Russian Journal of Applied Chemistry, Vol. 78, No. 3, 2005, pp. 435 437. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3,
2005, pp. 438 440.
Original Russian Text Copyright
2005 by Igumnov, Lekontseva, Shipigusev, Mukhametshin.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
A New Procedure for Preparing
Perfluoroalkoxypropanoic Acid Fluorides
S. M. Igumnov, G. I. Lekontseva, A. A. Shipigusev, and V. F. Mukhametshin
Perm Branch, Prikladnaya Khimiya Russian Scientific Center, Federal State Unitary Enterprise, Perm, Russia
Received September 15, 2004
Abstract Condensation of perfluoro carboxylic acid fluorides with hexafluoropropene epoxide in the pres-
ence of N, N, N , N -tetraalkyldiaminomethanes was studied.
Perfluoroalkoxypropanoic acid fluorides (PFPAFs)
are starting compounds for preparing perfluoroalkyl
vinyl ethers (monomers for fluoro rubbers, elastomers,
vulcanizates with high heat, ozone, and weather re-
sistance), emulsifiers, fluorinated surfactants, chemi-
cally and thermally stable liquids, lubricating oils, and
polymeric materials [1].
where R = F, CF , C F , CF (CF ) , HCF (CF ) ,
F 3 2 5 3 2 3 2 2 3
CF (CF ) , CF (CF ) , BrCF , or C F OCF .
3
2 5
3
2 7
2
2 5
2
In the process, we used new catalysts, N, N, N , N -
1
2
3 4
tetraalkyldiaminomethanes R R NCH NR R (see
2
1
4
table), where R R are linear or branched alkyls
(C C ) or perfluoroalkyls (C C ), C H OH groups,
1
6
1
6
2 4
or fragments forming with the nitrogen atom a hetero-
ring containing one more nitrogen atom or an oxygen
atom. Examples are bis(dimethylamino)methane, bis-
(diethylamino)methane, dipiperidinomethane, dimor-
pholinomethane, and bis[di( -hydroxyethyl)amino]-
methane.
Procedures for preparing PFPAFs are based on the
reaction of hexafluoropropene epoxide (HFPE) with
perfluoro carboxylic acid fluorides (PFAFs) in polar
aprotic solvents in a wide temperature range (from
80 to 200 C) in the presence of various catalysts,
e.g., alkali metal halides [2], quaternary ammonium
salts [3], tris(dimethylamino)difluorophosphorane [4],
sulfonium salts [5], tetraalkylurea [6], and N, N, N , N -
tetraalkyldiaminodifluoromethane [7].
Condensation of HFPE with PFAF is performed in
a polar aprotic solvent (acetonitrile or diglyme) in the
presence of a nonpolar perfluorinated solvent (perfluo-
roheptane, perfluorooctane, perfluoromethylcyclohex-
ane, perfluoroethylcyclohexane, perfluorodecalin, per-
fluoro-2-methyldecalin) acting as extractant for the
forming PFPAF.
As a rule, reactions with low-boiling PFAFs, e.g.,
with carbonyl fluoride, trifluoroacetyl fluoride, or
pentafluoropropionyl fluoride, are performed at a pres-
sure ranging from 0.7 to 24 atm. As solvents are used
mixtures of polar aprotic solvents [dinitriles of satu-
rated aliphatic dicarboxylic acids (C C ), dimethyl
We found that the optimal catalyst concentration is
10 15 wt %; with its lower amounts, the yield of the
target product decreases, and with larger amounts the
PFPAF yield does not increase further.
5
8
ethers of polyethylene glycols CH O(CH CH O)
3
2
2
n
CH , n = 2 6] [8] or of polar aprotic (acetonitrile,
3
The starting components, HFPE and PFAF, are
taken in a molar ratio from 1 : 1 to 1 : 2. Under these
conditions, the reaction mainly yields the monoaddi-
tion product, with a minor impurity ( 1 3 wt %) of
the HFPE isomerization product, pentafluoropropano-
ic acid fluoride.
diglyme) and nonpolar (pentane, hexane, cyclohexane,
or a halogenated alkane, e.g., trifluorotrichloroethane)
solvents [7]. The PFPAF yield in these procedures
does not exceed 50%, being in some cases as low as
6 12%.
In this work, with the aim to increase the reaction
selectivity, we studied the conditions of condensation
of HFPE with PFAFs according to the scheme
The synthesis is performed in a stirred vessel at
ambient pressure. The condensation product formed
in the process is extracted with the organofluorine
solvent. After the reaction completion, the PFPAF is
distilled off from the extract, and the nonpolar organo-
fluorine solvent is reused. The reaction products are
R COF CF CF CF2
+
RF CF2OCFCOF
CF3
,
F
3
O
1070-4272/05/7803-0435 2005 Pleiades Publishing, Inc.