NUCLEOPHILIC ISOMERISATION OF HEXAFLUOROPENE OXIDE
A.F.Gontar
A.N.Nesmeyanov Institute of Organoelements
Compounds RAS. 119991, Vavilova str.28, Moscow, Russia.
e-mail:
gontar@ineos.ac.ru
Attempts to obtain pentafluoropropionyl fluoride (PPF)
undertaken earlier [1-8] , except for the synthesis method of this
compound by the action of Yarovenko reagent on pentafluoropropionic acid
[9], have no preparative importance.
With the goal to develop a convenient method to
obtain PPF in the present work we studied "nucleophilic" isomerization
of hexafluoropropene oxide (HFPO). The latter is an available product of
fluoroorganic manufacture.
We studied the action of various reagents (KF, CsF,
pyridine, triethylamine and other bases) on HFPO both in a flow system
by passing through a heated pipe filled with fluorides of alkali metals
and by bubbling HFPO through a base solutions (pyridine, triethylamine,
quinoline) followed by capturing the forming products.
As the result of these experiments it has been found
that variations of HFPO flow rate, temperature, time of interaction and
other process parameters do not allow to attain full conversion of HFPO
into PPF and as the boiling temperatures of these substances are very
close (~-28 o C) it is impossible to isolate PPF in pure form.
At the same time it was found that full HFPO
isomerization takes place in a close system under the action of
quinoline.
The found method is extremely convenient and allows
producing PPF in great quantities.
Experimental
Quinoline (200g, 1.55 mol) and hexafluoropropylene
oxide (2400g, 14.46 mol) are placed in a steel autoclave ( 2L water
capacity) with a needle valve cooled to a temperature of -70 oC.
The autoclave is hermetically sealed and heated. At a temperature of 10oC
there is observed a temperature jump up to 60oC in the
autoclave.
The autoclave is placed in a rocking furnace, the
temperature is raised to 100 oC and kept for 2 hours. Then
the autoclave is cooled to room temperature, the product is collected
through the needle valve in a trap cooled with dry ice. There was
obtained 2200g of Hexafluoropropionyl fluoride of 97% purity in 92%
yield, BP=-28oC.
19F NMR: 8.0 ppm (CF3), 46 ppm ( CF2),
-98 ppm (COF)
References
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