Compositions of 1-bromopropane and an organic solvent
Reference Number: N 03-04
Inventors: Thenappan, Alagappan; Stachura, Leonard Michael; Paonessa, Martin Richard; Cook,Kane David
Owner: NISTAC
USPTO Link:6365565
Invention Summary
The invention relates to novel compositions comprising effective amounts of 1-bromopropane
and at least one organic solvent selected from the group consisting of methanol, ethanol,
1-propanol, 2-propanol, 2-methyl-2-propanol, 2,2,2-trifluoroethanol, tetrahydrofuran,
nitromethane, ethyl acetate, acetonitrile, hexane, 1,3-dioxolane, 1-chloro-2-methylpropane,
1,1,1,2,3,4,4,5,5,5-decafluoropentane, methyl ethyl ketone and cyclohexane. The invention
further relates to azeotrope-like compositions comprising from about 27 to about 99.9
weight percent 1-bromopropane and from about 0.1 to about 73 weight percent of at
least one organic solvent selected from the group consisting of methanol, ethanol,
1-propanol, 2-propanol, 2-methyl-2-propanol, 2,2,2-trifluoroethanol, tetrahydrofuran,
nitromethane, ethyl acetate, acetonitrile, hexane, 1,3-dioxolane, 1-chloro-2-methylpropane,
1,1,1,2,3,4,4,5,5,5-decafluoropentane, methyl ethyl ketone and cyclohexane, which
compositions boil at from about 50.4.degree. C. to about 69.8.degree. C..+-. about
2.0.degree. C. at 760 mmHg.
The 1-bromopropane and organic solvent components of the invention are commercially
available and may be obtained readily in pure form.
The term "azeotrope-like" is used herein for the preferred mixtures of the invention
because in the claimed proportions, the compositions of 1-bromopropane and organic
solvent are constant boiling or essentially constant boiling. All compositions within
the indicated ranges, as well as certain compositions outside the indicated ranges,
are azeotrope-like, as defined more particularly below.
From fundamental principles, the thermodynamic state of a fluid is defined by four
variables: pressure, temperature, liquid composition, and vapor composition, or P-T-X-Y,
respectively. An azeotrope is a unique characteristic of a system of two or more components
where X and Y are equal at a stated P and T. In practice, this means that the components
cannot be separated during a phase change, and therefore are useful in solvent and
aerosol solvent applications.
For the purposes of this discussion, by azeotrope-like composition is intended to
mean that the composition behaves like a true azeotrope in terms of its constant boiling
characteristics or tendency not to fractionate upon boiling or evaporation. Thus,
in such systems, the composition of the vapor formed during evaporation is identical
or substantially identical to the original liquid composition. Hence, during boiling
or evaporation, the liquid composition, if it changes at all, changes only slightly.
This is contrasted with non-azeotrope-like compositions in which the liquid and vapor
compositions change substantially during evaporation or condensation.
One way to determine whether a candidate mixture is azeotrope-like within the meaning
of this invention, is to distill a sample thereof under conditions (i.e., resolution--number
of plates) which would be expected to separate the mixture into its separate components.
If the mixture is not an azeotrope or azeotrope-like, the mixture will fractionate,
i.e., separate into its various components with the lowest boiling component distilling
off first, and so on. If the mixture is azeotrope-like, some finite amount of the
first distillation cut will be obtained which contains all of the mixture components
and which is constant boiling or behaves as a single substance. This phenomenon cannot
occur if the mixture is not azeotrope-like, i.e., if it is not part of an azeotrope
system.
It follows from the above that another characteristic of azeotrope-like compositions
is that there is a range of compositions containing the same components in varying
proportions which are azeotrope-like. All such compositions are intended to be covered
by the term azeotrope-like as used herein. As an example, it is well known that at
different pressures the composition of a given azeotrope will vary at least slightly
as does the boiling point of the composition. Thus, an azeotrope of A and B represents
a unique type of relationship but with a variable composition depending on the temperature
and/or pressure. As is readily understood by persons skilled in the art, the boiling
point of an azeotrope will vary with the pressure.
In the process embodiment of the invention, the compositions of the invention may
be used to clean solid surfaces by treating said surfaces with said compositions in
any manner well known in the art such as by dipping or use of open or closed vapor
degreasing apparatus.
It should be understood that the present compositions may include one or more additional
components (such as stabilizers, inhibitors or antioxidants), some of which may form
new azeotrope-like compositions. Such additional components typically are added at
the expense of 1-bromopropane and in amounts known to one skilled in the art. Preferably,
such components are added in an amount of up to about 5 weight percent based on the
weight of the 1-bromopropane component, and more preferably in an amount of up to
about 5 weight percent based on the total weight of the composition. Any such compositions
are considered to be within the scope of the present invention as long as the compositions
contain all of the essential components described herein.
Stabilizers typically are added to solvent compositions to inhibit decomposition
of the compositions; react with undesirable decomposition products of the compositions;
and/or prevent corrosion of metal surfaces. Any combination of conventional stabilizers
known to be useful in stabilizing halogenated hydrocarbon solvents may be used in
the present invention. Suitable stabilizers include alkanols having 4 to 7 carbon
atoms, nitroalkanes having 1 to 3 carbon atoms, 1,2-epoxyalkanes having 2 to 7 carbon
atoms, phosphite esters having 12 to 30 carbon atoms, ethers having 3 or 4 carbon
atoms, unsaturated compounds having 4 to 6 carbon atoms, acetals having 4 to 7 carbon
atoms, ketones having 3 to 5 carbon atoms, and amines having 6 to 8 carbon atoms.
Other suitable stabilizers will readily occur to those skilled in the art. See, for
example, U.S. Pat. No. 5,665,172.