ACKNOWLEDGMENT
The authors express appreciation to the Environmental Research Laboratory, University of Washington, and its former director, Ross N. Kusian, for the loan of special equipment. LITERATURE CITED
(1) Birdsall, C. M., Jenkins, A. C. Spadinger, E., ANAL. CHEM.24, 662-4 (1962). ,- - -- ,. (2) Boelter, E. D., Putnam, G. L., Lash, E. I., Zbid., 22,1533-5 (1950).
(3) Byers, D. H., Saltzman, B. E., Am. Znd. H y g. Assoc. J . 19,251-7 (1958). (4) Goldman, F. H., Jacobs, M. B.
“Chemical Methods in Industrial Hygiene,” pp. 104-5, Interscience, New York, 1953. (5) Haagen-Smit, A. J., Brunelle, M. J.,
J. Air Pollution 1,51-9 (1958). (6) Renzetti, N. A,, ANAL. CHEM.29, 869-74 (1957). (7) Saltzman, B. E., Gilbert, N., Am. Znd. Hug. ASSOC. J . 20,379-86 (1959). (8) Smith, R. G., Diamond, P., Am. Znd. Hy g. Assoc. Quart. 13,235-8 (1952). (9) Storlazzi, M., Bovee, H. H., “Design
of Referee Method for the Determina-
tion of Trace Concentration of Ozone in Air,” p . 8-11, Environmental Research Laporatory, Dept. of Publie Health and Preventive Medicine, University of Washington, Senttle, Wash., 1955. (10) Thorp, C. E., “Bibliogrnphy of Ozone Technology,”‘Vol. I, Armour Research Foundation, Chicago 16, Ill., 1954. (11) Wadelin, C. W., ANAL. CHEM.29, 441-2 (1957).
RECEIVED for review November 14 1960. Accepted April 5, 1961. Research s u p orted in part by a grant, AT 57-20?, &om the U. S. Public Health Service.
Spot Tests Based on Redox Reactions with Devarda’s Alloy and Raney Alloy FRITZ FEIGL laboraforio da Product30 Mineral, MinistGrio da Agriculfura, Rio de Janeiro, Brazil Translated by RALPH E. OESPER, University of Cincinnati Reductive cleavages of various organic compounds can be accomplished by a wet method using Devarda’s alloy or nickel-aluminum a l k y (Raney alloy). These reactions are due to the action of nascent hydrogen or nickel hydride. Raney nickel, formed by the activation of Raney alloy, is shown to be the more powerful reductant. Analytical applications of the redox reactions with Devarda’s alloy or Raney alloy can be achieved if products are formed which may be detected directly or indirectly in the gas phase. In this way it was possible to develop new tests for: benzonitrile, tribromoaniline, arylsulfinic, arylsulfonic, aminophenylarsonic, and stibinic acids, sulfanilic acid and its derivatives, phenylhydrazine (hydrazones, osazones), pyridine, aromatic sulfones, and Raney alloy. All of these tests can be carried out successfully by spot test analysis and they have microanalytical limits of identification. REPORT (a) announced that certain organic compounds undergo hitherto unreported reductive cleavages if their aqueous alkaline solutions were treated with nickel aluminum alloy (Rrtney alloy, Murex, Ltd., London). The resulting Raney nickel acts, through its content of nickel hydride, as a powerful hydrogen donor. Application of these findings, together with comparison studies of the action of Devarda’s alloy in alkaline or acid surroundings, led to the new and selective tests described here.
A
DETECTION METHODS
Benzonitrile, by Reductlon to Benzylamine. The action ,of, metallic
sodium on alcohol solutions t o yield the corresponding primary amines from nitriles has already been used for preparation purposes (18). Accordingly, benzylamine can be prepared by this procedure from bemonitrile (phenyl cyanide) : CsHrCN
+ 4H
O .-L
C‘HICH~NHS (1)
The benzylamine condenses with sodium l ,%naphthoquinone4sulfonate to give a quinoidal brown-violet product
(9,11): 0
&OsNa 0
PRELIMINARY
11 18
0
ANALYTICAL CHEMISTRY
The sulfurous acid resulting from this and analogous reactions of the sulfonate with compounds bearing active CHs- and “2groups cannot be detected, as it reduces the reagent to 1,2-naphthol-4sulfonic acid (14). The hydrogenation (Equation 1) proceeds rapidly if the solution of benzonitrile is warmed along with Devarda’s alloy or Raney alloy; the resulting benzylamine is carried along with the water vapors and can be detected in the
gas phase by the color reaction, Equation 2. Consequently, a far-reaching sensitive test for benzonitrile could be developed on this basis, assuming the absence or the formation of bases that are volatile with water vapor and that enter into condensation reactions analogous to Equation 2 with sodium 1,s naphthoquinone-4-sulfonate. Such interfering compounds include: aniline, tolidine, naphthylamine, nitro-, chloro-, and bromoaniline, and piperidine ( 4 ) . If the possible presence of such materials must be taken into account, a preliminary separation from the benzonitrile is essential. The test solution should be acidified with dilute sulfuric acid and shaken with ether. The interfering bases remain in the water layer as sulfates, and the ether extract can then be tested for benzonitrile. Procedure. A micro test tube ia used. One drop of the alcohol or ether solution is mixed with 1 drop of 5% caustic alkali solution, and several milligrams of Devarda’s alloy are added. The suspension is warmed cautiously until the vigorous evolution of hydrogen has subsided. The mouth of the test tube is then covered with a piece of filter paper moistened with a freshly prepared 0.5% water solution of sodium 1,2-naphthoquinone4sulfonate. The test tube is then placed in a boiling water bath. A positive response is indicated by the development of a brown-violet stain on the reagent paper within a few minutes. Limit of identification: 3 pg. of benzonitrile. Tribromoaniline, by Conversioninto Aniline. Tribromoaniline, which is readily obtained by bromination of aniline or acidic aniline salt solutions,
does not respond to the various spot tests for primary amines employed in spot analysis (6). I t does not yield a yellow Schiff's base with p-dimethylaminobcnznldehydc, nor does i t product a rrd-violct p-quinoid condensation product with sodium 1,2-naphthoquinonc-4-sulfonate. If an ctlirr or alcohol solution of tribromonniline or the water solution of its salts is warmed with caustic alkali and Devarda's alloy or Raney alloy, aniline results. The latter is volatile with water vapor and can be detected in the gas phase by the reagents just mentioned. I t has not been detcrmincd whether the bromine is complctcly removed, but the following reaction is valid a t least in part:
+
+
CaHzBr,NWz G €1" 3 NaOH -c CsHaNH, 3 NaBr 3 H*O (3)
+
+
This dchnlogcnation, combined with the color reaction of the resulting aniline in the gas phase, provides a reliable test for tribromoaniline. I t is assumed that other polyhalogenated anilines will behave in the same manner as tribromoaniline with respect to this method of removing halogen, and if so the value of the new procedure will be cnhanced since they too arc not amenable to the usual conlensation reactions typical of primary rtrylamines. Tribromoaniline is rcduced more rttpidly by R m e y alloy than with ilevarda's alloy. Nevertheless, the latter is preferablo because the Raney alloy used here yielded ammonia in distinct amounts when centigram amounts were warmed with caustic alkali. The ammonia doubtless came from nitridcs in the alloy and is deleterious here because it gives a blue coloration on the sodium 1,Znaphthoquinone-4-sulfonate paper. Procedure. A tiny portion of the solid or a drop of its solution in organic liquids or acids is treated in a micro test tube with 1 to 2 drops of 5% cpmtic alkali solution and several milligrams of Devarda's alloy. Gentle warming is used a t first until the vigorous evolution of hydrogen has lessened, and then the mouth of the test tube is covered with a piece of filter paper moistened with 0.5% aqueous solution of sodium 1,Znaphthoquinonc-4-sulfonate solution. The test tube is placed in boiling water. A red-violet stain appears on the yellow paper. If Raney alloy is used, the test for aniline should be made with a disk of filter paper moistened with p-dimethylaminobenzaldehyde. If aniline has been formed, a yellow stain appears on thc colorless paper. Limit of identification: 10 pg. of tribromoaniline. Arylsulfinic Acids, by Reductive Cleavage with Raney Alloy. Thiophenol results if benzenesulfinic acid
is treated with zinc and hydrochloric acid (10) : CsHsSOsH
+ 4 H"
+
CsHiSH
+ 2 HsO
(4)
The reduction, which of course can also be accomplished with Devarda's alloy, is readily detected, since, on warming, the thiophenol (boiling point, 104' C.) volatilizes and will give a yellow stain of Pb(SCsH& on lead acetate paper. As little aa 15 fig. of benzenesulfinic acid can be detected in this manner within the technique of spot testing. If Raney alloy is used in place of zinc or Devarda's alloy, hydrogen sulfide results and is distinctly detectable by the darkening of lead acetate paper. The fact that the reduction may be truthfully represented by the net equation : CaHsSOzH 6 H" -C CsHs 2 Hz0 HIS ( 5 )
+
+
+
or, in other words, that the reaction proceeds farther with Raney alloy, may be ascribed to the action of the nickel hydride in the Raney nickel formed. This hydride, which may be represented as NitH (9), is obviously a more powerful and rapid reductant than nascent hydrogen; its action with benzenesulfinic acid may be : CaH,SOzH 6 NhH + GHe 2 HzO HIS 12 Ni" (6)
+
+
+
+
Consideration likewise must be given to the reduction of the thiophenol produced initially: CsHt,SH 4-2 NiZH + CsHs H%S 4 Ni" (7)
+
+
The more powerful reducing action of Raney alloy, in either acidic or alkaline media, is likewise shown in the last five tests described here. The arylsulfinic acids behave in the same way as benzcnsulfinic acid toward these reductants. The reduction with R m e y alloy is recommended for the test because a higher sensitivity can be attained in the detection of hydrogen sulfide as compared with thiophenol. Arylsulfonic acids were not affected when warmed in acid media with Raney alloy or Devarda's alloy. Therefore the following test permits an excellent differentiation between arylsulfinie and arylsulfonic acids or their alkali salts. Procedure. A micro test tube is used. A slight quantity of the solid test material or a drop of its solution, together with a few milligrams of Raney alloy, are treated with several drops of dilute hydrochloric or sulfuric acid. After the vigorous evolution of hydrogen has subsided, a piece of lead acetate paper is placed over the mouth of the tube. The contents are gently warmed in the water bath and then the temperature is increased.
A gray or black stain due to lead sulfide appears on the paper if the response
is positive. In case only sli h t amounts are suspected, it is advisa le to make
5
a blank test with the Raney alloy alone, since a t times the latter contains slight amounts of sulfides which may react with acids. However, a comparison of this kind is required only when quantities of sulfinic acid below around 10 fig. are to be detected. The test revealed: 4 fig. of benzenesulfinic acid; 5 fig. of toluenesulfinic acid; 6 fig. of naphthalenesulfinic acid. Aminophenylarsonic and Aminophenylstibinic Acids, by Reductive Splitting Off of Aniline. If these arsonic or antimony acids or their alkali salts are warmed with caustic alkali and Devarda's alloy, aniline is split out:
+ + +
H~N-CaH4--A.a (Sb)O(ONa), 2 H" NaOH --* As(Sb)(ONa), HzO CsHbNH,
+
The realization of this redox reaction and the detection of the resulting aniline in the gas phase through the color reaction with p-dimethylaminobenzaldehyde make possible a selective test for arsanilic acid and the corresponding antimony acid. The production of aniline from these acids can also be accomplished by warming them with caustic alkali and Raney alloy, but aniline is then also produced from aminophenylsulfonic acid (see below), which is not the case if Devarda's alloy is employed. Consequently, reduction with the latter can be used to detect arsanilic (stibinic) acid in the presence of aminophenylsulfonic acid. The nitrophenyl arsonic (stibinic) acids behave in the same manner as the aminophenyl acids, since they are converted into the latter by the action of the reducing agent. Procedure. Same as for detection of benzonitrile. The following quantities were detected: 6 fig. of arsanilic acid; 6 pg. of p-aminophenylstibinic acid; 5 pg. of p-nitrophenylstibinic acid; 6 p g . of p-nitrophenylarsinic acid. Arylmono- and Arylpolysulfonic Acids, by Reductive Removal of Sulfur. If arylsulfonic acids are warmed with Raney alloy in the presence of caustic alkali, neither SOs-a or S-l ions can be detected in the resulting sohtion. However, the unused alloy will contain nickel sulfide which can be revealed through the formation of hydrogen sulfide when warmed with dilute mineral acid. Since Devarda's alloy is without action in this case, the effective reductant cannot be nascent hydrogen, and i t may be assumed that i t is the nickel hydride in the Raney nickel formed from the alloy which is VOL. 33, NO. 8, JULY 1961
1 119
responsible for the reductive desulfurization: ArS08Na
+
+ +
+
6 NizH -*. ArH NiS NaOH 2 HzO 11 Ni" (8)
+
The ease with which the sulfur is removed from arylsulfonic acids is truly astounding. It is in accordance with desulfurization effects through Raney nickel first observed by Bougault and coworkers ( I ) , later employed by Trifonoff and coworkers (12) in the semimicrodetermination of sulfur in organic compounds. Recently, Granatelli (8) described the determination of microgram quantities of sulfur by reduction with freshly prepared Raney nickel to yield nickel sulfide. The realization of Equation 8 and the dctection of the resulting nickel sulfide make possible the detection of aromatic mono-, di-, and trisulfonic acids. Arylsulfinic acids show analogous behavior. The test described here requires the absence of thioketones, thiol compounds, disulfides, and sulfides, since they react with Raney nickel to yield nickel sulfide. The presence of these interfering materials (with the exception of thioethers and disulfides) can be established by their catalytic hastening of the iodine azide reaction (6). A preliminary test of this kind will be necessary, however, only in the rare instance when these compounds are soluble in dilute alkali, as is true of sulfonic acids. Aliphatic saturated sulfonic acids yield little or no nickel sulfide on warming with caustic alkali and Raney alloy. This fact was established for taurine, 1,lOdecanedisulfonic acid, 1,Zethanedisulfonic acid, camphorsulfonic acid, sodium 3 - methyl - 1- butanesulfonate, sodium 2-propanesulfonate, sodium 1butanesulfonate. On the other hand, sodium %propene - 1 - sulfonate and benzylsulfonic acid react in the same manner as purely aromatic sulfonic acids. Therefore, it appears that carbon double bonds adjacent to the SOaH (Na) group activate the reducibility by Rancy nickel, and that OH groups in aliphatic sulfonic acids have a similar effect though in a less pronounced fashion. This was observed in the cases of ClCH&H(OH)CH&O3Na and HOCH2CH&03Na, which, in amounts over 1000 fig., yielded nickel sulfide on treatment with caustic alkali and Raney alloy. Procedure. A little of the solid or a drop or two of its solution is placed in a micro test tube; then several milligrams of Raney alloy and 1 drop of 5% caustic alkali are added and the mixture is warmed in a water bath. If the evolution of hydrogen becomes too turbulent, the warming should be interrupted occasionally. The warming is continued 1120
*
ANALYTICAL CHEMISTRY
for nbout 3 minutes; the contents are allowed to cool, and then several drops of dilute hydrochloric acid are added. After the evolution of hydrogen has stopped, a picce of lead acetate paper is placed over the mouth of the test tube which is then warmed in the water bath. A brown or gray stain of lead sulfide signals a positive response. The test revealed the following, in micrograms: sulfosdicylic acid, 5 ; sulfanilic acid, 2.5; metanilic acid, 5 ; saccharin, 1 ; anthraquinone-2,6disulfonic acid, 1; anthraquinone-1,&disulfonic acid, 1 ; 1-amino-8-naphthol3,6disulfonic acid, 2 ; l-naphthylamine3,6,8-trisulfonic acid, 2.6; potassium I-anthraquinonesulfonate, 2.5; 1-amino2-naphthol-4-sulfonic acid, 2.5; 8quinolinol-&sulfonic acid, 5 ; 8-quinolinol7-sulfonic acid, 5 ; methyl orange, 2.5; naphthalene-l,&disulfonic acid, 5 ; l,R naphthol-3,6disulfonic acid (sodium salt), 5 . The instance of methyl orange indicates the possibility of using this test for the rapid recognition of SOaH(Na) groups in dyestuffs. Sulfanilic Acid and Derivatives, by Splitting Off of Aniline. The removal of sulfur from arylsulfonic acids by Raney nickel formed from Raney alloy also holds for their derivatives. Among these, special interest is attached to sulfanilic acid, sulfanilamide, and sulfa compounds. The following reactions can be readily accomplished in all cases:
+
CeH4(NH2)SOsNa 6 NilH CsHaNHz NiS NaOH 2 H20 11 NiO (9) CsH4(NH2)S02NH2 6 Ni2H + CsHaNHz NiS NHa 2 HzO 11 NiO (10) CeH4(NH2)SOzNHR 6 NizH CsHaNHz NiS NHzR 2 HzO 11 Nio (11)
+
+
+
-+
+
+
+ +
+
+
+
+
+
-+
+
+
Since aniline in its gas phase can be readily detected by the color reaction given in the detection of benzonitrile, k s t s for sulfanilic acid and its derivatives can he based on the above reactions. Metanilic acid behaves like sulfanilic acid in this respect, since anilinr results when the sulfur it3 removed in both cases. Naphthylaminesulfonic acids can be looked on as derivatives of anilinesulfonic acids. When they are desulfurized under the conditions Kiven here, they yield naphthylamines which are volatile with mater vapor and which can he detected in the gas phayc in the same way as aniline. It may be of practical interrst that Sulfanilic and anthranilic acids, which both show the spot tests for primary amines, can be easily differentiated in that only sulfanilic acid yields aniline
on warming with caustic alkali and Raney alloy. Procedure. Same as for arylmonoand arylpolysulfonic acids, with pdimethylaminobenzaldehyde as reagent for the resulting volatile primary arylamines. The following were detected: 5 fig, of sulfanilic acid; 5 pg. of sulfanilamide; 6 pg. of l-naphthylaminesulfonic acid; 10 pg. of Znaphthylamine-4,6-disulfonic acid. When the procedure was applied to 10 sulfa compounds, the limits of identification ranged from 5 to 10 fig. (7). On warming with Raney alloy and alkali, methyl orange [p-(p-dimethylaminopheny1azo)benzenesulfonic acid, sodium salt] undergoes the reduction: ( CH&N-CsH4-N=N-CaH4-SOtNs+ 4 NizH 4 (CHa)2N-CsH4-NHz
+ 8 NiO
HzN-CsH4-SO"a
+ (12)
which is followed by Equation 9 leading to the production of uickel sulfide and aniline. The detection of the latter permits the detection of as little as 5 pg. of methyl orange. An analogous cleavage with Raney nickel is undergone by tropaeolin 0 (sodium azoresorcinolsulfanilate); 5 fig. of this dye can be detected by this method. The findings with these two dyestuffs lead to the expectation that the reductive cleavage with Raney alloy can be employed for the detection of those azo dyes derived from arylaminosulfonic acids. Trials along these lines are in progress. Phenylhydrazine, Phenylhydrazones, and Phenylosazones, by Reductive Cleavage to Aniline. If phenylhydrazine is warmed with alkali hydroxide and Raney alloy or Devarda's alloy, it is reductively cleaved : CsHsNHNH9
+ 2 H"
-+
CsHsNHz
+ a"
(13)
This cleavage is shown by the fact that the gas phase contains ammonia and aniline which may be detected by appropriate reagent papers. Aniline is likewise given under these conditions bp phenylhydrazones and phenylosnzones, probably through the reaction :
I I
C=N-NHCsH&
+ 4 H"
LH-NHZ
I
-.c
+ CsHsNHz
(14)
The realization of Equations 13 and 14 combined with the detection of the resulting aniline permit the detection of phenylhydrazine, phenylhydrazones, and phenylosazones. If the corresponding naphthyl compounds are warmed in alkaline solution with Devarda's alloy, the naphthyl-
amines are obtained. They are volatile with water vapor, and can likewise be detected through the production of ycllow Schiff bases with p-dimethylaminobenzaldehyde. Procedure. Same as for detection of benaonitrile. The test revealed: 5 pg. of phenylhydrazine; 5 pg. of tribromophenylhydrazine; 6 pg. of naphthylhydrazine; 5 pg. of propionaldehydiphenylhydrazone; 6 pg. of dihydroxytartaric acid osazone. The behavior of tribromophenylhydrazine shows that on treatment with caustic alkali and Devarda’s alloy there is concurrent reductive cleavage and removal of halogen. Pyridine, by Conversion into Piperidine. A study of the behavior of caustic alkali water solutions in pyridine on heating with Devarda’s alloy or Raney alloy showed that only in t h r second case were vapors evolved which, on contact with filter paper moistened with a solution of sodium 1,2 - naphthoquinone - 4 - sulfonate, produced a red-violet stain, indicating the formation of piperidine. Cons+ quently, the reaction dors not involve nascent hydrogen, but rather the nickel hydride present in the Raney nickcl:
(15)
The piperidine produced in Equation 15 can be detected readily through condensation with sodium 1,2naphthoquinone - 4 - sulfonate, and therefore a test for pyridine can be based on this reduction provided ammonia, arylamines, and benzylamine are absent. The last two compounds are volatile with water vapor, and react with the sulfonate reagent paper. Procedure. A micro test tube is used. A drop of the alkaline test solution is treated with the least feasible quantity of Raney alloy (approximately 1 mg. and the mouth of the test tube is covered with a piece of filter paper moistened with a freshly prepared 0.5yoaqueous solution of sodium 1,2-naphthoquinone4-sulfonate. After the stormy evolution of hydrogen has abated, the test tube is placed in boiling water. A positive response is shown by the development of a red-violet stain on the reagent paper within 1 to 3 minutes. Limit of identification: 2.5 pg. of pyridine. Piperidine is likewise produced by the action of Raney alloy and caustic alkali on pyridine-2-sulfonic acid, because of simultaneous desulfonation and reduction. Limit of identification: 10 pg.
Behavior of Sulfones on Warming with Caustic Alkali and Raney Alloy. As was expected, arylsulfones behave as derivatives of arylsulfonic acidsLe., they yield nickel sulfide when warmed with alkali and Raney alloy. The nickel sulfide can be detected as described for arylmono- and arylpolysulfonic acids. Should the arylsulfone contain an amino group attached to the nucleus, aniline will also
Sulfanilic acid Na benzenesulfinate Pyridine
from that shown by Devarda’s alloy. Therefore i t appeared likely t h a t these three compounds could be used to detect Raney alloy. Trials mere set up in which 1 drop of 10% solutions of these three reagents were warmed for 2 or 3 minutes with 1 mg. of Raney alloy or 20 mg. of Devarda’s alloy. The divergent behavior is clearly evident from the following compilation :
Raney Alloy Pronounced aniline reaction Pronounced H2S reaction Strong piperidine reaction
be formed along with the nickel sulfide and may be detected in the gas phase by the color reaction with p dimethylaminobenzaldehyde or sodium 1,2 - naphthoquinone - 4 - sulfonate. The procedure was tested with 4,4diaminodiphenyl sulfone, and the following amounts were detected : 2.5 fig. of H z N - c s H ~ - s O r c e H ~ -NH2 through the NiS formation 5 fig. of H2N--C$-tS02-C,H4-NH1 through the aniline formation Aliphatic sulfones, such as sulfonal, trional, tetronal, di-n-butyl sulfone, di-whexadccane sulfone, and diacetyl sulfone, yielded no nickel sulfide when warmed with caustic alkali and Raney alloy. In contrast, benzyl ethyl sulfone behaves like a purely aromatic sulfone; 2.5 pg. could be detected through the forniation of nickel sulfide. This same behavior is shown by: di-p-nitrobenzyl sulfone, di-p-methoxyphenyl sulfone, and di-pphenyl ethyl sulfone. Obviously, in the aralkyl sulfones the removal of sulfur by Raney alloy is activated by carbon double bonds adjacent to the SOzgroup (compare detection of arylmono- and arylpolysulfonic acids). Therefore, it seems possible to differentiate in this way between aryl and aralkyl sulfones on one hand and purely aliphatic sulfones on the other. Mention should be made here of the behavior of di-p-nitrobenzyl sulfone, OZN-C~H,-CH~~O~-CH~-C~H,NOz. As was expected, treatment of this compound with Ranpy alloy produced not only nickel sulfide through desulfurization, but also p-methylaniline through reduction. The latter can be detected in the gas phase by the same color reaction as is given by aniline. This spot test piocedure will reveal 10 pg. of di-p-nitrobenzyl sulfone. Raney Alloy. As shown by the tests for arylsulfinic acids, sulfanilic acid and its derivatives, and pyridine, the nickel hydride present in Raney nickel formed from Raney alloy reacts with alkaline solutions of benzenesulfinic acid, sulfanilic acid, and pyridine in a manner t h a t differs
Devarda’s Alloy No aniline reaction No HzS reaction No piperidine reaction
The redox reactions with these three compounds were so distinct that amounts of Raney alloy too small to be weighed on a macrobalance--i.e., less than 0.1 mg., can be detected in this way. Samples of h n e y alloy were exposed to the air for several weeks without apparent decrease in the reductive activity. Heating to 250’ C. for 30 minutes likewise had no damaging effect. ACKNOWLEDGMENT
The author is grateful for the help rendered by D. Haguenauer-Castro and E. K. Libergott and for their valuable assistance in carrying out numerous tests and trials. He is also indebted to the Conselho Nacional de Pesquisas, Brazil, for its financial support of this research. LITERATURE CITED
(1) Bougault, J., Cattelain, E., Chabner, P. Com t . rend. 208,657 (1939). (2) hhrlic!, P., Herter, C. A., Z. phys. Chem. 41, 329 (1909). (3) Feigl,F., An ew. Chem.73,113(1961). ( 4 ) Feigl, F., 8hemisl Atualyal 50, 15 (1961). ( 5 ) Feigl, F., “Spot Teat in Organic Analysis,” 6th ed., p. 270 ff., Elsevier,
Amsterdam, Van Nostrand, New York,
1960. (6) Feigl, F., Mikrochem. 15, 1 (1934). (7) Feigl, F., Z . Lebenam. Untersuch. u. Forsch. 1961, in press. (8) Granatelli, L., ANAL. CHEW31, 434 (1959). ( 9 ) Merck Index, 7th ed., p. 827, Mcrck & Co., Rahway, N. J., 1952. (10) Otto, R., Ber. deut. chem. Ges. 10, 940 (1887). 111) Sachs. F.. Craveri. M.. Zbid.,. 38,. . 3658 (1905).’ (12) Trifonoff, A,, Ivanoff, T., Pavloff, D., Compt. rend. A d . bulgare sci. 7, 1 (-1954): (13) Wagner, R. E. Zook, H. D., “Synthetic Organic hemistry,” p. 659, Wiley, New York, 1953. (14) Witt, 0. N., Kaufmann, H., Ber. deut. c h m . Ges. 24, 3163 (1891). I
,
RECEIVEDfor review January 5, 1081. Accepted March 30, 1961. VOL. 33, NO. 8, JULY 1961
1121
