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Sublimation chromatography of some aromatic amines on montmorillonite clay-cellulose columns
SHORT
240
COMMUNICATIONS
as a blank. All 4 solutions were extracted twice with DIECA-chloroform before addition of 64Mn. This was done to ensure that the solutions were stripped of manganese already present which might influence extraction of S”Mn. It can be seen that over 99% of the manganese was extracted in the first extraction except in the blank solution containing only citrate. The lower extraction in this case is probably due to the fact that all the citrate present wcasavailable to compete for manganese with the DIECA-chloroform system. In the bone, milk and teeth solutions citrate was already. complexing with calcium. Since citrate appears to show some ability to complex manganese increasing the ratio of citric acid to the sample above, the 2.0 used here couldresult in lessened extraction efficiency. The distribution of 6‘lMn between the two phases under the conditions used shows the Mn-DIECA complex to have a distribution coefficient of about ISO or would ensure better in favour of the chloroform phase. In practice 2 extractions complete extraction of manganese and allow for any small loss in efficiency with variation in PH. Evaporation of the chloroform ph&es after extraction and digestion with nitric-perchloric-sulfuric acid mixture permits calorimetric determination of manganese as pcrmanganatc in low volume (less than 1 ml) since major cations and anions arc almost completely absent. The assistance of W. MCCABE, Institute of Nuclear Scientific & Industrial Research, is @-atefully acknowlccl6ed.
Science,
Lower
Dept.
w. n.
Soil Bawcau, Department
N.Z.
0fSciedific
Hartt (New
&
~~uhdrin2
of
HEALY
IZesea7ch,
Zealmtrl)
Yorlc, rg57, p. 217. 2 IS. J, HEWITT, Ttdr. Cowm. No. a2, Cotnmonwcalth Agriculturnl l3urcnu. p, 73. 3 c. s. ~'IDER, .%ii crrzd ~korl .LIIrcrlysis, lntcrscicncc, New York, 1950, IX Jdts. d) W. 13. I-Il%ALY, J. Agr. FoodClrerll.. i-3(1058) 006. 5 G. DINSTL AND S.I-lIxIlr, Mi/rroclri~~~.~Icf~c, (1962) 321.
(Received Amt.
Chh.
June xst, Acfa,
1965)
34 (1966)
23%-340
9wblimation chromatography” montmorillonite clay-cellulose
of some columns
aromatic
amines
on
Several years ago, it was reported’ &at mixtures of some aromatic atnincs, e.g., o- and+phenylenediamine, etc., form chromatograms when the solution is placed on the surface of montmorillonite clay (Japanese acid clay) and that the chromatographic color reactions can be used for detection of the amines. In the course of these experiments, it was noticed that a small crystal of the amines placed on the surface of the clay produces a coloration, without any solvent, after being in contact for a few ~~9k-l~. ChiWl.
.dCtR,
34 (1966) 2r{O-243
SHORT
CONMUNICATIONS
341
days. This coloration can probably be attributed to complex formation after the adsorption of sublimed amine vapor on the clay. From these earlier results, it appeared that a chromatograpl~ic separation might be possible if the sublimed mixed vapor of the amincs penetrated into the clay column; for the competitive adsorption required for chromatography should occur between the clay and the sublimed amines. Under suitable conditions, adjacent colored zones might be formed in the clay column.
, bdk fl
glass WOOI
\
suction
g urn stopper
column (montmortllonite clay U poper cellulose)
sample
hot water
t
heat
l;ig.
I.
Dcvicc
for “sublin~zltion cllrorn~Ltogr.?plly”.
After some preliminary tests, experimental results worth evaluation were obtained with a column consisting of the clay and paper cellulose in the device shown in Fig. I. Some of the chromatograms obtained are shown in Fig. 2. A notable difference between the suggested method and conventional gas chromatography is that the sample constituents are detected by means of the formation of adjacent colored zones actually on the column. The term “sublimation chromatography” is suggested as descriptive of the main feature of the method.
Aj!$aratzcs
and reagents
The apparatus is shown in Fig. I. The recommended method for the preparation of the clay-cellulose mixture for the column is as follows: place 5-6 sheets of g-cm diameter filter paper into 250 ml of water and stir electrically until a pulp is obtained. Then add x0-15 g of montmorillonite clay and continue stirring for some time. Remove excess of water from the mixture by centrifuging or filtering, dry at IOO--110~ and then break up the dried cotton-like material for convenience in packing it into the column. Commercial cellulose powder (Toyo Roshi Ltd.; 100-200 mesh) can be used instead of filter paper but gives an inferior mixture in regard to the separation of colored zones and is only suitable for two-component mixtures. The chromogenic activity of the clay for amines varies widely, owing to the variations of the impurities contained in the clay and of its surface acidity. Strongly A,nal. Clrint. Acta,
34 (1966)
240-243
SHORT
242
COMMUNICATIONS
diph.
p-anls o-phen. (orange-
red)
p- phen
purple black) Ky. 2. illustration
clialninc:
panis.,
p-anis
p-phen
p-phen
(cl
b)
(a)
o-phen
of the chromatogram. p-phcn., fxmisidinc; cliph., tliphcnylaminc.
(d) $-phcnylcncdiaminc;
o-phen
p-pkn (e) o-phen.,
o-phcnylcnc-
acidic montmorillonitc clay with a moclcrate chromogenic activity is preferable for the preparation of the column. To prcparc a chromatographic column, pack the clay-cellulose mixture quite loosely into a glass tube 40 mm long and G mm in diameter and hold it in position with glass wool plugs. Proccdzcra
Place a small amount (total weight 0.5-x nq) of a mixture of the amines in the bottom of a short test tube, insert the column tube into the test tube and fix the two tubes together with a rubber stopper as shown in Fig. 1. Connect a suction pump to the upper end of the tube and place the test tube in hot water at go-xoo”. Apply gentle suction to facilitate the penetration of the amine vapors into the column. As warming is continued, the colorccl zones spread upwards. After 30-120 min, the period clepending on the amincs, the clay and the density of the packing, the column is removed from the tube.
Results
a,rtd discussiow In the separation
of o- ancl $-phenylcnediamines, as shown in Fig. 2a, a purpleblack zone due to the fi-compound is located at the lower end of the tube, and an orange-red zone clue to the o-compound is located immediately above it. The lower zone is sli+tly contaminnlecl with the orange color of the o-phcnylencdiamine, but the upper zone is completely free from the other constituent. Thus the appearance of the whole column is suitable for the purpose of topographical detection of the two constitucnts. A sublimation chromatogram of fl-anisidine and o-phenylenediamine is shown in Fig. zb. Of course, before any experiment, the colors caused by the action of the individual amines must be establishecl. The colomtion of the clay by the chemisorption of sublimed amines is often slightly different from that obtained when a solution of the amines is applied; this may be due to the fact that in sublimation chromatography the colored zones are formed at higher temperature. Examples of three-component chromatograms, formed from o- and p-phenylenediamine and cliphenylamine or p-anisidine, are shown in Fig. 2c, d and e. The use of clays which are too color-sensitive does not give good separation of zones because the colors are too deep; however, with such clays results can be imA?&. Clrim.Ada, 34 (1C~66)
240-243
SHORT COMMUNICATIONS
243
proved by the addition of a minute amount of hexamcthylenetetramine to the mixture of aromatic amines. The sublimed vapor of aliphatic amines mixed with that of the aromatic amines often causes hypsochromic effects on the coloration of the clay. Ethylenediamine can he used instead of l~examethylenctetramine. The present investigation covered only a limited application, but in general it appears likely that sublimation chromatograms should be formed when the sublimed vapors of suitable organic compounds are introduced into a column consisting of suitable coloring agents and cellulose. Advantages of the method are that samples below I mg in weight can be used and that the chromatograms can be stored for reference, as the colors are almost permanent. Disadvantages are that the number of constituents to be separated must bc limited, and that the lower zone is sometimes contaminated with the upper constituent. Department of Chemistry, Faculty of Science, Kumamoto University, Kumamoto (Japan) I D.
YAMAMOTO,
DAISRI YAMAMOTO AKI KO Fu KUI~O~IE
J. Chem. Sot. Japun, 79 (1938) 1030.
(Received May 3rd, x@j) .4tl&. C/jirn./ICfa, 34 (xgG6)2.)~-243
Simultaneous by titration
determination of terephthalic in dimethylformamide
acid and p-toluic
acid
Two major obstacles lie in the path of a simultaneous determination of a monocarboxylic acid, such a~ fi-toluic acid, and terephthalic acid. The first of these is the insolubility of terephthalic acid in most of the common solvents. The second is the nearly equal strength of the ionizable hydrogens of terephthalic acid, yielding, under most circumstances, a titration curve with only one equivalence point. Despite these obstacles, 2 titrimetric methods have been proposed for this determination. VALCHA~ used a solvent of pyridine-chloroform (x:4) and titrated potentiometrically with ethanolic sodium hydroxide. KUDLACEK et al.2 dissolved the sample in excess base and back-titrated with standard acid. DEAL AND WYLD~ found that terephthalic acid dissolved in dimethylformamide yielded a curve with 2 equivalence points when titrated with tetrabutylammonium hydroxide. However, the break at the first equivalence point was too slight to be analytically useful. VALCHA’S method is time-consuming, and the odor of the solvent is disagreeable. In addition to requiring two standard solutions, the method of KUDLACEK et al. is valid only when the sample contains nothing but terephthalic and p-toluic acids. These disadvantages are absent from the present method, in which aqueous potassium hydroxide is used as the titrant. A separate break is observed in the titration curve for each of the ionizable hydrogens of terephthalic acid; the fi-toluic acid is titrated with the second of these. Aural.Chipn.A&Z, 34 (rgG6)243-245
240
COMMUNICATIONS
as a blank. All 4 solutions were extracted twice with DIECA-chloroform before addition of 64Mn. This was done to ensure that the solutions were stripped of manganese already present which might influence extraction of S”Mn. It can be seen that over 99% of the manganese was extracted in the first extraction except in the blank solution containing only citrate. The lower extraction in this case is probably due to the fact that all the citrate present wcasavailable to compete for manganese with the DIECA-chloroform system. In the bone, milk and teeth solutions citrate was already. complexing with calcium. Since citrate appears to show some ability to complex manganese increasing the ratio of citric acid to the sample above, the 2.0 used here couldresult in lessened extraction efficiency. The distribution of 6‘lMn between the two phases under the conditions used shows the Mn-DIECA complex to have a distribution coefficient of about ISO or would ensure better in favour of the chloroform phase. In practice 2 extractions complete extraction of manganese and allow for any small loss in efficiency with variation in PH. Evaporation of the chloroform ph&es after extraction and digestion with nitric-perchloric-sulfuric acid mixture permits calorimetric determination of manganese as pcrmanganatc in low volume (less than 1 ml) since major cations and anions arc almost completely absent. The assistance of W. MCCABE, Institute of Nuclear Scientific & Industrial Research, is @-atefully acknowlccl6ed.
Science,
Lower
Dept.
w. n.
Soil Bawcau, Department
N.Z.
0fSciedific
Hartt (New
&
~~uhdrin2
of
HEALY
IZesea7ch,
Zealmtrl)
Yorlc, rg57, p. 217. 2 IS. J, HEWITT, Ttdr. Cowm. No. a2, Cotnmonwcalth Agriculturnl l3urcnu. p, 73. 3 c. s. ~'IDER, .%ii crrzd ~korl .LIIrcrlysis, lntcrscicncc, New York, 1950, IX Jdts. d) W. 13. I-Il%ALY, J. Agr. FoodClrerll.. i-3(1058) 006. 5 G. DINSTL AND S.I-lIxIlr, Mi/rroclri~~~.~Icf~c, (1962) 321.
(Received Amt.
Chh.
June xst, Acfa,
1965)
34 (1966)
23%-340
9wblimation chromatography” montmorillonite clay-cellulose
of some columns
aromatic
amines
on
Several years ago, it was reported’ &at mixtures of some aromatic atnincs, e.g., o- and+phenylenediamine, etc., form chromatograms when the solution is placed on the surface of montmorillonite clay (Japanese acid clay) and that the chromatographic color reactions can be used for detection of the amines. In the course of these experiments, it was noticed that a small crystal of the amines placed on the surface of the clay produces a coloration, without any solvent, after being in contact for a few ~~9k-l~. ChiWl.
.dCtR,
34 (1966) 2r{O-243
SHORT
CONMUNICATIONS
341
days. This coloration can probably be attributed to complex formation after the adsorption of sublimed amine vapor on the clay. From these earlier results, it appeared that a chromatograpl~ic separation might be possible if the sublimed mixed vapor of the amincs penetrated into the clay column; for the competitive adsorption required for chromatography should occur between the clay and the sublimed amines. Under suitable conditions, adjacent colored zones might be formed in the clay column.
, bdk fl
glass WOOI
\
suction
g urn stopper
column (montmortllonite clay U poper cellulose)
sample
hot water
t
heat
l;ig.
I.
Dcvicc
for “sublin~zltion cllrorn~Ltogr.?plly”.
After some preliminary tests, experimental results worth evaluation were obtained with a column consisting of the clay and paper cellulose in the device shown in Fig. I. Some of the chromatograms obtained are shown in Fig. 2. A notable difference between the suggested method and conventional gas chromatography is that the sample constituents are detected by means of the formation of adjacent colored zones actually on the column. The term “sublimation chromatography” is suggested as descriptive of the main feature of the method.
Aj!$aratzcs
and reagents
The apparatus is shown in Fig. I. The recommended method for the preparation of the clay-cellulose mixture for the column is as follows: place 5-6 sheets of g-cm diameter filter paper into 250 ml of water and stir electrically until a pulp is obtained. Then add x0-15 g of montmorillonite clay and continue stirring for some time. Remove excess of water from the mixture by centrifuging or filtering, dry at IOO--110~ and then break up the dried cotton-like material for convenience in packing it into the column. Commercial cellulose powder (Toyo Roshi Ltd.; 100-200 mesh) can be used instead of filter paper but gives an inferior mixture in regard to the separation of colored zones and is only suitable for two-component mixtures. The chromogenic activity of the clay for amines varies widely, owing to the variations of the impurities contained in the clay and of its surface acidity. Strongly A,nal. Clrint. Acta,
34 (1966)
240-243
SHORT
242
COMMUNICATIONS
diph.
p-anls o-phen. (orange-
red)
p- phen
purple black) Ky. 2. illustration
clialninc:
panis.,
p-anis
p-phen
p-phen
(cl
b)
(a)
o-phen
of the chromatogram. p-phcn., fxmisidinc; cliph., tliphcnylaminc.
(d) $-phcnylcncdiaminc;
o-phen
p-pkn (e) o-phen.,
o-phcnylcnc-
acidic montmorillonitc clay with a moclcrate chromogenic activity is preferable for the preparation of the column. To prcparc a chromatographic column, pack the clay-cellulose mixture quite loosely into a glass tube 40 mm long and G mm in diameter and hold it in position with glass wool plugs. Proccdzcra
Place a small amount (total weight 0.5-x nq) of a mixture of the amines in the bottom of a short test tube, insert the column tube into the test tube and fix the two tubes together with a rubber stopper as shown in Fig. 1. Connect a suction pump to the upper end of the tube and place the test tube in hot water at go-xoo”. Apply gentle suction to facilitate the penetration of the amine vapors into the column. As warming is continued, the colorccl zones spread upwards. After 30-120 min, the period clepending on the amincs, the clay and the density of the packing, the column is removed from the tube.
Results
a,rtd discussiow In the separation
of o- ancl $-phenylcnediamines, as shown in Fig. 2a, a purpleblack zone due to the fi-compound is located at the lower end of the tube, and an orange-red zone clue to the o-compound is located immediately above it. The lower zone is sli+tly contaminnlecl with the orange color of the o-phcnylencdiamine, but the upper zone is completely free from the other constituent. Thus the appearance of the whole column is suitable for the purpose of topographical detection of the two constitucnts. A sublimation chromatogram of fl-anisidine and o-phenylenediamine is shown in Fig. zb. Of course, before any experiment, the colors caused by the action of the individual amines must be establishecl. The colomtion of the clay by the chemisorption of sublimed amines is often slightly different from that obtained when a solution of the amines is applied; this may be due to the fact that in sublimation chromatography the colored zones are formed at higher temperature. Examples of three-component chromatograms, formed from o- and p-phenylenediamine and cliphenylamine or p-anisidine, are shown in Fig. 2c, d and e. The use of clays which are too color-sensitive does not give good separation of zones because the colors are too deep; however, with such clays results can be imA?&. Clrim.Ada, 34 (1C~66)
240-243
SHORT COMMUNICATIONS
243
proved by the addition of a minute amount of hexamcthylenetetramine to the mixture of aromatic amines. The sublimed vapor of aliphatic amines mixed with that of the aromatic amines often causes hypsochromic effects on the coloration of the clay. Ethylenediamine can he used instead of l~examethylenctetramine. The present investigation covered only a limited application, but in general it appears likely that sublimation chromatograms should be formed when the sublimed vapors of suitable organic compounds are introduced into a column consisting of suitable coloring agents and cellulose. Advantages of the method are that samples below I mg in weight can be used and that the chromatograms can be stored for reference, as the colors are almost permanent. Disadvantages are that the number of constituents to be separated must bc limited, and that the lower zone is sometimes contaminated with the upper constituent. Department of Chemistry, Faculty of Science, Kumamoto University, Kumamoto (Japan) I D.
YAMAMOTO,
DAISRI YAMAMOTO AKI KO Fu KUI~O~IE
J. Chem. Sot. Japun, 79 (1938) 1030.
(Received May 3rd, x@j) .4tl&. C/jirn./ICfa, 34 (xgG6)2.)~-243
Simultaneous by titration
determination of terephthalic in dimethylformamide
acid and p-toluic
acid
Two major obstacles lie in the path of a simultaneous determination of a monocarboxylic acid, such a~ fi-toluic acid, and terephthalic acid. The first of these is the insolubility of terephthalic acid in most of the common solvents. The second is the nearly equal strength of the ionizable hydrogens of terephthalic acid, yielding, under most circumstances, a titration curve with only one equivalence point. Despite these obstacles, 2 titrimetric methods have been proposed for this determination. VALCHA~ used a solvent of pyridine-chloroform (x:4) and titrated potentiometrically with ethanolic sodium hydroxide. KUDLACEK et al.2 dissolved the sample in excess base and back-titrated with standard acid. DEAL AND WYLD~ found that terephthalic acid dissolved in dimethylformamide yielded a curve with 2 equivalence points when titrated with tetrabutylammonium hydroxide. However, the break at the first equivalence point was too slight to be analytically useful. VALCHA’S method is time-consuming, and the odor of the solvent is disagreeable. In addition to requiring two standard solutions, the method of KUDLACEK et al. is valid only when the sample contains nothing but terephthalic and p-toluic acids. These disadvantages are absent from the present method, in which aqueous potassium hydroxide is used as the titrant. A separate break is observed in the titration curve for each of the ionizable hydrogens of terephthalic acid; the fi-toluic acid is titrated with the second of these. Aural.Chipn.A&Z, 34 (rgG6)243-245