .0047 .0083 .0087 .0134 .0132 .0138 .0161
found, mole
.0416
5
OF
2271
PRODUCTS FORMED 6
7
ol
CHzOHCOOH found, mole
0.0410
0 229 .225 .2044 ,2106 .l787 .1781 .158 .156 .1270 .1219
found, mole
I
.a408 .os01 ,0799 .1786 .1726 .2605 .2622 .3489 .347
the gasometer a t the end of the apparatus train, (B) , and the total yield of carbonic acid, measures The total yields of each gas, determined by stand- the extent of the occurrence of the secondary ard methods of gas analysis, serve to measure the reaction, equation (C). extent of the Occurrence of reactions represented All of the analytical data thus secured are emby equations (B) and (D). bodied in the tables. For convenience in reference The total carbonic acid formed (equations A, thereto, the equations for the four postulated B, and C) was calculated from the amounts of reactions are herewith retabulated. carbon dioxide absorbed in weighed ascarite CHzOHCOOH 2Hz02 +HCOOH COz 3HzO towers. (A) The resultant reaction mixtures, containing 2CHzOHCOOH 3H202 --+ HB 2HCOOH + 2C02 4Hn0 (B) practically only formic acid (equations A and B) HCOOH HzOz +COz 2Hz0 (C) and some unaffected glycolic acid, gave the fuch2H202 +2H20 02 (D) sin test for traces of aldehydes, the quantities of Table I records the molar quantities of the which, however, were too small to be determined hydrogen peroxide and glycolic acid initially quantitatively. Tests for the presence of glyoxy- present in the reaction mixtures of the five suclic and oxalic acids were negative. cessive duplicate sets of runs, and the molar Aliquot portions of the reaction mixture weie yields of the respective resultant products. titrated for total acidity with standard alkali. Table I1 records in columns 1, 2, 3 and 4, the Subtracting the acidity due to the initially added percentages of hydrogen peroxide equivalent to sulfuric acid, gave the acidity due to the formic the products of the reaction as calculated from acid and unreacted glycolic acid. The yields of the respective equations for the proposed reacformic acid, determined gravimetrically by the tions. Column 5 notes the sum total percentage standard mercuric chloride method, permitted of hydrogen peroxide used. calculations, by difference, of the quantities of TABLE I1 glycolic acid remaining unchanged in the reaction PERCENTAGE QUANTITIES OF HYDROGEN PEROXIDE USED mixtures. EQUIVALENT TO YIELDSOF PRODUCTS FORMED In calculating the extents of the occurrence of 1 2 3 4 5 % Hz02 %HzOz Total % the two principal concomitant reactions, equations J%E&%H =HzCOs e02 HzOz= Eqs. Eq. ( A ) Eq. (B) Eq. (CJ Eq. (D) ( A , B , C , D ) (A) and (B), and the secondary reaction, equation Run 25.44 6.759 5.200 65.60 102.00 (C), the quantity of glycolic acid which reacts to Ia 5.040 65.28 101.12 25.28 5.520 give hydrogen, as well as some of the formic and I b IIa 24.72 6.601 5.921 64.07 101.31 carbonic acids, is based upon the yield of hydrogen ti. 322 100.ti9 IIb 24.80 5.640 63.93 in conformity with equation (€3). The remainder 71.44 103.28 20.40 4 I979 6.460 IIIa of the glycolic acid reacting serves as the basis for IIIb 100.06 19.40 5.223 69.04 6.398 calculating the yields of formic and carbonic acids IVa 69.45 100.62 18.13 5.359 7.68 in conformity with equation (A). The difference IVb 69.90 100.98 18.40 5.279 7.40 between the sum of the yields of carbonic acid, Va 4.14 69.78 7.71 99.51 17.88 obtained in conformity with equations (A) and Vh 68.94 100.67 8.34 18.56 4.83
+ + +
+
+ + + +
+
H. SHIPLEY FRYAND KENNETH L. MILSTEAD
2272
Table 1.11 records in columns 1 and 2 the pertentage quantities of glycolic acid reacting according to equations (&A) and (B), respectively. gives the percentages Of the initially Column :% used glycolic acid which did not react. The sums of the Percen%es r ~ O r d e din columns 1, 2 and 3, given iI1 Column 4, account for all Of the initially used glycolic acid, active and non-reactive. TABLE I11 OF GLYCOLIC ACID, NON-REACTIVE, AND TOTAL
PERCENTAGE QUANTITIES
REACTIVE,
VOl. 57
reactions assumed to occur leads to the summary and conclusions given below. Grateful acknowledgments are extended to Mrs. Ernst Twitchell, whose renewal of the Ernst Twitchell Fellowship in Chemistry made this study possible, and to the Roessler and Hasslacher Chemical Company for kindly donating the specially prepared hydrogen peroxide used in this investigation. Summary and Conclusions
1. Since the ratio of the yields of formic acid to those of hydrogen (Table I, columns 3 and 3) e(i, z , 3 ) were invariably greater than 2:1, which ratio, Run E ~ (B) . Ia 6.630 1.920 91.60 99.88 according to the single equation (B), is 2:1, it Ib 6.322 1.841 90.01 98.17 follows that the reactions represented by quations I Ia 12.36 4,400 81.75 98.51 (A) and (B) were concurrent. IIb 12.40 3.760 84.24 100.40 2. The extents of the occurrence of the reacIIIa 20.40 6.640 98.52 tions represented by equations (A), (B), and (C) 71.48 IIIb 19.40 6.960 71.24 97. BO with increasing concentrations of hydrogen peroxide IVa 27.20 10.72 63.22 101.14 are shown by the data in columns 1, 2, and 3, IVb 27.60 10.56 a. 44 Va 35.76 11.04 50.81 97.61 respectively, of Table 11, and likewise columns 1, Vb 37.12 12.88 48.75 98.75 2 , and 3, respectively, of Table IV, to be as follows : (A) shows a tendency to decrease; (B), small IV records the Percentage Yields Of car- variations; and (C), a tendency to increase. bon dioxide as calculated in relation to the reac3. The of the percentage quantities tions represented by equations (A),(B)*and (c)* (Table 11) of the hydrogen peroxide active in the The relative yields facilitate comparisons of the several reactions, equations (A), (B), and (c) , extent of the occurrence of each of these reactions and the inactive or directly decomposed hydrogen as affected by the increasing concentrations of peroxide, equation (D), are, within the limits of Peroxide used in the successive experimental error, practically 100% of the initial I-V. quantities of the hydrogen peroxide employed in TABLE IV each experimental run. PERCENTAGE YIELDS O F CARBON DIOXIDEI N RELATION TO 4. In parallel with (3), the sums of the perOCCURRINGREACTIONS centage quantities (Table 111) of glycolic acid 1 2 3 % cot % cot % con oxidized, equations (A) and (B), and recovered Run Bq. (A) Eq. (B) Eq. (C) Ia 58.80 17.98 23.22 unchanged, are, within the limits of experimental Ib 58.98 17.17 23.89 error, practically 100% of the initial quantities IIa 54.61 19.44 25.9'7 of the glycolic acid employed in each experimental IIb 55.07 16.69 28.24 run. IIIa 51 .00 16.60 32.40 5. The above results, particularly (3) and (4), IIIb 49.53 17.77 32.68 serve to check quantitatively the accuracy not IVa 44.58 17.52 37.90 only of the experimental method employed, but IVb 44.54 17.14 38'32 also of the equations derived for the three reacVa 46.08 14.22 39'69 tions assumed to occur, and the extents of their 1% 44.61 15.48 39.90 occurrence, respectively, when hydrogen peroxide reacts with glycolic acid. 11, survey of the analytical data of the above tables in relation to the derived equations for the CINCINNATI, OHIO RECEIVED JULY 22, 1935 1 %, CHIOHCOOH C: HCOOH Eq. ( A )
2
% CHzOHCOOH H2
3
% CHIOHCOOH unchanged
4 Total % CH~OHCOOH
