I N D USTR I A L A N D EN GI N E E R I N G C H E M I ST R Y
November 15,1934
The total weights of silver and hydrochloric acid solution are found by simple addition as follows: Grams 2.36636 0.00158 0.00021
Original weight of silver 1.5s ml. of dilute silver solution 0.21 ml. of dilute silver solution Total Original weight of acid 0.5:1 ml. of dilute acid
0.053 gram of original acid
2.36815 74.7501 0.0530
-
74.8031
The weight normality is then 1000 X 2.36815 74.8031 X 107.88 = 0'29346
The above specimen calculation presupposed three trialand-error additions to bring about equivalence. I n none of the actual experiments, however, was this necessary. The preliminary test described above was so effective that two additions always gave the end point.
CONCLUSION Readers are likely to assume that this silver method for standardizing an acid is too cumbersome to employ. Trial will show, however, that this is not the case. The procedure appears cumbersome because it is unfamiliar, but it is, for example, no more difficult or time-consuming than the con-
433
stant-boiling acid method (1) so often employed. Also, it is not offered as a rapid method of standardizing hydrochloric acid but rather as a reliable one. Nothing has been said about applying vacuum corrections to the weighings. Such corrections are not necessary, since the paper deals with a comparison of two procedures, the atomic weight or precision method of standardizing and the analytical method. Owing to the small difference in density between silver and the brass of the weights, a vacuum correction applied to the weight of silver would affect the normality of the acid somewhat less than one unit in the fifth decimal place. The vacuum correction in weighing the hydrochloric acid solution would be large, but it can be avoided by the simple expedient of defining a weight normal solution as one that contains a hydrogen equivalent in 1000 grams of solution as weighed with brass weights in air.
LITERATURE CITED (1) Foulk and Hollingsworth, J. Am. Chem. Soc., 45, 1222 (1923), (2) Lamb, Carleton, and Meldrum, Ibid., 42, 251 (1920). (3) Richards, Proc. Am. Acad. Arts Sci., 30, 380 (1894). (4) Richards and Archibold, Ibid., 38, 441 (1902). (5) Richards and Wells, J. Am. Chem. Soc., 27,475 (1905). (6) Richards and Willard, Ibid., 32, 4 (1910). RECEIYBDJuly 27, 1934. Presented before the Division of Physical and Inorganic Chemistry at the 88th Meeting of the American Chemioal Society, Cleveland, Ohio, September 10 to 14, 1934.
Estimation of Aldehydes by the Bisulfite Method An Improved Procedure A. ERICPARKINSON AND E. C. WAGNER John Harrison Laboratory of Chemistry, University of Pennsylvania, Philadelphia, Pa.
T
HE bisulfite method of Ripper (27) was initially tested
only with formaldehyde, acetaldehyde, benzaldehyde, and vanillin. A study by Feinberg (7) included also salicylaldehyde, p-hydroxybenzaldehyde, and anisaldehyde, results for these being only semi-quantitative. Jolles determined furfural and pentoses (IS)and acetone (12,29); Meyer (26, 26) recommends the method for several aldehydes in addition to those mentioned, but without evidence that its applicability has been tested. The bisulfite method has been used for estimation of lactic acid via acetaldehyde (2,3,9, IO), and of some unsaturated aldehydes (11, 15, dG). Reports as to the accuracy of the method are conflicting, in some cases because of failure to appreciate the nature of the reactions involved and the conditions essential to accuracy. The reaction between carbonyl compounds and bisulfite is reversible :
R.CO
I
+
-HSOs
R.C(OH)SOs-
I
The distribution a t equilibrium varies with the identity of the carbonyl compound, the pH, temperature and concentration of the solution, and the excess of bisulfite. The results of analysis depend further upon the specific rates of the addition and dissociation reactions, these also being affected by the conditions mentioned. Kerp and collaborators (14) made equilibrium studies of the bisulfite compounds of formaldehyde (6),acetaldehyde, benzaldehyde, furfural, acetone, and glucose, and Stewart and Donnally (31) reported a more
elaborate study of benzaldehyde-bisulfite. Using Kerp's data, Kolthoff (19) calculated the inherent error in analysis due to dissociation. A consideration of available evidence permits the following conclusions: 1. Thc accuracy of analysis is determined primarily by the value of the equilibrium constant for the dissociation. When this is of the order of IO-* or less, accurate analysis is feasible (formaldehyde, acetaldehyde, benzaldehyde, furfural). When K equals 10-3 (acetone), analysis is posgible if bisulfite is used in luge excess. When K is greater than 10-8 (glucose), the results are too low. 2. The accuracy of the method is increased, especially when K is unfavorably high, by excess of bisulfite and by increase in the concentrations of both reactants. When K e uals 10-7 (formaldehyde) or IO+ (acetaldehyde), even dilute so?utions can be analyzed using only a moderate excess of bisulfite. 3. The accuracy of analysis is affected by temperature, but here two conflicting effects are to be noted. The error due to dissociation can be decreased by working at low temperature, as the value of K decreases with decreasin temperature (14, SI), but the rate of the addition reaction is &ereby decreased, and the time necessary for attainment of e uilibrium ma exceed the 15 to 60 minutes usually specified. ?he analysis orsome aldehydes requires a low temperature at the time of titration; in such cases the reaction liquid may be allowed to stand a suitable interval at room temperature and then chilled for a time before and during titration. 4. The rates of addition and dissociation are affected by the hydrogen-ion concentration, the former decreasing with increasing acidity, while the latter and the dissociation constant are at a minimum somewhat in the acid region (at about pH = 1.8 for
434
ANALYTICAL EDITION
Vol. 6, No. 6
TABLEI. ANALYSISOF ALDEHYDESBY MODIFIEDRIPPER-FEINBERG AND EXCESS-IODINE PROCEDURES COMPOUND^
Solution 2
HD-NaOH: 36.29%
Acetaldehyde b B. p. 24.8-25O B. p. 22.5-25O B. p. 21.5-21.9'
Propionaldehyde B. p. 48.4-48.6' B. p. 48.4-48.5' Uaed promptly n-Rut yraldelpdeh B. p. 75.4
Isobutyraldehyde; B. p. 64.2-64.6
n-Valeraldehydeh B. p. 102.4O
Isovaleraldekydeh B. p. 92.5
n-Heptaldehy$ei B. p. 151.4 Redistilled: B. p. 152.4'
INDICATED PURITY
OF
Ripper-Feinberg T B M P E R A T U R ~ method
Excess iodine method
TIME
0.2144
0.3
60
27
35.36 35.13 35.23 35.16 Av. 35.22
35.80 36.02 35.44 35.60 Av. 35.72
0.2159
0.3
30-60
23
35.43 35.75 35.60 Av. 35.59
36.54 36.57 36.39 36.49 Av. 36.50
Oram
Formaldehyde Solution 1 Romijn: 35.92% HLh-NaOH: 35.95%
CONCN.
NaHSOa M
SAMPLE
Min.
c.
%
0.13-0.25 0.12-0.16 0.1681 0.1433 0.1298
0.3-0.4 0.4 0.4 0.4 0.4
60 35 45 30 30
21-24 20-23 22 23 24
93.10: 94.00
0.15-0.22 0.1673 0.1421 0.1401
0.4 0.4 0.4 0.4
30-240 45 45 45
21-24 26 28 28
90.02~.~ 90.20
0.1346 0.1532 0.1376 0.1387 0.1587
0.4 0.4 0.4 0.4 0.4
60 60 60 60 45
26 21 21 25 25
0.1290 0.1350 0.1235 0,1888 0.1729 0.1878
0.4 0.4 0.4 0.4 0.4 0.4
60 60 45 60 15 60
21 21 21 22 22 In ice
0.1906 0.1517 0.2055 0.1626
0.4 0.4 0.4 0.4
30 45 60 45
24 26 24 In ice
0.1484 0.1429 0.1407 0.1416 0.1397 0.1392
0.4 0.4 0.4 0.4 0.4 0.4
45 45 45 60 45 60
25 22 23 25 I n ice In ice
0.1886 0.1452 0.1642 0.1380 0.1359 0.1399
0.4 0.4 0.4 0.4 0.4 0.4
45 45 45 45 45 60
25 24 28 25 303 323
...
98: oor
... ... ...
93:3s
...
... 9i:97 88.83 8s: 74 Av. 90.18
(88.18) 94.87 97: 32 Av. 96.10 92.17
...
si:5s 93:is Av. 92.41
ei,'ie ... 89:i7 Av. 90.'62
benzaldehyde bisulfite), and increa.se as the acidity diminishes (14, 31, 32). Practical application of these relationships was made by Tomoda (32) in the estimation of acetaldehyde, the excess bisulfite being titrated as usual, the H adjusted to about 8 (sodium bicarbonate) to accelerate the &sociation of the bisulfite compound, and the bound bisulfite then titrated as a direct measure of the aldehyde. A similar procedure was described recently bv Lea (23) for heptaldehyde. Donnally (6) applied a more rigid control to the analysis of formaldeh de and benzaldehyde, making three pH adjustments: one Godium bicarbonate) for the addition, a second at about pH 2 (acetic or phosphoric acid) for titration of excess bisulfite, and a third (sodium carbonate) for titration of bound bisulfite. Such procedures are theoretically superior to the method of Ripper, afford a direct instead of an indirect analysis, and eliminate the blank analysis. The accuracy, however, is not necessarily increased, for the direct titration starts a t the end point of the excess-bisulfite titration, and the imperfections in this end point will affect equally the results by both methods. Donnally obtained for formaldehyde nearly identical results by both titrations, but results for benzaldehyde were high as calculated from the titration of excess bisulfite. This is attributed to oxidation of bisulfite by air, but it is not clear why such incidental oxidation did not similarly affect the results for formaldehyde. 5. An inherent source of inaccuracy in the Ripper method is the manner of titration-the addition of iodine to bisulfitewhen, as is well known, correct results are obtained only by the reverse procedure (17, 33). The irregularity has been assigned variously to reduction by the hydriodic acid of reaction, to loss of sulfur dioxide by volatilization, and to air oxidation of sulfite, the last being probably the chief source (8, 16, 20,24). As aldehyde bisulfites are not per se reactive with iodine, but reduce
%
97.24d 98.620 98.36 98.90 99.42 Av. 98.89f 95.53dto 98.38 98.75 97.88 Av. 98.57 99.31 97.90 98.26 98.65 98.40 Av. 98.50 95.66 95.82 95.48 96.19 95.65 95.93 Av. 95.79 95.90 95.87 96.13 97.10 Av. 96.25 97.08 98.23 97.30 98.00 97.54
A ~ 9i.'63 . 96.59 97.28 96.23 96.81 97.18 98.99 Av. 97.18b
it only a t the rates at which they dissociate (14, 21, 31, 32), the reversal of the Ripper titration is feasible if the specific dissociation rate in any case is not too high. This modificationaddition of an aliquot of the reaction liquid to a measured excess of iodine and prompt back-titration with thiosulfate-was used by one of the writers (W.) in 1925 in the early trials of the excessiodine method described below, and was independently adopted as preferable by Kolthoff (18) for analysis of formaldehyde, acetaldehyde, benzaldehyde, and furfural. This paper presents results obtained by the excess-iodine method just mentioned, in comparison with results given by a somewhat modified Ripper-Feinberg procedure, both applied to the following compounds: formaldehyde, acetaldehyde, propionaldehyde, n- and isobutyraldehydes, n- and isovaleraldehydes, n-heptaldehyde, acetal, benzaldehyde, salicylaldehyde, vanillin, piperonal, paraldehyde, crotonaldehyde, and cinnamaldehyde, the last three not being analyzable by the procedures used. The results show a marked superiority for the excess-iodine procedure. Under the conditions employed, the acidity of the unbuffered bisulfite was somewhat too high for the most rapid attainment of equilibrium, and especially toward the end of the titration, probably exceeded the optimum for greatest stability of the bisulfite compound. The unfavorable effect of the first condition was counterbalanced by use of a rather large excess of bisulfite of greater concentration (0.3 to 0.4 M ) than was specified by Ripper or
November 15,1934
INDUSTRIAL AND E N GINEER I N G CHE M I STRY
435
TABLE I (Continued) COMPOUND'
8
0
h I
i k 1
Mi%
c.
%
%
0.1669
0.3
24
0 0
Room
1 67.30
... ...
l&:7z 123.21
178.11 195.71 117.61 96.61 105.11
97.02 94.5s 97.56
97.21 98.06
0.1592 0.1842 0.1668 0.1595 0.1661
0.4 0.4 0.4 0.4 0.4
30 45 45 45 60
22 22 24 25 23
.Redistilled: B. p. 102.7-102.8°
0.4853 0.4826 0.4710 0.4716 0.4695 0.4666 0.4470 0.4670 0.4310 0.6234 0.5053 0.4845
0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3
60 60 120 120 120 120 150 150 16 hra. 180 135 135
Room Room 25 26 27 26 25 24 Room In ice Room 24
Benzaldehydeh n. p. 178.5" Redistilled in Nn: B. p. 178.4"
0.2510 0.2485 0.3936 0.2459
0.4 0.4 0.4 0.4
45 45 45 45
27 27 28 29i
Saiicylaldehydeh B. p. 196-196.3'
0.2665 0.2736 0.2648
0.4 0.4 0.4
45 45 45
26i 27i 27i
Cinnamaldehydeh B. p. 250.7-251.3'
0.2907
0.4
45
243
Vanillinh M. p. 81.5'
0.2414 0.2419 0.2464
0.4 0.4 0.4
45 45 45
24i
27i 26i
96146
Pi eronalh p. 36.8-37.0'
0.2278 0.2286
0.4 0.4
45 45
25i 2%
98.80
k.
f
TIM^
M
0.3
Acetal 13. p. 102.4-102.7°
c d
NaHSOa
Gram
0 . 2 5 g.PhSOaH 1 g. PhSOaH 0.2074
Crotonaldehyde B. p. 102.3O
6
INDICATED PURITY Ripper-Feinberg Excess iodine method TEMPERATUBE method
90 +21 hrs. +75 min. 45 hrs.
Paraldehyde n. p. 123.6-124.4°
a
SAMPLB
CONCN. OF
+ +
Boiling and melting points are corrected values, Boiling points for acetaldehyde affected by positive error due to superheating through co1um.n wall. Average of 7 determinat;ons. Average of 6 determinations. Average of 4 determinations. Other workers (fa, 18, 24, 67,68, 84, cf $2, 90) have reported higher values for acetaldehyde. Specimen deteriorated. 6 cc. of alcohol used. i0 cc. of alcohol used. Chilled in ice during titration. Using the direct titration (bound bisulfite) method, Lea (88) obtainedfor heptaldehyde 19 results which ranged from 93.3 to 97.0 per cent and averaged 95.6 per cent. Note irregular effect of double bond.
Feinberg. That of the second condition was decreased, in the analysis of aldehydes whose bisulfite compounds gave evidence of too rapid dissociation at room temperature, by chilling in ice (after standing at room temperature) for a short time before and during contact with iodine. (Analysis by Ripper's method at low temperature has been recommended by several chemists, 4, SO, 34.) This precaution was advantageous in the estimation of aromatic and higher aliphatic aldehydes. Rationalization of the bisulfite procedure must await extension of methods such as those used by Kerp et al., and by Stewart and Donnally, t o other compounds, so as to permit selection of optimum conditions for addition and titration. This work is projected for the near future.
EXPERIMENTAL In most of the trials the sodium bisulfite soluREAGENTS. tions were 0.3 or 0.4 M . They were not stabilized ($0,16, 84), the effective concentration being determined for each series of analyses by means of a parallel blank. Sodium thiosulfate (0.1 N ) was standardized weekly or oftener against potassium iodate. Iodine (0.1 N ) was standardized frequently against the thiosulfate. Though prepared as directed by Ripper (27) and later by Chapin (I), the solutions lost strength rapidly. ALDEHYDES.Commercial specimens of U. S. P. strength formaldehyde were used, assayed by the iodometric method of
... ...
95:i5 97:22 9+:44 97.02 97.23 Av. 96:+3 (8b:sl)
:
9i i5 94.44
... ... e.,
...
,,.
... ...
si:33 se:99 9i:k 97.30 90.52 9s: b4 Av. 97.22 95.65 96.35 96.52 97.69 96.31 96.21 95.82 Av. 96.11 175.21 97.89 96.99 90.96 Av. 97.28 100.75 100.40 Av. 100.58
Romjjn and the alkaline hydrogen peroxide method of Blank and Finkenbeiner. Liquid aldehydes were Eastman Kodak Company products. Thev were shaken with sodium carbonate solution, dried with calcium chloride, and specimens of good boiling point obtained by means of an 8-ball Snyder column. If necessary, specimens were redistilled, using a semi-micro column, until maximum results were obtained by analysis. Specimens which suffered rapid air-oxidation or polymerization were redistilled before each analysis and used promptly. Benzaldeh de was finally distilled under nitrogen, and samples were coiected directly in the measured bisulfite solution. The deterioration of most of these aldehydes was rapid, and in general it was found that analytical purity could be assumed only for specimens freshly purified. The deterioration of several aldehydes was plainly due to oxidation. Some deteriorated samples left droplets insoluble or slowly soluble in bisulfite solution, suggesting the presence of polymers; the trials with paraldehyde indicated that aldehyde polymers cannot be estimated by the bisulfite method. Vanillin and piperonal were Kahlbaum specimens, recrystallized from 10 and 50 per cent alcohol, respectively. ANALYTICAL PROCEDURDS. Each analysis required two 50-CC. volumetric flasks, into each of which 25 cc. of bisulfite solution were pipetted. Into one flask was introduced the sample (0.002 to 0.004 mole) as described below. The liquids were diluted to the mark, mixed, and the stoppered flasks ailowed to stand for the selected period (usually 30 to 60 minutes). An aliquot of each (usually 10 cc.) was withdrawn with a pipet calibrated against the flasks, and the titratable bisulfite determined as described below. In certain cases indicated in Table I the liquid was chilled in ice during the last 10 minutes of the standing period and throu hout the determination of bisulfite. About 2 cc. of formalin were introduced into a weighed 100-cc. volumetric flask containing about 25 cc. of water, the increase in weight was determined and the solution diluted to the mark, and 10-cc. aliquots were used for analysis. Freshly distilled acetaldehyde was transferred to a weighed glass ampoule, which was sealed off and reweighed. The ampoule was broken under bisulfite solution in the reaction flask, the solution diluted to the mark, and a volume of water equal to that displaced by the ampoule added from a Mohr pipet. For water-soluble aldehydes the stoppered 50-cc. flask containing 25 cc. of bisulfite solution was weighed, the sample dropped
ANALYTICAL
436
into the liquid, and the fla.sk reweighed. For aldehydes insoluble or slightly soluble in water, 5 cc. (in some cases 10 cc.) of aldehyde-free alcohol were stratified upon the bisulfite solution before introducing the sample. Solid aldehydes were intraduced through a wide-stem funnel. When alcohol was used in an analysis i n equal volume was added to the blank. To determine excess bisulfite by the modified Ripper-Feinberg method, 10 cc. of solution were withdrawn, and the pipet was thrust nearly to the bottom of an Erlenmeyer flask and allowed to drain. Excess bisulfite was titrated at once and rather rapidly with 0.1 N iodine, with the addition of 5 CC. of 0.5 per cent starch indicator near the end point. With aliphatic aldehydes the end points were generally satisfactory. With aromatic aldehydes the end color was transitory, only a few seconds; unless such titrations were run rapidly the approximately correct end point was inevitably O V W I X ~ . To determine the effective strength of the bisulfite solution, an aliquot of the blank was similarly titrated. To determine free bisulfite by the excess-iodine method, 50 or. of 0.1 N iodine were pipetted into an Erlenmeyer flask, and a 10CC. aliquot of the analysis liquid was allowed to flow in while rotating the flask. The excess iodine was immediately titrated with 0.1 N sodium thiosulfate. In some cases the flask was immersed in an ice bath during the period excess iodine was present. An aliquot of the blank analysis liquid was treated similarly. The end points by this procedure were in all cases satisfactory. Results of trials by the two methods are given in Table I. The results in Table I show that the excess-iodine procedure is in general superior to the modified Ripper-Feinberg method. The effect of time was not pronounced, and it appears that 45 to 60 minutes, and in some cases less time, will yield maximum values for most of the compounds tested. The effect of low temperature was generally favorable though rather small for aliphatic aldehydes, but was pronounced for aromatic aldehydes, analysis of which requires chilling of the liquid before titration. Neither method can be considered precise, except for formaldehyde, and agreement of duplicates within 0.5 per cent is in general to be considered good. OF ALDEHYDE BISULFITESIN CONTACT WITH DECOMPOSITION
IODINE dissociation of In the excess-iodine procedure hyde bisulfite must occur between the moment the aliquot is added to excess iodine and that a t which the end point of the thiosulfate titration is reached. In practice this is decreased by chilling the liquid. To obtain an approximate idea as to the relative rates of dissociation of various aldehyde bisulfites in contact with iodine under the conditions of analysis, self-explanatory tests were made (Table 11). TABLE 11. DECOYPOSITION OF ALDEHYDE BISULFITESIN CONTACT WITH IODINE
EDITION
Vol. 6 , No. 6
sulfite compounds of aromatic aldehydes dissociate much rapidly; in ice the rate is much decreased, but is sufficiently high to show that even with prompt titration of excess iodine a sensible negative error will enter the results. CONCLUSIONS The RiPPer-Feinberg bisulfite method Yields low results with many aldehydes because of the reversible dissociation of the aldehyde bisulfites, and because of inaccuracy in the titration of excess bisulfite by iodine. T~ avoid the titratiOn error a procedure is used in which a n aliquot of the analysis liquid is added to a measured excess of iodine, and the excess titrated promptly with thiosulfate. With aldehydes whose bisulfitecompounds dissociate toorapidly at PeratUre the liquid is chilled in ice before and during contact with iodine. Both methods have been applied to a more extended list of aldehydes than has previously been tested by the bisulfite method; the excess-iodine procedure gave the higher and more consistent results and better end points. The aldehydes tested, and averaged purity results by the excess-iodine method, are as follows: formaldehyde (100 per cent) , acetaldehyde (98.9 per cent), propionaldehyde (98.6 Per cent), %-butyraldehyde (98.5 Per cent), isobutyraldehyde (95.8 Per cent), n-valeraldehyde (96.3 Per cent), isovalerald&‘de (97.6 Per cent) n-hePtaldehYde (97.2 Per cent), acetal (97.2 Per cent), benzaldehyde (97.1 Per cent) salicylaldehyde (96.1 Per cent), vanillin (97.3 Per cent), Piperonal (100.6 Per cent) * Paraldehyde, CrotonaldehYde, and CinnamaldehYde could not be satisfactorily analyzed. LITERATURE CITED
{i; ~ ~ ~ ~ ~ , J j . A ~ ~ l ~ ~ ~ ~ ~ ~ (3) D ~&,&em. ~ z., 51,396 ~ ~(1913).~ ,
Dodge, Rep. 8th. Intern. Congress Applied Chem , 17, 15 (1912). Donnally, IND.Exa. CHEM.,Anal. Ed., 5, 91 (1933). Donnally, Thesis, Univ. of California, 1932. J.i 499 87 (1913). Feinbergf Am. Ferguson, J . Am. Chem. Soc., 39, 364 (1917). Friedmann, Cotonio, and Shaffer, J . Biol. Chem., 73, 335 (1927). Furth, van, and CharnaW &&em. 2.7 26, 199 (1910). Ivanov, Arch. Hyg., 73, 307 (1911). ~ ~ l l ~39,~1306 , (1906). Jolles, 2. anal. Chem., 45, 196 (1906) : 46. 764 (1907). Kerp, Arb. kais. Gesundh., 21, 180 (1904); Kerp and Baur, Ibid., 26, 231, 269 (1907); Kerp and Wohler, Ibid., 32, 120 (1909); Chem. Zentr., 1904, 11, 57; 1907, 11, 970, 971; 1909, 11, 710. (15) Kerp and Wohler, Arb. kais. Gesundh., 32, 99 (1909); Chem. Zentr., 1909, 11, 708. (16) Kolthoff, 2. anal. Chew., 60, 448 (1921). (17) Kolthoff-Furman. “Volumetric Analvsis.” Vol. 11. D. 399. John
(4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)
.
I
mr:i-..
R.
IMMEDIAT~ TITRATION TITRATION AFTER E X T ~ N D E D WITH IODINE Excmss I O D I N E ~ CONTACT Indicated Time of Indicated purity Temp. contact purity c. % C. Hours % Room 35.5 Room 3 35.7 24 96.5 Room 1 93.0 24 97.1 Room 16 89.9 1 97.0 23 98.9 23 23 95.0 23 0.75 93.2 23 79.9 23 1 77.3 1 77.8 24 94.5 24 1 41.8 35-40 1 91.3 25 93.9 25 1 92.8 22 98.2 22 1 93.0 25 96.8 25 1 51.3 95.7 2? 27 1 70.5 In ice 96.2 In ice 1 1.4 27. In ice 97.0 In ice 1 73.9
OF
ALDEHYDE^ Formaldehyde Acetaldehyde Propionaldehyde n-Butyraldehyde Iso-butyraldeh yde n-Valeraldehyde Isovaleraldehyde n-Heptaldehyde Benaaldeh de Salicylalde%yde Vanillin
Temp.
_Z A_
1
. .-
7 4
In ice 1 86.4 1 15.1 28 0 Time of contact of aldehyde bisulfite with exceas iodine not over 5 minutes. Piperonal
In ice
100.4
The results in Table I1indicate that the bisulfite compounds of lower aliphatic aldehydes react somewhat slowly with iodine, formaldehyde bisulfite being wholly stable. The bi-
(20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32) (33) (34)
pp. 177-88, John Ibid., pp. 235-8. Kurtenacker, 2. anal. Chem., 64, 56 (1924). Langedijk, Rec. trav. chim., 46, 218 (1927). Lea, IND. ENQ.CHEM.,Anal. Ed., 6, 241 (1934). Lukas, Chem. Listy, 26, 26 (1932). Meyer, H., “Nachweis und Bestimmung organischer Verbindungen,” pp. 55, 56, 58, 66, 277, 278, J. Springer, Berlin, 1933. Meyer, H., “Analyse und Konstitutionsermittlung organisoher Verbindungen,” 5th ed., p. 451, J. Springer, Berlin, 1931. Ripper, Monatsh., 21, 1079 (1900). Rosario, del, Philippine J. Sci., 5, 29 (1910). Stepp and Engelhardt, Biochem. Z., 111, 8 (1920). Stewart, J . Chem. SOC.,87, 185 (1905). Stewart and Donnally, J . Am. Chem. Soc., 54, 2333, 3555, 3559 (1932). Tomoda, J . SOC.Chem. Ind. Japan, 30, 747 (1927); J . SOC. Chem. Ind.. 48. 79 (1929). Treadwell-Hall, ’“Analytical Chemistry,” Vol. 11, 6th ed., p. 588, John Wiley & Sons, N. Y., 1924. Wagner, J., Biochem. Z., 194,441 (1928).
R ~ C E I V EJD U 12, ~ 1934. ~
