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Description  |
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FIELD OF THE INVENTION
This invention relates to liquid compositions comprising a major amount of
at least one fluorine-containing hydrocarbon, and a minor amount of at
least one lubricant. More particularly, the invention relates to liquid
compositions useful as refrigeration liquids.
BACKGROUND OF THE INVENTION
Chlorofluorocarbons, generally referred to in the industry as CFCs, have
been widely used as propellants in aerosols, although use in aerosols has
been diminishing in recent years because of demands of environmentalists
for the reduction if not a complete ban on the use of CFCs because of the
detrimental effect of CFCs on the atmosphere's ozone layer. CFCs also have
been used because of their unique combination of properties as
refrigerants, foam-blowing agents, and specialty solvents within the
electronics and aerospace industries. Examples of CFCs which have been
utilized for these purposes include CFC-11 which is
chlorotrifluoromethane, CFC-12 which is dichlorodifluoromethane, and
CFC-113 which is 1,2,2-trifluoro-1,1,2-trichloroethane.
Since 1976, when the aerosol industry began to feel the pressure to reduce
if not eliminate the use of CFCs, the aerosol industry has progressively
moved toward the substitution of hydrocarbon propellants for CFC
propellants. The hydrocarbons, such as butane, are readily available and
inexpensive, and the quality of the final product generally has been
unaffected by the substitution of propellants. However, the problem of
finding a safe replacement of CFC refrigerants and foam-blowing agents has
been more difficult to solve. Several replacement candidates have been
suggested as alternatives to the fully halogenated hydrocarbons, and these
include halogenated hydrocarbons containing at least some hydrogen atoms
such as HCFC-22 which is difluorochloromethane, HCFC-123 which is
1,1-dichloro2,2,2-trifluoroethane, HFC-134a which is
1,1,1,2-tetrafluoroethane and HCFC-141b which is
1,1-dichloro-1fluoroethane.
The ozone depletion potential of these proposed substitutes is
significantly less than the ozone depletion potential of the previously
used CFCs. The ozone depletion potential is a relative measure of the
capability of the material to destroy the ozone layer in the atmosphere.
It is a combination of the percentage by weight of chlorine (the atom that
attacks the ozone molecule) and the lifetime in the atmosphere. HCFC-22
and HFC-134a generally are recommended as being candidates in refrigerant
applications, and HFC-134a is particularly attractive because its ozone
depletion potential has been reported as being zero.
In order for any of the replacement materials to be useful as refrigerants,
the materials must be compatible with the lubricant utilized in the
compressor. The presently used refrigerants such as CFC-12 are readily
compatible with mineral lubricating oils which are utilized as the
lubricant in air-conditioner compressors. The above-described refrigerant
candidates, however, have different solubility characteristics than the
refrigerants presently in use. For example, mineral lubricating oil is
incompatible (i.e., insoluble) with HFC134a. Such incompatibility results
in unacceptable compressor life in compression-type refrigeration
equipment including refrigerators and air-conditioners including auto,
home and industrial air-conditioners. The problem is particularly evident
in automotive air-conditioning systems since the compressors are not
separately lubricated, and a mixture of refrigerant and lubricant
circulates throughout the entire system.
In order to perform as a satisfactory refrigeration liquid, the mixture of
refrigerant and lubricant must be compatible and stable over a wide
temperature range such as from about 0.degree. C. and above 80.degree. C.
It is generally desirable for the lubricants to be soluble in the
refrigerant at concentrations of about 5 to 15% over a temperature range
of from -40.degree. C. to 80.degree. C. These temperatures generally
correspond to the working temperatures of an automobile air-conditioning
compressor. In addition to thermal stability, the refrigeration liquids
must have acceptable viscosity characteristics which are retained even at
high temperatures, and the refrigeration liquid should not have a
detrimental effect on materials used as seals in the compressors.
Compositions comprising a tetrafluoroethane and polyoxyalkylene glycols are
discussed in U.S. Pat. No. 4,755,316. The compositions are useful in
refrigeration systems. Refrigeration oils are described in U.S. Pat. Nos.
4,248,726 and 4,267,064 which comprise mixtures of a polyglycol and 0.1 to
10% of glycidyl ether type epoxy compounds, or epoxidized fatty acid
monoesters, and optionally, epoxidized vegetable oil. The lubricating oils
are reported to be useful in refrigerators using a halogen-containing
refrigerant such as Freons 11, 12, 13, 22, 113, 114, 500 and 502
(available from DuPont), and in particular with Freon 12 or 22.
U.S. Pat. No. 4,431,557 describes fluid compositions comprised of a fluoro-
and chloro-containing refrigerant, a hydrocarbon oil, and an alkylene
oxide additive compound which improves the thermal resistance of the oil
in the presence of the refrigerant. Examples of hydrocarbon oils include
mineral oil, alkyl benzene oil, dibasic acid ester oil, polyglyools, etc.
The composition may contain other additives including loadcarrying
additives such as phosphorus acid esters, phosphoric acid esters, etc.
Examples of fluorocarbon refrigerants include R-11, R-12, R-113, R-114,
R-500, etc.
U.S. Pat. No. 4,428,854 describes absorption refrigerant compositions for
use in refrigeration systems comprising 1,1,1,2-tetrafluoroethane and an
organic solvent capable of dissolving the ethane. Among the solvents
disclosed are organic amides, acetonitrile, N-methyl pyrroles, N-methyl
pyrrolidine, N-methyl-2-pyrrolidone, nitromethane, various dioxane
derivatives, glycol ethers, butyl formate, butyl acetate, diethyl oxalate,
diethyl malonate, acetone, methyl ethyl ketone, other ketones and
aldehydes, triethyl phosphoric triamide, triethylene phosphate, triethyl
phosphate, etc.
Stabilized absorption compositions comprising (a) a halogenated hydrocarbon
refrigerant, (b) a liquid absorbent of a polyethylene glycol methyl ether,
and (c) at least one stabilizer are described in U.S. Pat. No. 4,454,052.
Examples of stabilizers include phosphate esters, epoxy compounds, and
organotin compounds. The polyethylene glycol methyl ether-type compounds
are of the general formula
CH.sub.3 --O--(CH.sub.2 H.sub.4 O).sub.n.sup.R
wherein n is an integer of 1 to 6, and R is H, CH.sub.3 -- or CH.sub.3
CO--. A variety of halogenated hydrocarbons are described including
1,1,-difluoromethane, 1,1,1,2-tetrafluoroethane, etc.
U.S. Pat. No. 4,559,154 relates to absorption heat pumps utilizing as
working fluid, a saturated fluorohydrocarbon or fluorohydrocarbon ether
having from 3 to 5 carbon atoms. Solvents reported to be useful with such
fluorohydrocarbons include ethers such as tetraglyme, amides which can be
lactams such as the N-alkyl pyrrolidones, sulfonamides and ureas including
cyclic ureas.
SUMMARY OF THE INVENTION
A liquid composition is described which comprises
(A) a major amount of at least one fluorine containing hydrocarbon
containing one or two carbon atoms; and
(B) a minor amount of a soluble organic lubricant comprising at least one
organic nitro compound characterized by the formulae
R.sub.z N(H).sub.x [CH.sub.2 C(R.sup.1)(R.sup.2)NO.sub.2 ]y (I)
and
CH.sub.2 [N(R)CH.sub.2 C(R.sup.1)(R.sup.2)NO.sub.2 ].sub.2 (II)
wherein R is a hydrocarbyl group, a polyaminoalkyl group, or R.sup.4
XR.sup.5 -- wherein R.sup.4 is H, hydrocarbyl, hydroxyalkyl or aminoalkyl,
X is 0 or NR.sup.6, wherein R.sup.6 is H or a nitroalkyl group, and
R.sup.5 is an alkylene group, or R.sup.4 X is a morpholinyl group attached
to R.sup.5 through the nitrogen atom; and
R.sup.1 and R.sup.2 are each independently H or lower aliphatic groups;
x is 0 or 1;
Y is 1 or 2; and
z is 1 or 2, provided that the sum of x, y and z is 3. Liquid compositions
also are described containing fluorine-containing hydrocarbons also
containing other halogen such as chlorine. The liquid compositions are
useful particularly as refrigeration liquids in refrigerators and
air-conditioners including auto, home and industrial air-conditioners.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Throughout this specification and claims, all parts and percentages are by
weight, temperatures are in degrees Celsius, and pressures are at or near
atmospheric pressure unless otherwise clearly indicated.
As used in this specification and in the appended claims, the terms
"hydrocarbyl" and "hydrocarbylene" denote a group having a carbon atom
directly attached to the polar group and having a hydrocarbon or
predominantly hydrocarbon character within the context of this invention.
Such groups include the following:
(1) Hydrocarbon groups; that is, aliphatic, (e.g., alkyl or alkenyl),
alicyclic (e.g., cyoloalkyl or cycloalkenyl), and the like, as well as
cyclic groups wherein the ring is completed through another portion of the
molecule (that is, any two indicated substituents may together form an
alicyclic group). Such groups are known to those skilled in the art.
Examples include methyl, ethyl, octyl, decyl, octadecyl, cyolohexyl, etc.
(2) Substituted hydrocarbon groups; that is, groups containing
non-hydrocarbon substituents which, in the context of this invention, do
not alter the predominantly hydrocarbon character of the group. Those
skilled in the art will be aware of suitable substituents. Examples
include halo, hydroxy, alkoxy, etc.
(3) Hetero groups; that is, groups which, while predominantly hydrocarbon
in character within the context of this invention, contain atoms other
than carbon in a chain or ring otherwise composed of carbon atoms.
Suitable hetero atoms will be apparent to those skilled in the art and
include, for example, nitrogen, oxygen and sulfur.
In general, no more than about three substituents or hetero atoms, and
preferably no more than one, will be present for each 10 carbon atoms in
the hydrocarbyl group.
Terms such as "alkyl", "alkylene", etc. have meanings analogous to the
above with respect to hydrocarbyl and hydrocarbylene.
The term "hydrocarbon-based" also has the same meaning and can be used
interchangeably with the term hydrocarbyl when referring to molecular
groups having a carbon atom attached directly to the polar group.
The term "lower" as used herein in conjunction with terms such as
hydrocarbyl, hydrocarbylene, alkylene, alkyl, alkenyl, alkoxy, and the
like, is intended to describe such groups which contain a total of up to 7
carbon atoms.
(A) Fluorine-Containinq Hydrocarbon.
The liquid compositions of the present invention comprise a major amount of
at least one fluorine-containing hydrocarbon. That is, the
fluorine-containing hydrocarbons contain at least one C--H bond as well as
C--F bonds. In addition to these two essential types of bonds, the
hydrocarbon also may contain other carbon-halogen bonds such as C--C1
bonds. Because the liquid compositions of the present invention are
primarily intended for use as refrigerants, the fluorine-containing
hydrocarbon preferably contains one or two carbon atoms, and more
preferably two carbon atoms.
As noted above, the fluorine-containing hydrocarbons useful in the liquid
compositions of the present invention may contain other halogens such as
chlorine. However, in one preferred embodiment, the hydrocarbon contains
only carbon, hydrogen and fluorine. These compounds containing only
carbon, hydrogen and fluorine are referred to herein as
fluorohydrocarbons. The hydrocarbons containing chlorine as well as
fluorine and hydrogen are referred to as chlorofluorohydrocarbons. The
fluorine-containing hydrocarbons useful in the composition of the present
invention are to be distinguished from the fully halogenated hydrooarbons
which have been and are being used as propellants, refrigerants and
blowing agents such as CFC-11, CFC-12 and CFC-113 which have been
described in the background.
Specific examples of the fluorine-containing hydrocarbons useful in the
liquid compositions of the present invention, and their reported ozone
depletion potentials are shown in the following Table I.
TABLE I
______________________________________
Compound
Designation Formula ODP*
______________________________________
HCFC-22 CHClF.sub.2
0.05
HCFC-123 CHCl.sub.2 CF.sub.3
<0.05
HCFC-141b CH.sub.3 CCl.sub.2 F
<0.05
HFC-134a CH.sub.2 FCF.sub.3
0
______________________________________
*Ozone depletion potential as reported in Process Engineering, pp. 33-34,
July, 1988.
Examples of other fluorine-containing hydrocarbons which may be useful in
the liquid. compositions of the present invention include trifluoromethane
(HCFC-23), 1,1,1-trifluoroethane (HCFC-143a), 1,1-difluoroethane
(HCFC152a), 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124),
1-chloro-1,1,2,2-tetrafluoroethane (HCFC-124a),
1-chloro-1,1-difluoroethane (HCFC-142b), and 1,1,2,2-tetrafluoroethane
(HCFC-134).
In general, fluorine-containing hydrocarbons which are useful as
refrigerants are fluoromethanes and fluoroethanes boiling at a relatively
low temperature at atmospheric pressure, e.g., below 30.degree. C.
Mixtures of fluorine-containing hydrocarbons may be used, and the amount
of each fluorohydrocarbon in the mixture may be varied as desired.
Examples of fluorohydrocarbon mixtures useful as (A) include: 142(b)/22;
134(a)/23; 22/124/152(a), etc. The useful fluorocarbon refrigerants serve
to transfer heat in a refrigeration system by evaporating and absorbing
heat at a low temperature and pressure, e.g., at ambient temperature and
atmospheric pressure, and by releasing heat on condensing at a higher
temperature and pressure.
The liquid compositions of the present invention contain a major amount of
at least one fluorine-containing hydrocarbon. More generally, the liquid
compositions will comprise from about 50% to about 99% by weight of the
fluorine-containing hydrocarbon(s). In another embodiment, the liquid
compositions contain from about 70% to about 99% by weight of the
fluorine-containing hydrocarbon(s).
(B) Soluble Organic Lubricant:
In addition to the fluorine-containing hydrocarbon, the liquid compositions
of the present invention contain a minor amount of a soluble organic
lubricant comprising at least one organic nitro compound characterized by
the formulae
R.sub.z N(H).sub.x [CH.sub.2 C(R.sup.1)(R.sup.2)NO.sub.2 ]y (I)
and
CH.sub.2 [N(R)CH.sub.2 C(R.sup.1)(R.sup.2)NO.sub.2 ].sub.2 (II)
wherein R is a hydrocarbyl group, a polyaminoalkyl group, or R.sup.4
XR.sup.5 -- wherein R.sup.4 is H, hydrocarbyl, hydroxyalkyl or aminoalkyl,
X is 0 or NR.sup.6, wherein R.sup.6 is H or a nitroalkyl group, and
R.sup.5 is an alkylene group, or R.sup.4 X is a morpholinYl group attached
to R.sup.5 through the nitrogen atom; and R.sup.1 and R.sup.2 are each
independently H or lower aliphatic groups; x is 0 or 1; y is 1 or 2; and z
is 1 or 2, provided that the sum of x, y and z is 3.
The hydrocarbyl groups R in Formulae I and II may be substituted or
unsubstituted alkyl or alkenyl groups and these groups may contain
substituents such as phenyl groups or non-hydrocarbon groups such as
nitro, amino, halo, etc. In one embodiment, the R groups will be alkyl or
alkenyl groups containing from 2 to about 50 carbon atoms. Examples of
such groups include ethyl, propyl, butyl, isobutyl, pentyl, octyl, nonyl,
dodecyl, dococyl, 5-chlorohexyl, 2,3,5-trimethylheptyl, oleyl, stearyl,
etc. The alkyl and alkenyl groups R may be linear or branched chain alkyl
groups, and in some embodiments, the branched chain alkyl groups are
preferred since the compounds containing branching appear to be more
soluble in the fluorine-containing hydrocarbons.
In another embodiment, the R group in Formulae I, and II may be R.sup.4
XR.sup.5 -- wherein R.sup.4 is H, hydrocarbyl, hydroxyalkyl, or amino
alkyl, X is O or NR.sup.6 wherein R.sup.6 is H or a nitro alkyl group and
R.sup.5 is an alkylene group, or R.sup.4 X is a morpholinyl group attached
to the alkylene group R.sup.5 through the nitrogen atom. The hydrocarbyl,
hydroxyalkyl and amino alkyl groups R.sup.4 generally will contain from 1
to about 20 carbon atoms, and the alkylene group R.sup.5 is a lower
straight or branched chain alkylene group.
As noted, the R group may be R.sup.4 XR.sup.5 wherein R.sup.4 is hydrogen,
hydrocarbyl, hydroxyalkyl or amino alkyl, and X is 0 or NR.sup.6 wherein
R.sup.6 is H or a nitroalkyl group and R.sup.5 is an alkylene group. The
hydrocarbyl groups generally are alkyl groups, and such alkyl groups, as
well as the hydroxyalkyl and aminoalkyl groups R.sup.4 generally contain
from 1 to about 20 carbon atoms. Examples of hydroxyalkyl groups include
hydroxymethyl, hydroxyethyl, hydroxypropyl, etc., and examples of
aminoalkyl groups include aminoethyl, aminopropyl, aminobutyl, etc. The
alkylene groups R.sup.5 generally are lower alkylene groups such as
--CH.sub.2 --, --(CH.sub.2).sub.2 --, --(CH.sub.2).sub.3 --, --CH.sub.2
--CH(CH.sub.3)--, etc.
The groups R.sup.1 and R.sup.2 are independently hydrogen or lower
aliphatic groups. Examples of lower aliphatic groups include methyl,
ethyl, n-propyl, isopropyl, n-butyl and 2-methylpropyl.
The organic nitro compounds useful as organic lubricants in the liquid
compositions of the present invention and represented by Formulae I and II
may be prepared generally by reacting an amine which may be a primary or
secondary amine with a nitro compound in the presence of formaldehyde.
Consistent with Formulae I and II, the amine may be represented by the
formula
R.sub.z N(H).sub.x
wherein z is 1 or 2 and x is 1 or 2, and the sum of z and x is 3. The nitro
compound which is utilized in the reaction may be represented by the
formula
R.sup.1 (R.sup.2)C(H)--NO.sub.2
wherein R.sup.1 and R.sup.2 are as defined in Formulae I and II. When
R.sup.1 and R.sup.2 are methyl groups, the nitro compound is
2-nitropropane. Other nitro compounds which may be utilized in the
reaction include nitromethane, nitroethane, 1-nitropropane, and other
nitroalkanes wherein there is at least one hydrogen on the carbon to which
the nitro group is attached.
Preferred organic nitro compounds of the present invention are those
derived from primary amines reacted with one or two equivalents of
formaldehyde and one or two equivalents of 2-nitropropane to form
compounds represented by the following Formulae III and IV
RNH[CH.sub.2 C(CH.sub.3).sub.2 NO.sub.2 ] (III)
RN[CH.sub.2 C(CH.sub.3).sub.2 NO.sub.2 ].sub.2 (IV)
wherein R is an alkyl or alkenyl group, or a polyamino alkyl group, or
R.sup.4 XR.sup.5 -- wherein R.sup.4 is H or hydrocarbyl, X is 0 or
NR.sup.6 wherein R.sup.6 is H or a nitroalkyl group, and R.sup.5 is a
lower straight chain or branched chain alkylene group, or R.sup.4 X is a
morpholino group attached to R.sup.5 through the nitrogen atom.
In another embodiment, the organic nitro compounds of the present invention
may be prepared by reacting a primary amine with excess formaldehyde in
the presence of the nitro compound to cross-link the nitrogen atoms of the
starting primary amine with one mole of formaldehyde, and the excess
formaldehyde is then available for the Mannich reaction to condense the
nitro groups onto one or both of the remaining hydrogens. For example, the
above reaction can be effected by utilizing two moles of the primary amine
such as oleylamine, at least three moles of formaldehyde and at least two
moles of the nitro compound, typically 2-nitropropane. This reaction can
be illustrated as follows
##STR1##
The typical conditions for reacting an amine, an aldehyde and the nitro
compound include preparing a mixture of the three components and heating
the mixture with stirring at a temperature between about 50.degree. and
150.degree. C. Generally, the reaction may proceed at any point from the
lowest temperature at which the reaction takes place up to but not
including the decomposition temperature of the component which decomposes
first. As water is formed during the reaction, it generally is removed
from the reaction vessel to facilitate and promote the reaction.
Typically, the reaction may be conducted at a temperature at which the
water is effectively removed by evaporation either at atmospheric pressure
or under vacuum. The desired products generally can be prepared by the
above reactions at a reaction time of from about 12 hours and more
particularly from 2 to about 5 hours.
The following examples illustrate the preparation of the organic nitro
compounds useful in the liquid compositions of the present invention.
EXAMPLE 1
A mixture comprising 2 moles of oleylamine, 2 moles of 2-nitropropane and 3
moles of paraformaldehyde is prepared, and nitrogen gas is bubbled through
the reaction mixture as it is heated to the reflux temperature. The
reaction proceeds exothermically over a period of about 4 hours with water
being collected in a trap. Evolved 2-nitropropane is returned to the
reaction vessel. The reaction proceeds, as measured by the water volume
collected divided by theory, to 93% completion. The product then is
filtered and recovered.
EXAMPLE 2
The amine utilized in this reaction is characterized by the formula
n-C.sub.13 H.sub.27 OCH.sub.2 CH.sub.2 CH.sub.2 NH.sub.2
The amine is commercially available under the general trade designation
SURFAM PA-17B from Sea Land Chemical. A mixture of 274 parts (1 mole) of
the amine, 178 parts (2 moles) of 2-nitropropane and 30 parts (1 mole) of
formaldehyde is prepared with stirring, and the mixture is heated to about
100.degree. C. An azeotrope of water/2-nitropropane evolves. The reaction
is continued until the theoretical amount of water is evolved, and excess
nitropropane is stripped by applying a slight vacuum. The product is a
yellow liquid which is filtered. The product contains 7.57% nitrogen
(theory 7.47), and infrared analysis of the product indicates very little
hydroxyl content and a nitro peak at 1530 cm.sup.-1. The product obtained
in this example contains material having the general structural formula
n-C.sub.13 H.sub.27 OCH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2
C(CH.sub.3).sub.2 NO.sub.2
EXAMPLE 3
The general procedure of Example 2 is repeated utilizing 1 mole of SURFAM
PA-17B, 3 moles of 2-nitropropane and 2 moles of paraformaldehyde. The
compound obtained in this manner contains 7.57% nitrogen (theory, 7.47%)
and comprises material of the proposed formula
n--C.sub.13 H.sub.27 OCH.sub.2 CH.sub.2 CH.sub.2 N[CH.sub.2
C(CH.sub.3).sub.2 NO.sub.2 ].sub.2
EXAMPLE 4
Aminopropyl morpholine (1 mole) is reacted with 1 mole of oleylchloride
(RCl) to form a compound comprising the structure
##STR2##
This amine (1 mole) is reacted with two moles of nitropropane and 1 mole
of formaldehyde by heating the mixture to the reflux temperature (about
120.degree. C.). The reaction mixture is heated for about 6 hours and
stripped for 30 minutes at 70.degree.-100.degree. C. under a slight
vacuum. The residue is filtered and the filtrate is recovered as the
desired product which may be characterized by the following formula
##STR3##
EXAMPLE 5
A mixture of 146 parts (2 moles) of n-butylamine and 178 parts (2 moles) of
2-nitropropane is prepared, and 90 parts (3 moles) of paraformaldehyde are
added. This mixture is stirred and an exothermic reaction begins raising
the temperature of the mixture to the reflux temperature of about
90.degree. C. When the refluxing subsides, the material which is collected
in the trap is returned to the flask and this mixture is maintained at
reflux until about 48 parts of water are collected. The residue is the
desired product containing 14.5% nitrogen (theory 15.5) The product of
this example contains material having a structural formula similar to that
of Formula V wherein R is n-butyl, and R.sup.1 and R.sup.2 are methyl
groups.
EXAMPLE 6
The amine utilized in this example is Duomeen O available from Akzo Chemie,
which has the general formula
R.sup.4 N(H)CH.sub.2 CH.sub.2 CH.sub.2 NH.sub.2
where R is an alkyl group containing 18 carbon atoms. A mixture is prepared
containing 350 parts (1 mole) of this amine and 530 parts (6 moles) of
2-nitropropane. The mixture is stirred and about 18 parts of
paraformaldehyde is added. The reaction mixture is heated to about
100.degree. C. and an additional 72 parts (a total of 3 moles) of
paraformaldehyde are added slowly, and the water formed by the reaction is
collected in a trap. An infrared spectrum of the residue shows no N-H, no
C=O, but a strong NO.sub.2 peak. The product contains 10.2% nitrogen
(theory 10.7%) and contains a material having the proposed structure
##STR4##
EXAMPLE 7
A mixture of 370 parts (2 moles) of dodecylamine, 120 parts (4 moles) of
paraformaldehyde and 356 parts (4 moles) of 2-nitropropane is prepared,
stirred and heated to about 80.degree. C. where upon an exotherm begins.
Water is removed as it is formed in the reaction. The residue is the
desired product containing 10.0% nitrogen (theory 10.85%). The product
contains material having the following proposed structure.
C.sub.12 H.sub.25 N[CH.sub.2 --C(CH.sub.3).sub.2 NO.sub.2 ].sub.2
EXAMPLE 8
A reactor is charged with 570 parts (3 moles) of a branched 12 carbon
atom-containing amine, and 45 parts (1.5 moles) of paraformaldehYde are
added at room temperature. This mixture is heated to 100.degree. C., and
when a theoretical amount of water has been evolved, 267 parts (3 moles)
of 2-nitropropane are added followed by an additional 90 parts (3 moles)
of paraformaldehyde. The reaction mixture is maintained at about
115.degree. C. for two hours, stripped for one hour at 100.degree. C.
under vacuum, and then filtered. The filtrate is the desired product
containing 9.44% nitrogen (theory 9.6). The product contains a material
characterized by Formula V wherein each R group is a 12 carbon atom
branched alkyl group and each R.sup.1 and R.sup.2 are methyl groups.
EXAMPLE 9
A mixture is prepared containing 380 parts (2 moles) of a 12 carbon atom
branched chain aliphatic amine, 356 parts (4 moles) of 2-nitropropane and
60 parts (2 moles) of paraformaldehyde. The mixture is heated to about
90.degree. C., and a water/nitropropane azeotrope evolves. About 35 parts
of water is collected in about 2 to 3 hours. The reaction mixture then is
stripped to remove excess 2-nitropropane. The residue is the desired
product containing 9.66% nitrogen (theory 9.06).
The organic lubricants characterized by Formulae I and II preferably
contain branched alkyl or alkylene groups and generally are free of
acetylenic and aromatic unsaturation. Some compounds of Formulae I and II
which contain such unsaturation may be insoluble in the
fluorine-containing hydrocarbons. The soluble lubricants of this invention
also are preferably free of olefinic unsaturation except that some
olefinic unsaturation may be present so long as the lubricant is soluble.
The organic nitro compounds are soluble in the fluorine-containing
hydrocarbons and, in particular, in the fluorohydrocarbons such as
1,1,1,2-tetrafluoroethane. The lubricants are soluble over a wide
temperature range and, in particular, at low temperatures. The solubility
of the lubricants in fluorohydrocarbons such as 1,1,1,2-tetrafluoroethane
at low temperatures is determined in the following manner. The lubricant
(0.5 gram) is placed in a thick-walled glass vessel equipped with a
removable pressure gauge. The tetrafluoroethane (4.5 grams) is condensed
into the cooled (-40.degree. C.) glass vessel, and the contents are warmed
to the desired temperature and mixed to determine if the lubricant is
soluble in the tetrafluoroethane. If soluble, the temperature of the
mixture is reduced until a separation and/or precipitate is observed. The
results of this solubility test conducted with several examples of the
organic nitro lubricants of the present invention are summarized in the
following Table II.
TABLE II
______________________________________
Liquid Containing
Solubility
Product of Example
.degree.C. (ppt.)
______________________________________
5 -40
7 -20
8 -35
______________________________________
The liquid compositions of the present invention comprise a major amount of
a fluorine-containing hydrocarbon and a minor amount of at least one
soluble organic lubricant comprising at least one organic nitro compound
of the types described above with respect to Formulae I and II. By "major
amount" is meant an amount greater than 50% by weight such as 50.5%, 70%,
99%, etc. The term "minor amount" includes amounts less than 50% by weight
such as 1%, 5%, 20%, 30% and up to 49.9%. In one embodiment, the liquid
compositions of the present invention will comprise from about 70% to
about 99% of the fluorine-containing hydrocarbon and from about 1 to about
30% by weight of the lubricant. In other embodiments, the liquid
compositions of the present invention may contain from about 5% to about
20% by weight of the lubricant.
The liquid compositions of the present invention are characterized as
having improved thermal and chemical stability over a wide temperature
range. Other additives, if soluble in the liquid, known to be useful for
improving the properties of halogen-containing hydrocarbon refrigerants
can be included in the liquid compositions of the present invention to
improve the characteristics of the liquid as a refrigerant. However,
hydrocarbon oils such as mineral oil generally are not included in and are
most often excluded from the liquid compositions of the invention,
particularly when the fluorine-containing hydrocarbon contains no other
halogen. Polyglycols and alkyl ethers which have been suggested in the
prior art as useful solvents for fluorine-containing hydrocarbons are not
required in the liquid compositions of the present invention and are
generally omitted from the liquid compositions.
The additives which may be included in the liquid compositions of the
present invention to enhance the performance of the liquids include
extreme-pressure and anti-wear agents, oxidation and thermal-stability
improv | | |
