in Mass Spectrometry,” Elsevier, Amsterdam, 1963. ( 3 ) Budziekiewicz, H., Djerassi, C., Williams D., “Structure Elucidation of Natural Products by 3Tass Spectrometry,” T’ol. 2. APPENDIX: Calculation of Molecular Formulae, HoldenDay, San Francisco, Calif., 1964. ( 4 ) Lederberg, J., “Computation of 110lecular Formulas for M a s s Spectrom-
etry,” Holden-Day, San Francisco, Calif., 1964. ( 5 ) Lederberg, J . , Tables and an Algorithm for Calculating Functional Groups of Organic Molecules in High Resolution Mass Spectrometry. Report to KASA under Grant XsG 81-60. STAR (Scientific and Technical Aerospace Report) accession No. K64-21426, 1964. ( 6 ) Lederberg, J., Wightman, >I., A Subalgol Program for Calculation of
Molecular Compositional Formulas from Mass Spectral Data. Report to NASA, June 15, 1964, ( 7 ) Owens, E. G., Sherman, A. AI., Technical Reoort N o . 265. Lincoln Laboratorv. hassachnsetts ‘ Institute of Technoidgy, April 3, 1962. (8) van Katwijk, J., d p p l . Spectry. 18, 102 (1964).
RECEIVED for review December 17, 1964. Accepted February 8, 1965.
Acid-Base Method for Determining Mixtures of Diethylene Triamine with Hydrazine or Substituted Hydrazines HUGH E. MALONE and RICHARD E. BARRON Air Force Rockef Propulsion Laboratory, Edwards AFB, Calif.
b A method is presented for determining admixtures of diethylene triamine-hydrazine (DETA-NzHd), DETAmonomethylhydrazine (MMH), and DETA-1,l -dimethylhydrazine (UDMH) in a nonaqueous titration system using methanol as a solvent, hydrochloric acid and methanol as the titrant, and both bromcresol green and bromochlorophenol blue as indicators. The method uses the reactions of salicylaldehyde which form the neutral azine with hydrazine, the neutral hydrazones with M M H and UDMH, and a Schiff base with DETA. The total basicity of the admixtures is determined on separate aliquots before and after the addition of salicylaldehyde.
T
HE REACTION of salicylaldehyde with primary amines was first used by Wagner et al. (8) to distinguish primary amines from secondary amines. Since then many investigators have used this same technique with modifications. Siggia et al. ( 5 ) and Critchfield ( 2 ) devised methods for determining mixtures of primary, secondary, and tertiary amines. Siggia (6) also determined 13 aldehydes, including salicylaldehyde, with U D M H by forming the corresponding hydrazones. RIalone (4) adapted the aldehyde technique for determining mixtures of aniline, NzH4, and furfuryl alcohol and (3) mixtures of N2H4and U D M H by forming the neutral azine with N2H4 and the basic hydrazone with U D M H in acetic b i d medium. Streim (7’) independently developed a method, similar to that presented, which uses different solvents and techniques.
taining40 ml. of methanol. Weigh to the nearest 0.1 mg.; obtain the sample weight by difference. Dilute to the 50-ml. mark with methanol and shake thoroughly. Determination of Total Basicity of Amine-N2H4 Mixtures. Pipet a 5.0ml. aliquot of the prepared sample into a 50-ml. beaker containing 20 ml. of methanol and add 4 drops of 0.2y0 bromcresol green indicator. Titrate with 0.1N HCl (1) in methanol until the blue color of the indicator turns yellow. Indicate this amount as value 1 in calculations. Titrate a blank for the bromcresol green and methanol. Determination of DETA. Pipet a 5.0-ml. aliquot of the prepared sample into a 50-ml. beaker containing 20 ml. of methanol. Add 2 ml. of salicylaldehyde and allow the sample to react for 5 minutes. Add 4 drops of bromochlorophenol blue indicator and titrate with O.lLV HC1 in methanol until the blue-green color of the solution changes to yellow. Indicate this amount as value B in calculations. Titrate a blank for the bromochlorophenol blue, the methanol, and the salicylaldehyde.
% N2H4 (or MMH or UDMH) (‘4 - a) - 2(B - b) X ’
Sample Weight =
( B - b ) X N HC1 X M E W Sample Weight I n the DETA determination above, the secondary amine titrates basic giving the % D E T A directly. This value must be multiplied by 2 because of the two primary amines titrating in the total base titration.
EXPERIMENTAL
DISCUSSION
Preparation of Sample. Pipet 0.4 ml. of the amine-N2H4 mixture into a tared 50-ml. volumetric flask con-
I n the methanol solvent system, D E T A reacts differently from hT2H4. It has three amino groups (two primary
548
ANALYTICAL CHEMISTRY
“2
+
HzC’
NH~
HzC’
I
I
HzC\
NH
ZH+ HzC \ +
NH
H&’
H&’
I HzC,
I
HzC, ”2.
“3
+NH~
H’
Hz?’ HzC
*NH~
HzC’
I
HzC +
\NH~
=
N H C I X‘MEW
% DETA
and one secondary) which titrate basic; however, only the two primary amino groups titrate as strong bases. This is due to the presence of two positive charges on the primary amino groups which decrease the basicity of the secondary amino group. The reactions for the DETA titration with 0.1N HC1 in isopropanol with methanol as a solvent were previously reported by Wagner et al. (8) and were postulated as follows :
A series of four samples of DETA were titrated in methanol with 0.1N HC1 in methanol to the bromcresol green end point to verify the reactions in Equation 1. Table I shows that the DETA titrates as a diamine in methanol. Table 1.
DETA Titrated as a Triamine and Diamine DETA in DETA in methanol, yo methanol, % (as triamine) (as diamine) 66.4 98.5 65.7 98.6 65.7 98.6 66.4 98.5
Reactions of Amine-Hydrazine with The experimental Salicyaldehyde. procedures developed are based upon the reactions of x2H4, substituted hydrazines, rind D E T A with salicylaldehyde in methanol. T h e reaction produces salicylidene azine as follows:
H
HO
(2)
and salicylidene dimethylhydrazone : H3C, Hac'
N-NHz
46 0 44 5 45 6 45 3 44 7 10 1 31 9 40 7 69 7 88.2
53 0 54 2 53 5 53 8 54 4 86 8 66 6 57 2 26 4 8.9
S2H4
DETA
H
+ 2H20 OH
Table II. Experimental UDMH IIETA
+
a
I;' c=o OH
51 50 50 51 9 30 69 86
2 3 6 0 6 4 3 8
NllH 49 49 50 49 50
6
5 1
7 1
47 48 47 47 89 67 27 9
4 4 6 5 9 0
7 7
DETA 49 5 49 7 49 0 49 7 49 1
Analysis of Amine-UDMH Mixtures Theoretical Variation, yo UDMH DETA UDLIH DETA 45 44 45 45 44 10 31 40
9 8
5 0
7
4 4 6 io 3 88.0
52 54 53 53 54 87 66
9 2 5 9 3 1
5 57 5 26 7 9.0
-0 1 -0 3 0 1 0 3 0 0 -0 3 0 5 0 1 0 6 0.2
Analysis of Amine-NzHI Mixtures N1H4 DETA N& 51 0 50 1 50 8 50 9 9 5 30 1 69 1 87 2
0 3 -0 3 -0.1
DETA
Analysis of Amine-MMH Mixtures AIIIH DETA LIMH
DETA
6 1 6 2
49 49 49 49 49
5 6 1 6 0
0 0 -0 0 0 0 0 -0
-0 3 0 1
0.1 0.0 0.0 0.0 0.0 -0.3 0.3
7
4 3 6 5 9 0 0 4
1 0 0 1 1
2 2 2 1 1 3 2 4
49 49 50 49 50
47 48 47 47 89 67 28 9
-0 0 0 -0 0
-0 -0 0 0 -0
0.0
1 1 0 1 1
0 0 -0 0 0
0 1 1 1 1
and salicylidene methylhydrazone :
Q
OH
RESULTS
and 1,'i-bis (N-salcylidene) diethylene triamine :
The N-0 aminoethylpiperaeine reacts also with salicylaldehyde to form N-/3 (N-salicylidene) aminoethylpiperazine.
Samples of D E T A in mixtures with UDMH, N2H4, and M M H were prepared to check the procedure. The purity of the N2H4 and substituted hydrazine was determined b y the standard iodate titration and by total alkalinity titration. The purity of DETA was determined by titrating the secondary amino group after the two primary amino groups were reacted with salicylaldehyde as described. Table I1 presents the experimental, theoretical, and variation from the calculated per cent obtained from mixtures of UDMH-DETA, N,H4-DETA, and MMH-DETA. Alkalinity Titration. Before t h e addition of salicylaldehyde, the following compounds titrate basic: N2H4; the two primary amino groups of D E T A ; the two amino groups of Y - p aminoethylpiperazine; ammonia (impurity in hr2H4); UDMH, nitrosodimethylamine, and dimethylamine (impurities in UD,MH); and hIhIH. Aniline, another impurity of N2H4, titrates neutral.
Salicylaldehyde Addition. After the addition of salicylaldehyde, N 2 H 4 , UDAIH, and M M H titrate neutral; the secondary amino groups of both D E T A and A'-p aminoethylpiperazine, dimethylamine, a n d nitrosodimethylamine titrate basic. Effect of Impurities. T h e normal concentrations of titratable impurities a r e : for N2H4 (0.2% ammonia and 0.6% aniline); for U D M H (0.10/, dimethylamine and 0.9% nitrosodimethylamine); for D E T A (6.OOj, paminoethylpiperazine). T h e impurities of M M H have not been determined. Aniline does not titrate a s a base using 0.1N HC1 in methanol as a titrate to the bromcresol green indicator end point. ACKNOWLEDGMENT
The authors thank Arie Korving for his technical assistance in the preparation of this paper. LITERATURE CITED
(1) Carlton, C. A., J . A m . Chem. SOC. 44, 1469 (1922). (2) Critchfield. F. E.. Johnson, J. B.. ANAL.CHEM.29,957 (1957). ( 3 ) Malone, H. E., ANAL.CHEM.33, 575 ( 1961). ( 4 j hlalone, €1. E., W A D C Tech. iVote 59-172 (1959).
(5) Siggia, S., Hanna, H. C., Rewenski, J. R., Ibid., 22, 1295 (1950). (6) Siggia, S., Stahl, C. R., Ibid., 27, 1975 (1955).
( 7 ) Streim. H. G.. hlcFarlane. F. B.. .VARTS' 0133, Tech. S o t e B'L'WRPS Proj. (1960). (8) Wagner, C. D., Brown, R. H., Peters, J., J . Am. Chem. SOC.69, 2609 (1947). VOL. 37, NO. 4, APRIL 1965
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