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.