1042
ANALYTICAL CHEMISTRY
three samples. Another set of three plates was used for the magnesium determinations on the same preparations. This gave a total of 12 exposures per element per sample or a total of 36 exposures for each element. The concentration ranges covered and the per cent average deviation from the mean for each element are summarized in Table IV. I n this laboratory, it is standard practice to expose samples in triplicate with one standard sample in triplicate on each plate. This will give reproducibilities comparable to those indicated in Table IV. In cases wheie accuracy requirements %re somewhat lower, it has been found that duplicate eyposures are adequate. ACKNOWLEDGMENT
The authors wish to thank R. S.Spriggs for a number of spectrographic determinations made to check the accuracy of the methods. The editing of this paper by C. T. Baroch and his constructive criticism are also appreciatell. LITERATURE CITED
(1) Applied Research Laboratories, Glendale, Calif., Spectiographer’s brews Letter, 2, S o 9 (October 1948).
( 2 ) Baird. JV. S., “Proceedings of the 6th Summer Conference on Spectroscopy and Its Applications,” pp. 80-7, X e w York,
John Wiley 8: Sons, 1939. ( 3 ) Cook, 31. A,, and Wartman, F. S., G. S. Bur. Xines. R e p t . Inaest. 4837 (February 1952). (4) Fuller, H. C., Baker, D. H., and Wartman. F. S.,Ihid., 4879 (June 1952). (5) Harvey, C. E., “Spectrochemical Procedures,” pp. 218-26, Glendale, Calif., Applied Research Laboratories, 1950. (6) Hasler, 31. F., and Dietert, H. W., J . Opt. SOC.diner., 33, 21828 (1943). (7) Kroll, W., Trans. Elecfrochem. Soc., 78, 35-17 (1940). (8) Slachler, R. C . , “Proceedings of the 7th Summer Conference on Spectroscopy and Its -4pplications,” pp. 65-7, New York, John Wiley 8: Sons, 1940. (9) Peterson, SI.J., .INAL. Cmxz., 22, 1398~-400(1950). (10) Wartman, F. S., et cl., U.S. Bur. Mines, Re@. Incest. 4519 (August 1949). RECEIVED for review December 2. 19.52. Accepted April 2 2 , 1953. Work conducted under the general direction of R. R. Lloyd, chief, Electrometallurgical Branch, 3Ietallurgical Division,’Region 111. Boiilder C i t y , S e v a d a , a n d under the immediate supervision of P. R. Pprry. chemist in charge of the Physical and Chemical Section.
Potentiometric Titration of Organic Derivatives of Hydrazine with Potassium Iodate W I L L l i M R . McBRIDE1, RONALD A . HENRY, 4ND SOL SKOLNIK* C h e m i s t r y Division, c‘. S . Naz.al Ordnance Test Station, Chiria Lake, Calif. The oxidation of numerous organic derivatives of hydrazine with potassium iodate has been studied by potentiometric methods in both hydrochloric and sulfuric acid solutions in order to determine the effect of the degree and kind of substitution on the stoichiometry. Neither procedure give8 a uniform stoichiometry with all the derivatives that have been considered. Monosubstituted hydrazines, their hydrazones, and acyl derivatives can generally be quantitatively analyzed; in this class of compounds the hydrazine group is oxidized with a 4-elertron change.
T
HIS work continues a study of the characteristic oxidation of hydrazine compounds with potassium iodate under various experimentd conditions and in this case is concerned with the behavior of organic derivatives of hydrazine. The Jamieson method ( 3 ) for the quantitative determination of hydrazino-nitrogen utilizes the visual disappearance of the iodine color from chloroform in an aqueous solution containing a high concentration of hydrochloric acid. This procedure has been shown to be applicable t o aminoguanidine salts, benzal aminoguanidine ( I ), seniicarbazide hydrochloride, some semicarbazones ( 7 ) , carbohydrazitle (Q), and nitroaminoguanidine ( 6 ) . Smith and Wheat ( 7 ) also found that the method was successful with p-bromophenylhydrazine but that anomalous results were obtained with furfural semicarbazone, thiosemicarbazide, and the phenylosazones of dextrose and lactose. Unespected results were also obtained when this method was applied to salts of di- and triaminoguanidine ( 4 ) . T w o quantitative potentiometric procedures were previously 1
Present Address, Department of Chemistry, University of Texas, Austin,
TVK.
* Present
address, U. S. Kava1 Powder Factory, Indian Head, Md.
Polysubstituted hydrazines undergo characteristic and reproducible oxidations, which vary from a 2to as much as a 6-electron change per hydrazino group, depending on the nature, number, and position of the substituents. Sufficient data are not yet available to classify or predict behavior. Certain compounds, containing more than one primary hydrazino group in the niolecule, behave anomalously. These procedures, although capable of yielding valuable information, are probably not of general applicability in analytical chemistry. reported (6) for the analysis of hydrazine salts with potassium iodate-the reduction of iodate ion to the iodine monochloride equivalence point in hydrochloric acid:
+
X?HsT 103-
+ H30’ + C1-
-P
IC1
+ X2 + 4H?O
and the reduction of the iodate ion to the iodine equivalence point in sulfuric acid:
5YzHo-
+ 4103-
+
5x2
+ 11HZO + HO’ + 212
For hydrazine sulfate. both end points were reproducible to within 0.2%. Since a broad range of experimental conditions still gave a stoichiometric oxidation with hydrazine sulfate, it seemed desirable to extend the application of these procedures to a series of organic derivatives in order to determine whether the titrations were again quantitative a t both the iodine monochloride and iodine equivalence points, and to determine what effect the degree and kind of substitution had on the stoichiometry. It n-as the further purpose of this investigation to examine some of the anomalous results obtained with the Jamieson method
V O L U M E 25, NO. 7, J U L Y 1 9 5 3 Table I.
1043
I'otentionietric Titrations of Monosubstituted Hydrazines, Their Hydrazones, and .4cyl Derivatives with Potassium Iodate Compound
Methylhydraaine sulfate
M.P.,
O
c.
141 5-142 5
Formula
Method
C H I S H N H Z HzSOa
I II-.4
Methylhj diazine picrate
169
I
C H s S H S H i CeHnNiOi
I1 Phenylhydrazine hydrochloride
240-242 (dec.)
I
C ~ H K N H P \ " HC1 Z.
I-.%
Semicarbazide hydrochloride
172-173 (dec.)
S H s C O S H S H i HC1
I 11--4 I1
Carbohydrazide
155-156
(SHz?;H)zCO
1 11-A
Carbohydrazide dipiciate ( 2 )
191-192 (deo.)
I
(SUH2SH)zCO. (CsHaXs0,)r
11--4
Grams of Compound
R l l . of 0.02500 F KIOI
76 Hydrazine Xitrogen
0,1026 0 1020 0.1161 0.1015
28.85 28.62 25.70 22.43 Theory =
1 9 ,i o
0 1072 0.1150 0.1035 0 1028
15.61 16.70 11.91 11.80 Theory =
10.20
0.1023 0.0815 0 1089 0.lli3
28.32 22,30 24.05 25.54 Theory =
19,39
' 0 . 1044 0 1006 0,0999 0 1028
37.23 3 5 . 80 28.48 29.25 Theory =
24 08 2.5 .OO 24 96 24 91 25.12
0.0401 0.0405 0 0469
35.05 28.30 33.05 Theory =
ti1.u 61,lQ 61 70 62 20
0.1149 0.1124 0 1164 0.1145
16.51 16,23 13.63 13.32 Theory
10.13 10. 11 10 25 10 19 10.22
=
19.65 10.38 19.35 19 44 10.17 10. 0 8 10.05 10.18 19.17 19 32 19 0 3 I9 38
Biurea
248
( h'HzCO S H) z
I
0,1043 0 1039
35.90 24.07 36.65 24.24 Theory = 2 3 . 7 3
3-Xethylbiurea
224.0-224 5
KHzCO?*"S(CHs)COKHz
I
0 lOii
32 25 20.98 Theory = 21.21
Aminoguanidine nitrate
146.0-146.5
SHZC(SH)SHSH~.HSOI
I IIS.4 I1
0 1106 0 10s 0 1025 0 1034
.32 02 28 32
0 Il,5i
13.33 . Theory =
8.11 8.46
0 . 1028
0.llOi 0 1043 0 1042
26.10 28.13 17.87 17.68 Theory =
11.86 11.87 11 98 11.89 12.18
0.1090 0 , 1038 0.1025 0 204.5
12.13 11 58 9.17 18 33 Theory
lI1-Dimethyl-3-aminoguanidine picrate (I)
161.5-163
(CH~)~SC(XH)SHSHZ.C~HIN~O~
I
1,2-Dimethyl-3-aminoguanidinehydroiodide
298-300 (dec.)
C H z S H C ( S C H a )S H K H z ' H I
I 11--4
1,1,2-Trimethyl-3-aminoguanidine picrate (I)
153-164
(CHs)zNC(SCHs)S H X H z ' CaHsNaOi
I
I1 Nitroaminoguanidine
190-191 (dec.)
NHzh'HC(SH)SHNOz
I 11-9 I1
Benzhydrazide
113-114
CaHsCOSHSHz
I 11-A
LO 28 20 21 20 37 23 85 23 94 20 27 Theorg = 20 44
7.80 7.81 83
'
85
=
8.12
0.1065 106~ 0 1010 0 1054
35.38 35.54 26 93 18.13 Theory =
23.27 23.33 23.35 23.37 23.53
0.0841 0 . io91 0.1047 0.1042
244 , 49 2 49 31 78 24 45 24 44 Theory =
200 , 40 2 40 20 4 1 20 45 20 54 20 58
a
sym- Diacetylhydraaine
139-140
(C HICONH) z
I
0 1066 0.1054
37 00 24 31 36 25 24 09 Theory = 24 13
Benzalazine
91-92
(C~HKCH=N)Z
I
0,1054 0,1088
20.55 13.66 21.45 13.81 Theory = 13 45
Benzal semicarhazone
216-217
SHzCONH.\=CHCaHs
I
0.1003 0.1004 0.1033 0.1003
24.35 24.35 20.09 19.45 Theory =
11-4
Benzal-l,l-diniethyl-2-aminoguanidine picrate (3) 205-206.5 Bend-5-hydrazinotetrazole
.
236-237 (dec.)
(CHo)nNC(n") NHN=CHCeHa' CaHsNaOi N-NH
/I
I
0,1022 0.1054
9.48 6 . .50 7.97 6.62 Theory = 6.68
I5
0.1127 0.1007
24.10 14.98 21.50 14.96 Theory = 14.89
0.1015 0.1066
30 00 20 70 31.45 20 67 Theory = 21.04
II-.4
>CNHN=CHC~H~
N-N Dibenaal carbohydrazide
O.
199-200
(CsHsCH=NNH)zCO
Compound hydrolyzed by boiling in 20% hydrochloric acid before titrating.
17.02 16,99 17 03 16.98 17 17
I-A
.
ANALYTICAL CHEMISTRY
1044
Table 11. Potentiometric Titrations of Miscellaneous Substituted Hydrazine Derivatives with Potassium Iodate Grams Compound unsym-Dimethylhydrazine picrate
M.P., 146-147
2-Met hylseniicarbazide picrate
136
O
Of
c.
Method
I S H ? C O S ( C H s )S H z C ~ H I N I O ~
0,1075 0.1045 0,1026 0.1041 0,1249
10.20 12.07
3.98 3.93
II-.4
0.1082 0.1178 0.1025 0,2078
6.50 7.30 5.05 10.16
1.91 1.97 1. 9 3 1.94
I
0 . 1092
II-.4 I1
0,0603 0,0666 0.0529
48.25 26.73 24.10 18.95
5.88 5 90 6.01 5.96
I -A
0.1146 0,1060
2 7 , .i8 26.15
6.99 6.14
I 11-A
0.1030 0,0998 0.1100 0.1001
25,7,5 25.28 18.80 17.33
4.05 4.10 3.48 3.51
I
0,1068 0.0506
37.50 17.90
5.92 5.97
I
0.0998 0.1037 0.1102 0.1153
11 97 12.42 10.46 11.17
1.99 1.99 1.97 2.01
0,1014 0,1008 0.0998 0,1025
2.5 00 23 80 12.80 13.80
5.97 6.20 3.88 4.08
0,1046 0.0524 0.0673 0,0529
57.88 28.96
11-A I1
2 6 , .50
21.73
7.64 7.64 6 SO 7.10
Ib
0.1045
11-A
1-Methyl-I-aminoguanidine pirrate
227 3-228.5
sum-Dimethylhydrazine dihydrochloride
166-167
1-.4b b
I
(CHaSH),. 2HC1
s urn-Dibenzylhydrazine hydrochloride
214-213 (dec.)
(CsHsCH?")?,
1-Sitroguanyl semicarbazide ( 2 )
210-211
N H z C O S H S H C ( S H )S H S O :
5,5'-Hydrazotetrazole
2,2'-Hydrazo-bis-isobutyronitrile
240-241 (dec.)
92 5-93.5
HCI
h'-XH\
[ I \h -X/
r-sH]
[ (CHr)zC( C S ) S H 11
11-I I1 1,.5-Diphenyl-carbohydrazide
172-173
I-A
(CsHsNHSH)nCO
11-A Diarninoguanidine sulfate
Diaminoguanidine picrate
Triaminoguanidine nitrate
Triaminoguanidine hydrochloride
230
191-192
212-213 (dec.)
227-228 (dec.)
( S I I ? S H ) ? C ( S H ). '/?HzSO,
(SH??;H)?C(SH) C ~ H I N ~ O
(SHzSH)zC(SSH?) HSOI
( S H z S H ) ? C ( S S H ? J'HC1
H
Calcd. Electron Change 2.05 2.07 5.08 5.01
0 . 10.52 0.1131 0.1071
b
145.5-146.5
i r i . of 0,02500 F KIOp 7 33 11.10 16.80 17.80 15.74 13,64 14 29 13.68 12.76
I," I-h b
Benzal2-methylsemicarbazide picrate
Compound 0 1036 0.1550
I
4.68
4.14 4 23 4.17 4.93
I
0 . 1101
11-A
0.1032
0,1047 0 1026
23 80 24.29 16.50 17.21
7 Sfi 7 5.5 6.27 6.67
I 11-A I1
0.0420 0 0403 0.0415 0,0420
24 95 23,65 23.55 23.60
9 ax 9.81 11.86 11.74
I
n.0478
11-h I1
0.052.i 0.0588 0.0512
33.40 3 6 . 8n 39.05 34.30
9.82 9.85 11.6i 11.7;
I
0.0494
5.93
3.93
I-.%
I
0.0318 0.0827
11.55 18.68
7.65 7 73
I
0.0985 0,1235
15.50 6.34c 18.48; 6.36 18.14d
5.87 1.92
s
3 , 5-Diamino-1, 2 , 4-triazole picrate
249 (dec.)
SHz--6
'C-SH?.C~H~SJO~
II
I1
K-1-
h-H2
/
h-
3, 4,5-Triamino-l, 2, 4-triazole picrate
282-284
SH?-C
/\ C-SH?.CeHxSaO. 'I I1
S--N
N/NH2 3,5-Dihydrazino-4-amino-l,2,4-triazole picrate (I) 15%.5-153.5
h'HzPI"& b--NHh'Hz.
I1 /I S--N
CeHsSrOr
I-.%
0.1221 Solution kept cold and titrated rapidly. Solution heated prior t o titration. or alternatively, titrated very slowly. First equivalence point. d Second equivalence point.
a b
5.59
:.??
J.JJ
V O L U M E 25, NO. 7, J U L Y 1 9 5 3
(4,7 ) on the basis that these anomalies could be removed or explained by employing the techniques developed earlier ( 5 ) . EXPERIMENTAL
The hydrazine derivatives were either commercially available materials or were prepared by reported methods unless otherwise indicated; they were recrystallized several times from suitable solvents and dried prior to titration. The potential meaj;urements were made with a Beckman p H meter, Model G, using a platinum electrode versus a saturated calomel electrode. I n titrations to the iodine monochloride equivalence point the hydrazine derivative waq dissolved in 60 ml. of 9 LV hydrochloric arid. The solution was cooled before the initially rapid addition of 0.0250 F potassium iodate solution. The equivalence point was determined either by allowing equilibrium to be attained after the addition of each increment of iodate solution, in which case the end point was taken as the maximum potential charge per unit volume; or by slow dropwise addition near the equivalence point until the potential increased to between 700 and 800 mv., in which case the end point was taken as the volume at which the continued increase in potential was noted. The essential difference between the two methods is the time involved in the titration. For titrations to the ‘ iodine equivalence point the hvdrazine derivative was dissolved in 60 ml. of 9 -V sulfuric acid. The equivalence point was again determined in either of the two mayoutlined above. Chloroform (15 nil.) \vas frequently added to dissolve an) during the titration, such as benzaldehyde from hydrazones: this solvent did not affect the results. In the accompanying tables the procedure for titrating in hydrochloric acid to the iodine monochloride equivalence point is referred to as I ; with the addition of chloroform as I-,4. Similarly, the procedure for titrating in sulfuric acid to an iodine equivalence point is referred to as 11; with chloroform as 11-A. K i t h some compounds overheating must be avoided during the preparation of the solutions, to prevent partial loss of the hydrazino group. For example, if nitroaminoguanidine is warmed nitroin acid solution prior to titration, the titer is l o ~ benzal ; aminoguanidine R hich hydrolyzes very slowly even on heating in acid solution cannot be analyzed for this same reason. On the other hand, the titer is high when 2,2-hydrazo-bis-isobutyronitiile is overheated, Variable results are also observed uith derivatives of 2-methylsemicarbazides; thus, M hen the conditions are most favorable for extensive hydrolysis, the titer approaches that required for an equivalent amount of methylhydrazine; if hj-drolysis is avoided, a completely different stoichiometry is operative. The experimental data for the potentiometric titrations are divided into two groups. Table I summarizes the information obtained v ith monosubstituted hydrazines, their hydrazones, and acyl derivatives. Since most of these compounds undergo a quantitative oxidation by one procedure or the other, and since the oxidation is analogous to the hydrazine sulfate titrations, the results are expressed directly in terms of per cent hydrazine nitrogen. Table I1 summarizes the results obtained Kith some polysubstituted hydrazine derivatives and polyhydrazino compounds. Since these compounds may not necessarily undergo a four-electron change per hydrazino group, like hydrazine and the monosubstituted hydrazines, the oxidations are reported in terms of electron change rather than in terms of per cent hydrazine nitrogen. These calculations were made as follows: n ater-insoluble products formed
Procedure I, Electron change = ml. of KIOI X F X 4 X mol. wt. of compd. 1000 x wt. of sample Procedure 11, Electron change = ml. of KIOI = F X 5 X mol. wt. of compd. 1000 X wt. of sample This investigation has been limited strictly to the utilization of the previously recommended analytical procedures ( 6 ) , and no
1045
systemat,ic variation of the experimental conditions has Iwen made for each compound. For this reason the analytical procedures as used are not necessarily the optimum ones for every compound. Data for thiosemicarbazide are not included in the tables sinre t’his compound does not show a characteristic or well-defined equivalence point in either procedure; this agrees with the obEervations of Smith and Wheat ( 7 ) . 5,5’-Hydrazotetrazole, s!/mdiacetyl hydrazine, and biurea are all so s l o ~ l yoxidized under the conditions of procedure I1 that significant analytical (lata are not available. DISCUSSION
The potassium iodate oxidation of numerous monosubstituted hydrazine compounds, t,heir simple hydrazones. and acyl derivatives is characterized by a four-electron change per hydrazino group in solutions of either hydrochloric or sulfuric acid. IYith many of these compounds the oxidation is rapid and s h o w a sharp inflection point, possessing a high degree of reproducibility. 1000
-
loo t
800
5.
e.
z..
600
3
1 3 400
-
200
0
>
3 i L . OF 4 0.025006 F KIOI 8
10
12
Figure 1. Potential-Volume Diagram Showing the 310mentary Inflection Point Obtained during the Titration of Phenj-lhydrazine in Hydrochloric Acid 0 Equilihrium potential; 0
Momentary potential
The conclusion can be made, therefore, that the same compounds which give quantitative results by the Jamieson method also lie have normally in either of the potentiometric methods. Furthermore, compounds which behave anomalously in the Jamieson method also seem to reveal similar peculiarities in the potentiometric titration in hydrochloric acid (procedure I ) although by proper choice of the experimental conditions or by proper interpretation of the potential-volume data some of these peculiaritieq can be overcome. Generally these anomalies are due to concurrent or consecutive completing reactions, which also consume iodate, or which involve the products of oxidation such as iodine or iodine monochloride. The amount of interference u hich they cause is determined by their rates relative to the rate of the piimary oxidation-reduction reaction involving the hydrazino group and the iodate. For example, titration of phenylhydrazine h j drochloride by procedure I reveals an initially rapid oxidation characterized by a four-electron change followed by a sloner consecutive reaction involving a further oxidation; this explains n hy this compound cannot be successfully titrated by the usual Jamieson method and points up one distinct advantage to the potentiometric method over the visual chloroform indicator method employed in the former procedure. In this titration since the initial oxidative reaction of phenylhj drazine, presumably a t the hydrazine portion of the molecule, is rapid, there is an essentially constant potential up to the equivalence point (Figure 1). -4t the equivalence point the potential increases rapidly and then gradually returns to a new and different constant potential. This rapid increase in potential followed by a slow decrease to a con-
1046
.
stant potential extends considerably past the equivalence point. A similar behavior is observed in sulfuric acid solut,ion, when the titration is performed in the presence of chloroform. The first large. momentary inflection point is select,ed as the equivalence point and corresponds to a satisfactory titer (see Table I). This method for determining the end point will presumably yield only essentially quantitative results, when the consecut,ive or concurrent oxidation reactions are much slower than the oxidation of the hydraziilo group. A comparison of the results obtained with triaminoguanidine salts by procedures I and I1 (Table 11)indicates that the anomalies previously reported ( 4 ) to occur in hydrochloric acid can be eliminated by proper selection of the reaction medium, Thus, the potentiometric titration of triaminoguanidine hydrochloride or nitrate in ~ulfuricacid approaches the espect,ed twelve-electron change-Le.. a four-electron change per monosubstitut,ed hydrazino group. The reason for t'he ten-electron change observed in the Jamieeon method and in procedure I must be related to a competing reaction involving the high chloride ion concentration. A careful analysia of the potential-volume 1)ehavior during the tit'ration of triaminoguanidine salts by procedure I. as vias done with ~jhenylh!.drazine, does not reveal any additional information; apparently, the competing reaction is as fast as t,he primary reaction involving the oxidation of the hydrazino groups. In contrast, to the results with'triaminoguanidine, the potentiometric titration of diaminoguanidine salts in a sulfuric acid solution consistently reveals an even more errat,ic and more anomalous behavior than is observed in hydrochloric acid (Table 11). Since the concentration of free iodine is always greater in the sulfuric acid medium, it can be assumed that the concurrent and consecutive reactions which cause the anomalies involve free iodine. This is supported by some unpublished work in this laboratory with the Jamieson met,hod which indicat'ed that, as the hydrochloric acid concentration increased and the fr'ee iodine concentration decreased, the results approached more closely the expected stoichiometry of a four electron change per hydrazino group. The oxidation of polysubstituted hydrazine derivatives is not in accord with the type of reaction or stoichiometry generally observed with hydrazine or derivatives of monosubstituted hydrazines. -4s can be seen from Table 11, the nature, the number, and the position (whether synimet~ricallyor unsymmetrically placed) of the substituents all seem to exert a marked influence on the stoichiometry. The rat,e at which these compounds are oxidizeJ is also apparently dependent' on these factors. Thus, the oxidation of some symmetrically disubstituted hydrazine derivatives wit,h potassium iodate is characterized by an immediate increase in the potential to a value which is the same as that found beyond the equivalence point; t.his is followed by a slow decrease to an equilibrium potential, This same behavior is repeated after the addition of each new increment of iodate solution; near the equivalence point the rate a t which the potential decreases becomes very slow. This type of titrat,ion may be expect'ed whenever the oxidation is 50 slow that a temporary excess of iodate is evident in the solution, Furthermore, it, appears to indicate an oxidation which ie preceded by a slow hydrolysis or which is followed by a hydrolysi~and/or a rearrangement react,ion. Such a mechanism
ANALYTICAL CHEMISTRY can be proposed to explain the six-electron change observed during the oxidation of sytiz-dimethylhydrazine. If one assumes that the initial step is an oxidation to the corresponding azo compound ( a tv o-electron change), which then rearranges to formal methylhytlra7ine. hydrolysis of the latter and oxidation of the methJIhydrazine in the normal manner would require an additional four-electron change. (Aldehydes, such as benzaldehyde or formaldehyie, do not interfere since they are not oxidized by potassium iodate under the conditionsof these titrations.) Three triazole compounds. containing various types of substituted hydraaino groups, have been titrated. Although no generalizations can be made ahout predicting the stoichiometry, it does appear that these compounds can be oxidized quantitatively by potassium iodate under suitable conditions. Interestingly, oxidation of hydrazino groups contained partially or completely within the ring system also seems to occur with two of the examples, otherwise it is difficult to account for the approximate fourelectron change observed for each adjacent pair of nitrogen atoms. COSCLL~SION
Although a fairly repreeent,ative selection of organic derivat,ives of hydrazine has been examined in the course of this study, data for many more examples will have to be collect,edbefore firm generalizations can be d r a m about t,he behavior of all classes of hydrazine derivatives and before the methods can become of general applicability to analytical chemistry. These preliminary studies do serve, however, t.o emphasize some of the problems and peculiarit,ies encountered in the oxidation of substituted hydrazines with potassium iodate. The results suggest the possibility of selecting or devising suitable conditions for quantitatively analyzing many hydrazine compounds even though the stoichiometry will depend on the structure of the compound and will have to be confirmed by act,ual test. -4t the same t,ime t,here are indications that t'he potentiometric methods are frequently capable of yielding both quantitative data and qualitatively interesting information which cannot be obtained by the visual or Jamieson method. ACKSOFLEDGMENT
The authors would like to thank Eugene Lieber for the constructive review of the manuscript and JTilliam G. Finnegan for the preparation of several compounds. LITERATURE CITED
Fuller, L. P., Lieber, Eugene, and Smith, C. B. L., J . A m . Chem. SOC.,59, 1150 (1937). (2) Henry, R. 8.,unpublished results. (3) Jamieson, G. S., .4m.J . Sci., 33,352 (1912). (4) Keim, G. I , Henry, R. rl., and Smith, G. B. L., J . -4m.C'hem. Soc., 72,4944 (1950). (5) McBride, 55'. R., Henry, R. A4., and Skolnik, Sol, . h a t . CHEM., 23.890 (1951). (6) AloBiide, R., Henry, R. A , and Smith, G. B. L., d . Am. Chem. SOC.,71,2937 (1949). (7) Smith, G. B. L., and Wheat, T. G., ANAL.CHEM.,11,200 (1989).
(1)
w.
RECEIVED for review October 8 , 1931. Accepted April 16, 1953.
