LITERATURE CITED
more than 2 mg. for laboratory reagent grade. ACKNOWLEDGMENT
The author expresses his gratitude to P. C. Carman of the National Chemical Research Laboratory, Pretoria, for his correction of the paper and to W. E. Schilz of the University of Pretoria for his advice and interest in the work.
(1) Belyavskaya, T. A., Chmutova, M, K., Nauch. Doklady Vysshei Shkoly, Khim. i Khim. Tekhnol. 1958, No. 2, 305-7. (2) Brown, W. E., Rieman, W., 111, J. Am. Chem. SOC.74, 1278 (1952). (3) Freund, H. F., Miner, F. J., ANAL. CHEM.24, 1229 (1952); 25, 564 (1953). (4) Lister, B. A. J., J. Chem. SOC.1951, 3123.
(5) Strelow, F. W. E., ANAL. CHEM.31, 1201 (1959). RECEIVEDfor review May 22, 1959. Accepted September 1, 1959. Published by permission of the South African Council for Scientific and Industrial Research. Abstracted from work done for a D.Sc. thesis at the Department of Inorganic and Analytical Chemistry, University of Pretoria.
Co Io r
Reaction for Determination of Some Meta-Dinitro Aromatic Compounds JAMES P. HEOTIS’ and JESSE W. CAVETT Research Division, Dr. Salsbury’s laboratories, Charles City, Iowa
b During the development of a colorimetric method for the determination of 3,5dinitrobenramide it was observed that 3,5dinitrobenzoic acid did not develop color with the reagents. This led to a study of the scope of the reaction. A theory of the color reaction is presented.
M
compounds react with acetone and alkali to produce quinoid ions of limited stability (1-4, 6, 8, 1 0 ) . Lewis and Seaborg (9) demonstrated that ammonia and primary amines reacted with them to forni orthoquinoid structures which were stabilized by double chelation. Porter (11) reported on the use of tetraethylammonium hydroxide and N,N-dimethylformamide in the determination of mono- and dinitro aromatic compounds. Most of the assays were dependent on a rather strict control of time of assay after the reagents were added. I n experiments designed to stabilize the color development of amines with 3,5dinitrobenzamide sufficiently for routine feed control, diethylamine and dimethyl sulfoxide appeared to be the solvent mixture possessing this property ( 5 ) . During the development of the assay method the free acid failed to produce color with the reagents used and this unexpected development led to a study of the scope of the reaction with other mets-dinitro compounds. ETA-DINITRO
EXPERIMENTAL
The reaction was carried out b y adding 2 ml. of diethylamine reagent to a solution containing 0.10 mg. of comPresent address, Research Division, Eaton Laboratories, Norwich, N. Y.
Table I.
Color Reactions of Various Meta-Dinitro Compounds
Color after DiethylCompound amine m-Dinitrobenzene Purple 3,5-Dinitrobenzamide Purple 3,5-Dinitrobenzoic acid, methyl ester Purple N-Methyl-3,5-dinitrobenzamide Purple 3,5-Dinitrobenzhydrazide Blue 3,5-Dinitrobenzoic acid, n-butyl ester Purple 3,5-Dinitrobenzoic acid, isopropyl ester Purple 3,5-Dinitrohippuric acid Purple 3,5-Dinitrobenzoyl-p-nitroaniline -4mber N,N-Di-( 2-hydrosyethyl)-3,5-dinitrobenzamide Purple 2,4Dinitrophenylhydrazine Red-orange 2,4-Dinitrophetiylacctic acid Green 2,4Dinitrotoluene Green 2,CDinitrophenyl thiocyanate Yellow-green 2,2’,4,4‘-Tetranitrophenyl Pink Bis-(2,4-dinitropheiiyl)disiilfide Orange 3,7-Dinitrophenothinzine sulfoxide Red N1-(2,PDinitrophenyl )-N*phthaloyl Amber 2,7-Dinitroanthraquinone Purple a Readings taken a t times specified after addition
pound i n 8 ml. of dimethyl sulfoxide (Stepan Chemical Co., Chicago 6, Ill.). Measurements were made on the Beckman DU spectrophotometer throughout the maximum absorption range, and the Klett-Summerson photoelectric colorimeter u i t h the KO.56 filter. The age of the diethylamine played a n important part in the development of color. The first diethylamine used was a 9-year-old sample. A new reagent from the same company gave readings which were one third of the earlier value. The reagent could be artificially aged b y refluxing a suspension of 40 grams of sodium or potassium fluosilicate per liter of dry diethylamine for 48 to 72 hours. Fluosilicate acted as a n
Klett Readings,‘ Minutes 20 60 120 38 4.5 45 656 700 700 600 680 670 780 780 780 500 700 770
Beckman DU Readings at 45-75 Minutes Wave length of max. absorp- Atisorption, mp tivity 57.5 78.i 570 16,065 555 16,960 566 15,410 575 14,610
650 660 630
..
650 650 610 520 530 550 145 250 290
555 565 555
14,610 14,150 5,810
...
...
180 550 17 19 95 220 28 243
295 550 19 24 79 258 28 250
350 560 25 30 65 280 26 275
--r rn
695 .-.
695 430 640 650
...
89.i 12,530 26,370 36,850 ...
103 122 136 ... 23 43 65 535 i,ow of reagents, using No. 56 filter.
inhibitor of the destruction of the quinoid ion. RESULTS
The data in Table I show that the magnitude of the absorbance of certain of the compounds was sufficient for the method to serve as a means of assay. The following compounds did not develop color or absorb light in the visible spectrum. 3.5dinitrobenzoic acid; 2,6-dinitro-4.-chloroaniline; 2,6dinitrohydroquinone-4-monoacetate;3,5-dinitrosslicylic acid; 3,&dinitrosalicylic acid, methyl ester; 3,Sdinitrosalicylamide; 2,4dinitroaniIine; 2,4VOL. 31, NO. 12, DECEMBER 1959
0
1977
dinitrodiethylaniline; 2,4dinitrobenzene sulfonic acid; 4,6dinitro-o-cresol; 5,7dinitro-fbquinolinol; 2,4-dinitrophenol; N,N-bis-(Zhydroxyethyl)-2,4 dinitroaniline; 2,2’,4,4’-tetranitrocarbanilide; and 6,8ainitro-2,4( 1H,3H)quinazolinedione. All of the 3,5disubstituted comDounds which reacted with the reagents ” have maximum absorption in region of 540 t o 575 mp; the 2,Pdisubstituted compounds, with the exception of 2 , 4 dinitrophenyl thiocyanate (Amsx. = 430 mp), absorbed at 640 to 695 mp.
R OzN-
EbNH2+
.
NOn
1 ! L
q\H R
)&
and/or
=
0-
NO2
O-
R
=
0-s
\
Et?”$+
CH,
H; -CONHI; -C02Me; -COZEt; etc.
MECHANISM OF COLOR PRODUCTION LiTERATURE CITED
The nature of the compounds formed with dimethyl sulfoxide is not yet clear. By analogy with the work of Canback ( 3 , 4 ) and Gitis (7) with acetone and that Of Saunders and Stark (la)with dialkyl phosphites, the following seems a plausible explanation.
( 1 ) Beckman, H. F., &Mottier, J., J . Agr. Food C h m . 7,280 (1959). (2) Bast, R. w.7 Nicholson, Frank, I N D . ENG.CHEM.,ANAL.ED. 7, 190 (1935). ( 3 ) Canbgck, T.,Farm. Reoy 48, 153 (1949). (4) Zbid., p. 217.
0
L
0-
_I
(5) Cavett, J. W., Heotis, J. P., J . Assoc. Ofic.Agr. Chemists 42, 239 (1959). (6) English, F. L., ANAL.CHEM.20, 745 (1949). ( 7 ) Gitis, S. S., J . Gen. Chenc. U.S.S.R. (Eng. transl.) 27, 1956 (1957). (8) Janovsky, J. V., Ber. deut. chart. Ges. 24, 971 (1891). (9) Lewis, G. N., Seaborg, G. T., J . A m . Chem. SOC.62, 2122 (1940). (101 Parkes, G. D . , Farthing, A. C., J . Chem. SOC.1948, 1275. (11) Porter, C. C., ANAL.CHEM.27, 805 (1955). (12) Saunders, B. C., Stark, B. P., Tetrahedron 4 , 197 (1958).
RECEIVED for review September 29, 1958. Accepted September 8, 1959.
Phenyl-Zpyridyl Ketoxime, a Reagent for Iron in Strong Alkalies A Method for Determining Oxidized Iron in the Presence of Metallic Iron FRED TRUSELL and HARVEY DIEHL Department of Chemistry, Iowa Sfate University, Ames, Iowa
b Phenyl-2-pyridyl ketoxime has been found useful for the determination of small amounts of iron in strongly alkaline materials, such as the hydroxides of sodium, potassium, and lithium, and sodium carbonate. The intense red iron(1l) derivative can b e extracted from strongly alkaline solutions into isoamyl alcohol, making it possible to prepare iron-free solutions of strong alkalies. “Oxidized” iron, but not metallic iron, reacts with the reagent in strong alkali and the reagent distinguishes between the two. Phenyl2-pyridyl ketoxime has been used also for the determination of iron in glass sand following fusion with sodium carbonate-sodium tetraborate mixture. 1978
ANALYTICAL CHEMISTRY
I
general, the reaction of the ferrous ion and 1,lO-phenanthroline or substituted phenanthrolines is complete only in essentially neutral solution. The exception to this is the reaction of 4,7-dihydroxy- 1,lO-phenanthroline, which is complete in highly alkaline media. This was discovered by Schilt, Smith, and Heimbuch(3) and applied by them to the determination of iron in caustic alkalies and in sodium carbonate fusions. Sen (4, 5) has reported that phenyl2-pyridyl ketosime forms a colored compound with iron(II), and that the optimum range for extraction into nonaqueous solvents is p H 6 to 11. During the present work it was found that phenyl-2-pyridyl ketoxime also N
reacts with iron in highly alkaline solutions and that the intense red color formed can be extracted from such solutions into isoamyl alcohol. The extraction technique provides a concentration method, thus increasing the sensitivity and furnishing a procedure for cleaning the iron out of the reagents and reducing the blank t o zero. The method is satisfactory for the determination of iron in the parts per million range and has been applied to the determination of iron in sodium, potassium, and lithium hydroxides, although with an unexpected result. EXPERIMENTAL
Phenyl-2-pyridyl Ketoxime and Its
Reactions with Metals.
SYNTHESIS
