Solvent-free Synthesis and Properties of Functionalized Hydrazines and Bishydrazines as Energetic Ingredients for Propulsion Applications

Article abstract of DOI:10.1002/asia.202001084

Functionalized hydrazines and bishydrazines are interesting straightforward precursors for accessing higher nitrogenated compounds. They offer structural diversity and promising energetic properties as well, namely for propulsion applications. A novel and

Full text of DOI:10.1002/asia.202001084

DOI: 10.1002/asia.202001084
Full Paper
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Solvent-free Synthesis and Properties of Functionalized Hydrazines
and Bishydrazines as Energetic Ingredients for Propulsion
Applications
John Eymann, Anne Dhenain, Lionel Joucla,* Guy Jacob, Emmanuel Lacôte, and
Chaza Darwich*[a]
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Abstract: Functionalized hydrazines and bishydrazines are
interesting straightforward precursors for accessing higher
nitrogenated compounds. They offer structural diversity and
promising energetic properties as well, namely for propulsion
applications. A novel and scalable synthesis has been
developed for a new family of bishydrazines, starting from
monomethylhydrazine (MMH). This solvent-free route repre-
sents a suitable alternative to the one described in the
literature. It was extended to design a new family of
unsymmetrical hydrazines bearing various functional groups.
A selected series of promising compounds, densified with
nitrogenated groups (amino, hydrazino or azido functions),
was identified as a class of plausible candidates for liquid
propulsion. Indeed, the energetic interest of such hydrazines
was demonstrated by computing their heats of formation
and specific impulse values in bipropellant systems. This led
to theoretical energetic performances comparable to that of
the MMH/N2O4 system already in use today.
Introduction
Bishydrazines have not been thoroughly studied in the
literature, especially as potential energetic ingredients. Indeed,
only a single bishydrazine synthesis was described,[4] through
the nitrosation/reduction of 1,2-dimethylethylenediamine
(DMEDA). This synthesis involves highly toxic and carcinogenic
nitrosamine derivatives and implies reduction conditions (LAH,
Hydrogen high pressure, etc.) unsuitable for an industrial
production.
We therefore propose a new, versatile and scalable route, –
i.e. suitable for an industrial production – to access these new
compounds. The synthetic strategy uses monomethylhydrazine
(MMH) as the starting feedstock and the corresponding
chloroalkyl substrates as functionalization reagents (Scheme 1).
We also report the results of our investigation into the
energetic properties of these nitrogenated hydrazines. We
selected the most relevant compounds for propulsion applica-
tions (N/C ratio�1) to perform impact sensitivity tests and DSC
measurements. We have undertaken a theoretical approach to
compute heats of formation (in the gas phase) using different
chemical quantum methods, in association with isodesmic
Rocket propellants performances are characterized by their
specific impulse (Isp). It is a function of the exit velocity of the
exhaust gases, which is proportional to the combustion temper-
ature and inversely proportional to the molecular weight of
gaseous products. Besides, nitrogen-nitrogen bond energy
increases significantly from a single over a double to a triple
bond (respectively 159, 418 and 942 kJmolÀ 1). This implies that
increasing the number of nitrogen-nitrogen single bonds in a
molecule results in higher, more positive heats of formation,
which in turn translates to a greater combustion temperature.[1]
In this regard, new hydrazine derivatives should be useful
energetic ingredients for higher performance space propellants.
This is supported by their overall high positive heats of
formation as well as their decomposition into nitrogen gas
(28 g/mol).
Functionalized hydrazines possess several advantages over
low-molecular weight hydrazines already in use in the space
industry. They tend to exhibit higher boiling points, higher
thermal stabilities, and lower vapor pressures. The latter feature
considerably decreases the risks of inhalation and/or explosion
especially during the launchers loading step.
Herein we consider a family of functionalized hydrazines
and bishydrazines for applications in the field of energetic
materials, in particular for space propulsion.[2,3]
[a] J. Eymann, Dr. A. Dhenain, Dr. L. Joucla, Dr. G. Jacob, Dr. E. Lacôte,
Dr. C. Darwich
Laboratoire Hydrazines et Composés Energétiques Polyazotés UCBL/CNRS/
CNES/ArianeGroup
Université Claude Bernard Lyon 1
2, rue Victor Grignard 69622 Villeurbanne cedex (France)
E-mail: lionel.joucla@univ-lyon1.fr
chaza.darwich@univ-lyon1.fr
Scheme 1. General synthetic pathway for accessing functionalized hydra-
zines and bishydrazines.
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/asia.202001084
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reactions. Calculated values were then injected into a thermo-
dynamics code to perform specific impulse calculations on
bipropellant systems involving these candidates as fuels, in
association with N2O4 as the oxidizer.
Table 1. Selectivity of the substitution reaction at various MMH/DCE
ratios.
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3
4
5
MMH equiv.
DCE equiv.
Monohydrazine[a]
Bishydrazine[a]
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1
1
4
8
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4
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83
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<5
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>95
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Results and Discussion
<5
>95
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9
[a] compound percentage monitored by NMR.
Following this synthetic pathway, the reaction between dihalide
derivatives and MMH was considered (Scheme 2).
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ing group participation) in the monohydrazinated derivative
leading to the aziridinium intermediate, which greatly facilitates
the second substitution (Scheme 3).
However, in the latter conditions, the reaction mixture
thickens rapidly, preventing the magnetic stirring from func-
tioning properly. On the other hand, this reaction is highly
exothermic, which could cause a reaction runaway. Hence, a
larger excess of MMH seems preferable to carry out this
synthesis, both to fluidize the reaction mixture and to dissipate
the heat released during the reaction (Table 1, line 5).
The monohydrazinated compound was purified by frac-
tional extraction using a 2 N hydrochloric acid solution. The
fractions containing the choro-monohydrazinated precursor
were collected, leading to pure compound with a 25% yield.
The dihydrazinated compound was purified by alkalinization
with a saturated sodium hydroxide solution, followed by a
Preliminary synthesis essays
Preliminary tests were carried out on 1,2-dibromoethane and
revealed its degradation by MMH resulting in an unworkable
reaction crude. The 1H NMR showed numerous peaks indicating
that side reactions are taking place. Therefore, the reactivity of
the dihalide must be reduced in order to control or prevent this
phenomenon. Hence, less reactive and cheaper chlorinated
substrates were selected. This would also drastically increase
the viability of this route on an industrial scale.
Synthetic route to the new bishydrazines
Unlike many nucleophilic species exhibiting slow kinetics
towards chloride substitution, hydrazines possess a strong
alpha effect.[5,6] This considerably accelerates the kinetics of
nucleophilic substitutions involving hydrazines which renders
the above-mentioned synthetic pathway plausible. Since the
modulation of the alpha effect by solvents is not well
understood,[7] this study was conducted without using solvents.
The neat reaction of 1,2-dichloroethane (DCE) and MMH was
described by Böhme et al.[8] in order to access new functional-
ized hydrazines. The formation of a chloro-monohydrazinated
compound was mentioned when the reaction was carried out
using an excess of DCE, though no dihydrazinated compound
was described.
°
distillation under reduced pressure (63 C, 1 mbar, yield=55%).
This method also allows for the recycling of both the excess of
MMH and the MMH.HCl by-product.
As this compound only gave two singlets in 1H NMR, further
analyses were conducted to confirm the bishydrazine’s struc-
ture. Hence, in addition to 13C NMR and MS analyses, the
compound was treated with a 2 N hydrochloric aqueous
solution in order to obtain crystals of its dihydrochloride salt
and perform a single-crystal XRD measurement (Figure 1).
Scope and limitations
Hence, it seemed necessary to study the selectivity of this
reaction by varying the MMH/DCE ratio. In these experiments,
the limiting reactant was added over 6 hours on the excess
reagent by means of a syringe-pump and temperature was
Structural diversity was ensured by extending this method to
various dichloride substrates (Scheme 4). Bishydrazines 1a and
1b are volatile and were therefore purified by distillation.
However, distillation attempts on bishydrazines 1c and 1d led
to thermal degradation. Although less effective, a demixing
purification step was successfully carried out to extract these
two bishydrazines from the reaction crude.
°
maintained at 20 C for 24 h.
Results showed that the proportion of the monohydrazi-
nated precursor is the highest when MMH was added slowly
(over 12 hours) on 10 equivalents of DCE (Table 1, line 3). On
the contrary, a 4-equivalent excess of MMH is sufficient to
selectively favor the dihydrazinated precursor (Table 1, line 4).
This can be attributed to the anchimeric assistance (neighbor-
Scheme 3. Mechanism of the dihydrazinated compound formation involving
an aziridinium intermediate.
Scheme 2. Synthetic pathway to access the described bishydrazine.
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Figure 1. Unit cell of 1,1’-(ethane-1,2-diyl)bis(1-methylhydrazine).2HCl salt
(ORTEP representation with 50% ellipsoid).
Scheme 5. Limitations of the synthetic method (quantitative conversions
were estimated by 1H NMR). Reaction conditions for a), b) and c): MMH
8 eq, neat, R.T./24 h.
As a non-separable mixture was obtained from (Z)-dichlor-
obut-2-ene, it was necessary to develop a hydrogenation
strategy for compounds 1c and 1d in order to access the
desired bishydrazines. Hydrogenation of compound 1c led to
1,1’-(butan-1,4-diyl)bis(1-methylhydrazine) 1e with a yield of
82%. Compound 1f was obtained by partial hydrogenation of
1d using a Lindlar catalyst (Scheme 6).
MS analysis of bishydrazine 1e revealed two fragments
resulting from alpha cleavage and beta elimination following
the protonation of the substituted nitrogen. The latter was only
observed with this bishydrazine due to the availability of beta
protons. The resulting fragment led to the formation of two
additional adducts (see SI, Scheme S1). This confirmed the
structure of this bishydrazine.
Scheme 4. Bishydrazines 1a to 1d obtained from the reaction between
MMH and the corresponding dichloride substrate. Reaction conditions:
MMH 8 eq, neat, R.T./24 h.
Disubstituted aliphatic alkynes give very weak C�C stretch-
°
ing band in IR spectroscopy. A 135 DEPT NMR analysis was
performed to confirm the structure of 1d. The disappearance of
the quaternary carbon signal as well as the phase shift of the
methylene group suggest the expected alkyne structure was
successfully obtained (see SI, Figure S1).
Extension of the scope to functionalized hydrazines
However, this synthesis displays some limitations arising
from a side-reactivity observed for dihalogenated substrates
presenting a saturated alkyl chain with n>2. Thus, 1,3-
dichloropropane and 1,4-dichlorobutane led to an intramolecu-
lar cyclization (Scheme 5, inputs a, b). As for (Z)-1,4-dichlorobut-
2-ene, it quantitatively led to an equimolar mixture of the
desired bishydrazine and the corresponding cyclized derivative
(Scheme 5, input c). These substrates are prone to intra-
molecular cyclization, which is the main side-reaction that
competes with the second substitution. The intramolecular
cyclization is either kinetically much faster than the second
substitution (inputs a, b) or showing a competitive rate when a
pre-arranged unsaturated substrate is used (input c).
In the case of 2,3-dichlorobutane, the reaction does not
occur -even when potassium iodide is added- because of the
lack of a primary halide, which inhibits the first substitution
step and makes beta anchimeric assistance not possible
(Scheme 5, input d). Results on bishydrazines 1a to 1d were
patented in 2019.[9]
β-hydroxysubstituted hydrazines were first described by Porath
et al.[10] They were synthesized via N-nitrosation of 2-(meth-
ylamino)-ethanol with butylnitrite, followed by a reduction step
with LAH. This synthesis raises the same toxicity and industrial
incompatibility issues than that of the dihydrazinated deriva-
tives described by Hogsett et al.[4]
Scheme 6. Hydrogenation of unsaturated bishydrazines 1c and 1d leading
to bishydrazines 1e and 1f.
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Therefore, a new synthesis was developed,[11] based on the
laboratory expertise in monochloramine (NH2Cl).[12] The hydrazi-
nated intermediate was then obtained by direct amination
(Raschig process) of 2-(1-methylamino)ethanol with monochlor-
amine (Scheme 7). This synthesis is less hazardous and offers a
clearly better yield (crude yield estimated by GC/MS=92%).
However, it requires the use of an excess of aminoethanol,
which hinders the purification of the hydroxylated hydrazine
3a.[11]
ucts were obtained, indicative of the reactant’s degradation.
Hence, 2-chloroethylhydrazine[8] was considered to access the
corresponding β-azidohydrazine. This was facilitated by the
selectivity study performed earlier (see Table 1). The
hydrochloride salt of this precursor was neutralized before the
aziding step (Scheme 9).
However, the resulting hydrazine proved to be very difficult
to extract from its aqueous medium. Additionally, the reaction
is very slow at room temperature and leads to various by-
products. Several solvents were tried to extract 4 from the
aqueous medium, and dichloromethane gave best extraction
results, its partition coefficient being 5 times higher than that of
other organic solvents tested. However, as an excess of sodium
azide was needed - otherwise, the reaction is very slow - using
dichloromethane as an extraction solvent is not a good option,
since the remaining NaN3 can react with CH2Cl2 to yield
extremely explosive diazomethane gas. Thus, ether was used to
extract the product, yielding 24% of 4 (under optimized
conditions: 20% KOH, continuous extraction for 7 h at ether
reflux).
The same approach was not possible with 1,3-dichloropro-
pane, since the reaction of the latter with MMH does not lead
to the corresponding γ-chlorohydrazine but to 1-meth-
ylpyrazolidine (Scheme 5, input a). As a consequence, the
corresponding γ-azidohydrazine could not be obtained this
way.
In a similar fashion, the aziding of dichloroalkyl substrates
proved not to be selective towards monoazidation and led to
unseparable mixtures (distillation of such highly nitrogenated
compounds is too risky).
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Therefore, the aforementioned synthesis method employed
for bishydrazines was adapted to chlorinated hydroxyalkyl
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substrates to establish
a broad approach for accessing
hydroxyl-substituted hydrazines. This led to the corresponding
hydroxylated hydrazines 3a to 3e (Scheme 8).
Moreover, aminated hydrazines 3f and 3g have been
synthesized in the same conditions established for hydroxylated
hydrazines with good yields (Scheme 8). An excess of MMH
comparable to that used for the synthesis of bishydrazines (see
Table 1, line 5) is necessary due to the neutralization of the
commercial hydrochloride salt.
The amine function could generate some incompatibility
issues in further reactivity studies involving the hydrazine
function. Consequently, the introduction of a suitable protect-
ing group was considered on the amine moieties. The
carboxybenzoyl group (Cbz) was selected for its easy removal
under mild catalytic hydrogenolysis conditions. These condi-
tions are also likely to be compatible with the hydrazine moiety
as well as its higher nitrogenated derivatives. The protection
step should obviously take place prior to the introduction of
the hydrazine function so as not to cause selectivity problems.
The commercially available hydrochloride salts were treated
with benzyl chloroformate (CbzCl) in an aqueous alkaline
medium to afford excellent yields of the protected intermedi-
ates (see SI, Scheme S2). A subsequent nucleophilic substitution
with MMH was performed to access hydrazines 3h and 3i with
95 and 98% yields (Scheme 8).
Synthesis of a bifunctionalized hydrazine
An alternate pathway was designed to access γ-azided
hydrazines using epichlorohydrin as a starting material. Ring
opening with sodium azide was described by Gharakhanian
et al.[13] Though the regioselectivity of this reaction is contrary
to what is usually observed in acidic media, it is not discussed
by the authors. The structure of this intermediate was studied
by 1H NMR (see SI, Figure S2), which showed that the most
deshielded signal appears as a doublet of doublets of triplets
(3JHH =6.6, 5.8, 4.4 Hz) and integrates for one proton. The other
four diastereotopic protons appear as a doublet of doublets
Attempts at activating compound 3a were performed using
tosylchloride in order to densify the structures with nitro-
genated functions. Unfortunately, only NH-tosylated by-prod-
2
with an important roof effect. Geminal JHH coupling constants
Scheme 7. Synthesis of 2-(1-methylhydrazinyl)-ethan-1-ol (3a) based on
monochloramine.[11]
were measured at 13.0 and 11.7 Hz. These data confirmed the
structure of 1-azido-3-chloropropan-2-ol. The second step
Scheme 8. Synthesis of functionalized hydrazines 3a to 3i starting from the
corresponding chloroalkyl substrates and MMH (* the aminated hydrazines
were obtained as neutral compounds R=NH2).
Scheme 9. One-pot aziding step leading to 1-(2-azidoethyl)-1-meth-
ylhydrazine (4).
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involves the nucleophilic substitution using MMH, which affords the determination of the HOF lies on differences between
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hydrazine 5 with a 98% yield (Scheme 10).
several enthalpies, the quantum methods used should be size-
consistent. Previous studies on HOF quantum calculations were
reported on related polynitrogenated compounds using various
levels of theory.[16,17] The resulting calculated HOF values were
compared with experimental ones, to select the most appro-
Energetic properties
The second part of this study consists in the investigation into priate and accurate level of theory for such compounds.
the energetic potential of the most relevant synthesized According to these results, compound method CBS-QB3 is the
hydrazines. Thereby, a series of energy-densified hydrazines (N/ most accurate. However compound methods are expensive and
C ratio�1) were selected, namely bishydrazine 1a, β-aminated time consuming. Thereby, Density Functional Theory (DFT)
hydrazine 3f, β-azided hydrazine 4, and γ-azided β-hydroxy- methods were also considered. The B3LYP hybrid functional
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lated hydrazine 5.
includes the effects of electron correlation and leads to well
optimized structures for compounds containing first-row ele-
ments. There are also semi-empirical methods that use fitting
parameters based on experimental data and which are good
enough for structure optimization of small organic compounds.
In this work, Gaussian software[18,19] was used to carry out
Impact sensitivity and thermal stability
First, their sensitivities towards impact were assessed using
standard BAM tests.[14] All four hydrazines showed no senstivity HOF calculations according to three types of quantum methods,
to impact (ISI>50 J) as a result of a series of ten tests, where with an increasing level of theory. First, geometry optimization
each hydrazine was subjected to a 5 Kg-weight fall from a and frequency calculations were carried out using the PM6
1.019 m height.
method. The same calculation procedure was then reiterated
On the other hand, their thermal stabilities were measured with the B3LYP/6-311+G(2d,p) level. Finally, HOF calculations
using DSC, which revealed two distinct behaviors. Indeed, both were performed using compound method CBS-QB3 as the
1a and 3f have high thermal stabilities up to 246 and 223 C highest calculation level. The B3LYP/6-311+G(2d,p) level was
°
respectively. This can be attributed to the intermolecular chosen on purpose, as it is the one used by the CBS-QB3
hydrogen bonding network promoted by amino and hydrazino method during the geometry optimization step.[20,21]
groups. On the other hand, 4 and 5 decompose at 153 and
The HOF cannot be calculated directly and thus one must
°
140 C respectively, due to the presence of highly energetic and include the compound of interest in a – often hypothetical –
unstable azido groups. However, these decomposition temper- reaction. Isodesmic bond-separation reactions are largely used
atures are still higher than that of MMH, which is stable up to for this purpose since they were designed with error cancella-
[15]
°
its boiling point if kept from contact with air (b. p.=87.5 C).
tion in mind. These hypothetical isodesmic reactions were used
to calculate the HOF of the selected hydrazines 1a, 3f, 4 and 5
(see SI for reactions, Scheme S3).
For each hydrazine, the gas phase enthalpy of each species
involved in these reactions were computed separately in order
Theoretical calculations of energetic performances
Quantum chemical calculations were performed in order to to determine ΔrH0. They were then used in conjunction with
assess the heats of formation (HOF) of these polynitrogenated experimental HOF of these species[22–25] to calculate the ΔfH0 of
hydrazines. They were then injected into a thermodynamic the hydrazine (see SI for equations and values, Table S1).
code to estimate the specific impulse values for bipropellant
propulsive systems involving these hydrazines as new rocket experimental gas phase HOF values are the NIST WebBook of
In this work, the two main databases used for the
fuels.
Chemistry[22] and the Handbook of Chemistry & Physics.[23]
Calculated HOF using PM6, B3LYP/6-311+G(2d,p) (geometry
optimization done with the same methods, respectively) and
CBS-QB3 for the selected series of hydrazines are reported in
Table 2. The experimental HOF value for the reference system
Gas phase Heat of Formation
Before doing any quantum calculation, one ought to select a (MMH) is mentioned in the footnote of Table 2.
suitable model – that is the association of a method and a basis
set. Quantum methods differ mostly in how they handle
electron correlation, which is an essential parameter for
accurately describing any molecular system. Moreover, since
Table 2. Computed gas phase HOF values for hydrazines 1a, 3f, 4 and 5.
Heat of formation [ΔfH0 (g), kcalmolÀ 1
]
Hydrazine
PM6[a]
B3LYP/6-311+G(2d,p)[a]
CBS-QB3
1a
3f
4
51.93
23.67
99.10
54.26
44.42
24.90
98.42
49.01
42.30
23.95
95.41
46.87
5
[a] geometry optimization done with the same theory level. [b] reference
system: experimental HOF value for MMH=12.68 kcalmolÀ 1 [26]
Scheme 10. Synthesis of hydrazine 5 starting from epichlorohydrin.
.
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Calculation results showed that PM6 and CBS-QB3 give the
highest and the lowest value respectively. As mentioned above,
CBS-QB3 provides the most accurate HOF compared to
experimental values. Thereby, one can conclude that the PM6-
computed HOF values are slightly overestimated for hydrazines
1a, 4 and 5. However, the effect of this HOF overestimation on
the energetic performance of the four hydrazines was further
studied. Therefore, the specific impulses (Isp) were calculated for
propulsive systems involving each of the selected hydrazines
using all the available HOF data.
Moreover, the calculated specific impulses indicate that the
energetic performance of 1a and 4 is comparable to the one of
the N2O4/MMH system already in use (Isp max =341.3 s based on
experimental HOF (MMH)=12.68 kcalmolÀ 1).[26] However, the 4-
based system (N/C ratio>1) requires a lower oxidizer amount
compared to 1a (N/C ratio=1) or MMH-based (O/F ratio=70/
30) ones. On the other hand, the introduction of an OH group
in the molecule drops its performance by 8 points (4 and 5).
The same trend can be observed to a lesser extent when
comparing the N/C ratios of 4 (N/C ratio>1) and 3f (N/C ratio=
1), for which the maximum Isp value is around 3 points lower.
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Specific Impulse
Conclusion
Isp values were computed with OPHELIE, which is a thermody-
namic code used at ArianeGroup. It is a variant of the CEC71
program,[27] which is one of the Chemical Equilibrium Calcu-
lations software programs used by NASA to calculate theoretical
rocket performances. These calculations involve a number of
assumptions. Among them, one can list complete, adiabatic
combustion and ideal-gas law. Theoretical performance can
vary depending on which assumptions were made for the same
propellant and operating conditions.
In this work, Isp was calculated for a finite-area combustion
(FAC) model, where the combustion chamber is assumed to
have a constant cross-sectional area. Chamber pressure and
area ratio (ɛ=Ae/At) were set at 7 MPa and 40 respectively. In
these conditions, the calculated HOF values were used for the
computation of the Isp in bipropellant systems with N2O4 as the
oxidizer. For each hydrazine, several compositions were tested
with varying Oxidizer/Fuel (O/F) ratios to maximize Isp (Isp max).
Results are depicted in Table 3. For comparison purposes, the
Isp max value for the reference system (N2O4/MMH) and the
corresponding O/F ratio are mentioned in the footnote of
Table 3.
A novel and versatile synthesis for a family of functionalized
hydrazines and bishydrazines is reported. It is based on the
alkylation of MMH by chloroalkyl substrates. This synthesis is
versatile and led to six new bishydrazines and eleven function-
alized hydrazines. Its main limitations were observed in the case
of substrates prone to intramolecular cyclization or presenting
secondary halides. The properties of the four most energetic
hydrazine derivatives revealed low sensitivities to impact and
good thermal stabilities. Their HOF values were computed using
three different levels of theory (PM6, B3LYP and CBS-QB3
chemical quantum methods) and were then used for assessing
the energetic performances of the selected hydrazines in
bipropellant systems with N2O4 as the oxidizer. Three of the
studied hydrazines exhibit Isp
values similar to that of the
max
MMH/N2O4 propellant system. These results establish this class
of hydrazine derivatives as key ingredients for new rocket fuels,
offering structural diversity and promising energetic prospects
simultaneously.
One can observe that PM6-computed HOF led to Isp values Experimental Section
that are close to those obtained from B3LYP and CBS-QB3-
computed HOF. The latter methods provide an accurate
prediction of specific impulses as the corresponding HOF
discrepancies were not transferred to the Isp values (less than 1
point). In all cases, these discrepancies are of low consequence
for energetic performance assessments and this method can be
used to get a quick order of magnitude for HOF (and thus Isp)
values, while B3LYP and CBS-QB3 give more reliable results for
this study.
General procedure for the synthesis of bishydrazines 1a to
1d
MMH (8 eq) was introduced into a double-jacketed vessel and the
°
temperature was set at 20 C by means of a cryothermostat. An
Argon atmosphere was set up and the dichloride substrate (1 eq)
was added dropwise over 6 h by means of a syringe-pump. The
°
reaction mixture was stirred for 18 h at 20 C, after which the
reaction crude was subjected to either of the following work-up
methods:
A) Distillation: The reaction mixture was alkalinized with a freshly
prepared saturated aqueous solution of NaOH and the volatile
species were evaporated under reduced pressure. A filtration step
of salts formed, followed by vacuum distillation led to a pure
compound.
Table 3. Isp max computed with OPHELIE code for hydrazines 1a, 3f, 4 and
5.
I
sp max value [s]
Hydrazine
Formula
O/F ratio
PM6[a]
B3LYP[a]
CBS-QB3[a]
B) Demixing: The reaction mixture was alkalinized with a large
excess of a saturated aqueous solution of NaOH, until total
demixing of the compound. The organic phase was separated,
filtered off to get rid of residual salts and the volatile species were
evaporated under reduced pressure, leading to a pure compound.
1a
3f
4
C4H14N4
C3H11N3
C3H9N5
72/28
74/26
64/36
64/36
340.9
338.2
341.5
334.3
339.6
338.4
341.3
333.3
339.2
338.3
340.6
332.9
5
C4H11N5O
[a] Isp max values based on HOF that were calculated with this level of
theory. [b] reference system: Isp max value (N2O4/MMH)=341.3 s (O/F=70/
30), based on the MMH experimental HOF.[26]
Chem Asian J. 2020, 15, 1–12
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15
°
130.6 (NCH2CH); N NMR (CD3NO2, 25 C, 50 MHz): δ (ppm)=67.8
(NH2N(Me)CH2), 92.6 (NH2N(Me)CH2); HRMS (ESI+): [M+H]+ m/z=
145.1448 (calcd.), 145.1441 (found); IR (Golden Gate, ν (cmÀ 1))=
3302 (m), 2948 (m), 2834 (m), 2785 (m), 1607 (m), 1448 (m), 1414
(w), 1368 (w), 1233 (w), 1026 (m), 976 (m), 826 (m), 763 (m), 661 (m),
640 (m), 617 (m), 591 (m), 551 (m), 544 (m).
1,1’-(Ethane-1,2-diyl)bis(1-methylhydrazine) (1a)
1
2
3
4
5
6
7
8
9
1,1’-(But-2-yne-1,4-dyil)bis(1-methylhydrazine) (1d)
Compound prepared from DCE (15.0 mL, 189.5 mmol) and purified
°
according to method A (1 mbar, 63 C) leading to 12.39 g (55%) of
1
°
°
colorless liquid at R. T. (20 C). H NMR (D2O, 25 C, 300 MHz): δ
(ppm)=2.44 (s, 6H, NMe), 2.70 (s, 4H, NCH2); 13C {1H} NMR (D2O,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
25 C, 75 MHz): δ (ppm)=47.3 (NMe), 58.3 (NCH2); 15N NMR (CD3NO2,
°
°
25 C, 50 MHz): δ (ppm)=66.0 (NH2NMe), 93.4 (NH2NMe); HRMS
(ESI+): [M+H]+ m/z=119.1291 (calcd.), 119.1287 (found); IR (Gold-
en Gate, ν (cmÀ 1))=3301 (w), 3138 (w), 2943 (m), 2831 (m), 2770
(m), 1602 (m), 1445 (m), 1324 (w), 1058 (m), 1025 (m), 957 (m), 847
(w), 797 (m), 768 (m), 584 (w), 550 (w), 531 (w), 500 (m), 483 (m),
Compound prepared from 1,4-dichlorobut-2-yne (11.6 mL,
118.7 mmol) and purified according to method B, leading to
1
°
°
13.48 g (80%) of yellow liquid at R. T. (23 C). H NMR (CDCl3, 25 C,
°
°
467 (m). DSC (Medium pressure Steel crucible, À 50 to 400 C, 5 C/
300 MHz): δ (ppm)=2.50 (s, 6H, NMe), 3.20 (s(b), 4H, NNH2), 3.52 (s,
4H, NCH2C); C { H} NMR (CDCl3, 25 C; 75 MHz): δ (ppm)=47.5
13
1
°
°
min): Td (onset)=246 C; ISI (BAM, constant energy) >50 J.
15
°
(NMe), 51.8 (NCH2), 79.9 (CH2C); N NMR (CD3NO2, 25 C, 50 MHz): δ
(ppm)=61.1 (NH2N(Me)CH2), 89.1 (NH2N(Me)CH2); HRMS (ESI+): [M+
H]+ m/z=143.1291 (calcd.), 143.1292 (found); IR (Golden Gate, ν
(cmÀ 1))=3296 (w), 2946 (w), 2781 (w), 1603 (m), 1445 (m), 1324 (m),
1098 (m), 1028 (m), 949 (m), 800 (m), 643 (m).
1,1’-(Propane-1,2-diyl)bis(1-methylhydrazine) (1b)
Synthesis of bishydrazines 1e and 1f by catalytic
hydrogenation
1,1’-(Butane-1,4-diyl)bis(1-methylhydrazine) (1e)
Compound prepared from 1,2-dichloropropane (20.0 mL,
204.6 mmol) and purified according to method A (10À 2 mbar, 42 C),
°
1
°
leading to 12.22 g (45%) of colorless liquid at R. T. (16 C). H NMR
°
(CDCl3, 25 C, 300 MHz): δ (ppm)=0.67 (d, 3H, CHMe, J=6.6 Hz),
1.95 (dd, 1H, CHHCHMe, J=12.5, 5.2 Hz), 2.19–2.23 (s, 6H, NMe),
2.41 (dd, 1H, CHHCHMe, J=12.5, 8.0 Hz), 2.69 (ddq, 1H, CH2CHMe,
13
1
°
J=8.0, 6.6, 5.2 Hz), 2.80 (s(b), 4H, NNH2); C { H} NMR (CDCl3, 25 C,
75 MHz):
δ
(ppm)=10.9 (CHMe), 45.7 (MeNNH2CHMe), 50.5
(MeNNH2CH2CHMe), 59.3 (CHMe), 66.5 (NCH2CHMe); 15N NMR
Hydrazine 1c (2.42 g, 16.76 mmol) was introduced into a 300 mL
thermostated hydrogenation reactor and diluted in 100 mL of
absolute ethanol. Pd/C catalyst was then added (247.0 mg, 1 wt%
Pd) and a 20 bars hydrogen atmosphere was set up in the reactor.
°
(CD3NO2, 25 C, 50 MHz): δ (ppm)=66.1 (NH2N(Me)CHMe), 68.3
(NH2N(Me)CH2), 83.6 (NH2N(Me)CHMe), 94.0 (NH2N(Me)CH2); HMRS
(ESI+): [M+H]+ m/z=133.1448 (calcd.), 133.1441 (found); IR (Gold-
en Gate, ν (cmÀ 1))=3301 (w), 3149 (w), 2967 (w), 2942 (w), 2834
(w), 2785 (w), 1593 (m), 1571 (m), 1445 (m), 1419 (w), 1377 (w),
1308 (w), 1262 (w), 1106 (m), 1091 (m), 1069 (m), 1040 (m), 974 (m),
956 (m), 930 (m), 912 (m), 890 (m), 824 (m), 802 (m), 774 (m), 746
(m), 673 (m), 582 (m), 572 (m), 558 (m), 546 (m), 538 (m), 520 (m),
513 (m), 500 (m), 491 (m), 476 (m), 465 (m).
°
The reaction was allowed to continue for 5 h at 20 C, after which
the reaction mixture was filtered off on celite and the solvent
evaporated under vacuum to lead to pure compound as a yellow
liquid (2.01 g, 82%).
1H NMR (CDCl3, 25 C, 300 MHz):
δ (ppm)=1.54 (quint., 4H,
°
MeNCH2CH2, J=3.5 Hz), 2.42 (m, 4H, MeNCH2CH2), 2.43 (s, 6H, MeN),
1
2.85 (s(b), 4H, NNH2); 13C { H} NMR (CDCl3, 25 C, 75 MHz): δ (ppm)=
°
25.3 (MeNCH2CH2), 49.8 (MeN), 63.4 (MeNCH2CH2); 15N NMR (CD3NO2,
1,1’-((E)-But-2-ene-1,4-diyl)bis(1-methylhydrazine) (1c)
°
25 C, 50 MHz): δ (ppm)=68.3 (NH2N(Me)CH2), 92.7 (NH2N(Me)CH2);
HMRS (ESI+): [M+H]+ m/z=147.1604 (calcd.), 147.1605 (found); [M
+Na]+ m/z=169.1424 (calcd.), 169.1426 (found); IR (Golden Gate, ν
(cmÀ 1)): 3295 (w), 2942 (m), 2783 (m), 1599 (w), 1446 (m), 1377 (w),
1051 (m), 940 (m), 821 (m).
Compound prepared from (E)-1,4-dichlorobut-2-ene (15.0 mL,
141.6 mmol) and purified according to method B, leading to
1
°
°
14.99 g (73%) of amber liquid at R. T. (22 C). H NMR (CDCl3, 25 C,
300 MHz): δ (ppm)=2.38 (s, 6H, MeNNH2), 2.91 (s(b), 4H, NNH2) 3.03
(dd, 4H, NCH2CH, J=3.6, 1.7 Hz), 5.64 (m, 2H, NCH2CH); 13C {1H} NMR
°
(CDCl3, 25 C, 75 MHz): δ (ppm)=48.8 (MeNNH2), 65.1 (NCH2CH),
Chem Asian J. 2020, 15, 1–12
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1,1’-((Z)-But-2-ene-1,4-diyl)bis(1-methylhydrazine) (1f)
3-(1-Methylhydrazinyl)propan-1-ol (3b)
1
2
3
4
5
6
7
8
9
Compound
prepared
from
3-chloropropan-1-ol
(44 mL,
526.4 mmol), yielding 53.26 g (97%) as a colorless liquid at R. T.
1
°
°
(19 C). H NMR (CDCl3, 25 C, 300 MHz): δ (ppm)=1.74 (tt, 2H,
NCH2CH2CH2OH, J=5.8, 5.4 Hz), 2.47 (s, 3H, NMe), 2.61 (t, 2H,
NCH2CH2CH2OH, J=5.8 Hz), 3.52 (s(b), 3H, CH2OH, NNH2), 3.70 (t, 2H,
Hydrazine 1d (2.50 g, 17.56 mmol) was introduced into a 300 mL
thermostated hydrogenation reactor and diluted in 100 mL of
absolute ethanol. The mixture was then loaded with Lindlar catalyst
(247.0 mg, 10 wt%) and a 20 bars hydrogen atmosphere was set up
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
13
1
°
NCH2CH2CH2OH, J=5.4 Hz); C { H} NMR (CDCl3, 25 C, 75 MHz): δ
(ppm)=29.6 (NCH2CH2CH2OH), 50.4 (NMe), 62.6 (NCH2CH2CH2OH),
°
in the vessel. The reaction continued for 3 h at 20 C, after which
15
°
63.2 (NCH2CH2CH2OH); N NMR (CD3NO2, 25 C, 50 MHz): δ (ppm)=
the reaction mixture was filtered off on celite and the solvent was
evaporated under reduced pressure, yielding the pure compound
as an orange liquid (2.22 g, 88%).
67.9 (NH2N(Me)CH2), 91.4 (NH2N(Me)CH2); HRMS (ESI+): [M+H]+
m/z=105.1022 (calcd.), 105.1025 (found), [M+Na]+ m/z=127.0842
(calcd.), 127.0845 (found); IR (Golden Gate, ν (cmÀ 1)) =3300 (m(b)),
2944 (m), 2846 (m), 1609 (w), 1450 (w), 1377 (w), 1219 (w), 1058
(m), 969 (w), 930 (w), 822 (w), 750 (m), 695 (m), 676 (m), 659 (m),
634 (m), 624 (m), 582 (m), 568 (m), 481 (m), 466 (m), 456 (m).
1
°
H NMR (CDCl3, 25 C, 300 MHz): δ (ppm)=2.47 (s, 6H, NMe), 3.17
(dd, 4H, NCH2, J=1.1, 4.1 Hz), 5.73 (m, 2H, NCH2CH); 13C {1H} NMR
(CDCl3, 25 C, 75 MHz): δ (ppm)=49.3 (NMe), 60.1 (NCH2), 129.5
°
15
°
(NCH2CH); N NMR (CD3NO2, 25 C, 50 MHz): δ (ppm)=68.5 (NH2N
(Me)CH2), 93.3 (NH2N(Me)CH2); HRMS (ESI+) [M+H]+: m/z=
145.1448 (calcd.), 145.1448 (found), [M+Na]+ m/z=167.1267
(calcd.), 167.1267 (found); IR (Golden Gate, ν (cmÀ 1))=3301(w),
3138(w), 2946(w), 2830(w), 2774(w), 1601(w), 1446(m), 1320(w),
1256(w), 1107(w), 1030(m), 939(m), 828(m), 696(w), 567(w), 536(w),
520(w), 513(w), 502(w), 492(w), 482(w).
4-(1-Methylhydrazinyl)butan-1-ol (3c)
General procedure for the synthesis of hydrazines 3a to 3e
Compound prepared from 4-chlorobutan-1-ol (4.2 mL, 35.4 mmol),
yielding 4.59 g (92%) as a yellow liquid at R. T. (21 C). 1H NMR
°
An inert Argon atmosphere was set-up inside a thermostated
°
°
double-jacketed vessel, then MMH (4 eq) was introduced at 20 C.
(CDCl3, 25 C, 300 MHz): δ (ppm)=1.67 (m, 4H, NCH2CH2CH2CH2OH),
The chlorinated hydroxyalkyl substrate (1 eq) was added slowly
(over 6 h) by means of a syringe-pump and the solution was stirred
2.48 (t, 2H, NCH2CH2CH2CH2OH, J=5.9 Hz), 2.50 (s, 3H, NMe), 3.59 (t,
2H, NCH2CH2CH2CH2OH, J=5.1 Hz), 3.85 (s(b), 3H, CH2OH, NNH2); 13
C
{1H}
NMR
(CDCl3,
25 C,
75 MHz):
δ
(ppm)=25.7
°
°
for an additional 18 h at 20 C. The reaction mixture was then
alkalinized by adding a freshly prepared aqueous solution of NaOH
(50 wt%, 2.05 eq). The reaction crude was then evaporated under
reduced pressure to remove residual MMH and water and then
diluted in acetonitrile in order to precipitate salts, which were
filtered off. The solvent was then evaporated under reduced
pressure, leading to a pure compound.
(NCH2CH2CH2CH2OH), 32.0 (NCH2CH2CH2CH2OH), 49.8 (NMe), 62.8-
63.0 (NCH2CH2CH2CH2OH); HRMS (ESI+): [M+Na]+ m/z=119.1179
(calcd.), 119.1178 (found).
5-(1-Methylhydrazinyl)pentan-1-ol (3d)
2-(1-Methylhydrazinyl)ethan-1-ol (3a)
Compound prepared from 5-chloropentan-1-ol (1.06 mL, 8.2 mmol),
yielding 1.06 g (98%) as a colorless liquid at R. T. (21 C). H NMR
1
°
°
(CDCl3,
25 C,
300 MHz):
δ
(ppm)=1.41
(m,
2H,
NCH2CH2CH2CH2CH2OH), 1.57 (m, 4H, NCH2CH2CH2CH2CH2OH), 2.45
(t, 2H, NCH2CH2CH2CH2CH2OH, J=7.2 Hz), 2.46 (s, 3H, NMe), 2.90 (s
(b), 3H, CH2OH, NNH2), 3.63 (t, 2H, NCH2CH2CH2CH2CH2OH, J=
°
Compound prepared from 2-chloroethan-1-ol (16.7 mL, 248 mmol),
°
°
yielding 18.52 g (83%) as a colorless liquid at R. T. (23 C). d (23.3 C)
1
°
=1.0234; H NMR (CDCl3, 25 C, 300 MHz): δ (ppm)=2.47 (s, 3H,
6.4 Hz); 13C {1H} NMR (CDCl3, 25 C, 75 MHz):
δ (ppm)=23.5
NMe), 2.52 (m, 2H, NCH2CH2OH), 3.59 (s(b), 3H, MeN(NH2)CH2CH2OH),
13
1
(NCH2CH2CH2CH2CH2OH), 27.2 (NCH2CH2CH2CH2CH2OH), 32.6
°
3.72 (m, 2H, NCH2CH2OH); C { H} NMR (CDCl3, 25 C, 75 MHz): δ
(ppm)=51.7 (NMe), 61.9 (CH2OH), 62.2 (CH2N); 15N NMR (CD3NO2,
(NCH2CH2CH2CH2CH2OH),
49.7
(NMe),
62.7-63.3
(NCH2CH2CH2CH2CH2OH); HRMS (ESI+): [M+H]+ m/z=133.1335
°
25 C, 50 MHz): δ (ppm)=66.4 (NH2NMe), 91.8 (NH2NMe). HRMS
(ESI+): [M+H]+ m/z=91.0866 (calcd.), 91.0862 (found); [M+Na]+
m/z=113.0685 (calcd.), 113.0686 (found); IR (Golden Gate, ν (cmÀ 1))
=3301 (m(b)), 2946 (m), 2836 (m), 2789 (m), 1607 (w), 1448 (m),
1364 (w), 1272 (w), 1079 (m), 1034 (m), 880 (m), 833 (w), 770 (m),
699 (w), 681 (w), 631 (w), 555(m), 538 (m), 480 (m), 472 (m).
(calcd.), 133.1335 (found).
Chem Asian J. 2020, 15, 1–12
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6-(1-Methylhydrazinyl)hexan-1-ol (3e)
3-(1-Methylhydrazinyl)propan-1-amine (3g)
1
2
3
4
5
6
Compound prepared from 6-chlorohexan-1-ol (1.02 mL, 7.3 mmol)
7
8
9
1
Compound prepared from 3-chloropropylamine hydrochloride
°
yielding 1.05 g (98%) as a colorless liquid at R. T. (21 C). H NMR
(2.00 g, 15.4 mmol) yielding 1.06 g (67%) as an orange liquid at R. T.
°
(CDCl3,
25 C,
300 MHz):
δ
(ppm)=1.36
1.53 (m,
(m,
4H,
4H,
1
°
°
(18 C). H NMR (CDCl3, 25 C, 300 MHz): δ (ppm)=1.65 (quint., 2H,
NCH2CH2CH2NH2, J=7.0 Hz), 2.44 (s, 3H, NMe), 2.47 (t, 2H,
NCH2CH2CH2NH2, J=7.0 Hz), 2.75 (t, 2H, NCH2CH2CH2NH2, J=7.0 Hz);
°
NCH2CH2CH2CH2CH2CH2OH),
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
NCH2CH2CH2CH2CH2CH2OH), 2.43 (t, 2H, NCH2CH2CH2CH2CH2CH2OH,
J=7.5 Hz), 2.44 (s, 3H, NMe), 2.81 (s(b), 3H, CH2OH, NNH2), 3.61 (t,
2H, NCH2CH2CH2CH2CH2CH2OH, J=6.5 Hz); 13C {1H} NMR (CDCl3,
13C {1H} NMR (CDCl3, 25 C, 75 MHz):
δ
(ppm)=31.5
(NCH2CH2CH2NH2), 40.5 (NCH2CH2CH2NH2), 50.0 (NMe), 61.3
(NCH2CH2CH2NH2).
°
25 C, 75 MHz): δ (ppm)=25.8 (NCH2CH2CH2CH2CH2CH2OH), 27.1
(NCH2CH2CH2CH2CH2CH2OH), 27.5 (NCH2CH2CH2CH2CH2CH2OH), 32.8
(NCH2CH2CH2CH2CH2CH2OH),
49.7
(NMe),
62.8-63.4
(NCH2CH2CH2CH2CH2CH2OH); HRMS (ESI+): [M+H]+ m/z=147.1492
General procedure for the synthesis of hydrazines 3h and 3i
(calcd.), 147.1486 (found).
The Cbz-protected chloroalkylamine precursor (1 eq, see SI for
synthesis procedure details) was introduced under Argon into a
General procedure for the synthesis of hydrazines 3f and 3g
°
25 mL schlenk tube and its temperature was maintained at 20 C by
means of a cryothermostat. MMH (circa 8 eq) was then added and
An inert Argon atmosphere was set-up inside a thermostated
double-jacketed vessel, MMH (8 eq) was then introduced into it and
°
the reaction mixture was stirred overnight at 20 C, after which it
was neutralized by adding a saturated aqueous solution of NaOH
(1.05 eq). The aqueous phase was extracted with dichloromethane
and the organic phases were collected, dried over MgSO4 and
evaporated under reduced pressure leading to a pure compound.
°
the temperature was maintained 20 C. Chloroalkylamine
hydrochloride (1 eq) was then added by portions and the reaction
°
mixture was stirred for 18 h at 20 C, after which it was alkalinized
using an aqueous solution of NaOH (1.05 eq, 50 wt%). The reaction
crude was then evaporated under reduced pressure, to get rid of
water and residual MMH, and it was diluted in acetonitrile to
precipitate salts which were filtered off. Solvent was evaporated
under reduced pressure, leading to pure hydrazine.
Benzyl (2-(1-methylhydrazinyl)ethyl)carbamate (3h)
2-(1-Methylhydrazinyl)ethan-1-amine (3f)
Compound prepared from Benzyl (2-chloroethyl)carbamate (17.0 g,
79.6 mmol) yielding 17.39 g (97%) as a colorless liquid at R. T.
1
°
°
(33 C). H NMR (CDCl3, 25 C, 300 MHz): δ (ppm)=2.48 (s, 3H, NMe),
2.52 (t, 2H, MeNCH2CH2NHCO2, J=5.5 Hz), 2.80 (s(b), 2H, NNH2), 3.37
(q, 2H, MeNCH2CH2NHCO2, J=5.5 Hz), 5.10 (s, 2H, NHCO2CH2), 5.70
Compound prepared from 2-chloroethylamine hydrochloride
(10.0 g, 86.2 mmol) yielding 7.96 g (Quant.) as a pale pink liquid at
13
1
°
(s(b), 1H, CO2NH), 7.36–7.73 (m, 5H, Haro); C { H} NMR (CDCl3, 25 C,
75 MHz): δ (ppm)=39.5 (MeNCH2CH2NHCO2), 51.3 (MeN), 60.9
(MeNCH2CH2NHCO2), 66.7 (CO2CH2), 128.1-128.2-128.6 (Caro), 136.9
1
°
°
°
R. T. (22 C). d (21.6 C)=1.0402; H NMR (D2O, 25 C, 300 MHz): δ
(ppm)=2.45 (s, 3H, NMe), 2.63 (m, 2H, H2NN(Me)CH2), 2.80 (m, 2H,
15
°
(OCH2C), 156.6 (C=O); N NMR (CD3NO2, 25 C, 50 MHz): δ (ppm)=
13
1
°
CH2NH2); C { H} NMR (DMSO d6, 25 C, 75 MHz): δ (ppm)=39.2
64.9 (NH2NMe), 80.8 (NHC(O)), 90.8 (NH2); HRMS (ESI+): [M+H]+
m/z=224.1394 (calcd.), 224.1391 (found), [M+Na]+ m/z=246.1213
(calcd.), 246.1208 (found); IR (Golden gate, ν (cmÀ 1))=3326 (w(b)),
3033 (w), 2948 (w), 2837 (w), 2793 (w), 1699 (s), 1599 (w), 1521 (m),
1454 (m), 1408 (w), 1329 (w), 1249 (s), 1140 (m), 1047 (m), 1014(m),
907 (w), 827 (w), 774 (w), 736 (m), 697 (s), 636 (w), 608 (w), 574 (w),
538 (w), 517 (w), 491 (w), 460 (m).
(CH2NH2), 49.9 (NMe), 64.3 (H2NN(Me)CH2); 15N NMR (DMSO d6/
°
CD3NO2 (50/50), 25 C, 50 MHz): δ (ppm)=20.0 (CH2NH2), 63.4 (NH2N
(Me)CH2), 91.9 (NH2N(Me)CH2); HRMS (ESI+): [M+H]+ m/z=90.1026
(calcd.), 90.1032 (found), [M+Na]+ m/z=112.0845 (calcd.),
112.0856 (found), [2 M+H]+ m/z=179.1979 (calcd.), 179.1989
(found), [2 M+Na]+ m/z=201.1798 (calcd.), 201.1816 (found); IR
(Golden gate, ν (cmÀ 1))=3282 (w(b)), 2947 (w), 2880 (w), 2843 (w),
2791 (w), 1603 (w), 1449 (w), 1361 (w), 1326 (w), 948 (w), 877 (w),
830 (w), 761 (m); DSC (Medium pressure Steel crucible, À 50 to
Benzyl (3-(1-methylhydrazinyl)propyl)carbamate (3i)
°
°
°
°
400 C, 5 C/min): Tb (onset)=136 C, Td (onset)=223 C; ISI (BAM,
constant energy) >50 J.
Compound prepared from Benzyl (3-chloropropyl)carbamate
(821.6 mg, 3.6 mmol) yielding 841.5 mg (98%) as a yellow liquid at
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+Na]+ m/z=168.0856 (calcd.), 168.0858 (found); IR (Golden gate, ν
(cmÀ 1))=3313 (w(b)), 2946 (w), 2842 (w), 2094 (s), 1603 (w), 1447
(m), 1273 (m), 1073 (m), 1028 (w), 930 (m), 900 (w), 873 (w), 823 (m),
661 (m), 555 (m), 528 (w), 484 (m), 471 (m), 459 (m); UV (EtOH): λmax
(nm)=223, λ2 (nm)=283; DSC (Medium pressure Steel crucible,
°
°
R. T. (33 C). H NMR (CDCl3, 25 C, 300 MHz): δ (ppm)=1.74 (quint.,
2H, MeNCH2CH2CH2NH, J=6.4 Hz), 2.46 (s, 3H, MeN), 2.50 (t, 2H,
MeNCH2CH2CH2NH, J=6.4 Hz), 3.28 (q, 2H, MeNCH2CH2CH2NH, J=
6.4 Hz), 5.09 (s, 2H, CO2CH2), 5.48 (s(b), 1H, CO2NH), 7.29-7.36 (m, 5H,
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4
5
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7
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13
1
°
H
aro); C { H} NMR (CDCl3, 25 C, 75 MHz): δ (ppm)=27.4 (N(Me)
CH2CH2CH2N), 40.2 (N(Me)CH2CH2CH2N), 50.5 (NMe), 61.2 (N(Me)
CH2CH2CH2N), 66.6 (CO2CH2), 128.2–128.6 (Caro), 136.9 (OCH2C), 156.6
°
°
°
À 50 to 400 C, 5 C/min): Td (onset)=139.9 C; ISI (BAM, constant
energy) >50 J.
15
°
(C=O); N NMR (CD3NO2, 25 C, 50 MHz): δ (ppm)=66.6 (NH2NMe),
81.7 (NHC(O)), 90.9 (NH2); HRMS (ESI+): [M+H]+ m/z=238.1550
(calcd.), 238.1547 (found), [M+Na]+ m/z=260.1369 (calcd.),
260.1367 (found), [2 M+Na]+ m/z=497.2847 (calcd.), 497.2843
(found).
Acknowledgements
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We gratefully acknowledge our sponsors, CNES, ArianeGroup,
CNRS and Université Claude Bernard Lyon 1, for funding this work.
J. E. thanks Université Claude Bernard Lyon 1 for his Ph.D.
scholarship. Authors also thank Erwann Jeanneau (ISA, Lyon) for
X-Ray measurement and crystal structure solving, Anne Baudoin
(CCRMN, ICBMS, Lyon) for NMR analyses and the Centre Commun
de Spectrométrie de Masse (ICBMS, Lyon) for mass spectrometry
measurements.
Synthesis of 1-(2-azidoethyl)-1-methylhydrazine (4)
An aqueous solution of 1-(2-chloroethyl)-1-methylhydrazine
hydrochloride (7.35 g, 50.9 mmol in 100 mL water, see SI for
synthesis procedure details) was introduced into a 250 mL two-
°
neck round-bottomed flask. The solution was cooled at 0 C and
Conflict of Interest
neutralized by adding NaHCO3 (4.28 g, 51 mmol). When the solution
temperature increased to room temperature, 10.17 g of NaN3
(156 mmol) were added by portions to the reaction mixture, which
The authors declare no conflict of interest.
°
was then stirred for 6 h at 50 C. Afterwards, the solution was
alkalinized with potassium hydroxide (30 g) and continuously
extracted with ether (150 mL) for 10 h. The organic phase was dried
Keywords: bishydrazines · functionalized hydrazines · scalable
synthesis · monomethylhydrazine · energetic materials
over Na2SO4 and evaporated leading to hydrazine 4 as a yellow
1
°
liquid (yield=24%). H NMR (CDCl3, 25 C, 400 MHz): δ (ppm)=2.54
(s, 3H, NMe), 2.59 (t, 2H, CH2N, J=5.7 Hz), 2.89 (s, 2H, NH2), 3.47 (t,
13
1
°
2H, N3CH2, J=5.7 Hz,); C { H} NMR (CDCl3, 25 C, 100 MHz): δ
(ppm)=48.8 (NMe), 51.1 (N3CH2), 60.4 (CH2N); 15N NMR (CD3NO2,
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°
25 C, 50 MHz): δ (ppm)=64.5 (N(Me)NH2), 69.5 (CH2
N=N+ =NÀ ), 92.4 (NH2), 209.6 (CH2N=N+ =NÀ ), 248.4 (CH2N=N+ =
NÀ ); HRMS (ESI+): [M+H]+ m/z=116.0931 (calcd.), 116.0932
(found); IR (Golden gate, ν (cmÀ 1))=2945(w), 2094(s), 1599(w), 1446
(m), 1278(m), 1066(w); UV (Et2O): λmax (nm)=244, λ2 (nm)=302; DSC
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(-50 to 250 C, 5 C/min): Td (onset)=152.9 C; ISI (BAM, constant
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1
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°
°
°
(16 C). d (16.3 C) =1.1493; H NMR (D2O, 25 C, 400 MHz): δ (ppm)
=2.49 (s, 3H, NMe), 2.64 (d, 2H, NCH2CHOHCH2N3, J=7.1 Hz), 3.31
(dd, 1H, NCH2CHOHCHHN3, J=6.7, 13.0 Hz), 3.43 (dd, 1H,
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1
°
J=7.1, 6.7, 3.7 Hz); C { H} NMR (CDCl3, 25 C, 75 MHz): δ (ppm)=
52.5 (NMe), 54.5 (CH2N3), 62.1 (CH2N(Me)NH2), 70.7 (CHOH); 1À5N NMR
+
°
(CD3NO2, 25 C, 50 MHz): δ (ppm)=65.9 (CH2N=N =N ), 67.1
(NH2N), 91.9 (NH2N), 207.2 (CH2N=N+ =NÀ ), 248.8 (CH2N=N+ =NÀ );
HRMS (ESI+): [M+H]+ m/z=146.1036 (calcd.), 146.1037 (found), [M
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Manuscript received: September 10, 2020
Revised manuscript received: October 12, 2020
Version of record online: ■■■, ■■■■
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FULL PAPER
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J. Eymann, Dr. A. Dhenain, Dr. L.
Joucla*, Dr. G. Jacob, Dr. E. Lacôte,
Dr. C. Darwich*
1 – 12
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A versatile synthesis based on MMH
and chloroalkyl substrates has been
devised leading to seventeen new
functionalized hydrazines and bishy-
drazines. These derivatives are key-in-
gredients for accessing higher polyni-
trogenated structures with energetic
interest and tunable properties. Three
of them (N/C ratio�1) showed a low
impact sensitivity, a good thermal
stability and a specific impulse value
similar to that of MMH bipropellant
systems.
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Solvent-free Synthesis and Prop-
erties of Functionalized Hydra-
zines and Bishydrazines as
Energetic Ingredients for Propul-
sion Applications