The structures of bis(3-aminophenyl)phosphinic acid and its derivatives in the solid state

Article abstract of DOI:10.1007/s11172-018-2085-8

According to IR spectroscopy data, solid bis(3-aminophenyl)phosphinic acid has a zwitterionic structure.

Full text of DOI:10.1007/s11172-018-2085-8

Russian Chemical Bulletin, International Edition, Vol. 67, No. 2, pp. 382—384, February, 2018
382
The structures of bis(3ꢀaminophenyl)phosphinic acid
and its derivatives in the solid state
M. P. Pasechnik,a A. G. Matveeva,a O. I. Artyushin,a K. V. Tcarkova,b and N. A. Bondarenkob
аA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Eꢀmail: matveeva@ineos.ac.ru
bInstitute of Chemical Reagents and High Purity Chemical Substances of National Research Center Kurchatov Institute,
3 ul. Bogorodsky val, 107076 Moscow, Russian Federation.
Fax: +7 (495) 963 7070. Eꢀmail: bond039@mail.ru
According to IR spectroscopy data, solid bis(3ꢀaminophenyl)phosphinic acid has a zwitꢀ
terionic structure.
Key words: bis(3ꢀaminophenyl)phosphinic acid, bis(3ꢀaminophenyl)phosphinic acid
potassium salt, bis(3ꢀaminophenyl)phosphinic acid triethylammonium salt, butyl bisꢀ
(3ꢀaminophenyl)phosphinate, bis(3ꢀammoniophenyl)phosphinic acid dichloride, diphenylꢀ
phosphinic acid, IR spectra, zwitterion, Hꢀbonds.
Scheme 1
Polyimide compounds obtained by copolymerization
of tetracarboxylic acid dianhydrides and bis(aminoaryl)
derivatives are excellent materials used in the production
of ionometric membrane fuel cells.1,2 The use in the coꢀ
polymerization reaction of modified diamines containing
sulfonic acid groups SO3H3—5 in the molecule makes it
possible to significantly increase the proton exchange of
the polyimide material.
In order to study polyimide materials based on diꢀ
amines modified with phosphorusꢀcontaining acidic
groups, we synthesized bis(3ꢀaminophenyl)phosphinic
acid (1), a structural analog of bis(aminophenyl) ether in
the molecule of which the oxygen atom is replaced by the
hydroxyphosphoryl group P(O)OH.
Reagents and conditions: i. 1,2ꢀpropylene oxide, EtOH, 15—16 h,
~20 °C; ii. 1 N NaOH, H2O, pH 5, ~20 °C.
Acid 1 was obtained from bis(3ꢀammoniophenyl)ꢀ
phosphinic acid dichloride6 using two procedures: by the
reaction with propylene oxide according to the known
procedure7 and neutralization of its aqueous solution with
an alkali to рН 5 (Scheme 1).
Earlier, compound 1 was isolated by neutralization of
an aqueous solution of its sodium salt with acetic acid.8,9
However, the authors8,9 reported for acid 1 only its meltꢀ
ing point and gave no data of structure.
It should be noted that diamines used in соpolymerꢀ
ization reactions should have free amino groups,5 while
in the molecule of amino acid 1 containing both an acid
and a base group, there is a possibility of the formation of
zwitterion 1´. However, it is known that in some polyꢀ
morphous forms of aminobenzoic acids the stabilization
of the HOOC group by intermolecular Нꢀbonds interꢀ
feres with the formation of zwitterions in the solid state.10
In order to establish the structure of amino acid 1, we
studied it by IR spectroscopy in comparison with derivaꢀ
tives and structural analogs containing in the molecule
either only a base or only an acid group. Potassium (2)
and ammonium (3) salts of bis(3ꢀaminophenyl)phosꢀ
phinic acid; potassium salt of diphenylphosphinic acid
(4) and diphenylphosphinic acid (5), which do not conꢀ
tain amino groups; as well as butyl bis(3ꢀaminophenꢀ
yl)phosphinate (6) and bis(3ꢀammoniophenyl)phosphinic
acid dichloride (7) were used as such objects. Table 1
summarizes vibrational frequencies of the phosphorusꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 0382—0384, February, 2018.
1066ꢀ5285/18/6702ꢀ0382 © 2018 Springer Science+Business Media, Inc.

Structure of bis(3ꢀaminophenyl)phosphinic acid
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
383
and nitrogenꢀcontaining groups of the investigated comꢀ
pounds in the solid state.
formation of intermolecular (IM) Нꢀbonds with amino
groups, while splitting of these bands may indicate a diꢀ
versity of these associations.
The IR spectra of salts 2 and 3 exhibit several bands
(three and more) in the region of stretching vibrations
ν(NH2), while theoretically only two bands of symmetric
ν (NH2) and asymmetric ν (NH2) vibrations should be
s
as
observed. The splitting of these bands is apparently exꢀ
plained by the presence of Hꢀbonds of different strength.
In the spectrum of amino acid 1, there are also three
bands in this region, which can be assigned to the vibraꢀ
tions of the NH2 group involved in the formation of IM
Hꢀbonds. Their frequencies are close to those in the specꢀ
trum of benzamide. (For example, the spectrum of solid
benzamide exhibits three bands with the frequencies at
3372, 3290, and 3175 cm–1, which is explained by the
association of cyclic dimers in chains.11) However, in
addition to these, the broad bands with the maxima at
2870 and 2600 cm–1 are also observed, which are similar
to the bands in the spectrum of dichloride 7 and correꢀ
spond to the vibrations of the +NH3 group. The IR specꢀ
tra also exhibit frequencies of bending vibrations δ(NH2)
and δ(+NH3) (see Table 1), which confirms the assignꢀ
ment made.
Compound
X
OH
O–K+
O–Et3NH+
O–K+
OH
Y
1
2
3
4
5
6
7
NH2
NH2
NH2
H
H
NH2
OBu
OH
+
NH3
From the analysis of the IR spectra, it follows that the
bands at 1180 cm–1 (ν(Р=О)) and 960 cm–1 (ν(Р—ОН))
correspond to vibrations of the Р(О)ОН group of dipheꢀ
nylphosphinic acid 5. The group РО – of potassium salt 4
is characterized by another pair of bands at 1193 and
1047 cm–1, belonging to the asymmetric ν (РО ) and
2
as
2
symmetric ν (РО ) vibrations, respectively. In the IR
s
2
spectrum of acid 1, we observed a split band with a maxiꢀ
mum at 1152 cm–1 and a band with a frequency of
In conclusion, the IR spectrum of bis(3ꢀaminoꢀ
phenyl)phosphinic acid 1 exhibits the bands correspondꢀ
1027 cm–1, which correspond to the ionized group РО
.
–
2
Similar bands are also observed in the spectra of salts 2
and 3. The lower values of these frequencies in comꢀ
pounds 1—3 as compared to salt 4 are explained by the
ing to the vibrations of the РО –, +NH3, and NH2 groups.
2
This means that acid 1 in the solid state has a zwitterionic
structure due to the intramolecular protonation of the
Table 1. Selected IR spectral data for bis (3ꢀaminophenyl)phosphinic acid (1), its derivatives, and structural analogs 2—7 in the
solid state (cm–1
)
Comꢀ
pound
X
Y
ν(P=O)
ν(P—O)
ν
as(PO2)
ν (PO2)
ν(NH2)
ν(NH3)
δ(NH2)
δ(NH3)
s
1
2
3
OH
NH2
—
11—
1152 v.s
1155 sh
1159 sh
1153 v.s
1163 v.s
1171 s
1176 s
1163 m
1153 m
1027 s
1035 s
1026 s
3412 m
3322 m
3220 w
3377 s
3330 m
3187 m
3412 m
3395 m
3353 m
3321 m
3207 m
—
2870 m.br
2600 m.br
1637 m
1586 m
1575 sh
1596 m
1576 w
1541 m
O–K+
NH2
NH2
—
—
11—
11—
—
—
—
—
O
– Et3NH+
1646 w
1592 m
1575 sh
4
5
6
O–K+
OH
H
H
—
11—
1193 v.s
1198 sh
—
1047 s
—
—
—
—
—
—
—
—
—
1180 m
1189 sh
1192 v.s
1174 m
960 s
980 sh
968 m
984 w
—
OBu
NH2
—
—
3453 m
3348 m
3330 m
3220 m
—
1631 m
1591 m
1577 sh
+
7
OH
NH3
1156 m
954 s
—
—
2850 s.br
2590 m
—
1544 s

384
Russ.Chem.Bull., Int.Ed., Vol. 67, No. 2, February, 2018
Pasechnik et al.
in H2O (80 mL) (pH 1) with vigorous stirring at ~20 °C until
the solution pH value reached 4.6—5.0, the resulting heterogeꢀ
neous mixture was concentrated dry in vacuo. Water (10 mL)
was added to the residue (5.61 g), the mixture was thoroughly
stirred, an undissolved precipitate was collected by filtration,
washed on the filter with water (4×10 mL), and dried in air to
obtain bis(3ꢀaminophenyl)phosphinic acid (1) (3.72 g, 96%) as
a cream crystalline compound, m.p. 285—288 °C (with deꢀ
comp.). After recrystallization from water, the yield of the acid
was 3.49 g (90%), m.p. 287—288 °C (with decomp.).
amino group. In addition, from the analysis of the IR
spectra it follows that compounds 1—3, 6, and 7 form IM
Hꢀbonds of different strengths between nitrogenꢀ and
phosphorusꢀcontaining groups.
Experimental
IR spectra of solid samples (in KBr pellets) of compounds
1—7 were obtained on a Bruker Tensor 37 FTIR spectrometer
1
13
(resolution 2 cm–1). Н, С{1Н}, 15N{1H}, and 31P{1Н} NMR
spectra of solution of acid 1 in DMSOꢀd6 were recorded on an
Avance 500 spectrometer (Bruker) using a BBIZ inversion senꢀ
The data were obtained using the equipment of the
Center for Molecule Composition Studies, A. N. Nesmꢀ
eyanov Institute of Organoelement Compounds, Russian
Academy of Sciences.
This work was financially supported by the Ministry
of Education and Science of the Russian Federation
within the framework of the Federal Target Program
(Agreement No. 14.625.21.0036 dated 27.10.2016,
a unique identificator of applied scientific studies
RFMEFI62515X0036).
1
sor. The operating frequencies for Н, 13С, 15N, and 31P nuclei
were 500.13, 125.77, 50.67, and 242.97 МHz, respectively. The
signals for the residual protons and carbon atoms of the solvent
1
13
in the Н and С NMR spectra were used as references, the
accuracy of determination of chemical shifts was no less than
0.01 and 0.03 ppm, respectively. Chemical shift value in the
15N and 31P NMR spectra were obtained relative to the exterꢀ
nal standards CH3NO2 and 85% H3PO4, respectively. The 1Н and
13
С NMR signals were assigned using heteronuclear (1Н—13
С
and 1H—15N) correlation techniques following the Bruker stanꢀ
dard operating procedures applying gsꢀHSQC and gsꢀHMBC
pulse field gradients. Melting points were measured with
Anschutz thermometers in a special block using capillaries.
Syntheses of salts 2—4 will be described in subsequent work.
Syntheses of diphenylphosphinic acid12,13 (5), butyl bis(3ꢀ
aminophenyl)phosphinate6 (6), and bis(3ꢀammoniophenyl)ꢀ
phosphinic acid dichloride6 (7) have been described earlier.
Bis(3ꢀaminophenyl)phosphinic acid (1). Method 1 (syntheꢀ
sis with propylene oxide). 1,2ꢀPropylene oxide (25 mL, 20.8 g,
357.7 mmol) was added dropwise to a mixture of thoroughly
powdered bis(3ꢀammoniophenyl)phosphinic acid dichloride6
(7) (5.0 g, 15.6 mmol) and ethanol (10 mL) with stirring at
~20 °C. The reaction progress was monitored by the disappearꢀ
ance of the chloride ion in the reaction mixture (test with
AgNO3 every 1—2 h). After 14 h of vigorous stirring, another
portion of 1,2ꢀpropylene oxide (5 mL, 4.1 g, 70.6 mmol) was
added and the mixture was allowed to stand for 1 h. A precipiꢀ
tate was collected by filtration, washed with ethanol (4×20 mL),
and dried in air to obtain acid 1 (3.3 g, 85%) as a cream crystalꢀ
line compound with m.p. 279—285 °C (with decomp.). After
two recrystallizations from H2O, the yield was 2.6 g (67%),
m.p. 286—288 °C (with decomp.). The literature data: m.p.
287—289 °C (with decomp.),8 m.p. 276—278 °C (with decomp.).9
1Н NMR, δ: 3.90 (br.s, NH2 + H2O); 6.65 (ddd, 2 Н,
HС(4), 3JН(4),Н(5) = 8.0 Hz, 4JH(4),H(2) = 4JH(4),H(6) = 1.2 Hz);
References
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6.82 (dddd, 2 Н, НC(6), 3JH(6),P = 11.6 Hz, 3JН
(5) = 7.5 Hz,
12. E. N. Tsvetkov, N. A. Bondarenko, I. G. Malakhova, M. I.
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Н
(6),
4JH(6),H(2)
=
4JH(6),H(4) = 1.2 Hz); 6.91 (ddd, 2 Н, НC(2),
3JH(2),P = 13.9 Hz, JH(2),H(4)
=
4JH(2),H(6) = 1.4 Hz); 7.08
4
(ddd, 2 Н, НC(5), JH(5),H(4) = 3JH(5),H(6) = 7.7 Hz, 4JH(5),P
=
3
13
2
= 4.2 Hz). С NMR, δ: 116.40 (d, С(2), JC,P = 11.3 Hz);
116.85 (d, С(4), 4JС,P = 2.7 Hz); 118.48 (d, С(6), 2JC,P = 9.5 Hz);
3
128.20 (d, С(5), JC,P = 14.5 Hz); 135.96 (d, С(1), JC,P
=
= 133.1 Hz); 148.85 (d, С(3), 3JC,P = 15.0 Hz). 31P NMR, δ: 25.8.
Method 2 (synthesis with an alkali). A 1 N aqueous solution
of NaOH was added dropwise to a solution of bis(3ꢀammoꢀ
niophenyl)phosphinic acid dichloride6 (7) (5.00 g, 15.6 mmol)
Received July 25, 2017;
in revised form November 24, 2017;
accepted December 8, 2017