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A.K. Gupta et al. / Journal of Fluorine Chemistry 129 (2008) 226–229
‘
‘naked fluoride anion’’ is easily generated because of higher
50 8C, ramped up to 280 8C at 25 8C/min. Nitrogen was used as
carrier gas (at a flow rate of 30 ml/min). Air for FID was
supplied at 300 ml/min and hydrogen at 30 ml/min. In all
analysis, 0.2 ml sample were injected and peaks recorded on
Iris32 data acquisition station. The GC–MS analyses were
performed in 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
ionic size of the potassium ion. The yields of the dialkyl-
fluorophosphate is also higher when KF was used in
comparison to other fluorinating agents.
The reaction of various dialkylphosphites with DCDMH–
KF afforded corresponding dialkylfluorophosphates in only
1
5–45 min with excellent yields (Table 2).
Caution! dialkylfluorophosphates are highly toxic com-
pounds and should be synthesized by trained personals using
efficient fume hood. Great caution should be exercised
especially while distilling them and residue must be properly
decontaminated by using 20% alkali solution.
with
30 m length  0.32 mm internal diameter  0.25 mm
film thickness was used at temperature program of 80 8C
(2 min)–20 8C/min–280 8C (3 min). Helium was used as the
carrier gas at a constant flow rate of 1.2 ml/min. The samples
were analyzed in splitless mode at injection temperature. The
molecular weight of all the synthesized compounds was
confirmed by methane chemical ionization (CI) technique in
mass spectrometer.
The important advantage of this reaction is the occurrence of
the reaction at room temperature and completion of the reaction
is indicated by the formation of amorphous precipitation of
dimethylhydantoin (DMH) and KCl. The heterogeneous
reaction mixture was filtered and filtrate was distilled to get
desired products.
4.1. Preparation of organic–inorganic hybrid (DCDMH–
KF) reagent
In order to study the up-scaling of this method, reaction was
carried at 1 mol level of diisopropylphosphite (1.0 mol) with
DCDMH (0.5 mol) and KF (1.1 mol) and gave the desired
fluorophosphates in 94% yield. It was also observed that when
in situ generated diisopropylchlorophosphate was isolated and
fluorine exchange reaction was performed by the use of KF
DCDMH–KF was prepared by combination of DCDMH
(1.0 mol, 197.0 g) and KF (2.2 mol, 127.6 g)) in a mortar and
pestle by grinding together until a fine, homogenous powder
was obtained (25–30 min). It was dried under vacuum at 100 8C
for 2 h and stored in a stoppered flask under desiccators. It was
used as and when required.
(1:2) then reaction took longer reaction times (90 min) under
reflux conditions and yield is also reduced (74%).
3
. Conclusions
4.2. Typical experimental procedure for fluorination of
diisopropylphosphite
In summary, we have described an efficient, convenient, and
one pot synthesis of dialkylfluorophosphates from dialkylpho-
sphites at room temperature. Moreover, the procedures offers
several advantages including excellent yield, operational
simplicity, cleaner reaction with 100% conversion, which
makes it a useful and attractive process for the synthesis of
dialkylfluorophosphates.
Diisopropylphosphite, 16.6 g (0.10 mol) was added to a
stirred suspension of DCDMH–KF reagent 16.23 g, (9.85 g,
0.05 mol of DCDMH and 6.38 g, 0.11 mol of KF) in dry
acetonitrile (40 ml) at room temperature in one shot. The
resulting mixture was stirred at room temperature and an
exothermic reaction took place which was monitored by GC
3
1
and P NMR. Reaction mixture was filtered to remove the
precipitate by suction. The solid precipitate was washed with
4
. Experimental
2
 10 mL of DCM. The filtrate and washings were combined.
Chemicals such as PCl , alkanols, KF and DCDMH were
3
The solvent was removed by distillation and product was
obtained by distillation under vacuum. b.p. 81–83/20 mmHg;
yield; 17.32 g (94%). Complete workup of the reaction was
carried out in efficient fume hood. Fume hood provided the best
protection against any exposures to dialkylfluorophosphates in
the laboratory and is the preferred ventilation control device.
Laboratory coat closed toed shoes, long sleeved clothing was
also used while synthesizing and handling the dialkylfluor-
ophosphates. Disposable latex gloves and safety glass were
worn as a normal practice during work up of the reaction
mixture.
purchased from E. Merk (India). Diisopropylphosphite and
diphenylphosphite were purchased from Aldrich Chemical
Company (USA). However, other phosphites used in this study
were prepared by the reported procedure [19]. The solvents
were dried and redistilled before use. Boiling points are
uncorrected. IR spectra were recorded on Bruker FT-IR
1
31
spectrometer model Tensor 27 on KBr disk. H and P NMR
spectra were recorded in CDCl on Bruker DPX Avance FT
NMR at 400 and 162 MHz, respectively, using tetramethylsi-
3
1
lane as an internal standard for H and 85% H PO as an
3
4
3
1
external standard for P NMR. A Chemito GC model 1000
instrument was used with flame ionization detector (FID). A
capillary column (30 m  0.25 mm ID, BP5) packed with 5%
phenyl and 95% dimethylpolysiloxane (SGE) coated on fused
silica was employed. The injection port and detector block
were maintained at 280 and 260 8C, respectively, and the
column oven was at programmed temperature profile started at
Acknowledgements
We thank Dr. R. Vijayaraghavan, Director, DRDE, Gwalior
for his keen interest and encouragement. Authors also thanks
Mr Deepak Pardasani for GC–MS and Avik Mazumder for
NMR analysis.