Convenient synthesis of dicyclohexyldithiophosphinic acid

Article abstract of DOI:10.1080/00397910903029909

Dicyclohexyldithiophosphinic acid was synthesized by a three-step strategy through the Grignard reaction of PSCl₃ with cyclo-C₆H ₁₁MgBr and the P-P bond-cleavage reaction of the intermediate. The ¹H NMR data of ammonium dicyclohexyldithiophosphinate 4 and dicyclohexyldithiophosphinic acid 5 were characterized by ¹H- ¹H correlation spectra. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910903029909

This article was downloaded by: [University of California, San Francisco]
On: 01 March 2015, At: 18:34
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
Convenient Synthesis of
Dicyclohexyldithiophosphinic Acid
Cai Jia a , Fengxian Yu a b , Fang Wang a , Wangsuo Wu b & Jing Chen
a
a Institute of Nuclear and New Energy Technology, Tsinghua
University , Beijing, China
b Institute of Radiochemistry and Nuclear Environment, Lanzhou
University , Gansu Province, China
Published online: 17 Jun 2010.
To cite this article: Cai Jia , Fengxian Yu , Fang Wang , Wangsuo Wu & Jing Chen (2010) Convenient
Synthesis of Dicyclohexyldithiophosphinic Acid, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 40:14, 2036-2041, DOI:
10.1080/00397910903029909
To link to this article: http://dx.doi.org/10.1080/00397910903029909
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Synthetic Communications1, 40: 2036–2041, 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910903029909
CONVENIENT SYNTHESIS OF
DICYCLOHEXYLDITHIOPHOSPHINIC ACID
Cai Jia,1 Fengxian Yu,1,2 Fang Wang,1
Wangsuo Wu,2 and Jing Chen1
1Institute of Nuclear and New Energy Technology, Tsinghua University,
Beijing, China
2Institute of Radiochemistry and Nuclear Environment, Lanzhou University,
Gansu Province, China
Dicyclohexyldithiophosphinic acid was synthesized by a three-step strategy through the
Grignard reaction of PSCl3 with cyclo-C6H11MgBr and the P-P bond-cleavage reaction
of the intermediate. The 1H NMR data of ammonium dicyclohexyldithiophosphinate 4
and dicyclohexyldithiophosphinic acid 5 were characterized by 1H-1H correlation spectra.
Keywords: Actinides=lanthanides separation; dithiophosphinic acid; synthesis
Diorganyldithiophosphinic acids as well as their derivatives have been investigated
for decades. The early research focused on their applications as lubricant additives,
insecticides, ore flotation agents, and rubber accelerators.[1] In recent years, many
reports have been delivered on the metal complexes of dithiophophiphinic acids,
especially on the separation of trivalent actinides from lanthanides,[2] which is very
important for the advanced nuclear fuel cycle and the exploration of sustainable
nuclear energy.
Because of the different substituent groups, there are various synthetic routes.
Diaryldithiophosphinic acids were obtained mainly by the Higgins’s method with
P2S5, benzene or substituted benzene, and AlCl3.[3] Di(n-alkyl)dithiophosphinic acids
were formed by the Grignard reaction of thiophosphoryl chloride (PSCl3) with
alkylmagnesium halides (RMgX), followed by treatment with Na2S ꢀ 9H2O and S
powder.[4] Another method, reacting dialkylphosphine with S in diluted aq. NH4OH
or NaOH and acidifying the resulting intermediate, gave not only the products of
aryl groups or n-alkyls but also those of sec-alkyls.[5] There have been some other
methods[6] reported on the synthesis of dithiophosphinic acid. Dicyclohexyldithio-
phosphinic acid was most frequently obtained by reaction of dicyclohexylphosphine
with S in aq. NH4OH or NaOH. Herein, we discuss the synthesis of the title
compound through the Grignard reaction of PSCl3 with c-C6H11MgBr and the
Received February 15, 2009.
Address correspondence to Jing Chen, Institute of Nuclear and New Energy Technology, Tsinghua
University, Beijing 102201, China. E-mail: jingxia@tsinghua.edu.cn
2036

CONVENIENT SYNTHESIS OF DICYCLOHEXYLDITHIOPHOSPHINIC ACID
2037
Scheme 1. Synthesis of dicyclohexyldithiophosphinic acid.
P-P bond-cleavage reaction of the intermediate compound, which avoids the
formation and application of extremely stimulating dicyclohexylphosphine.
PSCl3 reacted with the Grignard reagent from cyclohexyl bromide and Mg in
Et2O to form tetracyclohexyl-diphosphine disulfide 2. Formation of this intermedi-
ate was confirmed by Issleib and Tzschach.[7] Similar to the analogs of Me, Et, and
Bu, dicyclohexyldiphosphine disulfide exists in the trans (C2h) conformation.[8] This
crude intermediate reacted with Na2S ꢀ 9H2O and S in dioxane, giving sodium dicy-
clohexyldithiophosphinate 3. Acidification of compound 3 with 2 M HCl afforded a
crude product of the title compound. Treating this crude with NH3 and recrystalliz-
ing the resulting ammonium salt gave the white crystal powder 4. Acidification of 4
with 2 M HCl was achieved to give pure title compound 5 (Scheme 1).
The key for interpretation of 1H NMR spectra of compounds 4 and 5 lies in the
obvious chemical shift difference between equatorial and axial protons. The equatorial
protons occur at a lower field than the respective axial ones as a result of the deshield-
ing effect of the fields of C-C bonds. The signs of protons from low to high field in the
1H-1H correlation (COSY) spectrum of compound 4 are shown in Fig. 1. This is
similar to the 1H-1H COSY spectrum of the title compound 5 (Fig. 2).
In summary, we have described a new convenient synthesis of dicyclohexyl-
dithiophosphinic acid. Our chemistry with dialkyldithiophosphinic acids will be
reported in due course.
EXPERIMENTAL
Melting points were determined with an Electrothermal IA9100 and are uncor-
rected. Infrared (IR) spectra were recorded on a Nicolet Nexus 470 Fourier trans-
1
form IR (FTIR) spectrophotometer. H and 13C NMR spectra were recorded on a
Jeol ECA-600 FT-NMR spectrometer. Both low- and high-resolution mass spectra
were carried out on GCT-MS Micromass UK or Bruker Apex IX (7.0T) instruments.
Anhydrous ethyl ether (Et2O) and dioxane were prepared by a solvent purification
system. All experiments were performed under a nitrogen atmosphere.
Tetracyclohexyldiphosphine Disulfide (2)
Twenty were added ml of the solution of cyclohexyl bromide (61 ml, 0.5 mol) in
ethyl ether (130 ml) to a mixture of Mg dust (12.2 g, 0.5 mol), dried Et2O (20 ml), and

2038
C. JIA ET AL.
Figure 1. 1H-1H COSY spectrum of compound 4.
a little I2 to initiate the reaction. The rest of cyclohexyl bromide in ether was added
dropwise when stirring, keeping the reaction mixture mild refluxing. After the
addition of bromide, the solution was refluxed by heating until the Mg dust almost
disappeared. The resulted Grignard reagent was cooled down to less than 10 ꢁC.
Under N2, PSCl3 (13 ml, 0.125 mol) was dropped into the stirred Grignard solution
in an ice-water bath, keeping the reaction temperature at less than 10 ꢁC. After 24 h
of stirring at room temperature, the reaction mixture was poured into 0 ꢁC 10%
H2SO4 solution and stirred for a few minutes. The aqueous layer was extracted twice
with ether. The organic layers were combined, dried, and condensed, giving colorless
oil 2 (22.7 g, 80%), which was directly subjected to the next step.
Ammonium Dicyclohexyldithiophosphinate (4)
The mixture of compound 2 (22.7 g, 0.05 mol), Na2S ꢀ 9H2O (11.9 g, 0.05 mol),
and S powder (1.6 g, 0.05 mol) in dioxane (200 ml) was refluxed for 24 h. The hot reac-
tion solution was filtered, and the resulting light-yellow filtrate was condensed to give
a red brown solid (22.3 g). This solid was dissolved in water. After removal of the
upper oily layer, the aqueous layer was washed twice with petroleum ether. The aque-
ous layer was adjusted to pH 1 with 2 M HCl and filtered, giving 20 g light-yellow

CONVENIENT SYNTHESIS OF DICYCLOHEXYLDITHIOPHOSPHINIC ACID
2039
Figure 2. 1H-1H COSY spectrum of title compound 5.
solid. The product was dissolved in cyclohexane, and dry NH3 gas was bubbled in,
with a light yellow solid (18.5 g) obtained. This solid was recrystallized with
alcohol=benzene (1=50, v=v), giving white crystal powder 4 (16 g, 0.057 mol, 57%),
1
mp 179–180 ꢁC. H NMR (600 MHz, CD3OD) d ppm 1.17 (m, 6H, 2H4a, 2H3a,
2H5a), 1.40 (m, 4H, 2H2a, 2H6a), 1.59 (d, J4e,4a ¼ 11.7 Hz, 2H, 2H4e), 1.71 (m, 6H,
2H1, 2H3e, 2H5e), 1.92 (d, I2a,2e ¼ J6a,6e ¼ 13 Hz, 4H, 2H2e, 2H6e). 13C NMR
(150 MHz, CD3OD) d ppm 43.6, 43.3 (2C1), 26.5, 26.4 (2C3, 2C5), 26.1 (2C4), 25.8
(2C2, 2C6). 31P NMR (240 MHz, CD3OD) d ppm 86.1. HRMS-ESI calcd. for
C12H26NPS2 (MþNH4)þ: 261.0906. Found: 261.0903.
Dicyclohexyldithiophosphinic Acid (5)
The white crystal 4 (0.975 g, 0.0035 mol) was dissolved in water (10 ml) and
centrifuged. The solution was mixed with 2 M HCl (5 ml) and extracted twice with
ether (10 ml). The ether layers were combined, dried, and evaporated to give white
1
crystal powder 5 (0.79 g, 0.0030 mol, 86%), mp 101–102 ꢁC. H NMR (600 MHz,
CD3OD) d ppm 1.13 (q, J4a,3a ¼ J4a,5a ¼ 13.0 Hz, J4a,4e ¼ 12.4 Hz, 2H4a), 1.24 (q,
J3a,3e ¼ J5a,5e ¼ 12.4 Hz, J3a,2a ¼ J3a,4a ¼ J5a,6a ¼ J5a,4a ¼ 13.0 Hz, 4H, 2H3a, 2H5a),
1.36 (m, 4H, 2H2a, 2H6a), 1.63 (d, J4a,4e ¼ 12.4 Hz, 2H4e), 1.76 (d, J3a,3e ¼ J5a,5e
¼
11.04 Hz, 4H, 2H3e, 2H5e), 1.90 (s, 4H, 2H2e, 2H6e), 1.96 (m, 2H1). 13C NMR

2040
C. JIA ET AL.
(150 MHz, CD3OD) d ppm 25.56, 25.58, 25.67, 25.83, 25.93 (10C), 41.49, 41.80
(2C1). 31P NMR (240 MHz, CD3OD) d ppm 87.33. HRMS-TOF EIþ calc. for
C12H23PS2 Mþ: 262.0979. Found: 262.0981.
ACKNOWLEDGMENTS
This work was supported by the National Natural Science Foundation of
China (Project 20702028) and the National Program on Key Basic Research Project
(2007CB613506).
REFERENCES
1. (a) Craig, W. G.; Miller, C. O. Esters of di(organo)-phosphinodithioic acids. US Patent
2881200, 1959; (b) Schrader, G. Dithiophosphinic acid esters. Ger. Patent 1146883, 1963;
(c) Malz, H.; Schlesmann, H.; Dinges, K. Stabilization of acrylonitrile polymers. Ger.
Patent 1173645, 1964; (d) Wystrach, V. P.; Peters, G. A. Salts of 2-cyanoethylphosphino-
dithioic acids. US Patent 3138605, 1964; (e) Kozic, S. J.; Savides, C. Heat stabilizers for
polypropylene containing asbestos. Ger. Patent 2009943, 1970; (f) Wystrach, V. P.;
Rauhut, M. M.; Freyberger, W. L. Froth flotation of ores by secondary dithiophosphinic
acids or their salts or esters. Ger. Patent 1214171, 1966.
2. (a) Chen, J.; Jiao, R.; Zhu, Y. Purification and properties of Cyanex 301. Yingyong Huaxue
1996, 13(2), 45–48; (b) Sherif Abdel, H. H. N. Hochselektive extraktionssysteme auf basis
der dithiophosphinsauren: Experimentelle und theoretische untersuchungen zur actinoiden
¨
(III)—Abtrennung.=Highly selective extraction system based on dithiophosphinic acid:
Experimental and the theoretical analysis of actinoide (III)—separation. Schriften des
Forschungszentrums Juelich, Germany. Reihe Energietechnik=Energy Technology 2004,
29, 198; (c) Modolo, G.; Odoj, R. Synergistic selective extraction of actinides(III) over
lanthanides from nitric acid using new aromatic diorganyldithiophosphinic acids and
neutral organophosphorus compounds. Solvent Extraction and Ion Exchange 1999, 17(1),
33–53; (d) Modolo, G.; Odoj, R. The separation of trivalent actinides from lanthanides
by dithiophosphinic acids from HNO3 medium. Journal of Alloys and Compounds 1998,
271–273, 248–251.
3. Higgins, W. A.; Vogel, P. W.; Craig, W. G. Aromatic phosphinic acids and derivatives, I: Di-
phenylphosphinodithioic acid and its derivatives. J. Am. Chem. Soc. 1955, 77, 1864–1866.
4. (a) Christen, P. J.; van der Linde, L. M.; Hooge, F. N. The reaction of alkylmagnesium
halides with thiophosphoryl chloride, I: Formation of bi(dialkylphosphinothioyl) com-
pounds. Recueil des Travaux Chimiques des Pays-Bas et de la Belgique 1959, 78, 161–172;
(b) Kuchen, W.; Metten, J. Metal complexes of dialkyldithiophosphinic acids. Ger. Patents
1137732 and 19621011, 1962; (c) Kuchen, W.; Strolenberg, K.; Metten, J. Organophosphorus
compounds, VI: Dialkyldithiophosphinic acids and bis(dialkylthiophosphoryl)sulfanes.
Chem. Ber. 1963, 96, 1733–1740.
5. Rauhut, M. M.; Currier, H. A.; Wystrach, V. P. Preparation of dithiophosphinates from
secondary phosphines and sulfur under alkaline conditions. J. Org. Chem. 1961, 26,
5133–5135.
6. (a) Mastryukova, T. A.; Shipov, A. E.; Kabachnik, M. I. Dimethylphosphinothioic and
dimethylphosphinodithioic acids and their derivatives. Zh. Obshch. Khim. 1962, 32,
3579–3582. (b) Grishina, O. N.; Kosova, L. M.; Klyuchanskaya, S. M. Alkylthionopho-
sphine sulfides, XII: Reaction of alkylthionophosphine sulfides with organomagnesium
compounds. Zh.Obshch. Khim. 1971, 41(9), 1995–1999.

CONVENIENT SYNTHESIS OF DICYCLOHEXYLDITHIOPHOSPHINIC ACID
2041
7. (a) Issleib, K.; Tzschach, A. Preparation of secondary aliphatic phosphines. Chem. Ber.
1959, 92, 704–711; (b) Christen, P. J.; van der Linde, L. M.; Hooge, F. N. The reaction
of alkylmagnesium halides with thiophosphoryl chloride, I: Formation of bi(dialkylpho-
sphinothioyl) compounds. Recueil des Travaux Chimiques des Pays-Bas et de la Belgique
1959, 78, 161–172.
8. (a) Cowley, A. H.; White, W. D. The vibrational spectra and structures of phosphorus
compounds, I: Diphosphine disulfides. Spectrochim. Acta 1966, 22(8), 1431–1440; (b)
Exner, O.; Almasi, L.; Paskucz, L. Dipole moments and conformation of dialkyldithiopho-
sphinic acids and their derivatives. Coll. Czech. Chem. Commun. 1973, 38(3), 677–689.