Fluorinated alkanes and their uses

Details Fluorinated alkanes and their uses Fluorinated alkanes and their uses

1998-05-07

2001-04-03

Peselev, Elli (Department: 1623)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Halogenated hydrocarbon doai

Reexamination Certificate

active

06211248

ABSTRACT:

The invention concerns partially fluorinated alkanes according to the general formula I:
R
F
[CF
2
—CH
2
]R
H
  I
wherein R
H
is a substituent of the general formula C
n
H
x
, and R
F
is a substituent of the general formula C
m
F
x
.
In the event that sec-alkyls, tert-alkyls or cycloalkyls, or the perfluoro equivalents variants of these alkyl groups are used, the molecule is branched. Linear or branched molecules of this type are described, for example, in DE 42 05 341 A1 and in U.S. Pat. No. 5,275,669. Furthermore, the use of such alkanes in medicine, pharmacy and technology is known from these and other publications. Especially in DE 42 05 341 A1, the reduction of the concentration plays a decisive role which is reflected in the selection of compositions with short perfluorinated substituents. DE 195 36 504 A1 also describes fluorinated alkanes and their use.
Moreover, it is known that by extending the R
F
or R
H
substituents, and by combining various long substituents in such compositions, the surface and interfacial properties at phase boundaries to other media or surfaces treated with such compositions may be influenced. Associated therewith is the formation of hydrophilic or hydrophobic properties, which are reflected in dissolving properties or dissolving intermediary properties and in surface-active properties.
The variations of the R
F
or R
H
substituents known from the prior art, however, do not generally produce any alkanes with optimum biocompatible properties, since the aggregated systems produced by the interaction with other substances are often unstable. In this way, undesirable separations and short life spans of the mixtures and emulsions result.
In this context, biocompatibility refers both to the chemical inertness of a substance and its tissue tolerance.
The aforementioned problems of the known substances also occur in applications in which the biocompatibility is not of significance. Undesirable separation processes and short life spans of the substances are disadvantageous in every application, in particular, when using these substances as medical or technical solvents.
Thus, it is the object of this invention to further improve such a partially fluorinated alkane in such a way that the developing aggregated systems are more stable.
This invention in its broadest embodiment comprises partially fluorinated alkanes according to the general formula I:
R
F
[CF
2
—CH
2
]R
H
  I
wherein R
H
is a substituent of the general formula C
n
H
x
selected from the group consisting of n-alkyl, sec-alkyl, tert-alkyl or cycloalkyl; R
F
is a substituent of the general formula C
m
F
x
selected from the group consisting of n-perfluoralkyl, s-perflouroalkyl, t-perfluoroalkyl or perfluorocycloalkyl; n≧3; and the sum of n+m<18; with the provisos that:
(i) if R
H
is n-alkyl, R
F
is other than n-perfluoroalkyl, and
(ii) if R
F
is n-perfluoroalkyl, R
H
is other than n-alkyl.
Preferably, n>7 and m is between 5 and 8. More preferably, m>5 and n is between m−1 and m+2.
Preferably, the ratio of the steric volume of R
F
to R
H
is less than 0.7. Alternatively, the ratio of the steric volume of R
F
to R
H
is greater than 1.3.
It can thus be seen that in the compounds of this invention the desired properties are obtained when the alkane substituent R
H
contains at least four carbon atoms, the sum of the carbon atoms in the hydrogen substituent R
H
and in the fluorine substituent R
F
is less than 18 and also at least one of the two substituents (hydrogen substituent R
H
or perfluoro substituent R
F
) is formed like a branched alkyl.
For example, the fluorine substituent R
F
can be an n-perfluoroalkyl group, and the hydrogen substituent R
H
can be a sec-alkyl, tert-alkyl or a cycloalkyl group. Alternatively, the hydrogen substituent R
H
can be an n-alkyl group, and the fluorinated substituent is then branched, i.e. is a sec-perfluoroalkyl, a tert-perfluoroalkyl, or a perfluorocycloalkyl group. Both substituents R
F
and R
H
can also be branched; however, according to the invention, it is excluded that both substituents R
H
and R
F
are linear.
The compounds of this invention are synthesized by using conventional methods.
The described compositions are, in particular, highly purified prior to medical applications, by using known conventional processes. The compositions thus produced are then completely non-toxic since substitute reactions cannot occur either on the spacer group CF
2
—CH
2
or on the perfluorinated portion of the composition which would lead to toxic effects. The special solvent properties of the compositions are based the fact that they not only combine the properties of pure perfluorocarbons with the properties of pure hydrocarbons but form, after the dissolving process, aggregated systems of various structures which are stabilized by the anisotropic structure of the compositions according to the invention. This is made possible by the selection of the substituents according to the invention, whereby the different spatial requirements of the R
F
and R
H
substituents are also significant. The structural stabilization of the aggregated systems suppresses the separation of the resultant solutions and increases the solvent power of the compositions. Comparable effects can only be attained in purely linear R
F
—R
H
compositions by substantially longer chain lengths, or by differences in chain lengths which simultaneously results in undesirable properties such as, for example, higher boiling points or wax-like compositions as a result of which it can generally no longer be used as a biocompatible solvent and liquid implant, and the other applications are also only possible to a limited degree.
The alkane according to the invention can be advantageously used especially in the following cases of application.
Due to the dissolving power for hydrocarbons, in particular, mineral oils, tar and silicone oils, the partially perfluorinated alkanes according to the invention enable the purification of tissues contaminated with such substances. The contaminations form stable solutions with the alkanes of the invention, so that they can be washed out. In this way, silicone oils which escaped from defective implant cushions or used as liquid implants in ophthalmology, are carefully removed. The partially fluorinated alkanes according to the invention are especially suitable for attending to injuries into which oils, tar or fats based on mineral oil have penetrated. In particular, the removal of combustion residues from burn injuries is also possible. As a result of the ability of the partially perfluorinated alkanes of the invention to transport oxygen, the decontamination of tissues is additionally promoted by supplying them with oxygen.
An essential difference between partially fluorinated alkanes of the invention and conventional solvents is due to the fact that conventional solvents persistently damage tissue to be treated, but the partially fluorinated alkanes of the invention do not.
Furthermore, the partially fluorinated alkanes of the invention can be used to assist in the regeneration of tissue in smoker's lungs in that deposits within the lung are washed out by rinsing the lung. Due to the high dissolving power of the partially fluorinated alkanes according to the invention for oxygen and carbon dioxide, the oxygen supply can be maintained and the removal of carbon dioxide is not interrupted.
In their function as solvents, the partially fluorinated alkanes of the invention have the advantage that the size and spatial structure of the R
F
and R
H
substituents may be selected so as to be able to extract contaminants with minimum tissue penetration.
The biocompatible properties and the low surface tension as well as the special interfacial properties of the partially fluorinated alkanes make it possible to use these compositions as liquid implants. An example thereof is the use in ophthalmology, e.g. as a vitreous body substitute, as retina developing agents, as an aid in the las

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