Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to the stabilization
of halogenated hydrocarbons, especially those, which
are liquid at room temperature, against decomposition
in the presence of water. Halogenated hydrocarbons are
used, inter alia, for extracting, degreasing or purify-
ing metals and as solvents for other active ingredients.
In many application fields the halogenated hydro-
carbon is contacted with water which may cause a rapid
or slow decomposition, with hydrogen halogenide being
1~ formed. Thus, present metals, for example tin plate,
are corroded in many cases.
Hydrogenated hydrocarbons, preferably methylene
chloride and 1 r 1 ~1-trichloroethane, but also fluoro-
trichloromethane, are used as solvents for a ~ariety
of active ingredients, even for aerosol sprays. In
most cases, the halogenated hydrocarbon, for example
methylene chloride, is blended with other organic
solvents, such as alcohols or aliphatic hydrocarbons.
In general, a stabilization of the halogenated hydro-
carbon in the absence of water, is easy or unnecessary.Insecticides or hair sprays, which contain methylene
chloride, for example, are in general anhydrous.
An important advantage of the abovementioned
halogenated hydrocarbons, besides their high dissolving
power for many substances, is that they are classified
as non-combustible, according to the legal regulations
for compressed gas bottles that are binding within
the EC zone. When using said halogenated hydrocarbons
in spray formulations, especially in the presence of
other combustible components, the safety requirements
imposed on products which do not carry the sign
"combustible", can be met tthe declaration of combusti-
bility is obligatory in some countries if the proportion
by weight of combustible components, calculated
the total spray, is 45 % or more).
A disadvantage of the abovementioned chlorocarbon
solvents is their noticeable sensitivity to water. This
also applies to many other halogenated hydrocarbons,
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especially to those which have only a low halogenation
degree and contain less than 4 fluorine atoms in the
molecule~
Even in the presence of small portions of water in
an aerosol spray, pure methylene chloride, for examrle,
especially on contact with metals, is hydrolized in a
relatively short time (~ to 8 weeks) to such a degree
that the metallic compressed gas bottle underyoes
corrosion by the hydrogen chloride split off. ~
~0 sufficient high portion of water may be introduced
into the spray formula by blending the chlorohydro-
carbon with ethanole having a strength of 96 ~ by volume.
In most cases the content is also chemically attacked
by the hydrochloric acid formed, thus making the whole
content of the bottle unuseable.
Therefore many experiments have been ~arried out
to stabilize halogenated hydrocarbons, especially the
compounds methylene chloride and 1,~ trichloroe~thane,
which are of special importance for the manufacture
of aerosols, against hydrolysis by addition of inhibi~
tors. Epoxides and/or secondary amines, or e~ample,
have been added to halogenated hydrocarbons, especially
methylene chloride. From the toxicological point of view,
however, epoxides have to be considered as unacceptable.
2S Secondary arnines, in the presence of nitrites, can
lead to the formation of nitrosamines which may be
cancerogenic. Another disadvantage is that the effect of
the abovementioned stabilizers is slowly reduced and
temporally limited because the stabilizers either react
3~ with the halogenated hydrocarbon or with the hydrogen
halide formed therefrom. There have also been used
N-methylpyrrole and N-alkylmorpholine in order to
protect methylene chloride (in the absence of water~
against decomposition by metals or metal salts (GB-PS
932~38). This is also valid for the known tertiary
amines r such as triethylamine ~IS-patent application
370~309).
Therefore it was necessary to stabilize halogenated
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hydrocarbons against hydrolysis by toxicologically unobjectionable
compounds in such a way that their effectiveness is guaranteed for
a long time.
Now it has been found that halogenated hydrocarbons
selected from the group consisting of methylene chloride, 1~
trichloroethane, fluorotrichloromethane, and 1,1,2-trifluoro-1,2,2-
trichloroethane can be stabilized against decomposition by water,
by adding thereto from 0.001 to 10 % by weight of a kertiary amine
of the formula
RR R N (I)
wherein R and Rl, independently from one another stand for alkyl
groups with from 1 to 10 carbon atoms and R2 means isopropyl,
bwtyl-(2)~ tertiary butyl or cyclohexyl. The alkyl radicals may
be linear, branched or cyclic.
Preferred stabilizers are tertiary amines oE the formula
R2N-C(C~I3)3 (II~
with R having the abovementioned meaning.
Very efective stabilizers are also tertiary amines of
the formula 1 2
RR R N (III)
with R standing for alkyl with from 1 to 10 carbon atoms and Rl and
R2 independently meaning isopropyl, butyl-(2), tertiary butyl or
cyclohexyl.
R is preferably alkyl with 1 to 4 carbon atoms, especially
the methyl or ethyl radical. Tertiary amines of the formula ~II,
with Rl being identical with R2 are preferred because they can be
manufactured more easily.
Preferred concentration ranges for the tertiary amine,
employed according to the invention, are 0.005
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to 5 ~ by weight, specially 0.01 to 1 % by weight.
Furthermore, it has ~een found that the stabilizing
e~fect of the tert;ary amine is increased in the presence
of an ether. As ethers there are preferably employed
those compounds which only consist of C, H and O and
which have no other reactive groups. Specially preferred
are low molecular weight alkyl ethers or cy~loalkyl
ethers whose alkyl radicals contain from 1 to 6 C-atoms.
Ether contents of more than 1 % by weight proved to be
especially effective. Very favorable reactions showed
5- or 6-membered heterocyclic compounds, for example
tetrahydrofuran, or unbranched dialkyl ethers with 2
tQ 6 carbon atoms, such as diethyl ether, dimethyl
ether or methylethyl ether.
Subjec-t of the invention are, furthermore, aerosol
packages which contain a mixture of at least one
halogenated hydrocarbon, liquid at room temperature and
normal pressure, at least one liquefied aerosol
propellant, which is gaseous at room temperature and
normal pressure, as well as water. These packages may
also contain other organic solvents and active ingredients.
By the term "active ingredient'l in the presen~ appli-
cation there are to be understood substances which
cannot be considered as liquid halogenated hydro-
carbons, organic solvents or propellants, which, however,are important for the use of aerosol formulation.
Examples hereof are perfumes, dyestuffs and binding
agents (in lacquer sprays) and bactericides. These active
ingredients, in general, have only a small influence
on the hydrolysis of the halogenated hydrocarbons
presen-t. In sprays for producing low temperatures or
in paint removers based on methylene chloride, for
example, they are not necessary.
Of special interest are aerosol packages containing
35~rom 10-89.5 ~ by weight of liquid halogenated hydro-
carbon
0-75 ~ by weight of other organic solvents,
0.5-25 ~ by weight of water,
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0 - 35 % by weight of active ingredients and
10 - 70 ~ by weight of liquefied aerosol propellant gas,
the content being stabilized by an amount of a tertiary
amine of the formulae ~, II or III in the range from
~.OOQ01 to 0.1 part by weight per part by weight of
liquid halogenated hydrocarbon.
The stabilization according to t:he invention is of
special importance~ if the aerosol formulations mentioned
above are dispensed to aerosol packages made from
metal. In this case, the corrosive attack on the metal
(for example tin plate) may be substantially suppressed
ior a long time.
The following examples illustrate the invention:
E x a m p l e 5
Test mixtures were dispensed to welded tin plate
aerosol bottles (18 oz) without interior lacquer
protection. The bottles were closed by normal aerosol
valves provided with blank tin plate disks and after
being char~ed with the propellant, they were stored
at 40C in a vertical position. When the intended
storage time of, in general, 4, 8 and 12 weeks had
passed, the bottles still charged were cooled to
temperature lower than the boiling point of the propel-
lants employed, they were perforated at the dome by
means of a thorn and left to stand under a hood until
they had reached again room temperature, with the
portions of propellant evaporating gradually. The
remaining contents were poured into beakers and the
cleared bottles were opend by sawing~ The remaining
mixture (without propellant) as well as the opened tin
plate bottles were examined optically for signs of
corrosion. The statement "without result of an exami-
nation" means that the charge or the material of the
bottle were uncharged, as compared with the original
charge.
The following tables show the relation between
stabilizator for water-containing methylene chloride,
duration of storing and the corrosion of the aerosol
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bottles. Experiments 1 to 4 are comparative experiments.
Experiments 5 to 7 are in accordance with the invention.
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