Oxidation of white phosphorus by peroxides in water

Article abstract of DOI:10.1134/S0036024417100028

A mixture of hypophosphorous, phosphorous, and phosphoric acids is formed during the anaerobic oxidation of white phosphorus by peroxides [ROOН; R = Н, 3-ClC₆H₄CO, (СН₃)₃С] in water. The rate of reactions grows considerably upon adding nonpolar organic solvents. The activity series of peroxides and solvents are determined experimentally. NMR spectroscopy shows that the main product of the reaction is phosphorous acid, regardless of the nature of the peroxide and solvent. A radical mechanism of oxidation of white phosphorus by peroxides in water is proposed. It is initiated by the homolysis of peroxide with the formation of НO^? radicals that are responsible for the homolytic opening of phosphoric tetrahedrons. Further oxidation and stages of the hydrolysis of intermediate phosphorus-containing compounds yield products of the reaction.

Full text of DOI:10.1134/S0036024417100028

ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2017, Vol. 91, No. 10, pp. 1873–1876. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © R.R. Abdreimova, D.N. Akbaeva, G.S. Polimbetova, 2017, published in Zhurnal Fizicheskoi Khimii, 2017, Vol. 91, No. 10, pp. 1672–1676.
CHEMICAL KINETICS
AND CATALYSIS
Oxidation of White Phosphorus by Peroxides in Water
a,
b
a
R. R. Abdreimova *, D. N. Akbaeva , and G. S. Polimbetova
a
Sokolsky Institute of Fuel, Catalysis, and Electrochemistry, Almaty, 050010 Kazakhstan
b
Al-Farabi Kazakh National University, Almaty, 050040 Kazakhstan
*
e-mail: abdreimova_r@mail.ru
Received May 25, 2016
Abstract—A mixture of hypophosphorous, phosphorous, and phosphoric acids is formed during the anaero-
bic oxidation of white phosphorus by peroxides [ROOН; R = Н, 3-ClC H CO, (СН ) С] in water. The rate
6
4
3 3
of reactions grows considerably upon adding nonpolar organic solvents. The activity series of peroxides and
solvents are determined experimentally. NMR spectroscopy shows that the main product of the reaction is
phosphorous acid, regardless of the nature of the peroxide and solvent. A radical mechanism of oxidation of
white phosphorus by peroxides in water is proposed. It is initiated by the homolysis of peroxide with the for-
∙
mation of НO radicals that are responsible for the homolytic opening of phosphoric tetrahedrons. Further
oxidation and stages of the hydrolysis of intermediate phosphorus-containing compounds yield products of
the reaction.
Keywords: phosphorus, oxidation, hydrogen peroxide, hydroperoxide, water, mechanism
DOI: 10.1134/S0036024417100028
INTRODUCTION
EXPERIMENTAL
Peroxides [Н О (35% aqueous solution, 11.3 М),
3 3
2
2
The nonpolar tetrahedral molecule of white phos-
(
СН ) СООН (70% aqueous solution, 7.2 М), 3-
phorus (Р ) is most reactive under conditions of high
4
ClC H C(O)ОOH (57–86%; a mean value of 72%
6
4
temperatures, ionizing radiation, UV irradiation, and
in the presence of free radical sources; i.e., under con-
ditions where a homolytic reaction mechanism is pos-
sible [1–3]. Simple and universal sources of free radi-
cals, which are easily formed during the homolysis of
О–О peroxo bonds, are organic and inorganic perox-
ides. A number of processes using hydrogen peroxide
was considered for stoichiometric calculations)], and
deuterated water (D O) were obtained from Aldrich or
2
Fluka. White phosphorus was oxidized by peroxides in
inert atmosphere inside Schlenk flasks. A mixture of
D O, oxidizing agent (hydrogen peroxide, tert-butyl-
2
hydroperoxide, and 3-chloroperoxybenzoic acid), and
solvent (toluene, tetrahydrofuran, tetrachlorometh-
ane, and n-hexane) was purged with argon for 10 min,
and a weighed amount of white phosphorus was added
in an argon flow. The total volume of the solution was
less than 5 mL. The solution was quickly heated in an
oil bath up to the required temperature (60–90°C)
with intense stirring on a magnetic stirrer. Stirring
continued until the end of reaction (0.25–4 h). The
aqueous phase of the reaction mixture was then ana-
[
4–7] and organic peroxides [8–14] as environmen-
tally friendly and effective oxidizing agents have been
described recently. Considerably less attention has
been devoted to the oxidation of white phosphorus by
peroxides. It has been noted that the oxidation of Р in
4
aqueous solutions of hydrogen peroxide is accompa-
nied by the disproportionation of phosphorus into
phosphine and phosphoric acid [15]. It has also been
reported that the reaction between Р and (tert-BuO)
4
2
31
lyzed via P NMR spectroscopy with TPPMS oxide
and different alkenes at 150–160°C yields a mixture of
organophosphorus compounds with the general for-
mula of R P O H [16, 17].
+
–
[
TPPMS = Na Ph P(3-SO C H ) ] as an internal
2 3 6 4
standard, while the organic phase was analyzed via gas
chromatography/mass spectrometry (GC/MS) with
x
4
2
2
3
1
The aim of this work was to fill a gap in investiga- naphthalene as an external standard. P NMR spectra
tions of the oxidation of white phosphorus by perox- of the phosphorus-containing acids were recorded on
ides. Optimum temperature conditions, product com- a Bruker ACP200 spectrometer at 25°C using D O or
2
position, and the effect of oxidizing agents and sol- С Н solvents. GC/MS analyses were performed on a
6
6
vents were therefore determined, and a possible Shimadzu QP 5000 instrument equipped with a capil-
mechanism of oxidation of Р by hydrogen peroxide lary column (Supelco SPB-1; 30 m, ∅ 0.25 mm,
4
and hydroperoxides in water is proposed.
0.25 μm).
873
1

1874
ABDREIMOVA et al.
Table 1. Effect of temperature on the oxidation of Р by Table 2. Effect of temperature and solvents on the oxida-
4
hydrogen peroxide in water
tion of Р by hydroperoxides in water
4
Experi-
ment
Conver-
sion, %
Conver-
sion, %
С , С , С ,
Experi-
ment
1
%а
2
%а
3
%а
Т, °C
t, h С , % С , % С , %
1 2 3
Т, °C Solvent
t, h
а
1
2
3
25
60
90
8
57
70
2
1
1
3
20
12
3
24
35
2
13
23
1
2
3
4c
5
6
60 toluene
25 toluene
25 toluene
25 toluene
60 THF
100
100
0.25 15 67 18
0.5 13 71 16
b
63 0.5 12 37 14
100 0.5 14 70 16
100
100
100
25
Reaction conditions: argon atmosphere; solid P4 29.7 mg,
.24 mmol; 35% aqueous solution of H O 0.21 mL, 2.4 mmol;
D O 1 mL; 1–3 were determined by P{ H} NMR: 1 is
0
2
2
1
1
4
2
2
2
22 66 12
13 69 18
11 76 13
3
1
1
2
60 CCl4
60 n-hexane
P(O)H (OH), 2 is P(O)H(OH) , and 3 is P(O)(OH) .
2
2
3
7
d
8
90
–
1
20
4
5
8
RESULTS AND DISCUSSION
9
10
60 THF
60 toluene
90
100
16 69
20 72
It was found that as the result of the reaction
between white phosphorus and peroxides (ROOН) in
Reaction conditions: argon atmosphere; solid P , 29.7 mg, 0.24 mmol;
4
water under argon at 25–90°C and ROOН-to-Р
oxidizing agent: (СН ) СООН 70% aqueous solution, 0.33 mL,
4
3 3
2
.4 mmol (experiments 1–8); 3-ClC H C(O)ОOH, 0.58 g,
6 4
molar ratio corresponding to 10, a mixture of hypo-
2
.4 mmol (experiments 9, 10); D O 1 mL; solvent 1 mL.
2
phosphorous Р(О)Н (ОН) (1), phosphorous
2
а
31
1
Determined by P{ H} NMR: 1 is P(O)H (OH), 2 is
P(O)H(OH) , and 3 is P(O)(OH) .
СН ) СООН 0.165 mL, 1.2 mmol.
Solution of Р in toluene, 1 mL.
2
Р(О)Н(ОН) (2), and phosphoric Р(О)(ОН) (3)
2
3
2
3
acids was formed. Products of the reaction were iden-
b
c
d
(
3 3
3
1
1
tified and their yields were determined via P{ H}
4
NMR spectroscopy of the aqueous phase with D O
2
D O 2 mL, without solvent.
2
instead of Н О by recording the signals of three fully
2
deuterated phosphorus-containing acids [18, 19].
tor: an organic phase with dissolved white phospho-
Deuterated hypophosphorous acid 1-d appeared as a
3
1
rus, and an aqueous phase in which inorganic acids 1–
quintet (δ 11, 47 ppm, J
acid 2-d yielded a 1 : 1 : 1 triplet centered at δ 5.0 ppm
= 85.6 Hz); phosphorous
P–D
3
were concentrated. Peroxide was distributed in both
3
phases. With the addition of toluene, the oxidation of
1
(
JP–D = 102.5 Hz); while the signal of phosphoric
Р by tert-butylhydroperoxide at 60°C was complete
4
acid 3-d was a sharp singlet at δ 0.56 ppm, indicating
3
within 15 min (Table 2, experiment 1).
there were no direct P–D bonds.
Full conversion of white phosphorus was achieved
even at room temperature (experiment 2). When the
There was virtually no oxidation of Р by hydrogen
peroxide in water at room temperature (Table 1,
experiment 1).
4
ROOН-to-P molar ratio was reduced to 5, the con-
4
version of Р fell consistently (experiment 3). Identical
4
A mixture of phosphorus-containing acids was
rates of the reaction were observed whether Р was
4
formed in low yields within one hour at a temperature
added in solid form or dissolved in toluene (experi-
of 60°C (experiment 2). The partial conversion of Р is
4
ments 2, 4). The highest rate of the oxidation of Р by
4
presumably caused by the insolubility of white phos-
phorus in water and the side thermal decomposition of
Н О into О and Н О at elevated temperatures. When
tert-butylhydroperoxide was observed in toluene
(
0.25–0.5 h), while the full conversion of white phos-
2
2
2
2
phorus was achieved after 1 h in THF and CCl , and
4
the temperature was raised to 90°C, the rate of the
reaction grew only slightly, due to a simultaneous rise
in the rate of the undesirable side reaction of thermal
decomposition of hydrogen peroxide (Table 1, experi-
ment 3). We found no proof that the disproportion-
ation of Р proceeds in the presence of Н О as was
after 4 h in n-hexane (experiments 5–7). When there
was no organic solvent, the conversion of Р was only
4
2
5% after 2 h even at 90°C (experiment 8). When the
oxidizing agent was replaced with 3-chloroperoxyben-
zoic acid, the reaction proceeded much more slowly;
however, the distribution of products 1–3 and the
effect of solvents did not change (Table 2, experi-
ments 9, 10). Regardless of the conditions, the main
product of the oxidation of white phosphorus by
hydroperoxides in water was phosphorous acid 2 (up to
4
2
2,
claimed in [15]. The authors of that work presumably
detected the disproportionation of product
P(O)Н(OH) 2 into РН and P(O)(OH) 3 upon heat-
2
3
3
ing.
During the oxidation of Р by hydroperoxides, 76%). Analysis of the organic phase by means of
4
nonpolar organic solvent was added in order to GC/MS revealed the presence of the products of
improve the solubility of ROOН and white phospho- reduction of hydroperoxides, i.e., tert-butanol and
rus. Two phases were in this case observed in the reac- 3-chlorobenzoic acid.
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A
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OXIDATION OF WHITE PHOSPHORUS BY PEROXIDES
1875
According to our experimental results, the prepara- medium [2]. Assuming an identical character of the
tion of phosphorus-containing acids via the oxidation products of the oxidation of Р by hydrogen peroxide
4
of Р by peroxides is described by stoichiometric equa- and hydroperoxides in water, we propose a general
4
tions
radical mechanism of these reactions, which are initi-
ated by the homolysis of ROOН with the formation of
P +6H O +2ROOH→4P(O)H (OH)+2ROH,
4
2
2
1)
∙
∙
(
1)
2)
RO and НO radicals:
(
P +6H O +6ROOH→4P(O)H(OH) +6ROH,
•
•
4
2
2
(
ROOH → RO + HO .
(4)
(
2)
∙
At temperatures of 25–90°C, only НО radicals,
P +6H O +10ROOH→4P(O)(OH) +10ROH,
4
2
3
which are strong oxidizing agents of organic and inor-
(
3)
(3)
ganic substrates [20], react with Р molecules. The
4
R =H, t-Bu, 3-ClC H CO.
6
4
∙
∙
reaction of (СН ) СО and 3-ClC H C(O)О radicals,
3
3
6
4
which have lower chemical activity, bonding directly
The rate of reactions (1)–(3) is limited to that of the
homolytic cleavage of the unstable О–О bonds of
to white phosphorus in this range of temperatures is
∙
ROOН, which depends not only on temperature and unlikely [2]. HО radicals attacking the Р
tetrahedron
4
the structure of R, but also on the character of its asso- results in the homolytic cleavage of the first Р–Р bond
∙
ciation with solvent molecules and viscosity of and the formation of (Р ОH) radicals (Scheme 1)
4
P
P
P
HO
P OH HO
P
P
P OH
OH
P
HO
P
P
P
P
P
HO P
HO
P OH
P OH
P
OH
HO
HO
HO
HO
P OH
OH HO
P
HO
HO
HO
HO
P
OH
OH
P
OH
P
P
P
P
P
HO P
P OH
P(OH)2
OH
OH
HO P
O
HO
ROOH
HO P OH
3
P
HO
HO P
HO
OH
HO OH
ROH
H O
OH
2
O
HO
HO
ROOH
ROH
O
HO P H
OH
P P
OH
HO P H
2
R = H, t-Bu, 3-ClC H CO
1
H
6
4
Scheme 1. Scheme of the proposed mechanism of Р oxidation by peroxides in water.
4
∙
Bonding to the latter, HО radical could yield inter- phosphorous acid 2 as the result of the rapid sponta-
mediate bicyclic dihydroxytetraphosphine P (OН) . neous interconversion of structural isomers. It is
4
2
known that tautomeric equilibrium between Р(ОН)
The sequential cleavage of the other five Р–Р bonds
3
∙
and Р(О)Н(ОН) 2 in aqueous solution shifts almost
under the action of HО radicals with the generation of
2
Р(ОH)2∙ radicals, intermediate cyclic P (OН) and
completely toward phosphorous acid 2 [21]. Accord-
4
4
ing to the composition of the products, some part (15–
P (OН) , and linear P (OН) and P (OН) com-
3
3
3
3
2
4
3
0%) of trihydroxyphosphine is oxidized by peroxide
pounds is then possible. We suggest that the hydrolysis
of tetrahydroxydiphosphine P (OН) into hypophos-
and transformed into phosphoric acid 3. Hypophos-
phorous acid 1 can also undergo peroxide oxidation
into phosphorous acid 2 (scheme).
2
4
phorous acid 1 and trihydroxyphosphine Р(ОН) , the
3
precursor for P(III) and P(V) acids, is also possible.
Another possible way of forming intermediate
Compared to the cleavage of the first of the six
∙
∙
Р(ОН) is the recombination of НО and Р(ОН) rad- Р‒Р bonds of the tetrahedral Р molecule, subsequent
4
3
2
icals, which is also shown in the scheme of the mech- steps of the cleavage of other Р–Р bonds of intermedi-
anism. Trihydroxyphosphine is transformed into ate compounds
P
(OН)
4
,
2
P (OН) ,
4 4
P (OН) ,
3 3
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 91 No. 10 2017

1876
ABDREIMOVA et al.
P (OН) , and P (OН) proceed more quickly, in duces acids 2 and 3 via the spontaneous interconver-
3
5
2
4
accordance with the substantial increase in the reac- sion of structural isomers and oxidation by peroxide,
tivity of Р–Р bond with upon moving from cyclic respectively.
polyphosphines to linear counterparts, and with the
increased number of substituents (hydroxyl groups)
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4
[
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4
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5
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6
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(
2
2
7
1
CONCLUSIONS
9
Under anaerobic conditions, white phosphorus is
8
readily oxidized by hydrogen peroxide and hydroper-
1
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4
2
It was determined experimentally that tert-butylhy- 15. W. C. Schumb, Ch. N. Satterfield, and R. L. Went-
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1
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2
2
2
2
Eng. Chem. 52, 401 (1960).
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1
1
8. Zs. Wittmann and Zs. Kovacs, Talanta 32, 581 (1985).
31
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2
0. W. A. Waters, Mechanism of Oxidation of Organic Com-
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∙
∙
ide ROOН to yield RO and НO radicals, was pro-
2
1. M. Kh. Karapet’yants and S. I. Drakin, General and
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∙
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2
2. I. F. Lutsenko and M. V. Proskurnina, Russ. Chem.
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2
4
mediate trihydroxyphosphine Р(ОН) . The latter pro-
Translated by A. A. Muravev
3
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2017