ANALYTICAL CHEMISTRY
1658
are often present in the resin, and many laboratories are not equipped for infrared spectrophotometric analysis, the subsequent procedure is suggested. PROCEDURE
Saponification, Acidification, and Extraction. Dissolve 20 to 50 grams of vehicle with 25 ml. of benzene in a 1-liter Erlenmeyer flask. Add approximately 300 ml. of 0.5N alcoholic potassium hydroxide, attach an air condenser, and reflux over a 95' F. water bath for 1.5 hours. Filter off the dipotassium phthalate, using a fritted-glass funnel of medium porosity, and transfer the filtrate to a 800-ml. beaker. Drive off the solvents in a water bath, keeping the volume between 100 and 200 ml. by addition of water. Transfer the solvent-free sample to a 500-ml. separatory funnel, add 6N sulfuric acid in 1-ml. portions until the sample tests acid to litmus, then add 1 ml. more of acid. Cool, then extract with a t least three 100-ml. portions of ether. Collect the ether washings and wash them with four 25-m1. portions of yater. Combine the original water layer with the water washings. Evaporate the combined water layers over a steam bath toapproximately 150 ml. Reflux Distillation. Place the above water layer in a 250-ml. round-bottomed sinele-necked 2 4 / 4 0 8 flask. Add 50 ml. of xylene and a few Yboiling chips.' At'tach a Dean and Stark (Barrett type) receiver trap (20-ml. capacity), 24/40T, and a water condenser (400 mm. long) with a male 24/40$ joint with a drip tip. Place the assembly over a controllable heat source and apply heat. Reflux, drawin off the water layer from the trap until approximately 100 ml. t a v e been recovered. Evaporate the water sample to 5 to 10 ml. by any convenient method. Glycol Detection. Place 4 to 5 ml. of 0.4AVperiodic acid in a test tube, add 3 to 4 drops of concentrated nitric acid, and shake. Add 1 ml. of the evaporated water sample (above) and shake thoroughly. ,4dd 2 to 3 ml. of 0.1N silver nitrate. The formation of a white precipitate, silver, silver iodate ( AgIOa), indicates the presence of a vicinal glycol.
DISCUSSlOh
The portion of the procedure preceding the reflux distillation is usually carried out as the first step in other analyses conducted on alkyd resins, such as phthalic and oil-acid determinations. Utilizing the recovered water layer for the glycol analysis is logical and convenient. The reflux distillation is rapid and the periodate test is simple. This makes the procedure adaptable to the analysis of large numbers of samples or the rapid analysis of a few samples. There are no known substances in alkyd resins which would interefere with the procedure as outlined. Known samples in which the glycol made up as low as 5% of the total polyhydric alcohol content gave a positive glycol test. Lower percentages of glycol were not investigated. As all vicinal glycols of low molecular weight produce similar effects on the physical properties of alkyd resins, further identification of specific glycols is not warranted. However, methods for this identification are available. LITERATURE CITED
(1) Dean, E. W., and Stark, D. D., J Ind. Eng. C h a . . 12, 486-90 (1920).
Jordan, C., B. and Hatch, V. 0.. ANAL.CHEM.,22, 177-9 (1950). f 3 ) Orchin. M.. J . Assoc. 0%. Bur. Chemists. 30. 651-5 (1947). (4j Palfray, L., Sabetay, S.;and iibmtnn-Metayer, G., d o m p t . rend.,
(2)
223, 247-9 (1946).
( 5 ) Shay, J. F., Skilling, S. S . , tiid Stafford, R. W., ANAL. C H E M . , 26,652-6 (1954).
(6) Trussler, R. B., IND.ENG.CHEM.,ANAL.ED.,18, 260-1 (1946).
RECEIVED for review May 15, 1954.
Accepted June 23, 1954
Determination of Carbon and Sulfur in Ferrous Metals A Combined Method ALBERT C. HOLLER with ROSEMARY KLINKENBERG and CHARLES FRIEDMAN' Twin City Testing and Engineering Laboratory, St. Paul, Minn., and
W. K. AITES Air Brake Division, Westinghouse Air Brake Co., Wilmerding, Pa.
A combined method is described for the determination of both carbon and sulfur in ferrous metals using a singly weighed sample with a Lindberg high frequency combustion furnace. The carbon is determined gravimetrically and the sulfur, acidimetrically or iodometrically. The gases from the combustion of the ferrous metals in oxygen are passed through a closed system, absorbing first the sulfur dioxide in an absorption-titration vessel, and finally the carbon dioxide on Ascarite after removal of moisture from the gases.
T
H E trend of industrial analytical chemistry is toward methods of analysis that give accurate results but are still rapid and simple to perform. This paper describes such a procedure for the determination of both carbon and sulfur in irons and steels using a singly weighed sample with a Lindberg high frequency combustion furnace. Holthaus (9) in 1925 seems to have been the first to propose a combination method. Since that time numerous others have been published (3-6, 11-13), but have not received wide acceptance. In the methods described herein, the sulfur is determined acidimetrically ( 7 , 8, 12) or iodometrically ( 2 , I$), and the carbon, 1
Present address, University of Minnesota, Minneapolis 14, Minn
gravimetrically. The gases from the combustion of the ferrous metals in oxygen are passed through a closed system, absorbing first the sulfur dioxide in an absorption-titration vessel, and finally, the carbon dioxide on .4scarite after the removal of the moisture from the gases. APPARATUS AND REAGENTS
Apparatus. The furnace used was a Lindberg high frequency combustion furnace, Model LI-BOOA, manufactured by the Lindberg Engineering Co., Chicago, Ill. The setup for the combined method for the determination of carbon and sulfur is shown in Figures 1 and 2. A is the exit end of the combustion tube of the Lindberg high frequency furnance. The sulfur absorption-titration vessel, B, consists of two parts joined together by means of a standard-taper ground joint and held together by means of springs. The top (female) portion has sealed into it a gas inlet tube (4 mm. in internal diameter) delivery tube, C, a buret ti D, and LL gas outlet tube (4 mm. in internal diameter), E . *he lower (male) portion is the absorption beaker, the back and the bottom of which are mirrored. The bubble tube, F, contains concentrated sulfuric acid and is connected to G, an absorption bulb filled with a good dessicant, preferably anhydrous magnesium perchlorate (&hydrone). The carbon absorption bulb, H , contains Ascarite in the lower half and Anhydrone in the upper half. The carbon absorption bulb is connected to a Lindberg flowmeter, I . In the case of cast irons, a special catalyst or Monolyzer bulb (necessary to convert any carbon monoxide formed to carbon dioxide) is inserted between G and H and is of the same type as
V O L U M E 2 6 , N O , 10, O C T O B E R 1 9 5 4 C and If. This bulb is prepared by filling an absorption bulb with
a thin layer of glass wool on the bottom, then approximately 10 grams of activated manganese dioxide (Sulsorbent) fallowed by a thin layer of glass wool then approximately 10 gram of the catalyst (MonolyBer), a ihin layer of glass wool, a layer of Anhydrone, and finally a layer of glass wool. Reagents. R. R. Alundum, SO-mesh, Norton Co., Worcester, Mass. Tin metal, granulated, 30-mesh, analytical reagent. Plast iron powder, Grade A 70 A-A10, -6 +20-mesh, obtainable from Lindberg Engineering Co., Chicago, Ill. Monolyzer, a catalyst obtainable from Lindberg Engineering Go., is a mixture of the oxides of silver, copper cobalt, and nickel. Standard sodium hydroxide, hydrogen peroiide absorbing solution, and bromocresol green indicator for use in the acidimetric sulfur determination were prepared as directed by Woodward (IB)andHollerandYeager(8). The reagents for use in the iodometric sulfur determinationnamely standard potassium iodate, hydrochloric acid absorbing solution, and starch-potassium iodide-were prepared as directed in ASTM methods ( 8 ) . PROCEDURES
In the procedure given, the following furnace practice (7) was used on all combustions regardless of the ferrous metal.
1659
the sodium hydroxide used in titrating tho sulfuric acid. During the 3-minute flush oeriod the carbon absorber is weighed. At the finish of this flush period, the absorber is replacea and the system is in order for the next determination. Iodometric Sulfur and Gravimetric Carbon in Steels. Weieh out a 0.5- to 1-gram sample of the steel and transfer to a c u p e l k Add approximately 0 5 gram of tin and cover with about 0.5
into tke combuhion tube. Lock into p&ti& and adjust the oxygen flow to GOO ml. per minute. Turn on the plate switch to start the oombustion, maintaining the oxygen flow a t 600 ml. per minute throughout the entire combustion, and pass the products of combustion into the absorption train. Titrate the sulfur dioxide &S rapidly as it comes over into the absorption-titration I
Remove the carbon absorber and weigh. SIightlG lower the loading mechanism t,o wash out any sulfur dioxide retained on the wetted walls of the delivery tube, and titrate to the blue starch end point. Acidimetric or Iodometric Sulfur and Gravimetric Carbon in Cast Irons, etc. The apparatus setup is modified by placing the Monolyzer or catalyst tube, J , between bulbs G and H . The determination techniques are the same as for steels, except that it is sometimes necessary to add 0.5 gram of "plast-iron" powder in addition to the other fluxes in order to get IL high rombustion temperature.
Figure 2.
Setup for the Cornhinled Method
Calculations. The percentage sulfur Iated by multiplying the number of milliliters of standard hy&oxide or iodate used in the titration by its factor (expressed in t e r m of per cent sulfur per milliliter pc?r 1 gram of sample) diFig,ure 1. Diagram of Apparatus for Combined Method A.
B. C.
D.
Exist end Lidbere H-F unit Sulfurab&wtion-t&tmtionw a d (pat. pending) Gss inlet delivery tube Buret tin
The percentage of carbon in the sample is low% Wt. of carbon dioxide abmrbed X 0.2729 Weight of sample
x
I""
- ,o
bLI.""..
EXPEI~MENTAL
Flow Rate of Oxygen. The flow rate nf oxygen through the ' system during the combustion period wa8 found to be an impor-
ANALYTICAL CHEMISTRY
1660
absorption-titration veosel, more distinct end points could be obtained owing to the extra amount of light that was reflected int.0 the vessel by the mirror (silvering).
Table I. Determination of Sulfur Factor by Acidimetric Method Solution Factor, % Sulfur per M1. of Solution per 1 Gram Sample 0.0125 0.0121 0.0124 0.0121 0.0121 0.0122 0.0121 0.0124 0.0121 0.0120 0.0123 A v . 0.0122
Bureau of Standards Standard Sample 12e, B.O.H. steel 72c, Cr-Mo steel 65c, basic electric steel 10e Bessemer steel 32c: Cr-Ni steel 1210, Cr-Ni (18-10) 101c, Cr-Ni (18-9) 1290, high sulfur steel 4g, cast iron 7e. cast iron 122b, car wheel
SULFUR FACTOR
tant factor in the method. For complete recovery of the carbon the flow rate must be maintained from 350 to 700 ml. per minute in the procedure using the acidimetric sulfur method. If the iodometric sulfur method is used, the flow can be from 500 to 900 ml. per minute. Therefore, a flow rate of 600 ml. per minute was taken as standard procedure. Figure 3 gives the results on the effect of flow rate versus the recovery of both carbon and sulfur. This figure shows some interesting results, especially in the sulfur determination. It was previously thought ( 7 ) that accurate sulfur results could be obtained only when high oxygen flow rates-Le., 1200 to 1500 ml. per minute-were used. An inspection of Figure 3 shows that flow rates as low as 100 ml. per minute yield accurate results. This no doubt is due t o the small heating zone which is present in a high frequency furnace (luring combustion, plus a temperature of over 3000" F.
In any type of combustion sulfur method much discussion arises concerning the method of obtaining the solution factor for the titrating reagent ( I d ) . In this work the solution factors were obtained by analyzing a number of Bureau of Standards steels and cast irons and taking the average factor of these results. Table I gives thc results of a typical run made to determine the sulfur factor for a standard sodium hydroxide solution. .In inspection of Table I s h o w that the factor varies little, if an!.. with the general composition of the ferrous metal and its sulfur content. RESULTS
The results obtained, using the procedures given to determine the carbon and sulfur content of Bureau of Standards steel samples, are shown in Table 11. The results were obtained using the acidimetric sulfur-gravimetric carbon method. Similar results with equal accuracv were obtained using the iodometric sulfur-gravimetric carbon method.
FLUXES A N D ACCELERATORS
Aites ( 1 ) discussed the effect of different fluxes and accelerators upon the combustion of ferrous metals. It was found that the following fluxes and accelerators gave the best combustion, fusion of the oxidized metals, and correct slag formation. The metal accelerators were granulated tin and plast-iron powder. The oxide fluxes were either Alundum or chromic oxide. The use of different fluxes is described in the procedures in order to show the flexibility of uses for these materials for either the acidimetric or iodometric sulfur method. OBSERVATION O F END POINT
The end point in both sulfur methods is sharp and definitp, but it \vas found that, by silvering the hack side and bottom of the
Figure 3.
Effect of Flow Rate of Oxygen on Recovery of Carbon and Sulfur
1. Recovery of iodometric sulfur 3. Recovery of gravimetric cartxin coinhined Kith iodometric sulfur 3. Recovery of gravimetric carbon combined with acidimetric sulfur 4 . Recovery of acidimetric su!fur .
~
~~
-
~
~
~~
~
~
Table 11. Results on Steel" National Bureau of Standards, Standard Sample 125, high silicon steel 126a, 36% Xi steel 160, 19 Cr-SNi-3Mo steel 101c, Cr-Ni(l8-9) steel 129a, highsulfur steel 72c, Cr-Mo steel 72e. Cr-hfo steel 65c basic electric steel ize', B.O.H. steel 12/, B.O.H. steel 139, Cr-Ni-&Io steel 10e, Bessemer steel 32c, Cr-Ni steel 13d B . 0 . H steel 13e,'B.O.H.'steel 132, Mo-W-Cr-V-steel 153 Mo-W-Cr-V-Co steel 16c,'B.O.H. steel 36a A.O.H. steel l z l b , Cr-Xi (18-10) 121b, Cr-Xi (18-10) 4g, cast ironb 4h, cast iron 7e, cast iron 122b, car wheel a Carbon gravimetric-sulfui b Carbon gravimetric-sulfur
Carbon Present,
%
0.058
0.056 0.044 0.072 0.097 0.329 0.344 0.339 0.371 0.480
Carbon Found.% Range Average 0.058-0.067 0.066 0.059-0.062 0.061 0.045-0.048 0.046 0.072-0.074 0.073 0.097-0.101 0.100 0.325-0.330 0.327 0.342-0.348 0.346 0.338-0.343 0.339 0.366-0.372 0.369 0.446-0.452 0.448 0.386-0.396 0.391 0.402-0.408 0.408 0,418-0.428 0.424 0.567-0.576 0.573 0.632-0.641 0.639 0.800-0.810 0.806 0.853-0.864 0.880 1.008-1.021 1.015 1.015-1.029 1.020 0.072-0.075 0.073 0.073-0.076 0.074 2.45 2 . 4 2 -2.47 2.42 2 . 4 3 -2.46 2.91 2.89 -2.93 3 . 1 0 -3.14 3.11
0.394 0.406 0.429 0.576 0.636 0.803 0.864 1.01 1 03 0.073 0,072 2.47 2.44 2.93 3.14 acidimetric. iodometric: catalyst bulb in train.
Deviation Average, Yo fO.008 +0.005 I-0.002 +0.001
i0.003 -0.002 70.002
*o.ooo
-0.002 -0.002 -0.003
=to.ooo -0.005 -0.003 T 0.003 f0.003 -0.004 '0.005 -0.010
*o.ooo
1-0.002 -0.02 -0.02 -0.02 -0.03
Sulfur Present, % 0,005 0.006
0.010 0.016 0.273 0.018 0,020 0.031 0.027 0,037 0.024 0.047 0.018 0,024 0.016 0.004 0.008
0.044 0.037 0,010 0.008 0.071 0.070 0.079 0.0116
Sulfur F o u n d , 2 Range 1,erape 0.003-0.005 0,004 0.005 0.004-0.006 0.008 0.007-0.009 0.017 0.016-0.018 0.275 0,273-0,276 0.017 0.016-0.018 0.019 0.018-0.020 0.030 0.029-0.032 0.027-0.030 0.029 0.035 0.034-0.037 0.025 0.024-0.026 0.045 0.043-0.046 0.018 0.017-0.019 n. 024 0.023-0.025 0.015 0.014-0.01R 0.005 0.004-0.007 0.007 0.006-0.008 0.045 0.043-0.046 0.037 0.037-0.039 0.011 0.010-0.012 0.006 0.006-0.007 0.070 0.070-0.072 0.069 0,068-0.070 0.079 0.078-0.081 0.115 0.114-0.117
Deviation Average, % -0.001 -0.001 -0.002 +0.001 f0.002 -C.OOl -0.001 -0,001 f0.002 -0.002 f0.001
-0.002
+o.ooo
10.000 -0.001 fO.OO1 -0,001 fO.001
+o.ooo
*0.001 -0.002 -0.001 -0,001 *o. 000 -0.001
S n . of Ihtns 10 10 10 10
'g2
2
10
10 10 10
in
10
10
'?
5 10 10
10 10 10
V O L U M E 26, NO. 10, O C T O B E R 1 9 5 4 Table I1 (bottom) gives the results obtained on Bureau of Standards cast irons using the catalyst hlonolyzer bulb in the system. The iodometric sulfur-gravimetric carbon method Ivas Equivalent results were obtained with the acidimetric sulfur-gravimetric carbon method.
1661 (7)
Holler, A. C., and Klinkenberg, R., ANAL. CHEM.,23,
(8) Holler, A. C., and Yeager, J. P., F o u n d r y , 72, 83 (1944). (9) Holthaus, c., 2. a ' W W . C'hem., 389 330 (1925). (10) Lindberg Engineering Co., Chicago, Ill., "Instructions for Installation and Ooeration of Lindbere Hieh Freauencv - ComI
LITERATURE CITED
Aites, 'Ar.K., Steel, 125,92 (Dec. 12, 1949). Am. Soc. Testing Materials, "hlethod of Chemical -1nalysis .Metals," p. 129, 1950. Boedanchenko. A. G.. Zaaodskava Lab. 6 . 369 (.1 9 3 3 . ~
~ - - ~ ~
.
~
1696
(1951).
(11) (12) (13)
-
bustion Furnace LI-500-.\." 1950. Misson, G., Chimie & I n d u s t r i e , Spec. No. 326 (March 1932). U. S. Steel Corp., "Sampling and Analysis of Carbon and Alloy Steels," p. 309, Reinhold Publishing Corp., New York, 1938. Zaffuto, G., Acti. X congr. intern. chim., 3, 487 (1939).
I
Ibid., 12,119 (i946)-. Burns, B., and Braude, G., Zhur. A n a l . K h i m , 4, 31B (1949). Gerke, F. K., and Kardakova, Z. I., Zavodskaya Lab.. 3, 9 i 7 (1934).
RECEIVED for review Dewniber 28,
1954. Accepted J u n e 28, 1954. Prcsented before the Pittsburgh Confprpnce on hnalytical Chemistry a n d Applied Spectroscopy. J l a r c h 1953.
Ultraviolet Absorption Spectra of the Hydrolysis Products of Diethyl Barbituric Acid G. R. JACKSON, JR., J. R. WESCHLER, and R. L. DANNLEY Department o f Chemistry, Western Reserve University, Cleveland, Ohio
The ultraviolet absorption spectra of the various hydrolysis ,products of diethyl barbituric acid are given.
I
N T H E course of an investigation of the effect of p H and temperature upon the hydrolysis of diethyl barbituric acid (barbital), the ultraviolet spectra of the possible hydrolysis products were determined t o ascertain whether these products interfere uith the quantitative determination of barbital b y the spectrophotometric method of Goldbauni ( 4 ) . EXPERIMENTAL
a-Ethyl butyramide was prepared in 60% yield by adding, drop by drop, 10 grams of a-ethylbutyrylchloride(EastmanWh1te Label) to 5 ml. of concentrated ammonium hydroxide which was cooled in a salt-ice bath. The addition of the acid chloride was regulated so that none of the mist of ammonium chloride escaped from the flask. After shnding 48 hours, the white solid which formed was removed by filtration, washed with water, and recrystallized from an ethyl alcohol-water mixture; white needles, melting point 102' to 105' C.; literature melting point, 105" C. ( 3 ) . a-Ethylbutyric Acid (Eastman White Label) was redistilled and the fraction boiling at 193" t o 194' C. was collected. Urea (hlerck reagent grade) was recrystallized from hot alcohol; melting point, 132' to 133' C. Diethyl Malonic Acid. .4 mixture of 25 grams of diethyl diethyl malonate (Eastman White Label), 25 grams of potassium hydroxide, 40 ml. of water, and 25 ml. of ethyl alcohol was refluxed for 20 hours. The solution was washed with ether to remove unchanged ester, made acid to Congo red, and extracted with ether. The ether extract was washed with water and then dried over anhydrous sodium sulfate. The ether was evaporated and the residue was cooled in ice. h white solid formed which was washed with ligroin, filtered, and recrystallized from chloroform; 4 0 3 yield, melting point, 126" C.; literature melting point, 125 to 127" C. ( 1 ) . a-Ethylbutyrylurea, prepared according to the procedure of Stoughton (j),had a melting point of 207' (literature melting point, 207") when recrystallized from an ethyl alcohol-water mixture. Diethyl malonuric acid, prepared according to the procedure of Fischer and Dilthey (Z), had a melting point of 162" C. (literature melting point, 162') when recrystallized from warm water . PROCEDURE FQR ULTRAVIOLET SPECTRA DETERMINATION
The same general method w&s used in making up the solutions of urea, a-ethylbutyric acid, a-ethylbutyramide, and diethyl
malonic acid. The amount of material calculated to be given upon complete hydrolysis of 0.5 gram of barbital to that product, was weighed out and diluted to 100 ml. with cold water. Two 1-ml. samples were pipetted and diluted to 50 ml., one with 0.45A' sodium hydroxide and the other with a borate-sodium hydroxide buffer of pH 10.3. Because of the insolubilitv of a-ethvlbutvrvlurea and diethvl malonuric acid in water, so1;tions !veri preparkd and the concehtrations determined as follows. -4 saturated solution of the compound was prepared by stirring 0.5 gram of the compound in 100 ml. of water for 0.5 hour. The resulting mixture was then filtered and the samples werc pipetted from the filtrate and diluted in the same manner as above. In addition another 1-ml. sample was taken, placed in a weighed evaporating dish, covered, allowed to evaporate, and weighed to determine the weight of compound in 1 ml. of solution. The solubility of a-ethylbutyrylurea was 0.0006 gram per ml. and that of diethyl malonuric acid was 0.0016 gram per ml. The ultraviolet absorption spectra of the compounds were determined on a Beckman Nodel DU spectrophotometer. RESULTS
The ultraviolet spectra of the various hydrolysis products show that all of the products give an optical density not over 0.03 unit except a-ethylbutyrylurea and diethyl malonuric acid. The latter products show considerable absorption a t the shorter wave lengths in very alkaline solution (0.45.V sodium hydroxide). However, a t 260 mp, the wave length a t which the concentration of barbital is determined in Goldbaum's method ( 4 ) , the ahsorp-
Table I.
h
230 235 240 245 250 255 260 2G5 270 275 280 285 290 295 300
Absorbances of a-Ethylbutyrylurea (12 y per M I . ) and Diethyl Malonuric Acid (32 y per Ml.) =-Et h ylbu t yrylii rea. PH 0.45-4' 10.3 NaOH
0.008 0,006 0.006
0.266 0.185 0.108 o.oci0 0.035 0.026 0.022 0.021 0.019 0.018 0,019 0,019
0.006 0.006
0,019 0.019 0,019
0.023 0.019 0,015 0.008 0.006 0.006 0.006
0.006
O.OOR
O.OOG
Diethyl Malonuric Acid 0.45.v PH XaOH 10.3 0.074 0.858 0.680 0.066 0.474 0.057 0.2R2 0.044 0.031 0.173 0.023 0.108 0.071 0,018 0,056 0.015 0.046 0.014 0.014 0.041 0,039 0.014 0.036 0.014 0.034 0.012 0.010 0.030 0 028 0.010
