OXIDATION OF PHOSPHINE WITH QUINONE AND QUINOID REDOX POLYMERS
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EXPERIMENTAL
conversion of the quinone structure into the energeti-
cally more favorable semiquinone or aromatic system
and the presence of two electrophilic (carbonyl and
unsaturated carbon atoms) and nucleophilic (carbonyl
oxygen atom) centers. Depending on the basicity,
phosphines react with either the carbonyl atom or the
unsaturated carbon atom of quinone, giving the P–C
coupling products. Unlike secondary and tertiary
phosphines, primary phosphines do not attach to ben-
zoquinones, but reduce them to hydroquinone, while
transforming into diphosphines. The behavior of PH3
in reactions with quinones, unlike that of other P(III)
compounds with a P–H group, was not studied [19].
The kinetic regularities of the oxidation of PH3 in
alcohol solutions of PFCS were studied based on phos-
phine absorption in a flow-through unit with a vigor-
ously agitated isothermal reactor to provide the kinetic
mode and gradientless conditions. The experimental
procedure was described in detail in [14, 16]. During the
experiments, the experiment time (min), redox poten-
tial (V), PH3 absorption rate (W, mol/(L min)), and
amount of absorbed PH3 (Q, M) were continuously
measured, and the composition of the liquid and gas
phases was periodically analyzed. The rate of reactions
(1) and (2) was assessed from the consumption of PH3,
quinone, and accumulation of organophosphorus
products. The test solutions were regenerated after
phosphine absorption with air oxygen. The quantita-
tive analysis of the organophosphorus products, qui-
none, and hydroquinone relative to the standard sam-
ples was performed on a GC-2010 Plus chromato-
graph equipped with a flame ionization detector and
Supelco SMS (30 m × 0.25 mm) (Shimadzu) capillary
columns. Hydrogen was used as the carrier gas. The
initial and final temperatures were 120 and 220°C; the
initial and end time 0–7 min. The heating rate was
25 K/min; the detector temperature 300°C.
Phosphine is not oxidized by benzoquine in alka-
line, neutral, and acidic media. The alcohol solutions
of benzoquinone do not absorb phosphine, and the
redox potential of the test solution does not change. In
mixed quinone–CuBr2–BuOH systems at 70°C, the
phosphine oxidation rate increases, and the amount of
absorbed PH3 corresponds to the total stoichiometry
of phosphine oxidation with copper(II) and p-benzo-
quinone (Fig. 1a). Three cycles were performed with
addition of a portion of quinone (curves 1–3). The
potential changed from 0.8 to 0.47 V during the exper-
iment (Fig. 1b), and the color of the solution changed
from dark brown to light yellow.
Quinoid redox ionites synthesized at the Institute
of Chemical Sciences were used; the commercial
weakly basic anionite AN-31 was used as the starting
matrix. The redox capacity of the samples based on
the 0.1 N solution of Fe2(SO4)3 was 1.3–2.9 mg-eq/g;
the anion exchange capacity 1.7–6.3 mg-eq/g; the
redox potential 0.69 V. The IR spectra of the synthe-
sized redoxites have intense characteristic absorption
bands related to the stretching vibrations of the C=O
(1653 cm–1) and phenol –C–O– (1210 cm–1) bonds of
the quinoid ring, as well as the >C = C< (1501 cm‒1),
=NH– (1580 cm–1), and C–N (1340 cm–1) bonds,
which confirms the presence of aminoquinoid poly-
mers.
The amount of absorbed PH3 and the change in the
potential during the experiment show that copper(II)
is reduced to copper(I) in solution, and quinone is
reduced to hydroquinone. After regeneration with air
oxygen, the potential and the color of the CuBr2–qui-
none solution returns to initial, but the reaction rate
decreases, and the amount of absorbed phosphine
corresponds only to the stoichiometry of the oxidation
of PH3 with copper. After three sequential cycles, the
yield of 2 was 86% (experiment 1, Table 1). The cop-
per(II) carboxylate complexes, namely, butyrates, stea-
rates, and acetates Cu(C3H7CO2)2, Cu(C17H35CO2)2,
and Cu(CH3CO2)2 are well soluble in alcohol. The use
of carboxylates as catalysts increases the reaction rate
and the amount of absorbed phosphine. The potential
of the solution changes from 0.4 to –0.05 V during the
experiment, and the color of the solution changes
from blue-green to dark brown. The amount of
absorbed PH3 and the change in the potential during
the test indicate that copper(II) is reduced to cop-
per(0) in solution, and quinone is reduced to hydro-
quinone (Figs. 2a and 2b). Regeneration of the waste
solutions in the system involving copper carboxylates
restores their activity without further quinone addi-
tions. The rate and amount of absorbed PH3 decrease,
but are higher than in the individual copper solutions.
In the stearate solutions, compound 2 formed after six
cycles with a yield of 89% (experiments 2 and 3,
Figs. 2a and 2b). After two cycles, the yield was 40%
for 1 and 33% for 2 in the presence of copper butyrate
and 52 and 32%, respectively, in the acetate system
RESULTS AND DISCUSSION
The quinone–hydroquinone system serves as a
classic example of an organic redox system and is often
used as an oxidizing agent and a component of the cat-
alytic system in liquid-phase processes. The main
chemical function of quinones in chemical and bio-
chemical processes is the electron transfer. Quinones
are single- and two-electron oxidizers of medium
strength; hydroquinones are relatively easily oxidizable
molecules. Therefore, quinones can serve as both oxi-
dants and catalysts. In addition, quinones occasionally
act as ligands in metal complex catalysis [17–19].
The products of the reactions of benzoquinone
with Р(III) derivatives (РН3, PhH2P, Ph2HP, Ph3P,
R3P, Ph2HPO, (HO)H2PO, (RO)3P, and (RO)2HPO)
are determined by the high redox potential due to the (experiments 4–7).
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 91 No. 12 2017