N e w Standard for Use in Ultimate Analysis of Organic Compounds Especially Suited for Microprocedures C. L. OGG
AND
C. 0.WILLITS
Eastern Regional Research Laboratory, Philadelphia 18, Pa.
F
OR the past three years S-benzylthiuronium chloride
(benzyl-isothiourea hydrochloride, listed by Eastman Kodak Company in Catalog 34 of Organic Chemicals) has been used in this laboratory as a standard material in the ultimate analysis of organic compounds. It more nearly fulfills the criteria established by Hillebrand (9)for judging the fitness of material used as a standard to check on analytical procedures than most of the standards in common use. Since 8-benzylthiuronium chloride contains the five elements most commonly encountered in organic analysis-namely, carbon, hydrogen, nitrogen, chlorine, and sulfur-and since it also contains a benzene ring, a thio ether linkage, amine and imine groups, and an ionizable chlorine atbm, it is suitable for checking the methods of analysis of any or all of the five elements in a wide variety of compounds. I t s use as a standard for carbon and hydrogen not only serves t o prove that combustion is complete but also shows the effectiveness of the removal of the acid-forming gases of the three elements most likely to interfere with this determination. The synthesis and recrystallization of the pure compound (1) require no unusual apparatus or techniques and its purity is readily established by confirming analyses for any two or mbre of the five elements. After drying a t 110' C., no precautions are required for its storage, since under ordinary conditions it is stable and nonhygroscopic,
Table Element Carbon Hydrogen
Sulfur
Chlorine Nitrogen
I. Analysis of's-Benzylthiuronium Chloride
hIetliods Dry combustion Dry combustion Catalytic combustion and peroxide bomb Catalytic combustion Dumas and Kjeldahl ,
Percentage Composition Found (Range) Theory 47.22-47.55 47.40 5.36- 5.53 5.47
15.71-15 89 17.41-17.59 13.68-13.88
.
15.82 17.49 13.82
The standard has been analyzed repeatedly for the different elements by the following procedures: dry combustion carbon and hydrogen, catalytic combustion and peroxide bomb sulfur, catalytic combustion chlorine, and Dumas and Kjeldahl nitrogen. Representative analytical data obtained on the compound are shown in Table I. LITERATURE CITED
(1) Donleavy, J. J., J. Am. Chem. SOC.,58, 1004 (1936). (2) Hillebrand, W.F., J. IND.ENG.CHEM.,8,466 (1916) P R E S E N T ~a tDthe Spring Meeting of the Philadelphia Section, AMBRICAN CHEMICAL SOCIETY, June 13,1945.
Determination of Sulfur in Sulfur Compounds with Benzidine Hydrochloride Water Quality Laboratories,
WESLEY S. PLATNER U. S. Fish and Wildlife Service, University of
I
N ORDER to determine total sulfur by the benzidine method
in waters containing bisulfites, sulfites, hyposulfites, and thiosulfates, it was necessary to oxidize these compounds to simple sulfates previous to adding the benzidine hydrochloride reagent. Oxidizing agents such as alkaline potassium permanganate (16),the Parr oxygen bomb (1, 19), or some of the strong oxidizing methods developed for blood, plasma, or urine ( 2 , 7 , 10, 14, 81) were found too lengthy and cumbersome to be practical for determinations of water samples on a, large scale, eipecially under field Conditions. Since the publication of the benzidine method (12) and its subsequent modification (6, 9, 1 7 ) , many variations of the method have appeared, both colorimetric (4, 8, 20, 22) and titrimetric (3, 6, 11, 13, 16, 18). In the present application to total sulfur determination, recently published data for quantitative precipitation of benzidine sulfate have been incorporated. The volumes, concentrations, and time allowed for precipitation have been found necessary under the conditions of this method.
THEMETHOD. Oxidation of the sulfur compounds with 30% hydrogen peroxide (Merck's Superoxol) was found most satisfactory, with no detectablc interferenre with the benzidine method.
Missouri, Columbia,
Mo.
Into an evaporating dish containing a sample of water carrying between 3 and 20 mg. of sulfur, put 2 drops of 1% alcoholic phenolphthalein, add dilute hydrochloric acid if alkaline or SOdium hydroxide if acid until the turning point of the indicator, then make the sample definitely alkaline with sodium hydroxide. Evaporate to about 5 ml., add 3oy0 hydrogen peroxide, a drop a t a time, and allow t o simmer. After a few minutes, repeat addition of the peroxide until the solution becomes colorless or foaming ceases. Throughout this period maintain the volume of approximately 5 ml. by addition of distilled water. Add 50 ml. of distilled water, heat the sample to 50" to 60' C., and add 10 ml. of benzidine reagent (11.2 grams of benzidine hydrochloride reagent grade, Eastman, and 11.6 ml. of concentrated hydrochloric acid, made up to 500 ml.). After a few minutes add 5 ml. of 99.5% acetone and let stand until cooled t o room temperature. Filter through sulfate-free filter paper. Wash the evaporating dish twice with 5 ml. of 50% acetone and pour over the precipitate. After complete drainage, further wash the precipitate twice with 3 ml. of 99.570 acetone and let drain but do not allow to dry. Remove filter paper and wash the precipitate from the filter paper into the evaporating dish in which the precipitation took place. Heat to boiling and add 3 drops of 1yo alcoholic phenolphthalein. With a microburet, titrate while hot with 0.01 N sodium hydroxide until near the end point, then boil again, and continue titration to first permanent pink color. Determine a blank on the reagents used.
334
.
May, 1946
ANALYTICAL EDITION
335
DISCUSSION
Recoveries of known quantities of sulfur ill various forms by this method are compared with unoxidized recoveries in Table I. The accuracy has been found to be *0.2 mg. if the amount of sulfur present in the sample is between 3 and 20 mg. Compounds such as p-aminodimetli~ laniline sulfate, potassium aluminum sulfate, and hydrazine sulfate have been tried with similar success. Mi'xtures of organic and inorganic sulfur compoundh as found in paper-mill waste$ k n d themselves well to this method, providing all the material i n wqwnsion is first filtered out. The sulfur content of pyritc waters i'r~~iii cod-mining operations can be determined as simple sulfate,' with the reservation that iron in excem of 2 p.p.m. be removed from solution by precipitation. The iron, if not rcrnoved, oxidizes from ferrous t o ferric and results in a fine dark precipitate, the presence of which altcrs the sulfate values. ACKNOWLEDGMENT
The writ,er wishes to thank 11.M. Ellis, in charge of the Water Quality Laboratories, Columbia, Mo., for his assistance and for t,hc opport,unit,yto wri'te this paper. LITERATURE CITED (1) ('dlan, T.
Table I.
Compound
Recovery before Oxidation with Superoxol DifferTheory ence Mg. Mu. Mg.
Determined
2.62 NaHSOs 0.96 ?;azSzO3.~€1:C) 0.21 NazSz0c.2Hz0 1 . 4 7 XFiZQ203 10.01 NazS08
10.16 9.12 10.32 12.17 10.76
-7.54 -%I6 -10.11 -10.70 -0.75
Recovery after Oxidation with Superoxol Differmined Theory ence
DeterMg.
Mu.
My.
9,96 9.24 10.15 12.29 10.57
10.16 9.12
-0.20 f0.12 -0.17 +0.12 -0.10
10.32
12.17 10.76
( 7 ) Hoffman, W. Y . , ant1 Cardon. It., .1. Riol. ( ' h e m . , 109, 717 (8) (9) (10) (11) (12) (13) (14) (15) (16)
P., and Tuennies, G,,IND.Exo. CHEY..A N . \ I . .ED.
13, 461 (1941). (2) Chatron, M . , Bull. soc. chim. bid., 13, 300 (1931). (3) ('ope, C. L., Biochem. J . , 25, 1183 (1931). (4) Cutlibertson, D. P., and Thornpsett.S. L., I6id..25, 1337 (1931). (5) F:isk, C. H., J . B i d . Chem.. 47, 69 (1921). (6) b riedheim, Carl, and Nydegger, O t t o , Z.angezc. Chem., 20, 9-22 ( 1907).
Determination of Sulfur in Solutions Containing Known Amounts of Sulfur Compounds
(17) (18)
(1935). Hubbard, R.S.,I b i d . , 88, 663 (1930). Knorre, G. von, Chem. I n d . (Germany), 28, 2--13 (19UG). Lesure, A., and Dunee, A , Bull. soc. chim. biol., 10, 879 (1928). XIcKittrick, D. S., aiid Schmidt, C. I,. A . , A r r h . Riochem., 6 411 (1946). Muller, Wolf, Chem. Bw., 25, 1587 ( 1 9 0 2 , . On-en, E. C., Bidchem. J . , 30, 352 (1936). Pohorecka, B. L., Bull. soc. chim. biol.,9, 2ti3 (1927). Pollock, R. N., and Partansky, -4.XI., IND. ENG.(:HEM., ANAL. ED.,6 , 330 (1934). Pon-ers, M. H., and Rakefield, 12. G., Proc. S h f l Meeting#, M a y o Clinic, 6 , 401 (1931). Kaschig, F., 2.angew. Chem., 16 ( 2 6 ) ,617; 16 ( 3 4 ) , 818 (1903). Rkau, E. L., and Newell, I. L., IND.EKG.CHEM.,ANAT,.ED.,5, im- (1933). ~ Tomkins, S. S., Ibid., 14, 141 (1942). Wakefield, E. G., J . Biol. Chem., 81, 713 (1929). White, H. L., Am. J . Phvsiol., 65, 537 (1923). Yoshimatsu,S., Tokokic J . Esptl .Wed., 7, 553 (1926). > - - - - ,
(19)
(20) (21) (22)
Separation of 2,4-Dinitrophenylhydrazones by Chromatographic Adsorption JOHN D. ROBERTS'
AND
CHARLOTTE GREEN
Department of Chemistry, University of California
Lor Angeles, Calif.
IK
D E T E R M I K I S G the structure of a riuniber of unsaturated compounds by ozonization, considerable difficulty has been experienced in separating small amounts of low molecular weight carbonyl compounds. The most satisfactory method of isolation is through t>he2,4-dinitrophenylhydrnzones, as these are readily formed and are insoluble in vater, but in many cases separation of the derivatives by fractional crystallization is unsatisfactory. Separations of a number of 2,4-dinitrophenylhydrazonesby chromatographic adsorption have been reported by Strain ( 4 ) , by Lucae, Prater and Morris ( d ) , and by Buchman, Schlatter, and Reims ( I ) , but only a ferv of the aliphatic derivatives have been investigated. I n the present work, the adsorption of 2,4dinitrophenylhydrazine and the 2,4-dinitrophenylhydrazonesof acetaldehyde, propionaldehyde, acetone, and methyl ethyl ketone was studied on columns of silicic acid-Super Cel.
PROCEDURE. 'l'he dinitropheriylhydrazones (3) were adsorbed from solutions in 1 to 2 benzene-ligroin (60" t o 90"). The adsorbent was Merck's silicic acid (reagent grade) mixed R-ith Super Cel in a 2 to 1 ratio by weight t o increase the rate of flow of solvents through the column. The most satisfactor? .olvent for development of tht. chromatograms was ligroin (60 I Present address, Converse hlpiriorial Laboratory, Harvnrd University, ('atirbridge 38, >lass.
t,o 90") containing 4% ether by volume. Mixtures of benzene and ligroin gave more diffuse bands. After the column was extruded and sectioned, the derivatives were eluted with ether and crystallized from ethanol. I n a typical experiment a mixture of about 5 mg. each of acetone and met,hyl ethyl ketone 2,4-dinitrophenylhydrazones W L ~ B chromatographed on a 3.4 X 17 cm. column. After development the column consisted of the following bands: 4 cm. colorless, 4 cm. yellow, 2.5 cm. colorless, and 3.5 cm. yellow. The upper zone yielded the acetone derivative, m.p. 122-124.5" C. The lower band gave the methyl ethyl ketone deriva,tiva, m.p. 115" C.
The 2,4-dinitrophenylhydrazuneswere lound to be adsorbed in the order: acetaldehyde, acetone, propionaldehyde, and methyl ethyl ketone. Each of these derivatives could -be separated from mixtures with the others and 2,4dinitrophenylhydrazine (strongly adsorbed) except for the hydrazone of acetone, which could not he separated from that of propionaldchgde. LITERATURE CITED
( I ) Buohmaii, Schlatter, and Reims, ..I. A m . (:hem. S o e . . 6 4 , 2701 (1942). (2) Lucas, Prater, and Morris, Ibid., 57, 725 (1935) (3) Roberts and Green, Ibid., 68, 214 (1946). (4) Strain, Ibid., 57, 758 (1935).
.
