330 JOURNAL OF CHEMICAL RESEARCH 2007
and extracting it with ether. After disappearance of the phosphonic/
phosphoric acd signal in 31P NMR, the reaction mixture was
washed with ether, filtered and the solvent was evaporated in rotary
evaporator. The residue was distilled under vacuum to afford the pure
compound. B.p.227–228–230°C/0.1mm Hg; yield: 32.10 g(96%);
1H NMR δ: 7.33(m, 10-H, Ar), 4.42(m, 2-H, CH2),1.75(m, 8H for
4 CH2), 1.30 (t, 3-H, CH3, J =); IR: (KBr) n(max) 2970, 2880 (CH),
1265 (P = O), 1040–1065 (P–O–C), 988–970 (P–O–Aryl) cm-1.
In conclusion, a simple, efficent and one-step method has
been developed for the synthesis of alkyl/aryl phosphonates
using immobilised p-TsOH–Celite as an efficent condensing
agent. The main advantage of this method is that it takes
place under mild reaction conditions at ambient temperature,
requires short reaction times, reduces hazards and the process
is operationally simple with excellent yields.
Experimental
We thank Dr R. Vijayaraghavan, Director, DRDE, Gwalior for
his keen interest and encouragement.
Boiling points are uncorrected. IR spectra were recorded on a Bruker
FT-IR spectrometer, model Tensor 27, on KBr disks. 1H and 31P
NMR spectra were recorded in CDCl3 on a Bruker DPX Avance FT-
NMR at 400 and 162 MHz respectively using tetramethylsilane as an
Receivedꢀ1ꢀMarchꢀ2007;ꢀacceptedꢀ23ꢀMayꢀ2007ꢀ
Paperꢀ07/4516ꢀ doi:ꢀ10.3184/030823407X218066
1
internal standard for H and 85% H3PO4 as an external standard for
31P NMR. A Chemito GC model 1000 instrument was used with a
flame ionisation detector (FID). A capillary column (30 m ¥ 0.25 mm
I.D-BP5) packed with 5% phenyl and 95% dimethyl polysiloxane
(SGE) coated on fused silica was employed. The injection port and
detector block were maintained at 280°C and 260°C respectively and
the column oven was used with a programmed temperature profile
started at 50°C, ramped up to 280°C at 25°C min-1. Nitrogen was
used as carrier gas (at a flow rate of 30 ml min-1). Air for the FID
was supplied at 300 ml min-1 and hydrogen at 30 ml min-1. In all
analyses, 0.4 ml sample were injected and peaks recorded on an Iris32
data acquisition station. The GC–MS analyses were performed by EI
(70 eV) in full scan mode with an Agilent 6890 GC equipped with
a model 5973 mass selective detector (Agilent Technologies, USA).
An SGE BPX5 capillary column with 30 m length ¥ 0.32 mm internal
diameter ¥ 0.25 mm film thickness was used at temperature program
of 80°C (2 min) –20°C/min–280°C (3 min). Helium was used as
the carrier gas at a constant flow rate of 1.2 ml min-1. The samples
were analysed in splitless mode at the injection temperature.
The molecular weights of all the synthesised compounds were
confirmed by the ammonia Chemical Ionisation(CI) technique in the
mass spectrometer.
References
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Preparationꢀofꢀp-TsOH–Celite
p-TsOH–Celite was prepared by combination of p-TsOH (0.2 mol,
34.4 g) and Celite (Celite®521, 0.2 mol, 12.0 g)) in a mortar and
pestle by grinding together until a fine, homogenous powder was
obtained (10–15 min). It was mixed with 150 ml of distilled water
and stirred for 1 h at room temperature and then water was removed
at redued pressure using a Heidolph rotary evaporator till dryness.
It was shaken with acetonitrile (100 ml), filtered and washed with
acetonitrile (3 ¥ 25 ml). It was further dried under vacuum at 100°C for
2 h and stored in a stoppered flask in a desiccator. However, in order
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were performed by scanning electron microscope (SEM). It was
observed that p-TsOH was finely and uniformly distributed on the
Celite.
7
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Experimentalꢀprocedureꢀforꢀdipropylꢀethylphosphonate
Ethyl phosphonic acd (11.0 g, 0.10 mol), p-TsOH–Celite (46.20 g,
0.20 mol) and dry propyl alcohol (12.0 g, 0.20 mol) were mixed
in a mortar at room temperature. The reaction mixture was ground
with a pestle and mortar. The progress of reaction was monitored
by TLC and 31P NMR after removing a few milligrams of reaction
mixture and extracting it with ether. After disappearance of the ethyl
phosphonic acd signal in 31P NMR, the reaction mixture was washed
with ether, filtered and the solvent was evaporated. The residue
was distilled under vacuum to afford the pure compound. B.p. 82–
1
83°C/18 mmHg; Yield –17.26 g, (89%). H NMR δ: 4.05(m, 4-H,
–OCH2, JH-H = 7.0 JH-P = 8.0 Hz), 1.74 (m, 4H, 2-CH2, JH-H = 7.04 Hz),
1.68 (m, 2H, CH2P, JP-H = 18.0, JH-H = 8.0 Hz), 1.09(td, 3H, CH3 JP-H
= 20.1 Hz), 0.98(t, 6-H, 2-CH3); 13C NMR δ: 19.6 (CH2P, J = 142.5
Hz), 6.54 (CH3 CH2P, J = 6.9 Hz), 67.50 (–OCH2 of propyl, J = 6.65
Hz), 23.75(middle CH2 of propyl, J = 6.5 Hz), 9.97(terminal methyl
of propyl) IR: (KBr) n(max) 2950, 2890 (C-H), 1250 (P = O), 1090,
1050 (P–O–C)cm-1. GC-MS(EI,%) 195(0.5), 179(1.0), 165(5.2),
153(100), 139(55), 111(100), 93(75), 81(40), 65(30)
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D.K. Dubey and A.K. Gupta, J.ꢀChem.ꢀRes., 2005, 3, 194.
Typicalꢀexperimentalꢀprocedureꢀforꢀdiphenylꢀhexylphosphate
Diphenyl phosphoric acd (25.0 g, 0.10 mol), p-TsOH–Celite (23.2 g,
0.10 mol) and dry hexyl alcohol (10.2 g, 0.10 mol) were mixed in a
mortar at room temperature. The reaction mixture was ground with
a pestle and mortar. The progress of reaction was monitored by TLC
and 31P NMR after removing few milligrams of reaction mixture
14 Q.Yao and S. Levchik, TetrahedronꢀLett., 2006, 47, 277; (b) M. Sathe,
A.K. Gupta and M.P. Kaushik, TetrahedronꢀLett., 2006, 47, 3107.
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Investigation Vol.13. Goskhimizdat, Moscow, 1953, 427; (b) L.D.A. Quin,
GuideꢀtoꢀOrganophosphorusꢀChemistry; John Wiley and Sons, 2000.
PAPER: 07/4516