Substitution reactions of mono- and trichloro acetic acids with ammonium dialkyl (alkylene) dithiophosphates

Article abstract of DOI:10.1080/10426500600892693

A reaction of mono- and trichloro acetic acid with ammonium salts of alkylene (dialkyl) dithiophosphate; [S₂NH₄; G = -CH ₂CH₂CHMe-, -C(Me)₂C(Me)₂-, -CH ₂C(Me)₂CH₂-, and -C(Me)₂CH ₂CHMe-; (RO)₂PS₂-NH₄; and R = C ₂H₅, C₃H₇, i-C₃H ₇;] in a 1:1 molor ratio in refluxing benzene solution yields low melting solids and light-yellow oily liquids of the type [(RO) ₂PS₂R' and S₂R, where R = CH₂COOH and Cl₂CCOOH], which are hygroscopic in nature. These newly synthesized complexes have been characterized by physicochemical and spectroscopic techniques (MW, IR, ¹H, and ³¹PNMR) On the basis of the previously discussed studies, the formation of a P-S-C chemical bond has been established.

Full text of DOI:10.1080/10426500600892693

Phosphorus, Sulfur, and Silicon, 182:219–226, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500600892693
Substitution Reactions of Mono- and Trichloro Acetic
Acids with Ammonium Dialkyl (Alkylene)
Dithiophosphates
Neelam Harkut
Padam N. Nagar
Department of Chemistry, University of Rajasthan, Jaipur, India
A
reaction of mono- and trichloro acetic acid with ammonium salts
of alkylene (dialkyl) dithiophosphate; [OGOPS NH ; G = CH CH CHMe
,
2
4
2
2
C(Me) C(Me)
,
CH C(Me) CH , and C(Me) CH CHMe ; (RO) PS -
2
2
2 2 2 2 2 2 2
NH ; and R = C H , C H , i-C H ;] in a 1:1 molor ratio in refluxing benzene solu-
4
2
5
3
7
3
7
tion yields low melting solids and light-yellow oily liquids of the type [(RO) PS Rꢀ
2
2
and OGOPS Rꢀ, where Rꢀ = CH COOH and Cl CCOOH], which are hygroscopic
2
2
2
in nature. These newly synthesized complexes have been characterized by physic-
1
31
ochemical and spectroscopic techniques (MW, IR, H, and PNMR) On the basis
of the previously discussed studies, the formation of a P
been established.
S C chemical bond has
Keywords [(Dialkoxyphosphorothioyl)thio]acetic acid; Dichloro alkylene dithiophos-
phato acetic acid; IR spectra; NMR spectra
INTRODUCTION
Earlier investigations on a variety of metal, organometal, and organic
derivatives of alkylene(dialkyl)dithiophosphates1−17 yielded interest-
ing chemical-bonding patterns as well as biological applications. It has
been observed that biological activity is markedly governed by the na-
ture of alkyl/aryl(substituted) groups substituted on an alkylene(alkyl)
dithiophosphato moiety.
In view of this, it was considered of interest to extend the
present course of investigations on the syntheses of mono-, chloro-,
and trichloro acetic acid derivatives of ammonium alkylene(dialkyl)
dithiophosphates.
Received March 31, 2006; accepted June 26, 2006.
Address correspondence to Neelam Harkut, Department of Chemistry, University of
Rajasthan, Jaipur, 302004 India. E-mail: neelam gats2005@rediffmail.com
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N. Harkut and P. N. Nagar
RESULTS AND DISCUSSION
Dialkyl dithiophosphato acetic acid and alkylene dithiophosphato acetic
acid have been synthesized by reacting monochloroacetic acid with am-
monium dialkyl (alkylene) dithiophosphates in refluxing benzene (8–
6 h). These displacement reactions appear to be slow due to the high
acidic strength of monochloro acetic acid, which generates chloride ions
very slowly. No change in the reactivity has been observed even when
using acetonitrile as a solvent.
ꢀ ꢁ
(RO)2P(S)SNH4 + ClCH2COOH−→ (RO)2P(S)SCH2COOH + NH4Cl↓
ꢀ ꢁ
OGOP(S)SNH4 + ClCH2COOH −→ OGOP(S)SCH2COOH + NH4Cl↓
(1)
These new derivatives are white-colored low-melting solids that are
hygroscopic in nature and are soluble in common organic solvents. Sim-
ilarly, compounds of the type dichlro dialkyl dithiophosphato acetic acid
and dichlro dialkylene dithiophosphato acetic acid have been synthe-
sized by reacting trichloroacetic acid with ammonium dialkyl/alkylene
dithiophosphates in refluxing benzene for 20∼22 h. Due to the high
acidic strength of trichloroacetic acid, the substitution of a chloride ion
is difficult and thus requires a longer time refluxing for completion.
ꢀ ꢁ
(RO)2P(S)SNH4 + Cl3CCOOH −→ (RO)2P(S)SCCl2COOH + NH4Cl ↓
ꢀ ꢁ
OGOP(S)SNH4 + Cl3CCOOH −→ OGOP(S)SCCl2COOH + NH4Cl ↓
(2)
An attempt has been made to synthesize 1:2 and 1:3 derivatives
of trichloroacetic acid, but it has been observed that in this reaction,
always and only 1:1 product has been isolated. The products formed
are pale-yellow oily liquids that are hygroscopic in nature and are sol-
uble in common organic solvents (tetrahydrofurane, ethanol, acetone
etc.).
IR Spectra
IR spectra of the newly synthesized derivatives show the following char-
acteristic changes (Table I).
1. A broad and intense νOH absorption band has been present
at 3520 cm−1 for the COOH group of monochloro acetic acid
derivatives, and a broad and intense absorption band for the νOH
group has been observed in the region 3300–3000 cm−1 for trichloro
acetic acid derivatives.

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N. Harkut and P. N. Nagar
2. A comparison of the νC O absorption band present in monochloro
acetic acid at 1736 cm−1 indicates a slight shift toward lower
wave numbers (10–20 cm−1). Similarly, a νC O absorption band of
trichloroacetic acid present at 1740 cm−1 shows a slight shift toward
lower wave numbers (10–20 cm−1) due to a lower electrical effect of
the chlorine atom.
3. The ν(P) OC and νP O(C) absorption band appears in the regions
1075–1025 cm−1 and 830–770 cm−1, respectively, while a broad ab-
sorption band around 915–970 cm−1 is due to ring vibrations in
monochloro acetic acid derivatives. For trichloro acetic acid deriva-
tives, the absorption band appears in the regions 1070–1040 cm−1
and 850–810 cm−1, respectively.
4. The νC–Cl absorption band present in the region 720–715 cm−1 has
disappeared in monochloro acetic acid derivatives, and in trichloro
acetic acid derivatives, the νC Cl absorption band present in the
region 750–780 cm−1 has shifted toward lower wave numbers (10–
15 cm−1) in comparison to its position in trichloroacetic acid.
5. νP S and νP S absorption bands have been observed at 665–
650 cm−1 and 580–530 cm−1, respectively, in monochloro acetic acid
derivatives. The νP S and νP S absorption bands have been ob-
served in the region 675–640 cm−1 and 590–540 cm−1, respectively,
in trichloro acetic acid derivatives.
6. A new medium intensity absorption band has been observed
in the region 560–675 cm−1, which was tentatively assigned to
phosphorus-sulfur-carbon(S P S C) chemical linkage in these
derivatives.
PMR Spectra
PMR spectra of these derivatives have been recorded in CDCl3, and
these are tabulated in Table II. The PMR spectra show a multiplet for
OCH2 and OCH protons due to long range coupling with the magneti-
cally active phosphorus atom. In addition to this, the PMR signal pre-
sented at δ 12–11.5 ppm is due to an acidic proton of substituted acetic
acid. Deammonization has been observed in the PMR spectra of these
derivatives, thus showing the formation of the (S P S C) chemical
bond.
31P NMR Spectra
A
31P NMR resonance signal in dialkyl (alkylene) dithiophosphato
acetic acid has been observed in the range 50.4 to 62.4 ppm, which
exhibits deshielding (δ 13–19 ppm) in the 31P chemical shift value in
comparison to dithiophosphates (70–104 ppm).

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N. Harkut and P. N. Nagar
31P NMR spectra of dichloro dialkyl (alkylene) dithiophosphato acetic
acid have been recorded in benzene. In a proton-decoupled 31P spectra,
one sharp signal has been observed at δ 50–60 ppm, which indicates
a presence of one type of phosphorus atom (Table II). The 31P NMR
chemical shift values observed in ammonium dialkyl (alkylene) dithio-
phosphate (77–102 ppm) was shifted upfield (δ = 18–28 ppm) in the
corresponding trichloro acetic acid derivatives, which indicates the co-
valent character of a sulphur-carbon linkage as well as an absence of
coordinating tendency in these derivatives.
On the basis of the previously discussed studies, the formation of
a phosphorus-sulfur-carbon (S P S C) chemical linkage with a free
thiophosphoryl group has been tentatively proposed.
EXPERIMENTAL
Solvents were dried by standard methods. Ammonium salt of di-
alkyl/alkylene dithiophosphates have been prepared by the method re-
ported in the literature.17 Sulphur was estimated gravimetrically as
barium sulphate (messenger method)17 and has been purified by vac-
uum distillation. Molecular weights were determined by the Knaur
Vapour Pressure Osmometer using a chloroform solution at 45◦C. IR
spectra were recorded in Nujol mull (4000–200 cm−1) on an FTIR spec-
trophotometer model Megna-IR-550 MICOLAC-USA. Carbon and hy-
drogen analyses were performed on a Perkin Elemer CHN/O analyzer.
1H NMR spectra were recorded in CDCl3 solution on a 90 MHz JEOL
FX 300 Mhz FT NMR spectrometer using TMS as an internal reference.
31P NMR were recorded in C6H6using H3PO4 as an external reference.
The experimental details of representative compounds are described in
the following sections. Analytical results are summarized in Table III.
Preparation of Ammonium Dialkyl (Alkylene)
Dithiophosphate Ligands17
These ligands can be prepared by the reactions of P2S5 with the cor-
responding alcohol/1,2 or 1,3 glycols in anhydrous benzene by passing
dry ammonia gas.
These may be purified by washing with benzene or ether or may be
crystallized from a benzene parent alcohol mixture.
Preparation of [(Diisopropoxyphosphorothioyl) thio]
Acetic Acid
A
mixture of ammonium diisopropyl dithiophosphate (2.42 g,
10.47 mmole) and monochloro acetic acid (0.98 g, 10.37 mmole) in

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N. Harkut and P. N. Nagar
benzene (50–60 mL) were refluxed for 6–8 h. Ammonium chloride that
precipitated was filtered off, and the product was obtained (1.70 g,
78.01%) after evaporating the solvent under reduced pressure; a
white low-melting solid was obtained. Relevant data are tabulated in
Table III.
Preparation of Dichloro [(4-Methyl-2-sulfido-1,3,2-
dioxaphosphinane-2-yl)thio] Acetic Acid
A benzene solution of trichloro acetic acid (1.21 g, 7.33 mmole) was
added into an ammonium salt of hexylene dithiophosphate (1.70 g,
7.42 mmole) and refluxed for 20–22 h. The ammonium chloride pre-
cipitated during the course of reaction was filtered off under anhydrous
reaction conditions, and the product was isolated after evaporating the
solvent under reduced pressure. A pale-yellow oily liquid was obtained
(2.23 g, 89.22%). Relevant data are tabulated in Table III.
REFERENCES
[1] H. P. S. Chauhan, C. P. Bhasin, G. Srivastava, and R. C. Mehrotra, Phosphorus,
Sulfur, and Silicon, 15, 99 (1983).
[2] K. C. Molloy, M. B. Hossain, D. V. Helim, J. J. Zuckerman, and I. Haidue, Inorg.
Chem., 18, 3507 (1979).
[3] K. C. Molloy, M. B. Hossain, D. V. Helim, J. J. Zuckerman, and I. Haidue, Inorg.
Chem., 19, 3507 (1980).
[4] R. C. Mehrotra, G. Srivastava, and B. P. S. Chauhan, Coord. Chem. Revs., 55, 207
(1984).
[5] A. Chaturvedi, P. N. Nagar, and G. Srivastava, Phosphorus, Sulfur, and Silicon, 80,
141 (1993).
[6] P. N. Nagar, Phosphorus, Sulfur, and Silicon, 79, 207 (1993).
[7] A. Chaturvedi, P. N. Nagar, and G. Srivastava, Main Group Met. Chem., 16, 45
(1993).
[8] A. Chaturvedi, P. N. Nagar, and A. K. Rai, Synth. React., Inorg. Met. Chem., 26,
1025 (1996).
[9] A. Chaturvedi, R. K. Sharma, P. N. Nagar, and A. K. Rai, Phosphorus, Sulfur, and
Silicon, 112, 179 (1996).
[10] R. Purwar and P. N. Nagar, Phosphorus, Sulfur, and Silicon, 86, 211 (1994).
[11] R. Purwar, M. K. Sharma, R. K. Sharma, and P. N. Nagar, Phosphorus, Sulfur, and
Silicon, 174, 15 (2001).
[12] N. Harkut and P. N. Nagar, Phosphorus ,Sulfur, and Silicon, 180, 2517 (2005).
[13] N. Harkut, A. Keshawat, and P. N. Nagar, Phosphorus, Sulfur, and Silicon, 181,
2177–2185 (2006).
[14] C. S. Sharma, M. K. Sharma, and P. N. Nagar, Phosphorus, Sulfur, and Silicon, 177,
981 (2002)
[15] C. S. Sharma and P. N. Nagar, Phosphorus, Sulfur, and Silicon, 179, 1793 (2004).
[16] C. S. Sharma and P. N. Nagar, Phosphorus, Sulfur, and Silicon, 181, 1 (2006).
[17] A. I. Vogel, A Textbook of Quantitative Inorganic Analysis, 4th Ed. (ELBS, London
1973).