Heterocyclization of amino alcohols into saturated cyclic quaternary ammonium salts

Article abstract of DOI:10.1016/j.mencom.2020.11.031

Cyclodehydration of available N-alkylethanolamines with aldehydes and simultaneous or subsequent quaternization afford functionalized quaternary ammonium salts of N-nitroimidazolidine, oxazolidine and annulated bismorpholine type. Further replacement of their anions with residues of explosive acids provides a series of energyintensive quaternary salts with a rich hydrogen content possessing satisfactory energy characteristics and sufficiently high thermal stability.

Full text of DOI:10.1016/j.mencom.2020.11.031

Mendeleev
Communications
Mendeleev Commun., 2020, 30, 781–784
Heterocyclization of amino alcohols
into saturated cyclic quaternary ammonium salts
Dmitry B. Vinogradov,* Pavel V. Bulatov, Evgeny Yu. Petrov and Vladimir A. Tartakovsky
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow,
Russian Federation. E-mail: lab42@mail.ru
DOI: 10.1016/j.mencom.2020.11.031
OH
Cyclodehydration of available N-alkylethanolamines with
aldehydes and simultaneous or subsequent quaternization
afford functionalized quaternary ammonium salts of
N-nitroimidazolidine, oxazolidine and annulated bis-
morpholine type. Further replacement of their anions with
residues of explosive acids provides a series of energy-
intensive quaternary salts with a rich hydrogen content
possessing satisfactory energy characteristics and sufficiently
high thermal stability.
RHN
R = H, Me
Me
Me
Me
Me
Me
Me
+
N
+
N
+
X–
X–
N
O
N
O2N
O
2X–
O
N
+
–
–
–
–
–
–
–
X = I , MeOSO3, H2NSO3, NO3, N(NO2)2, ClO4
Me Me
Keywords: ammonium quaternary salts, amino alcohols, nitrates, nitramines, aldehydes, heterocyclization.
Recently, attention has been paid to quaternary ammonium salts
with explosophore anions serving as fillers and/or combustion
modifiers in solid rocket fuels and energy-rich basis for liquid
water-based monofuels. This approach is interesting because the
synthesis can involve selecting cation–anion pairs, which would
provide the optimal set of properties for a specific task.1
It is known that sulfamate group can be easily converted to
the nitramine one by treatment with nitrating agents. It was
reported that N-(2-hydroxyethyl)sulfamates of type 2 (K, Na,
1
3
NH , Scheme 1) could be synthesized from ethanolamine 1a by
4
sulfonation with a pyridine–sulfotrioxide complex, however that
method was expensive and required large amounts of solvents.
In this work, potassium N-(2-hydroxyethyl)sulfamate 2 was
obtained in a more rational way. As shown in Scheme 1, sulfamic
acid was dissolved in a threefold excess of ethanolamine 1a
followed by keeping the resulting solution at an elevated
temperature for a few hours and treatment with an ethanolic
solution of potassium hydroxide. The resulting potassium
ethanolsulfamate 2 was reacted with paraformaldehyde in glacial
acetic acid followed by nitration with HNO /H SO mixture to
–5
Dinitramide salts are most stable in combinations with tertiary
and quaternary alkylammonium cations.6 For example,
crystalline tetramethylammonium dinitramide melts with
decomposition at 228 °C. This compound is soluble in water and
,7
8
water–alcohol solutions and is hydrolytically stable. Gafarov
reported a number of analogous salts and bis-azido-substituted
trimethylammonium bases as examples of functionalized
9
quaternary ammonium compounds. Earlier, Olah described
3
2
4
quaternary hydrazinium nitrates while Klapötke10 prepared
hydrazoic and other explosophore acid salts with polymethylated
hydrazines. It was noted that crystalline salts were more stable
than liquid or low-melting ones, and also the presence of a
quaternary ammonium fragment dramatically increased the heat
give N-[(2-nitroxyethyl)nitramino]methanol 3 (87%) with 13%
admixture of ethylene dinitrate. This crude mixture was treated
with N,N,N',N'-tetramethyldiaminomethane in acetonitrile to
afford colorless crystalline 3-nitro-1,1-dimethylimidazolidin-
1-ium 4a nitrate precipitated from the reaction mixture in 20%
yield. This transformation seems to proceed first through the
formation of a linear quaternary salt A (see Scheme 1) followed
by intramolecular quaternization into seven-membered
dication B. Unstable intermediate B would decompose into
3-nitro-1,1-dimethylimidazolidin-1-ium and dimethyl(methyl-
idene)ammonium cations, which was fixed in mother liquor.
Finally, nitrate 4a precipitates to achieve equilibrium ratios in
the mother liquor, which explains its low yield. A similar
mechanism for reaction with N,N,N',N'-tetramethyldiamino-
1
1
resistance and reduced sensitivity to shock and friction. Shreeve
reported a synthesis of energy-rich ionic liquids containing N-(2-
azidoethyl)-N,N,N-trimethylammonium and N,N-bis(2-azido-
ethyl)-N,N-dimethylammonium salts with nitrocyanamide,
dinitramide, dicyanamide and azide anions. The specific
–3
densities of these salts were within 1.15–1.41 g cm , while their
thermal decomposition temperatures were within 180–245 °C.
This work is a continuation of systematic studies1 on the
synthesis of energy-rich functionalized quaternary ammonium
and hydrazinium salts. Previously, we dealt mostly with
salts containing cations of linear structure. Here we propose the
synthesis of quaternary salts of cyclic structure. In addition,
we aimed at a qualitative assessment of the effect of their
cyclic nature on the primary set of physicochemical properties,
in particular, melting points and decomposition onset
temperatures. We chose herein industrially available
ethanolamine 1a and N-methylethanolamine 1b as the
promising raw compounds.
2
1
4
methane was documented. Further, nitrate 4a was first
converted to the base form in the aqueous solution by treatment
–
with Dowex 2×8 anionite (OH ) and then neutralized with
ammonium salt of dinitramide or perchloric acid in the same
solution to give salts 4b,c, respectively (see Scheme 1).
The synthesis of 3,3-dimethyloxazolidin-3-ium iodide 5a by
quaternization of 3-methyloxazolidine with methyl iodide in
1
5
95% yield was reported previously. The starting 3-methyl-
oxazolidine was obtained in ~40% yield by the solvent-free
©
2020 Mendeleev Communications. Published by ELSEVIER B.V.
–
781 –
on behalf of the N. D. Zelinsky Institute of Organic Chemistry of the
Russian Academy of Sciences.

Mendeleev Commun., 2020, 30, 781–784
i, ii
iii, iv
OH
v
ONO2
OH
HN
SO K
HO
N
9
6%
83%
H2N
3
NO2
1
a
2
3
NO2
N
Me
Me
Me
+
N
Me
Me
+
N
N +
N
NMe2
O N
2
HO
N
+
N
20%
Me
NO–3
+
NO2
H C NMe2
2
Me
Me
NO 3– –OH
NO 3– –OH
A
B
Me
Me
Me
Me
+
N
vi, vii or viii
+
N
X–
N
NO3–
N
O N
2
O2N
b X = N(NO2)2 (for vii), 65%
c X = ClO4 (for viii), 74%
4
a
4b,c
Scheme 1 Reagents and conditions: i, H NSO H, 178 °C, 9 h; ii, KOH, EtOH, room temperature, 40 min; iii, (CH O) , AcOH, room temperature, 20 min;
2
3
2
x
–
iv, HNO /H SO , –15 °C, 1 h; v, CH (NMe ) , MeCN, 45 °C, 30 min; vi, Dowex 2×8 (OH )/H O, room temperature, 1.5 h; vii, NH N(NO ) , H O, room
3
2
4
2
2 2
2
4
2 2
2
temperature, 20 min; viii, NH ClO , H O, room temperature, 20 min.
4
4
2
I–
Me
Me
Me
Me
+
N
+
N
OH
i
Me
ii
iii
–
N
MeN
H
N(NO2)2
9
2%
92%
O
O
O
1
b
5a
5d
–
3
H NSO
2
Me
Me
+
N
Me
+
N
Me
Me
+
N
iv
5%
v
vi, vii or viii
–OH
X–
5
a
c X = NO (for vi), 62%
5
3
Me
O
O
O
d X = N(NO ) (for vii), 90%
2
2
5b
5c–e
e X = ClO (for viii), 88%
4
Scheme 2 Reagents and conditions: i, (CH O) , 40 °C, 3 h; ii, MeI, MeCN, room temperature, 20 h; iii, AgN(NO ) , H O, room temperature, 30 min;
2
x
2 2
2
iv, Pb(H NSO ) , H O, room temperature, 30 min; v, NaOH, EtOH, THF, 0 °C, 40 min; vi, NH NO , H O, room temperature, 20 min; vii, NH N(NO ) , H O,
2
3 2
2
4
3
2
4
2 2
2
room temperature, 20 min; viii, NH ClO , H O, room temperature, 20 min.
4
4
2
reaction of N-methylethanolamine 1b with paraformaldehyde
to contamination with inorganic salts. In the meantime, a
in the presence of potassium carbonate followed by
similar reaction of iodide 5a with aqueous silver dinitramide
1
6,17
distillation.
We simplified the procedure by abandoning
provided
the
required
3,3-dimethyloxazolidin-3-ium
K CO and performing both stages (Scheme 2) in one pot to
dinitramide 5d in high yield (conditions iii). To obtain similar
salt with other anions, we employed a scheme involving the
conversion of sulfamate 5b to the base form in EtOH/THF
medium and deposition of inorganic sulfamate, followed by
‘one pot’ reactions with ammonium nitrate, dinitramide or
perchlorate. This approach gave the desired salts 5c–e in high
yields (see Scheme 2, conditions v–viii). Compound 5c is a
viscous oil, other salts are pale yellow (5d) or colorless (5e)
crystalline substances.
2
3
obtain iodide 5a in 92% total yield. The method of replacing
the salt anion in an ion-exchange resin (cf. Scheme 1) did not
give good results due to high solubility of 3,3-dimethyl-
oxazolidin-3-ium salts in water. Therefore, iodide 5a was
converted to sulfamate 5b by the reaction with aqueous lead
sulfamate (see Scheme 2, conditions iv). A similar reaction of
lead nitrate with iodide 5a afforded 3,3-dimethyloxazolidin-3-
ium nitrate 5c, however, the thus obtained salt was not pure due
Me
N
Me Me
Me Me
O
N
O
N
O
+
+
–
i
ii
I–
iii
2
2NO3
1
b
7
9%
15%
+
85%
+
N
O
N
O
N
O
Me
Me
7a
Me
Me Me
6
7c
Me Me
Me Me
Me Me
N
O
N
O
N
O
iv
2%
+
–
v
+
2OH–
vi, vii or viii
+
6
2MeOSO3
2 X–
3
+
+
+
O
N
O
N
O
N
Me Me
Me Me
Me Me
7
b
7c–e
c X = NO3 (for vi), 88%
d X = N(NO2)2 (for vii), 85%
e X = ClO4 (for viii), 100%
Scheme 3 Reagents and conditions: i, (CHOCHO) ∙2H O, 40 °C, 3 h; ii, MeI, MeOH, 40 °C, 10 h; iii, Pb(NO ) , H O, room temperature, 30 min;
3
2
3 2
2
iv, (MeO) SO , MeCN, 80 °C, 4 h; v, NaOH, EtOH, H O, THF, –10 °C, 30 min; vi, NH NO , H O, room temperature, 20 min; vii, NH N(NO ) , H O, room
2
2
2
4
3
2
4
2 2
2
temperature, 20 min; viii, NH ClO , H O, room temperature, 20 min.
4
4
2
–
782 –

Mendeleev Commun., 2020, 30, 781–784
prepare salts 8c–e in high yields was employed (see Scheme 3,
conditions v–viii). The salts appeared as colorless (7c,e) or pale
yellow (7d) crystals, had high melting points and melted with
decomposition. Diperchlorate 7e did not melt but decomposed at
CꢀꢁAꢂ
NꢀꢄAꢂ
Cꢀ2ꢂ
Cꢀꢄꢂ
Oꢀꢄꢂ
CꢀꢁAꢂ
Oꢀꢄꢂ
Cꢀ2ꢂ
Nꢀꢄꢂ
Cꢀꢃꢂ
Cꢀꢄꢂ
2
80 °C with a flash.
CꢀꢃAꢂ
Cꢀ2Aꢂ
The resulting quaternary salts 4, 5, 7 containing N-nitro-
NꢀꢄAꢂ
CꢀꢄAꢂ
Nꢀꢄꢂ
imidazolidine, oxazolidine and annulated bismorpholine rings
were thermally stable crystalline non-hygroscopic compounds
(with the exception for 5b) whose properties are given in
Table 1. For comparison, the corresponding properties of tetra-
methylammonium nitrate, dinitramide and perchlorate are also
included.
One can see from the data in Table 1 that the resulting target
nitrates, dinitramides and perchlorates of the corresponding
cyclic quaternary ammonium bases 4, 5, 7 have a more rich
oxygen balance (OB) and formation enthalpies in comparison
with the starting tetramethylammonium salts, but nevertheless
retain a sufficiently high hydrogen content and high heat
resistance.
Cꢀꢃꢂ
CꢀꢄAꢂ
CꢀꢃAꢂ
Cꢀ2Aꢂ
Cꢀꢁꢂ
OꢀꢄAꢂ
OꢀꢄAꢂ
Cꢀꢁꢂ
Figure 1 Molecular structure of isomeric (4aR*,8aR*)-4,8-dimethyl-
perhydro[1,4]oxazino[3,2-b][1,4]oxazine 6.
Though compounds 5c,d showed rather high thermal stability,
they had relatively low melting points. We assumed that their
annulated dimerized analogues would have higher melting points
and, accordingly, higher heat resistance. A synthesis of
4
,8-dimethylperhydro[1,4]oxazino[3,2-b][1,4]oxazine 6 (annulated
1
7
bis-N-methylmorpholine) was reported. A procedure of
quaternization of N-methyloxazolidine analogue15 was tested
hereintowarddiamine6(Scheme3). However, thisquaternization
with iodomethane proceeded slowly due to the steric hindrance
even at elevated temperatures. The yields of 4,4,8,8-tetra-
methylperhydro[1,4]oxazino[3,2-b][1,4]oxazine-4,8-diinium
salts 7a,b were also as moderate as 15–32% (see Scheme 3).
According to X-ray crystallographic data, bicyclic compound 6
In conclusion, we rationally synthesized a number of
quaternary salts of the N-nitroimidazolidine, oxazolidine and
annulated bismorpholine type with nitrate perchlorate and
dinitramide anions, and determined their melting points and
decomposition onset. These compounds combine a rich
hydrogen content with a sufficient oxygen balance and a
satisfactory (in the case of dinitramides) heat of formation,
they are stable in condensed state as well as in aqueous,
water–alcohol and water–acetonitrile solutions without
showing any noticeable hygroscopic properties. The resulting
compounds are generally stable up to 190 °C or above. The
physicochemical properties of these compounds may promote
their use as high-hydrogen components of various propellant
formulations. In addition, the good solubility of these salts in
water or in a water/alcohol system, combined with their
hydrolytic stability, makes it possible to use them as the main
energy carrier in liquid water-based monofuel propellant
systems.
has a cis-junction (4aR*,8aR* relative configuration) of two
†
6
-membered rings (Figure 1). Obviously, the quaternary salts 7
formed from diamine 6 retain this spatial arrangement.
The reaction of diiodide 7a with aqueous lead nitrate gave
dinitrate 7c in a high yield (see Scheme 3, conditions iii). Due to
high solubility of sodium iodide in alcohol, the technique of
synthesizing the other representatives by treatment with sodium
hydroxide followed by reactions with ammonium salts with
other anions was not satisfactory, Therefore, a different version
using bis(methoxysulfonate) 7b as the starting compound to
Table 1 The properties of functionalized salts of quaternary ammonium bases.
Cation/compound
Anion
Mp/°Ca
T (decomp.)/°Ca
DHf(s) (calc.)/kcal mol–1
H (%)
OB (%)d
–
410b
410b
228
300
199
190
216
205
Me N
NO
–78
–24.5
–62
–47
+7
8.88
6.71
6.97
5.81
4.80
4.92
–129.3
–88.8
–92.2
–84.6
–63.5
–65.1
4
3
–
Me N
N(NO )
228
4
2 2
–
4
Me N
ClO
300
4
–
4
4
4
5
5
5
5
5
7
7
7
7
7
a
b
c
a
b
c
d
e
a
b
c
NO3
198–199
82–83
–
2
N(NO )
2
–
4
ClO
215–216
184–185c
hygroscopic
oil
–30
–
I
–
3
H NSO
2
–
NO3
230
–77
–23
–60
7.37
5.81
6.00
–117.0
–84.6
–87.3
–
2
N(NO )
83–84
170
2
–
4
ClO
without melting
209–210
without melting
245–246
208–209
without melting
270–278
–
I
210
–
3
(MeO)SO
>280
246
–
3
NO
–130
–23
6.80
5.35
5.53
–112.8
–81.1
–83.8
–
2
d
e
N(NO )
209
2
–
ClO4
280 self-ignition
–97
aStuart SMP-10 instrument (2 °C min–1); b ref. 19; c 189 °C (ref. 15); d oxygen balance based on CO , for a compound C H N O , OB (%) =
2
a
b
c
d
=
1600(d – 2a – b/2)/MW, MW is molecular weight.
†
Crystal data for 6. Crystals of compound 6 suitable for the X-ray
reflections, Rint = 0.0274) and used in refinement, which converted to
wR = 0.0878, GOF = 1.085 for all independent reflections [R = 0.0308
was calculated for 2100 reflections with I > 2s(I)].
CCDC 2015569 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via https://www.ccdc.cam.ac.uk.
analysis were obtained by recrystallization from light petroleum.
C H N O , orthorhombic, space group Pbcn, 14.2653(3),
b = 4.66150(10) and c = 13.1875(3) Å, a = 90°, b = 90°, g = 90°,
V = 876.94(3) Å , Z = 4, d
F(000) = 376. Total of 37616 reflections were collected (2348 independent
2
1
a
=
8
16
2
2
3
–3
–1
= 1.304 g cm , m = 0.094 mm ,
calc
–
783 –

Mendeleev Commun., 2020, 30, 781–784
This research was supported by The Ministry of Science and
Higher Education of the Russian Federation (Agreement
with N. D. Zelinsky Institute of Organic Chemistry RAS no.
9 G. A. Olah, M. B. Sassaman, M. Zuanic, C. B. Rao, G. K. Surya
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0 A. Hammer, G. Holl, K. Hübler, M. Kaiser, T. M. Klapötke and
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1
1
1
0
75-15-2020-803).
1 Y.-H. Joo, H. Gao, Y. Zhang and J. M. Shreeve, Inorg. Chem., 2010, 49,
Online Supplementary Materials
3
282.
Supplementary data associated with this article can be found
in the online version at doi: 10.1016/j.mencom.2020.11.031.
12 V. A. Tartakovsky, P. V. Bulatov, E. Yu. Petrov and D. B. Vinogradov,
Boepripasy i Spetskhimiya, 2019, no. 3, 5, asset no. 2247c (in Russian).
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Received: 5th October 2020; Com. 20/6330
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