753
V O L U M E 26, NO. 4, A P R I L 1 9 5 4 Table 111. Periodate Oxidation of Flavonol and Quercetin
Compound Flaronol
Quercetin a
Run A B C D
Sample Used hIg. hlmoles 121.0 0.508 139.3 0.586 678.sa 2.83 112.2 0.473
A 43.0 B 41.6 Large column run.
0.142
0.138
Periodate hlmoles Reaction 3lmoles conTme, Hr. added sumed 0.723 0.531 69 0.723 0.558 45 7.60 2.73 17 0 . 7 2 3 0.474 69 0.718 0.718
0,306 0.301
0.25 0.50
Ratio, Moles HIOc Moles Compound 1.04 0.95 0.96 1. 0 0 2.15 2.20
tion of 2 moles of periodate. In an experiment which ran for 94 hours, over 3.5 moles of periodate were consumed. A more detailed study of this slower oxidation and an examination of the highly colored reaction products are now in progress, LITERATURE CITED
(1) Clutterbuck, P. W,,and Reuter, F., J . Chem. Soc., 1935, 1467.
(2) Fleury, P., and Lange, J., J . pharm. chim., (8) 17, 409 (1933). (3) Herissey, H., Fleury, P., and Joly, LI.,Ihid., 20, 149 (1934). (4) Jackson, E. L., “Organic Reactions,” Vol. 11, Roger Adams, Ed., pp. 341-75, Sew York, John U‘iley & Sons, 1944. (5) Jackson, E. L., and Hudson, C . S., J . A m . Chem. Soc., 58, 378 (1936); 59, 994 (1937). (6) Krewson, C. F., and Couch, J. F., Ibid., 70,257 (1948). (7) Linstedt. G., Sature. 156, 488 (1945). (8) llalaprade, L., Bull. SOC. chim.,(4) 43, 683 (1928). (9) Nalaprade, L., Compt. rend., 186, 382 (1928). (10) Morton, A. A . , “Laboratory Technique in Organic Chemistry,” p. 174, New York, AIcGraw-Hill Book Co., 1938. (11) Xicolet, B. H., and Shinn, L. A . , J . A m . Chem. Soc., 61, 1615 (1939). (12) Rappaport, F., and Reifer, I., Mikrochim. Acta, 2, 273 (1937). (13) Rappaport, F., Reifer, I., and Weinmann, H., Ibid., 1, 290 (1937). Re‘eves, R. E., J . A m . Chem. SOC.,63, 1476 (1941). Reichcl, L., and Steudel, J., Ann., 553, 83 (1942). Smith, G. F., “dnalytical Applications of Periodic Acid and Iodic Acid,” 5th ed., Columbus, Ohio, G . Frederick Smith Publishing Co., 1950. (17) Smith, 11. A , , Gnau, L., and Willeford, B. R . , forthcoming Dublication. (18) Willard, H. H., and Boyle, -A. J., ISD.Esc. CHEM.,A%ih..k~.ED., 13, 137 (1941). RECEIVEDf o r review Xovember 23, 1953.
Accepted December 28, 1953.
Determination of Boron in Boron-Carbon Film Resistors IRVING G. YOUNG Research Division, International Resistance Co., Philadelphia 8, Pa.
P
YROLTTIC carbon film resistors are prepared by “cracking” of hydrocarbon gases in a closed chamber and deposition of carbon on suitable ceramic bodies. The nature and properties of the films obtained depend on the reaction conditions as well as the ceramic surface. Recently, it has been found that addition of boron compounds to the reaction mixture produces films with new and interesting properties ( 3 ) . It xas, therefore, of great interest to determine the amount of boron in these films, and correlate this with film properties, The titration of boric acid with alkali in the presence of mannitol has long been used to determine boron (4). Wilcox ( 6 ) titrated 250 to 5500 y of boron with a precision of 5 to 10% while with known quantities in this range he obtained recoveries of 100 Z!Z 301,. Foote ( 2 ) obtained recoveries of 100 +C 1% when titrating known amounts of boron in the range 500 to 10,000 y . The experience of these workers as well as others (5) was useful in developing a procedure suitable for the determination of boron in the coatings of boron-carbon ceramic resistors.
Iiimble Resistant glass flask with standard-taper joint. Add 3 ml. of concentrated sulfuric acid, or enough to wet and cover the ceramic bodies, and 5 to 10 drops of concentrated nitric acid. Assemble the flask with a reflux water-cooled condenser and heat the flask gently with a small flame or a Glas-Col heater. Five minutes will usually suffice to dissolve the film completely; more nitric acid may be added dropwise through the top of the condenser, if necessary. Allow, to cool, dilute carefully with water, and transfer quantitatively to a 100-ml. beaker. If the volume is more than 50 to 60 ml., evaporate to this volume, by placing in an oven at 125” C.
APPARATUS
Table IT. Determination of Boron in Coating of Ceramic Resistors
Beckman Model G pH meter. Kimble microburet, platinum alloy tip, 5-ml. capacity, 0.01ml. subdivisions. Magnetic stirrer. Kimble Resistant glass beakers and flasks. REAGENTS
Sulfuric and nitric acids, concentrated, C.P. Saturated sodium hydroxide, prepared in “boron-free” flask. Sodium hydroxide, 0.015alr, carbonate-free. Mannitol, C.P. Methyl red indicator solution, 0.1%. Standard boric acid solution. Dissolve 0.5715 gram of C.P. boric acid in water and dilute to 1 liter; 1 ml. == 100 y of boron. PROCEDURE
Weigh a number of clean, dry ceramic resistors containing a total of 200 to 500 y of boron in the film. Place in a 150-ml.
Table I. B,
y
100 199 299 399 199 199
Titration of Know-n Amounts of Boron SaOH, M I 0.61 1.17 1.68 2.25 1.11 1.18
y/M.
164 170 178 178 179 168 A x - . = 173; 0 = 5 . 8
(All weights in micrograms) Total B Titrated B in Coating, ‘% Weight of Coating 3080 286 9.3 638 3140 % I O 267 3160 8.5 306 3020 10.1 Av. 9 . 3 ; D = 0.6 B5O 2170 209 8.5 2410 676 8.90 1970 196 9.9 3410 302 8.9 h v . 9.1; D = 0.5 ClOO 1250 145 11.6 1400 150 10.7 Av. 11.2 D4OO 790 48 6.1 640 40 6.2 Av. 6 .2 a Corrected f o r NBS borax added to sample.
Sample A18
ANALYTICAL CHEMISTRY
754 Wash the ceramic bodies thoroughly with water, dry a t 105" C., cool, and weigh. The weight of the coating is equal to the loss in weight of the ceramics corrected for the loss in weight of a similar number of uncoated ceramic bodies carried through the same procedure. The boron in the solution is determined as follows. Add 3 drops of methyl red indicator and, while stirring, neutralize with the saturated sodium hydroxide added dropwise from a buret. Add only 1drop in excess. lMake the solution just barely acid with 1 to 10 sulfuric acid and add 2 drops in excess. Cover the beaker, bring to a boil, and boil gently for 5 minutes. Cool in ice water until the solution has reached room temperature. Set up the beaker for titration with pH electrodes. Adjust the pH with the 0,015AVsodium hydroxide to a value between 7.0 and 7.3. Add 3.0 grams of mannitol and titrate with 0.015N sodium hydroxide back to the same pH. The sodium hydroxide is standardized against the stock boric acid solution in exactly the same way. The sample titration is corrected for a blank which has been carried through the entire procedure. RESULTS
Table I, 11, and I11 give data obtained when boron was determined in known solutions, coatings of ceramic resistors, and in National Bureau of Standards borax, respectively. DISCUSSION
The above results indicate that boron can be determined in the coatings of boron-carbon resistors with a precision and accuracy within about 5% where the amount of boron titrated varies from 50 to 500 7 . No account was taken of possible interferences except that due
Table 111. Determination of Boron in NBS Borax Carried through Analytical Procedure Recovery, %
B, Titrated
Av. = 99.4; c
=
2.8
to carbonates. According to Feigl (1) telluric and germanic acids are activated by polyhydroxy compounds, but their presence is unlikely. Most cations likely to interfere are similarly not present in the coatings, though they may be introduced from the ceramic. Interferences arising from the latter are minimized by always running uncoated ceramic bodies through the procedure and correcting the sample titration for any blank titration. LITERATURE CITED
(1) Feigl, F., "Chemistry of Specific, Selective, and Sensitive Reactions," p. 360, New York, Academic Press, 1949. (2) Foote, F. J.,ANAL.CHEM.,4,39 (1932). (3) Grisdale, R. O., Pfister, A. C., and Rooshroeck, W. V., Bell System Tech. J . , 30, 271 (1951). (4) Hillebrand, W. F., and Lundell, G. E.
F.,"-ipplied Inorganic Analvsis." D. 612. New York. John Wilev & Sons. 1929. ( 5 ) Hollanier,'lLI:, and kiernan, W,', ANAL.C A ~ Y .17, , 602 (1945). (6) Wilcox, L. V., Ibid., 2, 358 (1932). RECEIVED for review October 27, 1953.
Accepted J a n u a r y IS. 1954.
Benzilic Acid as a Reagent in Gravimetric Determination of Zirconium JOSEPH J. KLINGENBERG, PEPPINO N. VLANNES', and MELVIN G. MENDEL2 Xavier University, Cincinnati, O h i o
D
URING the investigation of the zirconium-precipitating
action of a number of glycolic acid derivatives by Oesper and Klingenberg (6) benzilic acid was found to give a very voluminous precipitate. Venkataramaniah and Rao (6) investigated this reaction further and found that quantitative precipitation occurs in solutions up to 0.225N in hydrochloric acid solution. The following work, carried out independently, parallels the results obtained by Venkataramaniah and Rao, but also studies the reaction under a wider range of conditions with thk resultant extension of the quantitative precipitation beyond the 0.225N hydrochloric acid range. (Contrary to the statement of Venkataramaniah and Rao, benzilic acid was not "totally rejected" as a zirconium reagent by Oesper and Klingenberg. The study of benzilic acid was delayed in favor of the more promising halomandelate reagents.)
tated by the addition of ammonium hydroxide. The gelatinous rnws is washed by reverse filtration until aliquots of the wash solution give negative tests for sulfate ion. The washed zirconium hydroxide is dissolved by the addition of hydrochloric acid, heating if necessary. White, tetragonal crystals of zircony1 chloride octahydrate are obtained by evaporation of the solution. Zirconyl chloride solution. Zirconyl chloride octahydrate is dissolved in distilled water containing 250 ml. of 12N hydrochloric acid per liter of solution. EXPERIMENT4L
Quantitative Action of Benzilic Acid. After considerable experimentation the following procedure was developed for the determination of zirconium. To a solution containing 0.0010 to 0.0600 gram of dissolved zirconium in a 250-ml. beaker are added 15 ml. of 12N hydro-
REAGENTS
Benzilic acid. Commercial benzilic acid is purified by recrystallization from hot water containing a little hydrochloric acid. By keeping the temperature below 95" C. the main contaminant, benzil, remains as a solid and can be removed from the dissolved benzilic acid by filtration. Zirconium sulfate solution. Commercial zirconium sulfate tetrahydrate is dissolved in distilled water containing 333 ml. of 12N hydrochloric acid per liter of solution. Zirconyl chloride octahydrate. Zirconium sulfate tetrahydrate is dissolved in water and zirconium hydroxide is precipi1 Present Address, Eastern Experimental Station, Bureau of Mines, College Park, Md. 2 Present Address, National Lead Co. of Ohio, Cincinnati, Ohio.
Table I.
iinalysis of Zirconium Solutions by Various Methods Reference t o Procedure
Zr(S0i)x Solution, Gram ZrOz/hll.a 0.0104
Method Benzilate .. p-Bromomandelate (6) p-Chloromandelate (6) Cupferrate (3) O.'Olb4 Hydroxide (3) 0,0104 Mandelate (6) 0.0104 Phosphate (3) 0.0104 a Based on average of nine analyses.
...
ZrOCla Solution A, Gram ZrOt/hLa
ZrOClr Solution B, Gram ZrOz/Ml.'
0.0089 0,0089
0.0278 0.0278 0.0279
0.0090
0.0280 0.0278
...
0.0089 0.0089
0.0279
...
