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New titrimetric microdetermination of formic and acetic acids in their mixture
MICROCHEMICALJOURNAL 14;289-292
New Formic
Titrimetric ,and Acetic
(1969)
Microdetermination Acids in Their
of Mixture
P. K. JAISWAL AND S. CHANDRA Research
Studies
Pathology Received
Centre,
January
Allahabad-2,
India
31,1969
INTRODUCTION
Literature concerning the microdetermination of formic and acetic acids in presence of each other, does not claim to have a relevant method. Although some methods have been developed such as chromatography (4), catalytic pyrolysis (3), cerimetry (I, 6) and by permanganate (5) in the relating topic. Present work deals with microdetermination of formic and acetic acids separately in mixture. Formic acid is determined by oxidation with ceric sulfate using chromium ion as catalyst. The remaining ceric sulfate was determined by standard ferrous ammonium sulfate using n-phenyl anthranilic acid as an indicator (7). In another portion of the mixture a known excess of standard Cu(II1) solution is added. It is then boiled for 0.5 hour and cooled. The remaining Cu(II1) solution is determined as has been described (2). In the case of oxidation of formic acid, probably the following reaction takes place: HCOOH
+ 0 + H,O + CO,.
Acetic acid is unaffected in the case of oxidation with ceric sulfate. In the final step both formic acid and acetic acid react wi?h Cu(II1) solution and following reaction appears to take place: HCOOH
+ CH,COOH
+ 50 + 3CO2 + 3H,O.
From the above equation it may be concluded that 2 equivalents is consumed for oxidation of formic acid and 8 equivalents are consumed for oxidation of acetic acid. Interference has been observed if other organic compounds are present. 289
290
JAISWAL
AND
CHANDRA
EXPERIMENTAL
METHODS
Reagents used. Formic acid, acetic acid, copper sulfate, potassium hydroxide, sodium bicarbonate, starch, sulfuric acid, and ferrous ammonium sulfate used were of ANALAR B.D.H. grade. Potassium tellurite (B.D.H. grade), potassium persulfate (B.D.H. grade), N-phenylanthranilic acid (B.D.H. grade), ceric sulfate (Technical B.D.H. grade) and chrome alum (extra pure) were used. Ceric sulfate (in 8N H,SO,) solution is standardized against a standard solution of ferrous ammonium sulfate (in 1N H&SO,) using N-phenyl’ anthranilic acid as indicator. The Cu(II1) solution is prepared by oxiding cupric sulfate with potassium persulfate and stabilizing it with potassium tellurate in alkaline medium (- 6 M). It is standardized by addition of known excess of sodium arsenite solution, and the remainder of it is determined iodometritally in bicarbonate media (2). PROCEDURE
Different sets are carried out by taking known volume of standard formic and acetic acids (see Table 1) raising the solution in 50 ml flasks. 5 ml of mixture is added to 20 ml of ceric sulfate solution in the presence of two or three drops of chrome alum along with the addition of sulfuric acid. It is then refluxed for 90 minutes (see Table 2). The remaining excess of ceric sulfate solution is titrated with standard ferrous ammonium sulfate using N-phenyl anthranilic acid as indicator. TABLE OBSERVATIONS
WITH Vol
Mixture no.
I
FORMIC taken
2.50 x 10-Z it4 HCOOH
AND ACETIC
ACID
(ml) 3.00 x lo-2 CH&OOH
M
Total vol of mixture prepared .-
1 2 3 4 5
5 10 12 15 20
20 15 13 10 5
50 50 50 50 50
FORMIC
AND
ACETIC
291
ACIDS
TABLE 2 FORMIC Vol
Mixture 110.
Mixture solution taken
1
5
2 3 4 5
5 5 5 5
ACID
DETERMINATION
Formic acid in mixture (g)
(ml)
1.00 X lo-* N ceric sulfate added
Cone H&Oh added
Ceric sulfate useda
20 20 20 20 20
30 30 30 30 30
2.50
0.000575
5.01
0.001154
0.001150
0.001384 0.001729 0.002236
0.001380 0.001725 0.002230
6.02 7.52 10.16
Found
Present 0.000575
a Remaining ceric sulfate is determined after refluxing it with the mixture for about 90 minutes.
In the second and final step the same volume is added to excess of Cu(III) solution (see Table 3). The mixture is boiled for about 0.5 hour and then cooled. The unconsumed Cu(II1) solution is determined as has been described earlier (2). RESULTS
AND DISCUSSION
Different sets for preparation of mixture are given in Table 1. Results for estimation of formic and acetic acids are given in Table 2 and 3. The TABLE ACETIC
ACID
3
DETERMINATION
Total formic and acetic acids 3.50 X 10m2M Cu(II1) found in Cu(II1) taken consumed” mixture (g)
Vol of soln (ml) Mix-
ture no.
Mixture taken 5 5 5 5 5
20 20 20 20 20
14.44 11.72 10.63 9.01 6.30
0.003854 0.004175 0.003724 0.003529 0.003229
Acetic acid in mixture (g) Found
Present
0.003600 0.002700 0.002340 0.001800 0.000893
0.003600 0.002700 0.002340 O.C4U800 0.000900
a Remaining Cu(II1) is determined after the mixture is boiled about 30 minutes.
292
JAISWAL
AND CHANDRA
final products are CO, and H,O. The amount of formic acid present is determined from ceric sulfate and the total amount of formic acid and acetic acid present in the mixture is determined by Cu(II1) solution. Thus the amount of formic and acetic acids in the mixture was determined separately up to micro scale. SUMMARY Titrimetric microdetermination of formic and acetic acids is described. Formic acid required two equivalents of the oxidant for complete oxidation, whereas, acetic acid required eight equivalents of the oxidant. Ceric sulfate oxidized only formic acid but Cu(II1) oxidized formic acid as well as acetic acid. Interference was observed if other organic compounds were present. ACKNOWLEDGMENTS The authors express their sincere thanks to Dr. K. L. Yadava, Dr. 0. C. Saxena of Allahabad University and Dr. V. C. Varshney of M.L.N. Medical College, Allahabad for their keen interest during the investigation. REFERENCES 1.
Cortes, C., Modern
application of cerates in organic determination. Gwordia. (1950). Chandra, S. and Yadava, K. L., Oxidation of some carbonyl compounds with Cu(II1). Microchem. J. 13, 491499 (1968). Ceteness Corporation of America, Removal of formic acid from mixture with acetic acid. Neth. Appl., 6504362 (1965). U.S. Appl. 10 pp. (1964). Ermolaevd, S. S. and Zarakovskaya, A. I., Sb. Tr. Tsentr. Nauchn. Issled. Lesokhim. Inst. 13, 94-106 (1959). Polak, H. L., Determination of formic acid, oxalic acid and acetic acid. Z. Anal. Chem. 176, 34-38 (1960). Sharma, N. N., Determination of formic acid in the mixture of acetic acid. Z. Anal. Chem. 162, 321-324 (1958). Sharma, N. N., Oxidation of carbohydrates. Z. Anal. Chem. 154, 340-344 (1957). Afinidad,
2. 3. 4. 5. 6. 7.
27, 289-294
New Formic
Titrimetric ,and Acetic
(1969)
Microdetermination Acids in Their
of Mixture
P. K. JAISWAL AND S. CHANDRA Research
Studies
Pathology Received
Centre,
January
Allahabad-2,
India
31,1969
INTRODUCTION
Literature concerning the microdetermination of formic and acetic acids in presence of each other, does not claim to have a relevant method. Although some methods have been developed such as chromatography (4), catalytic pyrolysis (3), cerimetry (I, 6) and by permanganate (5) in the relating topic. Present work deals with microdetermination of formic and acetic acids separately in mixture. Formic acid is determined by oxidation with ceric sulfate using chromium ion as catalyst. The remaining ceric sulfate was determined by standard ferrous ammonium sulfate using n-phenyl anthranilic acid as an indicator (7). In another portion of the mixture a known excess of standard Cu(II1) solution is added. It is then boiled for 0.5 hour and cooled. The remaining Cu(II1) solution is determined as has been described (2). In the case of oxidation of formic acid, probably the following reaction takes place: HCOOH
+ 0 + H,O + CO,.
Acetic acid is unaffected in the case of oxidation with ceric sulfate. In the final step both formic acid and acetic acid react wi?h Cu(II1) solution and following reaction appears to take place: HCOOH
+ CH,COOH
+ 50 + 3CO2 + 3H,O.
From the above equation it may be concluded that 2 equivalents is consumed for oxidation of formic acid and 8 equivalents are consumed for oxidation of acetic acid. Interference has been observed if other organic compounds are present. 289
290
JAISWAL
AND
CHANDRA
EXPERIMENTAL
METHODS
Reagents used. Formic acid, acetic acid, copper sulfate, potassium hydroxide, sodium bicarbonate, starch, sulfuric acid, and ferrous ammonium sulfate used were of ANALAR B.D.H. grade. Potassium tellurite (B.D.H. grade), potassium persulfate (B.D.H. grade), N-phenylanthranilic acid (B.D.H. grade), ceric sulfate (Technical B.D.H. grade) and chrome alum (extra pure) were used. Ceric sulfate (in 8N H,SO,) solution is standardized against a standard solution of ferrous ammonium sulfate (in 1N H&SO,) using N-phenyl’ anthranilic acid as indicator. The Cu(II1) solution is prepared by oxiding cupric sulfate with potassium persulfate and stabilizing it with potassium tellurate in alkaline medium (- 6 M). It is standardized by addition of known excess of sodium arsenite solution, and the remainder of it is determined iodometritally in bicarbonate media (2). PROCEDURE
Different sets are carried out by taking known volume of standard formic and acetic acids (see Table 1) raising the solution in 50 ml flasks. 5 ml of mixture is added to 20 ml of ceric sulfate solution in the presence of two or three drops of chrome alum along with the addition of sulfuric acid. It is then refluxed for 90 minutes (see Table 2). The remaining excess of ceric sulfate solution is titrated with standard ferrous ammonium sulfate using N-phenyl anthranilic acid as indicator. TABLE OBSERVATIONS
WITH Vol
Mixture no.
I
FORMIC taken
2.50 x 10-Z it4 HCOOH
AND ACETIC
ACID
(ml) 3.00 x lo-2 CH&OOH
M
Total vol of mixture prepared .-
1 2 3 4 5
5 10 12 15 20
20 15 13 10 5
50 50 50 50 50
FORMIC
AND
ACETIC
291
ACIDS
TABLE 2 FORMIC Vol
Mixture 110.
Mixture solution taken
1
5
2 3 4 5
5 5 5 5
ACID
DETERMINATION
Formic acid in mixture (g)
(ml)
1.00 X lo-* N ceric sulfate added
Cone H&Oh added
Ceric sulfate useda
20 20 20 20 20
30 30 30 30 30
2.50
0.000575
5.01
0.001154
0.001150
0.001384 0.001729 0.002236
0.001380 0.001725 0.002230
6.02 7.52 10.16
Found
Present 0.000575
a Remaining ceric sulfate is determined after refluxing it with the mixture for about 90 minutes.
In the second and final step the same volume is added to excess of Cu(III) solution (see Table 3). The mixture is boiled for about 0.5 hour and then cooled. The unconsumed Cu(II1) solution is determined as has been described earlier (2). RESULTS
AND DISCUSSION
Different sets for preparation of mixture are given in Table 1. Results for estimation of formic and acetic acids are given in Table 2 and 3. The TABLE ACETIC
ACID
3
DETERMINATION
Total formic and acetic acids 3.50 X 10m2M Cu(II1) found in Cu(II1) taken consumed” mixture (g)
Vol of soln (ml) Mix-
ture no.
Mixture taken 5 5 5 5 5
20 20 20 20 20
14.44 11.72 10.63 9.01 6.30
0.003854 0.004175 0.003724 0.003529 0.003229
Acetic acid in mixture (g) Found
Present
0.003600 0.002700 0.002340 0.001800 0.000893
0.003600 0.002700 0.002340 O.C4U800 0.000900
a Remaining Cu(II1) is determined after the mixture is boiled about 30 minutes.
292
JAISWAL
AND CHANDRA
final products are CO, and H,O. The amount of formic acid present is determined from ceric sulfate and the total amount of formic acid and acetic acid present in the mixture is determined by Cu(II1) solution. Thus the amount of formic and acetic acids in the mixture was determined separately up to micro scale. SUMMARY Titrimetric microdetermination of formic and acetic acids is described. Formic acid required two equivalents of the oxidant for complete oxidation, whereas, acetic acid required eight equivalents of the oxidant. Ceric sulfate oxidized only formic acid but Cu(II1) oxidized formic acid as well as acetic acid. Interference was observed if other organic compounds were present. ACKNOWLEDGMENTS The authors express their sincere thanks to Dr. K. L. Yadava, Dr. 0. C. Saxena of Allahabad University and Dr. V. C. Varshney of M.L.N. Medical College, Allahabad for their keen interest during the investigation. REFERENCES 1.
Cortes, C., Modern
application of cerates in organic determination. Gwordia. (1950). Chandra, S. and Yadava, K. L., Oxidation of some carbonyl compounds with Cu(II1). Microchem. J. 13, 491499 (1968). Ceteness Corporation of America, Removal of formic acid from mixture with acetic acid. Neth. Appl., 6504362 (1965). U.S. Appl. 10 pp. (1964). Ermolaevd, S. S. and Zarakovskaya, A. I., Sb. Tr. Tsentr. Nauchn. Issled. Lesokhim. Inst. 13, 94-106 (1959). Polak, H. L., Determination of formic acid, oxalic acid and acetic acid. Z. Anal. Chem. 176, 34-38 (1960). Sharma, N. N., Determination of formic acid in the mixture of acetic acid. Z. Anal. Chem. 162, 321-324 (1958). Sharma, N. N., Oxidation of carbohydrates. Z. Anal. Chem. 154, 340-344 (1957). Afinidad,
2. 3. 4. 5. 6. 7.
27, 289-294