The synthesis and evalution of novel aryl-substituted dithioimidophosphonates as an extrantant for metals

Article abstract of DOI:10.1080/104265090968064

A novel series of O,O′,O″,O?- tetraaryldithioimidophonates [(ArO)₂PS]₂NH 4 were synthesized by the reaction of O,O,-diaryl phosphorochlorothionates 2 and diarylphosphonothioic amide under a strong basic condition. The key intermediat

Full text of DOI:10.1080/104265090968064

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The Synthesis and Evalution
of Novel Aryl-Substituted
Dithioimidophosphonates as an
Extrantant for Metals
Ruiren Tang a b & Cancheng Gou a b
a School of Chemistry and Chemical Engineering,
Hunan University, Changsha, People's Republic of
China
b School of Chemistry and Chemical Engineering,
Central South University, Changsha, People's
Republic of China
Published online: 19 Aug 2006.
To cite this article: Ruiren Tang & Cancheng Gou (2005) The Synthesis and Evalution
of Novel Aryl-Substituted Dithioimidophosphonates as an Extrantant for Metals,
Phosphorus, Sulfur, and Silicon and the Related Elements, 180:12, 2725-2731, DOI:
10.1080/104265090968064
To link to this article: http://dx.doi.org/10.1080/104265090968064
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Phosphorus, Sulfur, and Silicon, 180:2725–2731, 2005
Copyright © Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/104265090968064
The Synthesis and Evalution of Novel Aryl-Substituted
Dithioimidophosphonates as an Extrantant for Metals
Ruiren Tang
School of Chemistry and Chemical Engineering, Hunan University,
Changsha, People’s Republic of China; School of Chemistry
and Chemical Engineering, Central South University, Changsha,
People’s Republic of China
Cancheng Gou
School of Chemistry and Chemical Engineering, Hunan University,
Changsha, People’s Republic of China
A novel series of O,Oꢀ,Oꢀꢀ,Oꢀꢀꢀ-tetraaryldithioimidophonates [(ArO) PS] NH 4 were
2
2
synthesized by the reaction of O,O,-diaryl phosphorochlorothionates 2 and di-
arylphosphonothioic amide under a strong basic condition. The key intermediates
2a∼2g were prepared from thiophosphyl chloride and substituted phenols under
phase transfer catalysis conditions for the first time. These teteraaryl dithioimi-
2+
3+
dophonates show high selectivity for Zn over Fe from a sulfate solution. The
31
effects of substituents on the P NMR of the titled compounds also are discussed.
Keywords 31P-NMR; dithioimidophospoinates; extraction; synthesis
Dithiomimidophosphinate (R2XPNXPR2)−(R CH3, or C6H5; and X S)1
are important compounds with interesting structures which can form
bis-coordinated complexes with divalent metals (such as Mn, Fe, Co,
Ni, and Pt) with a MS4 tetrahedral core2−5 and can be used for met-
alloenzymes targets.2−5 Recently, the Mrley, Eckhard, Bonford and
their colleagues reported independently that tetra-alkyl substituted
dithioimidophonates were powerful complexing agents for zinc from
aqueous solution with good selectivity over iron.6−8 Particularly the
commercial success in the selective solvent extraction of copper from
aqueous acidic solution derived from oxide ores using ring alkylated
Received September 14, 2004; in final form March 1, 2005.
Financial support from the Natural Science Foundation of China (No. 20376018) is
gratefully acknowledged.
Address correspondence to Cancheng Gou, Hunan University, School of Chemistry
and Chemical Engineering, Changsha 410083, Peoples’ Republic of China. E-mail:
ccguo@mail.hunu.edu.cn
2725

2726
R. Tang and C. Gou
o-hydrobenzophenone oxime6 and salicyladoxime has attracted great
interest in related processes that could be used for the selective solvent
extraction of other metals, especially for cases where the required metal
is in smaller concentration in solution than main element. However, to
our best knowledge, few articles about the aryl substituted dithioimi-
dophonates and their applications in such an area have been reported
in literature.
In order to explore the structures and the electronic properties of the
ligands and their selectivity in complexing with metals, in this article,
we report a facile method for preparing the key intermediates 2a∼2g
under phase-transfer catalyzed conditions and a series of novel aryl-
substituted dithioimidophonates [(X-ArO)2PS]NH (4). The synthetic
route is shown in Scheme 1. All the products except for 2a and 4a
have not been reported in literatures.
Compound
X
a
b
c
d
e
f
g
H
p-CH3 o-CH3 p-OMe p-NO2 p-t-C4H9 p-Cl
Scheme 1
RESULTS AND DISCUSSION
We tried to prepare diaryl-phosphorochloridothionate (2) by the direct
treatment of thiophosphyl chloride (PSCl3) with a phenol, but surpris-
ingly, PSCl3 does not react with phenol even under forcing conditions.
In the presence of aluminum chloride, phenol and PSCl3 remained un-
changed after 2 h at reflux. But, in the present of NaOH or triethy-
lamine, as an acid acceptor PSCl3 reacts with two equivalent phenol,
and O,O-diarylphosphorochloridothionate (2) is prepared in moderate
yield (see Table I, Non-Phase-Transfer Catalyst (PTC) conditions). Fur-
thermore, the formation of byproducts such as mono-aryl derivatives
[(ArO)P(S)Cl2] and thiophosphates [(ArO)3P(S)] is difficult to avoid.
In an attempt to improve the yields of the reactions, Phase-Transfer-
Catalysts9 (PTCs) such as Tetra Butyl Ammonium Bromide (TBAB)
and Benzyl Triethyl Ammonium Chloride (BTAC) have been used. As

Dithioimidophosphonates as an Extrantant for Metals
2727
TABLE I Preparation of (X-ArO)2 PSCl
Under PTCs
Under PTC conditions/%
Non-PTC/%
Number
PTCs
Yield of 2
Yield of 2
2a
2b
2c
2d
2e
2f
BTAC
BTAC
BTAC
BTAC
BTAC
TABA
BTAC
71.0
79.3
74.6
77.1
80.0
73.7
78.2
57.6
43.8
49.3
52.1
50.7
46.5
47.3
2g
expected, the yields of 2a∼2f were enhanced up to about 80%. Table I
compared the yields of compound 2 with and without PTC.
The 1H-NMR spectra of all compounds show that the two aryl groups
in 2 or four aryl groups in 4 are magnetically identical and have res-
onance at the same frequency because of some relative position to the
magnetically anisotropic benzene ring. On the other hand, the proton-
decoupled 31P-NMR spectra of compounds 4 in CDCl3 show one signal
at about δ = 50–55, which was assigned to the major isomer SS in which
the P atom is at the same chemical environments based on the 1H NMR
spectra, and not to the isomer SH in which proton-decoupled 31P-NMR
spectra should show two singlets for the two magnetically nonequiva-
lent P nuclear (Scheme 2). Hence, the 31P-NMR spectrometry provides
a convenient means for distinguishing these isomers (SS and SH).
Scheme 2
On the other hand, the 31P-NMR chemical shifts δ of compound 4
correlate linearly with the Hammett σ[10] constants of the substituents
X on the phenyl ring. The correlation between the 31P-NMR chemical
shifts of the P-atom of compound 4 and the Hammet constant (σ) of X10
can be depicted by the following equation:
δP = 1.6728σ + 50.5833
r = 0.96, n = 12, confidence level 99.9.
(1)

2728
R. Tang and C. Gou
A small-scale solvent extraction processes show the titled compounds
are fairly strong extractants and have a high selectivity for zinc (Zn2+
)
over iron (Fe3+) from a sulfate solution. The extracting ability for zinc
from a sulfate solutions is 4f > 4e > 4c > 4b > 4g > 4d > 4a. It needs fur-
ther studies to illustrate the effects of electronic properties, steric effects
of X, and other factors on their extracting and chelating behaviors.
EXPERIMENTAL
All reagents commercially available were purified and dried by the
standard procedures. Analytical thin-layer TLC was performed on a
5 × 10 cm precoated silica gel F-254 with detection under ultravio-
let light. Uncorrected melting points were determined on an XRC-1
apparatus. IR spectra were recorded on an Avatar 3600 spectropho-
tometer with KBr plates. 1H-NMR and 31P-NMR spectra were recorded
with an INOVA-200 MHz apparatus in CDCl3. MS were performed on
an HP5988A spectrometer. Elemental analyses were performed on a
Perkin-Elmer 2400 elemental analyzer.
General Procedure for the Preparation of 2 Under
PTC Conditions
To the suspension of 0.4 mol phenol and sodium hydroxide solution
(16.0 g, 0.4 mol in 24 mL water) in 80 mL, benzene was added under
vigorous stirring, then 1.2 mmol desired PTC was added to the reac-
tion mixture, followed by the dropwise addition of PSCl3 (34 g, 0.2 mol)
from the additional funnel over a period of 30 min. The reaction was
stirred until TLC showed no starting materials. Hundred milliliter of
water was added and the organic phase was separated. The aqueous
phase was extracted with 3 × 50 mL of benzene. The combined organic
phase was washed with water until the pH = 7 was dried over anhy-
drous Na2SO4, was evaporated, and the crude product was purified by
recrytalization give stable crystals.
2a
1
M.p.: 64–65◦C. Yield 71.0%. H NMR/δ: 7.14 (m, 10H, ArꢀH ). MS
(m/e, %): 284 (M+, 100), 286 (M+2, 33). IR (film) 1600, 1560, 1185,
750 cm−1
.
2b
M.p.: 71–73◦C. Yield 79.3%. 1H NMR/δ: 7.34∼7.27 (d, 8H, J = 7.2 Hz,
ArꢀH), 2.31 (s, 6H, CH3). MS (m/e, %): 312 (M+, 90), 314 (M+2, 30),

Dithioimidophosphonates as an Extrantant for Metals
2729
91 (100). IR (film): 1590,1560, 1493, 1181, 748 cm−1. Anal. cacld. for
C14H14O2ClPS: C 53.76, H 4.48; found: C 53.40; H 4.45.
2c
1
M.p.: 67–68◦C. Yield 74.6%. H NMR/δδ.28 (m, 8H, ArꢀH), 2.24 (s,
6H, CH3). MS (m/e, %): 312 (M+, 90), 314 (M+2, 30), 91 (100). IR (film):
1601, 1578, 1477, 1180, 750 cm−1
.
2d
1
M.p.: 68–69◦C. Yield 77.1%. H NMR/δ: 7.23 (m, 8H, ArꢀH), 3.59 (s,
6H, 0CH3). MS (m/e, %): 344 (M+, 100), 346 (M+2, 33). IR (film): 1596,
1573, 1182, 741 cm−1. Anal. cacld. for C14H14O4 ClPS: C 48.76; H 4.06;
found: C 48.48; H 3.97.
2e
M.p.: 75–76◦C. Yield 80.0%. 1H NMR/δ: 7.53 (d, 4H, J = 8.2 Hz, ArꢀH),
8.42 (d, 4H, J = 7.9 Hz, ArꢀH). MS (m/e, %): 374 (M+, 100), 376 (M+2,
33). IR (film): 1587, 1523, 1458, 1356, 1187, 768 cm−1. Anal. cacld. for
C12H8O6 ClPNS: C 38.45; H 2.14; N 7.48; found: C 38.79; H 2.08; N
7.39.
2f
1
M.p.: 81–83◦C. Yield 73.7%. H NMR/δ: 7.18 (m, 8H, ArꢀH), 1.09 (s,
18H, t-C4H9). MS (m/e, %): 396 (M+, 100), 398 (M+2, 33), 91 (100). IR
(film): 1600, 1471, 1390, 1375, 1185, 750 cm−1. Anal. cacld. for C20H26O4
ClPS: C 60.53; H 6.56; found: C 60.72; H 6.54.
2g
1
M.p.: 91–93◦C. Yield 78.2%. H NMR/δ: 7.31 (dd, 4H, JAB = 8.3 Hz,
JPB = 1.5 Hz), 7.35 (d, 4H, JAB = 8.3 Hz). MS (m/e, %): 352 (M+, 90), 354
(M+2, 90), 91 (100). IR (film): 3030, 1610, 1500, 790, 750 cm−1. Anal.
cacld. for C12H8O2Cl3PS: C 40.76; H 2.28; found: C 41.00; H 2.31.
General Procedure for the Preparation of 4
Ammoia gas was bubbled through
a
solution of O,O-
diarylphosphorochloridothionate (0.1 mol) in 250 mL benzene while
maintaining the reaction temperature below 40◦C for 2 h. The reaction
mixture was washed with water to remove ammonium chloride. The
organic layer was separated, dried, and evaporated to give crude 3,
which was used directly for the next step.
Five gram of sodium hydride in parafine (80%) was slowly added to
a wel-stirred solution of 0.1 mol of 3 and 100 mL anhydrous THF. After

2730
R. Tang and C. Gou
being refluxed for 2 h, the monosodium salt of 3 was formed. Then a
solution of 0.1 mol of 2 in 100 mL anhydrous THF was added dropwise
to the suspension reation mixture. The mixture was refluxed for about
6 h. Then the solvent was evaporated and the residue was diluted with
200 mL benzene, and washed with diluted hydrochloric acid (5%) and
then water. The mixture was dried over Na2SO4 and evaporated. White
or light color crystals were obtained after the recrystallization form
ethanol and benzene.
4a
Yield: 54%, white powder, m.p. 109–111◦C. IR: 3348, 1591, 1488, 890,
1017, 618 cm−1. 1HNMR: δ = 7.32 (m, 20H, phenyl-H), 6.32 (s, 1H, NH);
31PNMR, δ = 50.8. MS (FAB): m/z = 513 (M+, 90). Analysis (%): Calcd.
for C24H21NO4P2S2: C 56.14, H 4.09, N 2.73; found: C 56.36; H 3.97; N
3.04.
4b
Yield: 52%, white powder, m.p. 113–115◦C. IR: 3348, 1591, 1488,
1017, 889, 748, 618 cm−1.1HNMR: δ = 7.18 (d, 16H, J = 6.9 Hz, aryl-H);
5.72 (s, 1H, NH), 2.33 (s, 12H, CH3); 31PNMR, δ = 50.5. MS (FAB): m/z =
569 (M+, 91). Anal. cacld. for C28H29NO4P2S2: C 59.05, H 5.10, N, 2.46;
found: C 58.84, H 5.10, N, 2.27.
4c
Yield: 57%, white powder, m.p. 112–114◦C. IR: 327, 1559, 1480, 1340,
1510, 1195, 630, 676 cm−1. 1HNMR: δ = 5.82 (s, 1H, NH); 7.18 (m, 16H,
aryl-H); 2.34 (s, 12H, CH3); 31PNMR, δ = 50.5. MS (FAB): m/z 569 (M+,
85). Anal. cacld. for C28H29NO4P2S2: C 59.05; H 5.10; N 2.46; found: C
58.99; H 5.22; N 2.35.
4d
Yield: 55%, white powder, m.p. 98–101◦C. IR: 3258, 1590, 1488, 880,
1017, 618, 748 cm−1. 1HNMR: δ = 5.82 (d, 1H,b NH), 8.23–8.30 (dd, 16H,
Jab = 6.9 Hz, JPB = 1.3 Hz, aryl-H), 4.13 (s, 12H, CH3);31PNMR, δ = 50.5.
MS (FAB): m/z = 633 (M+, 95). Anal. cacld. for C28H29NO8P2S2: C 53.08;
H 4.49; N 2.21; found: C 52.94; H 4.38; N 2.29.
4e
Yield: 58%, light yellow powder, m.p. 218–220◦C. IR: 3348, 1590,
1485, 889, 1017, 618, 748 cm−1. HNMR: δ = 6.00 (s, 1H, NH), 7.78
1
(dd, 8H, JAB = 8.8 Hz, JPB = 1.5 Hz), 8.32 (d, 8H, JAB = 8.8 Hz);
31PNMR, δ = 50.5. MS (FAB): m/z = 693 (M+, 89); Anal. cacld. for

Dithioimidophosphonates as an Extrantant for Metals
2731
C24H17N5O12P2S2: C 41.56, H 2.46, N 10.10; found: C 41.21; H 2.41;
N 10.32.
4f
Yield: 38%, white powder, m.p. 165–166◦C. IR: 3235, 1605, 1509,
1495, 881, 1070, 630,749 cm−1. 1HNMR: δ = 5.60 (s, 1H, NH), 7.23 (m,
16H, aryl-H), 1.12 (s, 36H,t-Bu-H). 31PNMR, δ = 50.5. MS (FAB): 737
(M+,87). Anal. cacld. for C40H53NO4P2S2: C 65.12; H 7.19; N 1.90; found:
C 65.37; H 7.21; N 1.75.
4g
Yield: 56%, white powder, m.p. 126–128◦C. IR: 3315, 1600, 1483,
900, 1010, 628, 740 cm−1. HNMR: δ = 5.88 (d, 1H, NH), 7.25 (dd, 8H,
1
JAB = 8.2 Hz, JPB = 1.5 Hz), 7.36 (d, 8H, JAB = 8.2 Hz). 31PNMR, δ = 50.3.
MS (FAB): m/z = (%): 352 (M+,81). Anal. cacld. for C24H12Cl4NO4P2S2:
C 52.93; H 3.15; N 2.58; found: C 52.48; H 3.17; N 2.55.
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