Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 107S710
Processes are known for preparing acid chlorides containing
perfluoroalkyl groups, using general methods for preparing acyl chlorides,
such as they are described in Weygand-Hilgetag, Organisch-chemische Experi-
mentierkunst, 4th edition, 1970, pages 247 through 253. Carboxylic acids
are always the starting point, which are put to reaction with an excess of
inorganic acid chlorides, e.g. phosphorus trichloride, phosphorus penta-
chloride, thionyl chloride. Perfluoroalkyl carboxylic acid chlorides are
obtained in that way from the corresponding carboxylic acids according to
J. Am. Chem. Soc. 75, 87 (1953) and l.c 75, 968 ~1953). According to British
Patent Specification 1,102,903 are prepared in the same manner perfluoro-
alkylalkylene-carboxylic acid chlorides. A further possibility for preparing
acid chlorides containing perfluoroalkyl groups is the reaction of the
corresponding carboxylic acids with organic acid chlorides (J. Am. Chem. Soc.
70, 1968 (1948), l.c. 76, 1376 ~1954)).
All these processes use the analogous carboxylic acid as starting
product. The conversion, being quite often incomplete, requires long
- reaction periods and the work-up of the obtained reaction mixtures is always
associated with separating and eliminating by distillation the by-products,
- which are formed unavoidably, and the starting material which has not
~ 20 participated in the reaction.
- Subject of the present invention are perfluoroalkylacetyl chlorides
having the general formula
Rf.CH2. C \ I.
wherein Rf means a straight-chain perfluoroalkyl radical having from 4 to 12,
preferably from 6 to 12 carbon atoms.
- Subject of the present invention is also a process for preparing
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such perfluoroalkylacetyl chlorides having general formula
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f 2 . C \ II.
wherein Rf represents a straight-chain or branched perfluoroalkyl radical
having 2 to 12 carbon atoms, by reacting perfluoroalkyl ethanols having
general formula
Rf CH2 . CH2.OH III.
wherein Rf has the same meaning as in formulae I or II, with chlorine gas
while simultaneously exposing to W radiation in the presence of an inert
organic solvent at temperatures of from -20C to +120C.
The process develops according to the following reaction scheme;
W_r_d_ation O
Rf.cH2.cH2.oH + 2 C12 Rf.CH2.C + 3 HCl
Cl
the reaction supposedly running through the step of corresponding aldehydes.
The reaction may be carried out discontinuously or continuously as well.
A longitudinally shaped glass cylinder in an upright position, with
an W radiation emitter being located in the center, serves as a most useful
reaction vessel for a continuous preparation. The two reactan~s - chlorine
and perfluoroalkyl ethanol dissolved in a solvent - are processed in a
` counter current; the thoroughly reacted product leaves the glass cylinder
through a screen at the lower end and is evacuated through an ascending pipe
so as to maintain the level. The chlorine is introduced via a glass frit -
located immediately above the screen.
2 moles of chlorine are required for one mole of perfluoroalkyl
ethanol to be reacted; the chlorine is generally used in a slight excess
quantity.
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The reaction speed is very high; in general it is proportional to
the intensity of the radiation and, moreover, depends on the size and the
shape of the reaction vessel and the installation arrangement of the W
emitter. When a commercially available mercury-low pressure radiator, having
a power consumption of about 15 Watt, is used as a radiation source, from
0.1 to 0.15 moles of a 5 to 10% solution of perfluoroalkyl ethanol per hour
can be reacted in an inert solvent in a reaction pipe of about 300 1 effective
volume. The development and the termination of the reaction can be observed
by means of nuclear magnetic resonance spectrum analysis.
The reaction temperature may be chosen randomly within the range
of from -20C to +120C, the most useful working range keeps within 0 and
100C or at the boiling point of the solvent employed, the reaction heat
- which is built up and the thermal energy of the W-radiator may be removed
in that way by a reflux cooling device which is set up sideways.
`- The thus obtained acid chlorides may be separated from the solvent
by distillation. If the obtained product need not satisfy special purity
; standards, the crude product which is present in the solution may be used
directly for further reactions. In that case it is sufficient to eliminate
the residual chlorine from the solution by blowing in nitrogen or by
subjecting the mixture to a slight distillation. -
The alcohols necessary for preparing the acid chlorides of the
present invention are commercially available products and, besides, may be
manufactured in analogy to German Auslegeschrift 1,214,660, German
Offenlegungsschrift 2,318,677 and German Patent Specification 2,028,459.
Perfluoroalkyl ethanols in the proper sense of the invention are, for
example, perfluorobutyl ethanol, perfluorohexyl ethanol, perfluorooctyl
J
ethanol, perfluorodecyl ethanol, perfluorododecyl ethanol. Mixtures of such
alcohols may be successfully used as well.
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As solvents in the proper sense of the invention may be understood
those being inert against elementary chlorine and W-radiation and dissolving
at least 1 to 10 % of the reactants, such as 1,1,2-trichloro-1,2,2-trifluoro-
ethane, trichlorofluoromethane, tetrachlorodifluoroethane, carbon tetra-
chloride ~halogenated hydrocarbons).
UV-radiators suitable for carrying out the reaction according to the
invention are the commercially available mercury high pressure or low pressure
lamps with an output of about 150 to 15 Watt, made of quartz glass.
The perfluoroalkylacetyl chlorides and their mixtures which have
been prepared according to the process of the invention, are valuable inter-
mediate products for the manufacture of e.g. esters by means of reaction with
mono- or polyhydric alcohols and of polyglycols and polyglycol ethers, which
may be used as surface active substances and textile finishing agents.
Especially the perfluoroalkylacetyl chlorides esterified according
to the invention with polyethylene glycols, polypropylene glycols, and with
polyglycols having mixed ethylene oxide and propylene oxide units and those
obtained by esterification with the corresponding polyglycol monoethers
(chain length 2 to 40 alkylene oxide units) are excellent dry cleaning
detergents for solid matters, especially for textiles and metal parts in
organic solvents. By "dry cleaning detergents" are to be understood surface
active substances which enhance and extend the cleaning effect of organic
solvents insofar that water can be incorporated into the organic medium and
thus the cleaning effect has a grip also on hydrophilic contaminations.
These perfluoroalkylacetyl polyether esters have the general formula
Rf CH2 C (OCH2CHR)m-OR
~ O
wherein Rf has the aforementioned meaning and wherein m means a number from
2 to 40, R means a hydrogen atom or a methyl group and wherein R' means a
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hydrogen atom or an alkyl radical with 1 to 4 carbon atoms, mixtures with
different values for m or different substituents for R being also included.
They are prepared by esterification of the perfluoroalkylacetyl chlorides of
the invention with the aforementioned polyglycols or their monoethers accord-
ing to known methods in the presence of acid-binding agentsJ e.g. of tertiary
amines. The perfluoroalkylacetyl polyether esters of the aforementioned
formula may be used as dry cleaning detergents at substantially lower
application rates and produce a more important reduction of the interface
tension between organic solvent and water than conventional dry cleaning
detergents may ever produce.
The process according to the invention for preparing perfluoroalkyl-
acetyl chlorides in comparison to former processes has the undeniable
advantage that said chlorides may be obtained by one single processing step -
starting from the corresponding alcohols. A further advantage is the fact
that the reaction runs practically through to completion, so that high yields
are obtained and the resulting products are so pure that they may be reacted
further without undergoing any additional purification and elimination of the
solvent.
The following examples illustrate the invention:
E X A M P L E 1:
500 ml of 1,1,2-trichloro-1,2,2-trifluoroethane are filled into a
long glass cylinder of about 1 ltr. volume, equipped with a stirrer and a
15-Watt-mercury-low pressure-immersion lamp made of quartz glass being set up
in its center. Through a glass frit located at the lower end a constant
current of gaseous chlorine, previously dried over concentrated sulfuric
acid, is introduced at a speed of about 0.3 l/min; while radiation is going
on simultaneously. As soon as the solvent is saturated with gaseous chlorine,
100 g of perfluorooctyl ethanol (C8F17.CH2.CH2.0H), dissolved in 500 ml of
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the same solvent, are added within a period of about 40 minutes and while
agitating vigorously. The gaseous hydrogen chloride which is formed as by-
product, is removed with some excess chlorine via a reflux cooler set up on
top of the reaction vessel and is then neutralized by being introduced into
an aqueous sodium hydroxide solution.
After completion of the addition, radiation and simultaneously
metering-in of chlorine is continued for about 5 more minutes at about 26 to
28C while agitating, the reaction is then interrupted. The solvent is
finally distilled off through a column being replete with glass rings and
having a length of 30 cm.
As a residue are obtained 105.8 g ( = 99% of the theoretical yield)
of a colorless product which is slightly turbid. This product is submitted
to another distillation under reduced pressure. 101.8 g ~= 95% of the
theoretical yield) of perfluorooctylacetyl chloride (C8F17.CH2COCl) are
obtained, having a boiling point of 81 to 82C under 11 mm Hg. The
colorless, limpid product has a setting point of 29C.
E X A M P L E S 2 through 8:
~ The perfluoroalkylacetyl chlorides shown in the following table are
; prepared analogously.
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E X A M P L E 9:
This example describes the continuous preparation of a perfluoro-
alkylacetyl chloride mixture.
The reaction vessel is a glass cylinder in upright position, having
a length of about 25 cm and a diameter of about 5.5 cm and, at the upper end,
being equipped with a 15-Watt-immersion lamp, a reflux cooler and a dropping
funnel. The empty space around the immersion lamp is replete with Raschig
rings above a bottom screen. At the lower end of the reaction vessel a gas
inlet pipe is introduced sideways. The product which has undergone the
complete reaction, may be evacuated continuously through an ascending pipe
which is mounted to rise sideways.
About 350 ml of 1,1,2-trichloro-1,2,2-trifluoroethane are introduced
as solvent into the reaction vessel. While simultaneously emitting W
radiation, a constant current of dry chlorine gas is introduced at a speed
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of about 100 to 120 ml of chlorine per minute. To this solution of chlorine
is added dropwise, at a speed of about 500 ml per hour, a solution of 45.9 g
(1/10 mol) of a mixture of perfluoroalkylethanols in 500 ml of the afore-
mentioned solvent, the mixture having the following composition :
C6F13CH2CH20H ............. 38,6%
C8F17CH2CH20H ............. 31,9%
CloF21CH2CH20H ............ 20,9%
C12F25CH2CH20H ............ 6,5%
other components........... 2,1%
; (The composition of this industrial alcohol mixture was determined by gas
chromatographic analysis).
. The thoroughly reacted reaction product is removed from the reaction
mixture proportionally to the quantity of fresh product being fed in on the
other hand.
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The hydrogen chloride being formed during the reaction is passing
over at the top of the reflux cooler together with the excess of chlorine;
solvent which is distilling off, is condensed by the cooling device fixed
on top with a temperature of 0C in the cooling tank, and subsequently fed
` back into the apparatus.
After a total reaction time of 10 hours 459 g of the perfluoroalkyl
ethanol-mixture are reacted. When submitting the total reaction solution to
` a proton resonance spectrum analysis, the result shows that no more starting
product is present.
In order to obtain the acid chloride mixture, the solvent and the
residual chlorine component are distilled off at 47C; the resulting residue
is submitted to a distillation in vacuo for purification purposes. These
operations yield under a vacuum of 12 mm Hg and at a boiling interval of
58 to 105C a quantity of 358.2 g and, after further distillation under a
~j ~ high-vacuum of 0.2 mm Hg and at a boiling interval of 70 to 115C, a further
~- . quantity of 93.5 g of pure acid chloride. When submitting the distillation
residue of about 32 g to a proton resonance spectrum analysis, the result
shows a presence of 48%, i.e. about 3% of the total yield, of the wanted
`~ perfluoroalkylacetyl chlorides in this residue. The total yield of pure
acid chloride mixture amounts therefore to about 95%, calculated on the
originally used perfluoroalkylethanol mixture.
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