Preparation and some physicochemical properties of benzylammonium sulfates

Article abstract of DOI:10.1134/S1070363214040069

New method of preparation of multisubstituted benzylammonium cations via interaction in the SO₂-L-H₂O systems (L is benzylamine, α-phenylethylamine, N,N-dimethylbenzylamine, or dibenzylamine) has been developed. The products have bee

Full text of DOI:10.1134/S1070363214040069

ISSN 1070-3632, Russian Journal of General Chemistry, 2014, Vol. 84, No. 4, pp. 637–641. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © R.E. Khoma, A.A. Ennan, V.O. Gelmboldt, O.V. Shishkin, V.N. Baumer, A.V. Mazepa, Yu.E. Brusilovskii, 2014, published in
Zhurnal Obshchei Khimii, 2014, Vol. 84, No. 4, pp. 557–561.
Preparation and Some Physicochemical Properties
of Benzylammonium Sulfates
R. E. Khomaa,b, A. A. Ennana, V. O. Gelmboldtc, O. V. Shishkind,e,
V. N. Baumerd,e, A. V. Mazepaf, and Yu. E. Brusilovskiif
a Physicochemical Institute of Environment and Human Protection,
ul. Preobrazhenskaya 3, Odessa, 65082 Ukraine
e-mail: rek@onu.edu.ua, r_khoma@farlep.net
b Mechnikov Odessa National University, Odessa, Ukraine
c Odessa National Medical University, Odessa, Ukraine
d Institute of Single Crystals, National Academy of Sciences of Ukraine, Kharkov, Ukraine
eKarazin Kharkov National University, Kharkov, Ukraine
f Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine, Odessa, Ukraine
Received June 17, 2013
Abstract―New method of preparation of multisubstituted benzylammonium cations via interaction in the
SO2–L–H2O systems (L is benzylamine, α-phenylethylamine, N,N-dimethylbenzylamine, or dibenzylamine)
has been developed. The products have been studied by X-ray diffraction, IR, Raman spectroscopy, and mass
spectrometry.
Keywords: benzylamine, benzylammonium sulfate, X-ray diffraction, IR, Raman spectra
DOI: 10.1134/S1070363214040069
Benzylamine and its derivatives are known to form
salts with inorganic [1–7] as well as organic [8–10]
acids. Of these salts, nitrate [1], sulfate [2], dihydro-
phosphate [3], and hydroarsenate monohydrate [4] of
benzylammonium; sulfate and hydrophosphate of (S)-
α-phenylethylammonium [5]; trifluoroacetate of (R)-α-
phenylethylammonium [8]; as well as saturated [9] and
α,β-unsaturated [10] carboxylates of (±)-α-phenyl-
ethylammonium and its phenyl derivatives have been
described and characterized. The interest to the above-
mentioned compounds is due to their possible applica-
tions. The soluble benzylammonium salts have
attracted attention as drugs of enhanced bioavailability
[11]; in particular, dibenzylamine forms a water-
soluble antibiotic salt with penicillin [12]. Sulfate and
hydrophosphate of (S)-1-phenylethylammonium have
been studied as components of new dielectric
nonlinear optical materials [5]. Salts of N-alkyldi-
methylbenzylammonium with inorganic anions have
been used as antiseptics and disinfectants [13].
obtained from benzylamine, α-phenylethylamine, N,N-
dimethylbenzylamine, and dibenzylamine, respectively.
Under conditions of mass spectra detection,
compounds I, III, and IV underwent a so-called benzyl
cleavage [14]; the [C7H7]+ peak was found in the
spectra, being the most intense in the spectrum of
compound IV.
The structure of compound II as determined by
X-ray diffraction analysis was similar to that of benzyl-
ammonium described in [2].
The SO42– anion is located in the particular position
at the twofold axis, one C8H12N+ cation and half of
sulfate ion are located in the independent part of the
cell (Fig. 1). The bond lengths and bond angles
between the nonhydrogen atoms are collected in
Tables 1 and 2. At packing in the crystal a system of
hydrogen bonds is formed, their parameters are listed
in Table 3. The hydrogen bonds are formed between
ammonium group of the cation and oxygen atoms of
sulfate ions; the bonds are located in the vicinity of the
z = 1/2 plane, forming a layer in the 0 < z < 1 region.
In this work, we describe the preparation, structure,
spectral features, and thermal stability of sulfates I–IV
637

638
KHOMA et al.
Fig. 1. General view of molecule of compounds II (thermal
Fig. 2. Projection of molecule of compound II onto x0z
plane. Hydrogen bonds are denoted with dashed lines.
ellipsoids of probability level 50%). Symmetrically equi-
valent atoms are denoted as A.
In between these layers no hydrogen bonds are found,
as shown in Fig. 2. Due to this peculiar structural
feature, crystals of II are layered, are of poor quality
and tend to twinning.
at ~1118 cm–1 and a shoulder at 1160 cm–1 instead of a
singlet band at 1145 cm–1 and a shoulder at 1085 cm–1
as well as enhancement of the band at 1030 cm–1)
resulted from overlap of the cation bands with νаs(SО42–).
Selected parameters of IR spectra of the initial
amines and compounds I–IV are shown in Table 4.
In Raman spectrum of compound I, the intense
band at 966 cm–1 was observed, absent in the spectrum
of benzylamine; the band could be assigned to the full-
symmetrical vibrations νs(SО42–). As was discussed in
[15], the decrease in the symmetry of sulfate anion led
to the appearance of weak full-symmetrical vibration
band ν1(A1) in IR spectrum, its frequency being
practically equal to that of the Raman band. Therefore,
the newly appeared weak band at 961 cm–1 in IR
spectrum of sulfate I was assigned to νs(SО42–) (A1).
Assignment of vibration frequencies of SO42– in IR
spectrum of I was performed by comparison with IR
spectrum of initial benzylamine and the corresponding
Raman spectra taking into account the data reported in
[15].
Proper assignment of the νаs band of SО42– in IR
spectrum of I was complicated by the overlapping with
vibration bands of benzylammonium cation at ~1100 cm–1.
However, the corresponding Raman vibrations of
benzylammonium were relatively inactive, thus
allowing to extract three split components of thrice
degenerate asymmetric vibrations ν3(F2) as bands of
medium (1165 cm–1) and high (1093 and 1033 cm–1)
intensity. Hence, complication of IR spectrum of
sulfate I as compared with that of initial amine (the
appearance of a complex intense band with maximum
Table 2. Bond angles in the molecule of sulfate IIa
Angle
O2S1O2#1
O2S1O1
O2S1O1#1
O1S1O1#1
C6C1C2
C6C1C7
C2C1C7
C3C2C1
ω, deg
107.5(4)
109.0(3)
110.0(3)
111.1(5)
117.5(8)
120.6(7)
121.9(8)
124.8(10)
Angle
ω, deg
C2C3C4
C5C4C3
C4C5C6
C5C6C1
C1C7C8
C1C7N1
C8C7N1
117.4(10)
118.5(10)
124.5(11)
116.7(9)
114.3(7)
109.8(6)
108.2(6)
Table 1. Bond lengths in the molecule of sulfate II
Bond
d, Å
Bond
d, Å
Bond
d, Å
S1–O2 1.458(5)
S1–O1 1.473(5)
N1–C7 1.525(8)
C1–C2 1.425(11) C4–C5 1.366(17)
C1–C7 1.505(10) C5–C6 1.370(11)
C2–C3 1.305(13) C7–C8 1.523(12)
a
Symmetrical transformation to get the equivalent atoms: #1 – x +
2, y, –z + 1.
C1–C6 1.410(11) C3–C4 1.429(15)
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PREPARATION AND SOME PHYSICOCHEMICAL PROPERTIES
Table 3. Parameters of hydrogen bonds D–H···A in the molecule of sulfate II
639
Distance, Å
Bond
D–H···A
DHA angle,
deg
Atom coordinates
d(D–H)
d(H···A)
d(D···A)
N1–H1A···O2
0.89
1.92
2.805(8)
169.9
–x + 3/2, y + 1/2, –z + 1
N1–H1C···O2
N1–H1B···O1
0.89
0.89
1.90
1.85
2.786(6)
2.733(8)
171.6
169.4
x – 1/2, y – 1/2, z
Table 4. Wavelengths (cm–1) of IR absorption maxima in the spectra of starting amines and sulfates I–IV
δ(HN+H),
δ(CN+H)
Compound
ν(NH), ν(СН)
ν(N+H)
νаs(SО42–)
νs(SО42–)
δаs(SО42–)
δs(SО42–)
SО42– free ion (Td
symmetry) [15]
1105
ν3 (F2, IR,
Raman)
983
ν1 (A1,
Raman)
611
ν4 (F2, IR,
Raman)
450
ν2 (Е,
Raman)
Benzylamine
3379 s, 3290 s,
3062 s, 3027 s,
2920 s, 2753 m
I
3465 m.br, 3178 m, 2676 m,
1635 m 1160 sh, 1118 961 m
v.s, 1031 m
619 s, 573 m 471 w,
451 w
2997 s, 2887 s
2560 m,
2341 m,
2015 m
α-Phenylethylamine 3367 m, 3286 m,
3084 s, 3027 s,
2962 s, 2967 s
II
3440 m, 3000 s.br, 2752 sh,
1635
sh,
1614 s
1134 sh, 1122 v.s, 971 m
1090 s, 1061 s
635 sh, 620 m, 465 w,
2913 s.br
2668 m,
2535 m,
2151 m
588 m
430 w
N,N-
3027 s, 2893 s,
Dimethylbenzylamin 2846 s, 2804 s
e
IІІ
3406 s.br,
3038 m.br
2704m. br, 1649 m 1140 sh, 1090 961 m
709 m, 605 w 494 w,
415 m
2405 m. br,
2265 m
v.s, 1058 v.s,
1047 v.s
Dibenzylamine
3313 m, 3105 m,
3027 s, 2918 s,
2816 s
IV
3460 m, 3061 sh,
3290 sh, 3000 v.s,
2833 m
2641 m,
2474 m,
2364 m,
2341 m
1623 m, 1134 s.br
1615 m
920 m
668 m, 658 sh, 513 sh,
645 m
415 w
Two components of thrice degenerate bending
bands δаs(SО42–)(ν4) in IR spectrum of compound I
were observed as strong (619 cm–1) and moderate
intensity (573 cm–1) bands. In the Raman spectra, two
moderate intensity bands at 623 and 590 cm–1
corresponded to those IR bands, thus pointing at the
ν4(F1 > A2 + EU) splitting.
In the range of twice degenerate deformation
vibration ν2 (450 cm–1) of free SO42– ion, in IR spec-
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KHOMA et al.
trum of sulfate I the appearance of two well defined
shoulders (471 and 451 cm–1) of the out-of-plane
δ(ССН) bending at 485 cm–1 is notable. In the Raman
spectrum, δs(SО42–) vibrations were assigned to the
weak band at 446 cm–1.
Bands of stretching and bending vibrations of SO42–
anion in IR spectra of sulfates II–IV were assigned by
comparative analysis of spectra of the salts, of the
initial benzylamines, and of compound I. It follows
from Table 3 that the intrinsic vibrations of SO42– ion
appeared in IR spectra as the full set of possible
frequencies due to splitting of the F2 and Е vibrations
and activity of the А1 vibrations; that could point at a
low symmetry of the anion in the crystalline salts as
compared with Td symmetry of the free anion.
an endothermic effect at 90–150°C (Tmax 130°C, Δm
11.92%) along with two exothermic effects at 230–
360°C (Tmax 290°C, Δm 70.86%) and 530–610°C (Tmax
580°C, Δm 2.65%).
To conclude, this work demonstrated new examples
of stabilization of sulfate anion in the form of
alkylammonium salts prepared in the SO2–L–H2O
systems (L were mixed amines) in the presence of air
according to the formal scheme.
2SO2 + 4RnNH3–n + 2H2O + O2 → 2(RnNH4–n)2SO4.
The effect was reported for the first time in [18].
The possibility of mild oxidation of SO2 under the
specified conditions will be further studied in detail
involving other amine ligands.
In IR spectra of the salts the range of 3500–
2000 cm–1 contained complex bands of N–H stretching
vibrations of the NH3+, NH2+, and NH+ groups [15, 16].
Noteworthily, the bands at 2015 cm–1 (I), 2151 cm–1
(II), 2265 cm–1 (III), and 2341 cm–1 (IV) were due to
strong hydrogen bonds NH···О in the crystalline salts;
the presence and position of those bands in the IR
spectra could characterize the participation of benzyl-
ammonium cations in the hydrogen bonding [17].
EXPERIMENTAL
Technical grade sulfur(IV) oxide was used after
purification and drying [21]. All amines were of pure
grade and were used as received.
Analysis for carbon, hydrogen, and nitrogen
content was performed using a СНN elemental
analyzer; content of sulfur was determined using the
Scheniger method [19].
The characteristic scissor vibration bands of am-
monium groups, δ(HN+H) and δ(NN+H), were detected
in the relatively narrow region of 1650–1610 cm–1.
Raman spectra were obtained using a DFS-24
spectrometer with excitation at 532 and 632.8 nm
(neodymium and helium-neon lasers, respectively).
In the thermogram of sulfate I, two endothermic
effects were detected at 210–320°C (Tmax 280°C, Δm
69.86%) and 390–550°C (Tmax 460°C, Δm 7.94%) as
well as an exothermic effect at 550–660°C (Tmax 600°C,
Δm 7.94%). In the thermogram of compound II the
endothermic effect at 240–370°C (Tmax 300°C, Δm
64.29%) was detected along with the exothermic effect
at 390–660°C (Tmax 600°C, Δm 17.03%). When in air,
compounds I and II were stable, the decomposition
onset being detected at 210 and 240°C, respectively;
the (S) enantiomer II started decomposing at 230°C
[3]. Noteworthily, the low-temperature effects in
thermograms of compounds I and II corresponded to
elimination of the same fragments (M ≈ 218 g/mol),
evidently showing the special feature of thermolysis of
benzylammonium sulfates.
IR spectra were recorded using a spectrophotometer
Spectrum BX II FT-IR System (Perkin-Elmer) (KBr);
mass spectra were registered on a MKh-1321
instrument (direct amission of the sample into the ion
source, ionizing electrons energy 70 eV).
Thermal stability of the compounds was determined
by the differential thermal analysis (the Q-1500 D
Paulik–Paulik–Erdey derivatograph, platinum crucible,
in air, 20–1000°C at a rate 10 deg/min, sensitivity 1/5
of the maximum one, Al2O3 reference).
X-ray diffraction studies were performed using the
Oxford Diffraction diffractometer (MoKα radiation,
graphite monochromator, CCD detector Sapphire-3).
The structures were solved and refined using SHELX-
97 software package [20]. Hydrogen atoms positions
were found via differential analysis of electron density
and refined in the rider model. The basic
crystallographic parameters of compound II were as
follows: C16H24N2O4S, monoclinic, M 340.43, space
group С2, a 10.876(2), b 6.0814(10), c 13.609(4) Å;
β 92.47(3)°, V 899.3(4) Å3 at T 293(2) K, Z 2, dcalc
The thermogram of compound III contained three
endothermic effects at 90–140°C (Tmax 100°C, Δm
16.22%), 140–250°C (Tmax 170°C, Δm 18.24%), and
300–385°C (Tmax 350°C, Δm 46.62%) as well as an
exothermic effect at 400–590°C (Tmax = 550°C, Δm =
4.05%). The thermogram of compound IV contained
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 4 2014

PREPARATION AND SOME PHYSICOCHEMICAL PROPERTIES
1.257 g/cm3, F000 364, crystal 0.30×0.20×0.02 mm,
641
REFERENCES
μ 0.200 mm–1 [λ(MoKα) 0.71073 Å], transmission
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measured reflections, 1479 independent reflections
(Rint 0.0969), 986 reflections with Ihkl > 2σ(I), coverage
completeness 94.0%; final parameters of full-matrix
refinement of 108 parameters according to F2 using the
986 reflections: RF 0.0923, wR2 0.2041 (RF 0.1269,
wR2 0.2286 for all independent reflections), S 1.003,
Δρmin/Δρmax –0.253/0.387 e/Å3.
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Benzylammonium sulfate (I). Gaseous SO2 was
passed through a mixture of 10 mL of benzylamine
and 20 mL of water (0°C) at 50 mL/min till рН
dropped below 1.0. Then the reaction mixture was
isothermally evaporated at room temperature to full
dehydration. The so formed solid product was washed
with benzene and recrystallized from water. Yield
14.30 g (82.3%), white crystals with specific smell, mp
105–107°C. Mass spectrum, m/z (Irel, %): 107 (69)
[ML]+; 106 (100) [ML – H]+; 91 (13) [C7H7]+; 78 (15);
77 (22) [C6H5]+; 52 (8); 51 (15); 39 (7). Found, %: C
53.49; H 6.24; N 8.64; S 9.84. C14H20N2O4S. Cal-
culated, %: C 53.83; H 6.45; N 8.97; S 10.26. М 312.38.
α-Phenylethylammonium sulfate (II) was
prepared similarly from 10 mL of phenylethylamine
and 50 mL of water. Yield 13.37 g (89.1%), white
crystals (without further purification), mp 195–200°C.
Mass spectrum, m/z (Irel, %): 120 (8) [ML – H]+; 107
(8); 106 (100) [ML – СH3]+; 79 (24); 77 (13) [C6H5]+;
53 (9), 51 (10); 44 (18); 43 (7); 42 (13). Found, %: C
56.89; H 7.39; N 8.51; S 9.77. C16H24N2O4S. Cal-
culated, %: C 56.45; H 7.11; N 8.23; S 9.42. М 340.44.
N,N-Dimethylbenzylammonium sulfate (III) was
prepared similarly from 10 mL of N,N-dimethyl-
benzylamine and 50 mL of water. Yield 10.51 g
(92.8%), yellow oily liquid. Mass spectrum, m/z (Irel,
%): 135 (40) [ML]+; 134 (30) [ML – H]+; 92 (5); 91 (40)
[C7H7]+; 65 (13%); 58 (100); 44 (10); 42 (17). Found,
%: C 59.13; H 7.41; N 7.39; S 9.05. C18H28N2O4S. Cal-
culated, %: C 58.67; H 7.66; N 7.60; S 8.70. М 368.49.
Dibenzylammonium sulfate (IV) was prepared
similarly from 10 mL of dibenzylamine and 50 mL of
water. Yield 8.07 g (91.4%), white crystals, mp 93°C.
Mass spectrum, m/z (Irel, %): 198 (14) [ML+H]+; 196
(14) [ML – H]+; 120 (10); 106 (85); 105 (26); 92 (26);
91 (100) [C7H7]+; 77 (31%) [C6H5]+; 65 (14); 64 (17)
[SO2]+; 51 (14). Found, %: C 67.73; H 6.81; N 8.61; S
6.35. C28H32N2O4S. Calculated, %: C 68.27; H 6.55; N
5.69; S 6.51. М 492.63.
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