SYNTHESIS OF POLYFLUORINATED ETHERS
1647
IV IX under relatively mild conditions [see Exper-
imental, method (b)]:
Tosylation of common alcohols by the nucleophilic
substitution mechanism occurs under relatively mild
conditions; the subsequent reaction of the resulting
derivatives with telomeric alcohols gives the desired
compounds IV IX in high yields and does not require
any anhydrous medium [see Experimental, method (c)]:
H(CF CF ) CH OH + RX
2
2 n
2
A or B, catalyst, KOH
H(CF CF )CH OR + HX,
2
2
2
IV IX, 40 70%
KOH, H O
2
ROH + TsCl
[ROTs]
conditions: (A) CH Cl, H O, 40 C, 5 h, n = 2; (B)
2
2
HCl
+
THF, H O, 60 C, 5 h, n = 3. Catalyst: [Et BzN] Cl ;
2
3
H(CF CF ) CH OH, KOH, THF, H O, catalyst
2
2 n
2
2
X = Cl, Br; R = C H , n = 2 (IV); R = C H , n =
IV IX + TsOK.
87 96%
4
9
5
13
2
(V); R = C H , n = 2 (VI); R = C H , n = 3 (VII);
10 21 4 9
R = C H , n = 3 (VII); R = C H , n = 3 (IX).
6
13
10 21
It should be noted that isolation of the tosyl deriva-
tives (ROTs) is not necessary for performing the sec-
ond step of the synthesis successfully. Comparison of
the yields of IV IX in the processes whose second
step was performed with isolated and crude ROTs
shows that the difference in the yields is as small as
Comparative analysis of the two procedures for
preparing PFEs I IX shows that none of them ensures
quantitative yields of the desired compounds, and
no correlation can be revealed between the substrate
structure and PFE yield.
5
10%.
The highest yields of PFEs (up to 90%) are at-
tained when a two-step procedure is used: first a fluo-
rinated alcohol is converted to a sulfonate (mesylate,
tosylate, triflate) by the reaction with appropriate sul-
fonyl derivative [10], after which the sulfonate group
is readily replaced by the alcoholate ion formed from
a nonfluorinated alcohol in situ. According to [10],
this two-step process can be schematically represented
as follows:
Thus, the latter procedure is the best from the view-
point of conditions and results: reaction temperature
60 C, time (total of two steps) 8 h, and almost quan-
titative yields of the desired compounds.
The IR spectra of I IX contain the following char-
1
acteristic absorption bands, , cm : 1111 1142 (C F),
1
2
200 1204 (C O C), and 2856 2879, 2927 2959,
934 2966 (C H).
R SO Cl, NEt
The 1H and 19F spectra of all the PFEs prepared
have common features.
f
2
3
f
R CH OH
R CH OSO R
2 2
2
R OH, NaH, 10 h, 130 C
f
R CH OR ,
2
EXPERIMENTAL
f
where R = CF , C F ; R = CH , CF , p-C H CH ;
3
6
13
3
3
6
4
3
R = p-C H NO .
6
4
3
The IR spectra were recorded on a Perkin Elmer
Spectrum One Fourier spectrometer from thin films.
The H and F NMR spectra were measured on
The key step in this reaction is nucleophilic re-
placement of the RSO group, which can be per-
1
19
3
a Bruker DRX-400 spectrometer in CDCl , internal
formed in a virtually quantitative yield. However,
the reaction of sulfo derivatives with a fluorinated
alcohol involves the loss of a valuable chemical in
the first step. Furthermore, the use of NaH requires
anhydrous conditions, and the reaction requires heat-
ing at 130 C for 10 h.
3
references TMS and C F , respectively. The yields,
6
6
boiling points, and elemental analyses of I IX are
given in Table 1, and the NMR data, in Table 2.
Synthesis of polyfluorinated ethers. Method (a).
A mixture of 0.1 mol of alkyl halide, 0.25 mol of
KOH, and 50 ml of DMSO was heated with vigor-
ous stirring to 100 C to obtain a uniform mixture,
and 0.1 mol of telomeric alcohol (n = 1) was added
dropwise at this temperature over a period of 30 min.
The mixture was stirred for 8 h at 100 C. Then 150 ml
of water was added, and the mixture was neutralized
with HCl. The resulting neutral solution was extracted
Among the examined routes to PFEs, the most
promising is, apparently, introduction of a labile leav-
ing group into the hydrocarbon component. The re-
sulting derivative in the modified Williamson reaction
is a more active alkylating agent than alkyl halides.
Comparison of the reactivity of mesylates, triflates,
and tosylates, taking into account the reaction condi-
tions, shows that tosylates are not inferior to the other
reagents, but are preferable from the viewpoint of
convenience in handling and availability.
with CHCl (2 30 ml). The chloroform extracts
3
were combined and dried over CaCl ; the solvent was
2
distilled off. The residue was subjected to fractional
distillation to obtain 1-(1,1,3-trihydroperfluoroprop-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 78 No. 10 2005
Bazhin
