Note: Descriptions are shown in the official language in which they were submitted.
2~8~4~
2456R-02
Title: LIQUID COMPOSITIONS CONTAINING COMPLEX CAR~OXYLIC
ESTERS
Cross-Reference to Related A~lications
This is a continuation-in-part of U.S. Serial No.
608,600 filed on October 30, 1990, which is a
continuation of Serial No. 343,087 filed on April 25,
1989 and now abandoned.
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 a~ refrigeration
liquids.
Introduction to the ~nvention
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 year5 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
stratosphere'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-13 which is chlorotrifluoromethane,
2Q87947
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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 CF~
propellants. ~he 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
l,l-dichloro-2,2,2-trifluoroethane, HFC-134a which is
1,1,1,2-tetrafluoroethane and HCFC-141b which is
l,l-dichloro-l-fluoroethane.
The ozone depletion potential of these proposed
substitutes i5 significantly less than the ozone deple-
tion potential of the previously used CFCs. The ozone
depletion potential i5 a relative measure of the
capability of the material to dectroy the ozone layer in
the atmosphere. It i8 a combination of the percentage by
weight oE 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
2087947
-3-
utilized as the lubricant in air-conditioner compressors.
The above-described refrigerant candidates, however, have
different solubility characteristics than the refrig-
erants presently in use. For example, mineral
lubricating oil is incompatible (i.e., insoluble) with
HFC-134a. 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 0C and above 80'C. For some uses, 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 -4~-C to 80-C. These
temperatures generally correspond to the working tempera-
tures 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
polyoxyalky-lene glycols are discussed in U.S. Patent
4,755,316. The compositions are useful in refrigeration
systems. Refrigeration oils are described in U.S.
Patents 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 epo~idized 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 ll, 12, 13,
~0~9~
--4--
22, 113, 114, 500 and 502 (available from DuPont), and in
particular with Freon 12 or 22.
U.S. Patent 4,431,557 describes fluid compositions
comprised of a fluoro- and chloro-containing refrigerant,
a hydrocarbon oil, and an al~ylene 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, polyglycols, etc. The
composition may contain other additives including
load-carrying additives such as phosphorus acid esters,
phosphoric acid esters, etc. Examples of fluorocarbon
refrigerants inc~ude R-13, R-12, R-113, R-114, R-500,
etc.
U.S. Patent 4,428,854 describes absorption
refrigerant compositions for use in refrigeration syste~s
comprising 1,1,1,2-tetrafluoroethane and an organic
solvent capable of di solving 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
halo-genated hydrocarbon refrigerant., (b) a liquid
absorbent o~ a polyethylene glycol methyl ether, and (c)
at lQast one stabilizer are descrihed in U.S. Patent
4,454,052. Examples of stabilizer~ include phosphate
esters, epoxy compounds, and organotin compounds. The
polyethylene glycol methyl ether-type compounds are of
the general formula
CH3-0-(C2H40)nR
2~879~7
--5--
wherein n is an integer of 1 to 6, and R is H, CH3- or
CH3CO-. A variety of halogenated hydrocarbons are des-
cribed including 1,1,-difluoromethane, 1,1,1,2-tetra-
fluoroethane, etc.
U.S. Patent 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. Sclvents 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.
Summarv 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 at least one soluble organic
lubricant comprising at least one carboxylic ester of a
polycarboxylic acid and a polyhydroxy compound, or of a
mixture of monocarboxylic and dicarboxylic acids and a
polyhydroxy compound.
Liquid compositions also are described wherein the
fluorine-containing hydrocarbons also contain other
halogens such as chlorine. The llquid compositions are
useful particularly as refrigeration liquids in
refrigerators and air-conditioners including automotive,
home and industrial air-conditioners.
,Detailed DescriPtion of the Invention
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 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
20879~7
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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 le.g., cycioalkyl 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, cyclohexyl, 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 conte~t
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
2~9~ 7
describe such groups which contain a total of up to 7
carbon atoms.
When a compound or component is indicated herein as
being "soluble", the compound or component is soluble in
the liquid compositions of the inYention comprising the
fluorine-containing hydrocarbon and the lubricant. For
example, a compound or component is considered "soluble"
so long as it is soluble in the liquid compositions, even
though it may be insoluble in th~, fluorine-containing
hydrocarbon, Per se.
Viscosity, unless otherwise indicated, is kinematic
viscosity and is measured by ASTM D-2270.
For purpose of this invention, equivalent weight of
polyol is determined by dividing the formula weight of
the polyol by the number of hydroxyl groups. Equivalents
of polyol is determined by dividing the amount of polyol
by its equivalent weight. For polycarboxylic acids or
anhydrides, the equivalent weight is determined by
dividing the formula weight of the acid or anhydride by
the number of carboxylic groups which form esters. For
example, an anhydride contributes two carboxyl groups
which can form ester. Therefore, the equivalent weight
of anhydride, such as succinic anhydride, would be the
formula weight of the anhydride divided by the number of
carboxyl group. For succinic anhydride, the number is
two.
(A) Fluo~inç-Containin~ Hvdrocarbon.
The liquid compositlons of the present invention
comprise a major amount of at least one fluorine-contain-
ing hydrocarbon. That is, the fluorine~containing
hydrocarbons contain at least one C-H bond as well as C-F
bonds. In addition to theqe two essential types of bonds,
the hydrocarbon also may contain other carbon- halogen
bonds such as C-Cl bonds. Because the liquid composi-
tions 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.
2~8~`7
As noted above, the fluorine-containing hydrocarbons
use~ul 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 hydrocarbons
which have been and are being used as propellants,
refrigerants and blowing agents such as CFC-ll, CFC-12
and CFC-113 which have been described above.
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
Desiq~ation Formula~p~*
HCFC-~2 CHClF2 0.05
HCFC-123 CHCl2CF3<0.05
HCFC-141b CH3 12
HFC-134a CH2FCF3 O
* Ozone depletion potential as reported in
Enqineerinq, pp. 33-34, ~uly, 1988.
Examples o~ other fluorine-containing hydrocarbons which
may be useful in the liquid compositions of the present
invention include trifluoromethane (HFC-23), 1,1,1-tri-
fluoroethane (HFC-143a), l,1-difluoroethane (HFC-152a),
2-chloro 1,1,1,2-tetrafluo-
roethane (HCFC-124), l-chloro-1,1,2,2-tetrafluoroethane
(HCFC-124a), 1-chloro-l,l-difluoroethane (HCFC-142b), and
1,1,2,2-tetra fluoroethane ( HFC-134). In the
2 ~ 7
refrigerant ar~, the fluorohydrocarbons are often
identified merely with the prefi~ "R" in place of the
above letters. For example HFc-23 is R-23, HCFC-124 is
R~124, etc.
In general, fluorine-containing hydrocarbons which
are useful as refrigerants are fluorom~thanes and
fluoroethanes boiling at a relatively low temperature at
atmospheric pressure, e.g., below 30~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., near 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 the fluorine-containing
hydrocarbon. More generally, the liquid compositions
will comprise from about 50% to about 99% by weight of
the fluorine-containing hydrocarbon. In another
embodiment, the liquid compositions contain from about
70% to about 99% by weight of the fluorine-containing
hydrocarbon.
(~) Soluble Orqanic Lubricant.
In addition to the fluorine-containing hydrocarbons
described above, the liquid compositions of the present
invention also contain a minor amount of at least one
carboxylic ester of a polycarboxylic acid, preferably a
dicarboxylic acid and a polyhydroxy compound, or of a
mixture of monocarboxylic and polycarboxylic, preferably
dicarboxylic acids and a polyhydroxy compound.
The carboxylic ester lubricants utilized as
component (B) in the liquid compositions of the present
invention are reaction products of one or more carboxylic
2087~7
--10--
acids or anhydrides (or the lower esters thereof such as
methyl, ethyl, etc.) with polyhydrox~ compounds
containing at least two hydroxy groups. The polyhydroxy
compounds may be represented by the general formula
R(OH)n
wherein R is a hydrocarbyl group and n is at least 2.
The hydrocarbyl group may contain from 4 to about 20 or
more carbon atoms, and the hydrocarbyl group may also
contain one or more nitrogen and/or oxygen atoms. The
polyhydroxy compounds generally will contain from about 2
to about 10 hydroxy groups and more preferably from about
3 to about 10 hydroxyl groups. The polyhydroxy compound
may contain one or more oxyalkylene groups, and, thus,
the polyhydroxy compounds include compounds such as
polyetherpolyols. The number of carbon atoms and number
of hydroxy groups contained in the polyhydroxy compound
used to form the carboxylic ester may vary over a wide
range, and it is only necessary the carboxylic ester
produced with the polyhydroxy compounds be soluble in the
liquid compositions of the present invention.
The polyhydroxy compounds used in the preparation of
the carboxylic esters also may contain one or more
nitrogen atoms. For example, the polyhydroxy compound
may be an alkanol amine containing from 3 to 6 hydroxy
groups. In one preferred embodiment, the polyhydroxy
compound is an alkanol amine containing at lea~t two
hydroxy groups and more preferably at least three hydroxy
groups.
Specific examples of polyhydroxy compounds useful in
the present invention include ethylene glycol, diethylene
glycol, triethylene glycol, propylene glycol, dipropylene
glycol, glycerol, neopentyl glycol, 1,2-, 1,3- and
1,4-butanediols, pent~erythritol, dipentaerythritol,
tripentaerythritol, triglycerol, trimethylolpropane,
sorbitol, hexaglycerol, 2,2,4-trime thyl-1,3-pentanediol,
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--11--
etc. Mixtures of any of the above polyhydroxy compounds
can be utilized.
The carboxylic acids utilized in the preparation of
the carboxylic esters useful in the liquid compositions
of the present invention may be characterized by the
following general formula
RlCOOH
wherein R1 is (a) H, (b) a straight chain lower
hydrocarbyl group, (c) a branched chain hydrocarbyl
group, (d) a mixture of one or both of (b) and (c) with a
straight chain hydrocarbyl group containing from about 8
to about 22 carbon atoms or (e) a carboxylic acid or
carboxylic acid ester-containing hydrocarbyl group.
Stated otherwise, at least one R1 group in the ester
product must contain a lower straight chain hydrocarbyl
group or a branched chain hydrocarbyl group. The straight
chain lower hydrocarbyl group (Rl) contains from 1 to
about 7 carbon atoms, and in a preferred embodiment,
contains from 1 to about 5 carbon atoms. The branched
chain hydrocarbyl group may contain any number of carbon
atoms and will generally contain from 4 to about 20
carbon atoms. In one preferred embodiment, the branched
chain hydrocarbon group contain9 from 5 to 20 carbon
atoms and in a more preferred embodiment, contain~ ~rom
about 5 to about 14 carbon atoms. ~he higher molecular
weight straight ch~in hydrocarbyl group containing from 8
to about 22 carbon atoms will contain in some
embodiments, from 8 to about 18 carbon atoms, and in more
pre~erred embodiments from 8 to about 14 carbon atoms.
In one preferred embodiment, the branched chain
hydrocarbyl groups (Rl) are characterized by the
structure
-C(R )(R )(R )
21~879~
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~herein R2, R3 and R4 are each independently alkyl
groups, and at least one of the alkyl groups contains two
or more carbon atoms. Such branchsd chain al~yl groups,
when attached to a carboxyl group are referred to in the
industry as neo groups and the acids are referred to as
neo acids. The neo acids are characterized as having
alpha, alpha disubstituted hydrocarbyl groups. In one
embodiment, R2 and R3 are methyl groups and R4 is an
alkyl group containing two or more carbon atoms.
Any of the above hydrocarbyl groups (R1) may contain
one or more carboxy groups or carboxy ester groups such
a~ -CooR5 wherein R5 is a lower alkyl, hydroxy alkyl or a
hydroxy alkyloxy group. Such substituted hydrocarbyl
groups are present, for example, when the carboxylic acid
RlCOOH is a dicarboxylic acid or a monoester of a
dicarboxylic acid. Mixtures of monocarboxylic acids or
anhydrides and dicarboxylic acids or anhydrides are
useful in preparing the esters.
Examples of carboxylic acids containing a straight
chain lower hydrocarbyl group include formic acid, acetic
acid, propionic acid, butyric acid, pentanoic acid,
hexanoic acid and heptanoic acid. Examples of carboxylic
acids wherein the hydrocarbyl group is a branched chain
hydrccarbyl group include isobutanoic acid,
2-ethyl-n-butyric acid, 2-hexyldecanoic acid, isostearic
acid, ~-methylhexanoic acid, 3,5,5-trimethylhexanoic
acid, 2-ethylhexanoic acid, neoheptanoic acid,
neodecanoic acid, and ISO Acids and NEO Acids available
from Exxon Chemical Company, Houston, Texas USA. ISO
Acids are isomer mixtures of branched acids and include
commercial mixtures such as ISO Heptanoic Acid, ISO
Octanoic Acid, and ISO Nonanoic Acid, as well as
developmental products such as ISO Decanoic Acids and ISO
810 Acid. NEO Acids include commerically available
mixtures such as NEO Pentanoic Acid, NEO Heptanoic Acid,
and NEO Decanoic Acid, as well as developmental products
~87~7
such as ECR-903 (NE0 Cg) Acid, and ECR-903 (NE0 C1214)
Acid.
The third type of carboxylic acids which can be
utilized in the preparation of the carboxylic esters are
the acids containing a straight chain hydrocarbyl group
containing from 8 to about 22 carbon atoms. As noted
pre~iously, these higher molecular weight straight chain
acids can be utilized only in combination with one of the
other acids described above since the higher molecular
weight straight chain acids are not soluble in the
fluorhydrocarbons. Examples of such higher molecular
weight straight chain acids include decanoic acid,
dodecanoic acid, stearic acid, lauric acid, behenic acid,
etc.
In another embodiment, the carboxylic acids utilized
to prepare the carboxylic esters may comprise a mixture
of a monocarboxylic acid and a dicarboxylic acid.
Examples of useful dicarboxylic acids include maleic
acid, succinic acid, adipic acid, oxalic acid, pimelic
acid, glutaric acid, suberic acid, azelaic acid, sebacic
acid, etc. The presence of the dicarboxylic acids
results in the formation of complex esters of higher
viscosity. The complex esters are formed by having a
substantial portion of the dicarboxylic acids or
anhydrides react with more than one polyol. The reaction
is generally coupling of polyols through the dicarboxylic
acid or anhydride. In one embodiment, the complex ester
i8 characterized as containing greater than 50%,
preferably greater than 70%, more preferably greater than
80~ of the reaction mixture in the form of a bis-coupled
or dimer product. The bis-coupled product i5
characterized as the reaction of two polyols with one
dicarboxylic acid. In a preferred embodiment, the
bis-coupled product is characterized as having
substantially all the hydroxyl groups of the polyol
reacted with a mono- or dicarboxylic acid. Examples of
mixtures of mono- and dicarboxylic acids include succinic
~a87~7
-14-
anhydride and isononanoic acid; azelaic acid and
isooctanoic acid; adipic acid and isononanoic acid;
sebacic acid and isobutanoic acid; adipic and a mixture
of 50 parts isononanoic acid and 50 parts neoheptanoic
acid; and neoheptanoic acid and a mixture of 50 parts
adipic acid and 50 parts sebacic acid. An example of
such a mixture is 80 parts of neoheptanoic acid and 20
parts of succinic acid. Viscosity and average molecular
weight of the ester can be increased by increasinq the
amount of dicarboxylic acid and decreasing the amount of
monocarboxylic acid.
The carboxylic esters are prepared, as mentioned
above, by reacting at least one carboxylic acid or
anhydride with at least one polyhydroxy compound
containing at least two hydroxy groups. The formation of
esters by the interaction of carboxylic acids and
alcohols is acid catalyzed and is a reversible process
which can be made to proceed to completion by use of a
large amount of alcohol or by removal of the water as it
is formed in the reaction. If the ester is formed by
transesterification of a lower molecular weight carbox-
ylic ester, the reaction can be forced to completion by
removal of the low molecular weight alcohol formed as a
result of a transesterification reaction. The
esterification reaction can be catalyzed by either
organic acids or inorganic acids. Examples of inorganic
acids include sulfuric acids and acidified clays. A
variety of organic acids can be utilized including
paratoluene sulfonic acid, acidic resins such as
~mberlyst 15, etc. organometallic catalysts include, for
example, tetraisopropoxy orthotitanate.
The amounts of carboxylic acids and polyhydroxy
compounds included in the reaction mixture may be varied
depending on the results desired. If it is desired to
esterify all of the hydroxyl groups containing in the
polyhydroxy compounds, sufficient carboxylic acid should
be included in the mixture to react with all of the
-15- 2~8~7
hydroxyl groups. When mixtures of the acids are reacted
with a polyhydroxy compound in accordance with the
present invention, the carboxylic acids can be reacted
sequentially with the polyhydroxy compounds or a mixture
of carboxylic acids can be prepared and the mixture
reacted with the polyhydroxy compounds. In one
embodiment wherein mixtures of acids are utilized, the
polyhydroxy compound is first reacted with one carboxylic
acid, generally, the higher molecular weight branched
chain or straight chain carboxylic acid followed by
reaction with the straight chain lower hydrocarbyl
carboxylic acid. Throughout the specification and
claims, it should be understood that the esters also can
be formed by reaction of the polyhydroxy compound with
the anhydrides of any of the above-described carboxylic
acids. For example, esters are easily prepared by
reacting the polyhydroxy compounds either with acetic
acid or acetic anhydride.
In one embodiment, the esters are made by reacting a
polyol with a mixture of a dicarboxylic acid or anhydride
and a monocarboxylic acid. Preferably, one equivalent of
polyol is reacted with from about 0.07, preferably from
about 0.17 to about 0.33, preferably to about 0.23 moles
of dicarboxylic acid or anhydrid~ and from about 0.67,
preferably from about 0.77 to about 0.93, preferably to
about 0.83 mole~ of monocarboxylic acid.
The formation of esters by the reaction of
carboxylic acids or anhydrides with the polyhydroxy
compounds described above can be effected by heating the
acids or anhydrides, the polyhydroxy compounds, with or
without an acid catalyst to an elevated temperature while
removing water or low molecular weight alcohols formed in
the reaction. Generally, temperatures of from about 75C
to about 200-C or higher are sufficient for the reaction.
The reaction is completed when water or low molecular
weight alcohol is no longer formed, and such completion
2~87~i 7
-16-
is indicated when water or low molecular weight esters
can no longer be removed by distillation.
In some instances, it is desired to prepare
carboxylic esters wherein not all of the hydroxyl groups
have been esterified. Such partial esters can be
prepared by the techniques described above and by
utilizing amounts of the acid or acids which are
insufficient to esterify all of the hydroxyl qroups.
The following examples illu~trate the preparation of
various carboxylic esters which are useful as lubricants
(B) in the liquid compositions of the invention.
Example 1
A mixture of 92.1 parts (1 mole) of glycerol and
316.2 parts of acetic anhydride is prepared and heated to
reflux. The reaction is exothermic and continues to
reflux at 130-C for about 4.5 hours. Thereafter the
reaction mixture is maintained at the reflux temperature
by heating for an additional 6 hours. The reaction
mixture is stripped by heating while blowing with
nitrogen, and filtered with a filter aid. The filtrate
is the desired ester.
Example 2
A mixture of 872 parts (6.05 moles) of 2-ethyl-
hexanoic acid, 184 parts (2 moles~ of glycerol and 200
parts of toluene is prepared ancl blown with nitrogen
while heating the mixture to about 60-C. Para-toluene
sulfonic acid (S parts) is added to the mixture which is
then heated to the reflux temperature. A water/toluene
azeotrope distills at about 120'C. A temperature of
125-130'C is maintained Por about 8 hours followed by a
temperature of 140-C for 2 hour~ while removing water.
The residue is the desired ester.
Example 3
Into a reaction vessel there are charged 600 parts
(2.5 moles) of triglycerol and 1428 parts (14 moles) of
acetic anhydride. The mixture is heated to reflux in a
nitrogen atmosphere and maintained at the reflux
-17- 20~79~7
temperature (125-130C) for about 9.5 hours. The
reaction mixture is nitrogen stripped at 150C and 15
mm.Hg. The residue is filtered through a filter aid, and
the filtrate is the desired ester.
Example 4
A reaction vessel is charged with 23 parts (0.05
mole) of hexaglycerol and 43.3 parts (0.425 mole) of
acetic anhydride. The mixture is heated to the re~lux
temperature (about 139~C) and maintained at this
temperature for a total of about 8 hours. The reaction
mixture is stripped with nitrogen and then vacuum strip-
ped to 150C at lS mm.Hg. The residue is filtered
through a filter aid, and the filtrate is the desired
ester.
Example 5
A mixture of 364 parts (2 moles) of sorbitol, and
340 parts (2 moles) of a commercial C8 10 straight chain
methyl ester (Procter & Gamble), is prepared and heated
to 180C. The mixture is a two-phase system. Para-
toluene sulfonic acid (1 part) is added, and the mixture
is heated to 150~C whereupon the reaction commences and
water and methanol evolve. When the solution becomes
homogeneous, 250 parts (2.5 moles) of acetic anhydride
are added with stirring. The reaction mixture then is
stripped at lS0C and filtered. The filtrate is the
deslred ester of sorbitol.
2~87~7
-18-
Example 6
A mixture of 536 parts (4 moles~ of trimethylol
propane and 680 parts (4 moles) of a commercial C8 10
straight chain methyl ester is prepared, and 5 parts of
tetraisopropoxy orthotitanate are added. The mixture is
heated to 200~C with ni~rogen blowing. Methanol is
distilled from the reaction mixture. When the
distillation of methanol is completed by nitrogen
blowing, the reaction temperature is lowered to 150-C,
and 408 parts (4 moles) of acetic anhydride are added in
a slow stream. A water azeotrope begins to evolve when
50 parts of toluene are added. When about 75 parts of a
water/acetic acid mixture has been collected, the
distillation ceases. Acetic acid (50 parts) is added and
additional water/acetic acid mixture is collected. The
acetic acid addition is repeated with heating until no
water can be removed by distillation. The residue is
filtered and the filtrate is the desired ester.
Example 7
A mixture of 402 parts (3 moles) of trimethylol
propane, 660 parts (3 moles) of a commercial straight
chain methyl ester comprising a mixture of about 75% C12
methyl ester and about 2S% C14 methyl ester, (CE1270 from
Procter & Gamble), and tetraisopropoxy orthotitanate is
prepared and heated to 200'~ with mild nitrogen blowing.
The reaction is allowed to proceed overnight at this
temperature, and in 16 hours, 110 parts of methanol is
collected. The reaction mlxture is cooled to 150-C, and
100 parts of acetic acid and 50 parts of toluene are
added followed by the addition of an additional 260 parts
of acetic acid. The mixture i9 heated at about 150-C for
several hours yielding the desired ester.
Example 8
A mixture of 408 parts (3 moles) of pentaerythritol
and 660 parts (3 moles) of the CE1270 meth~l ester used
in Example 7 is prepared with 5 parts of tetraisopropyl
orthotitanate, and the mixture is heated to 220~C under a
2087947
--19--
nitrogen purge. No reaction occurs. The mixture then i5
cooled to 130C, and 250 parts of acetic acid are added.
A small amount of para-toluenesulfonic acid is added and
the mixture is stirred at about 200c for 2 days, and 60
parts of methanol are removed. At this time, 450 parts
of acetic anhydride are added and the mixture is stirred
at 150C until the acetic acid/water azeotrope no longer
evolves. The residue is filtered through a filter aid,
and the filtrate is the desired ester of pentaerythritol.
Example 9
A mixture of 850 parts (6.25 moles) of
pentaerythritol, 3250 parts (25 moles) of neoheptanoic
acid, and 10 parts of tetraisopropoxy orthotitanate is
prepared and heated to ltO-C. Water is evolved and
removed by distillation. When the evolution of water
ceases, 50 parts of acidified clay are added and some
additional water is evolved. A total of about 250 parts
of water is removed during the reaction. The reaction
mixture is cooled to room temperature and 310 parts of
acetic anhydride are added to esterify the remaining
hydroxyl groups. The desired ester is obtained.
Example 10
A mixture of 544 parts (4 moles) of pentaerythritol,
820 parts (4 moles) of Neo 1214 acid, a commercial acid
mixture available from Exxon, 408 parts (4 moles) of
acetic anhydride and 50 parts of Amberlyst 15 is prepared
and heated to about 120-C whereupon water and acetic acid
begin to distill. After about 150 parts of water/acetic
acid are collected, the reaction temperature increases to
about 200C. The mixture i5 maintained at this
temperature of several days and stripped. Acetic
anhydride is added to esterify any remaining hydroxyl
groups. The product is filtered and the filtrate is the
desired ester.
Example 11
A mixture of 1088 parts (8 moles) of pentaery-
thritol, 1360 parts (8 moles) of a commercial methyl
- 20~7~
-20-
ester of an acid mixture comprising about 55% of C8, 40%
of C10 and 4% of C6 acids ("CE810 ~ethyl Ester", Procter
& Gamble), 816 parts of acetic anhydride and lO parts of
paratoluene sulfonic acid is prepared and heated to
reflux. About 500 parts of a volatile material are
removed. A water azeotrope mixture then distills
resulting in the removal of about 90 parts of water.
Acetic anhydride (700 parts) is added and the mixture is
stirred as a water/acetic acid mixture is removed. The
reaction is continued until no more water is evolved and
no free hydroxy groups remain (by IR). The reaction
product is stripped and filtered.
Example 12
A mixture of 508 parts (2 moles) of
dipentaerythritol, 812 parts (8 moles) of acetic
anhydride, 10 parts of acidified clay as catalyst and lO0
parts of xylene is prepared and heated to loo-C. This
temperature is maintained until the solid
dipenta-erythritol is dissolved. A water/acetic acid
azeotrope is collected, and when the rate of evolution
diminishes, the reaction mixture is blown with nitrogen.
About 100-200 parts of acetic acid are added and the
reaction i8 continued as additional water/acetic
acid/xylene azeotrope is collected When an infrared
analysis o~ the reaction mixture indicates a minimum of
free hydroxyl groups, the reaction mixture i9 stripped
and filtered. The filtrate is the de9ired product which
solidifies.
E~ample 13
A mixture of 320 parts (l.Z6 moles) of
dipentaerythritol, 975 parts (1.25 moles) of neoheptanoic
acid and 25 parts of Amberlyst 15 catalyst is prepared
and heated to 130~C. At this temperature water evolution
is slow, but when the temperature is raised to 150~C,
about 65% of the theory water is collected. The last
amounts of water are removed by heating to 200~C. The
product is a dark viscous liquid.
2~879~7
-21-
Example 14
A mixture of 372 parts (1 mole) of
tripentaerythritol, 910 parts (7 moles) of neoheptanoic
acid and 30 parts of Amberlyst 15 catalyst is prepared
and heated to 110C as water is remo~ed. The mixture is
heated for a total of 48 hours, and unreacted acid is
removed by stripping the mixture. The residue is the
desired ester.
Example 15
A mixture of 1032 parts (6 moles) of neodecanoic
acid, 450 parts t3 moles) of triethylene glycol and 60
parts of Amberlyst 15 is prepared and heated to 130~C. A
water azeotrope is evolved and collected. The residue is
the desired product.
Example 16
A mixture of 1032 parts (6 moles) of neodecanoic
acid and 318 parts (3 moles) of diethylene glycol is
prepared and heated to 130C in the presence of 20 parts
of Amberlyst 15. After heating for 24 hours and removing
about 90 parts of water, 20 parts of Amberlyst 15 are
added and the reaction is conducted for another 24 hours.
The reaction is stopped when the theory amount of water
is obtained, and the residue is the desired ester.
Example 17
A mixture of 200 parts (2 moles) of succinic
anhydride and 62 parts (1 mole) of ethylene glycol is
heated to 120-C, and the mixture becomes a liquid. Five
parts of acidic clay are added as catalyst, and an
exotherm to about l~O~C occurs. Isooctanol (260 parts, 2
moles) is added, and the reaction mixture is maintained
at 130C as water i5 removed. When the reaction mixture
becomes cloudy, a small amount of propanol is added and
the mixture is stirred at 100C overnight. The reaction
mixture then is filtered to remove traces of oligomers,
and the filtrate is the desired ester.
2 ~ ~ r
-22-
Example 18
A mixture of 200 parts (2 moles) of succinic
anhydride, 62 parts (1 mole) of ethylene glycol and 1
part of paratoluene sulfonic acid is prepared and heated
to 80-90C. At this temperature, the reaction begins and
an exotherm to 140C results. The mixture is stirred at
130-140C for 15 minutes after 160 parts (2 moles) of
2,2,4-trimethylpentanol are added. Water evolves
quickly, and when all of the water is removed, the
residue is recovered as the desired product.
Example 19
A mixture of 294 parts (3 moles) of maleic anhydride
and 91 parts (1.5 moles) of ethylene glycol is prepared
and heated at about 180DC whereupon a strong exotherm
occurs and the temperature of the mixture is raised to
about 120-C. When the temperature of the mixture cools
to about 100C, 222 parts (3 moles) of n-butyl alcohol
and 10 parts of Amberlyst 15 are added. Water begins to
evolve and is collected. The reaction mixture is
maintained at 120C until 50 parts of water is collected.
The residue is filtered, and the filtrate is the desired
product.
Example 20
A mixture of 1072 parts (8 moles) of
trimethylolpropane, 2080 parts (16 moles) of
neopheptanoic acid and 50 parts of Amberlyst 15 is
prepared and heated to about 130-C. A water/acid
azeotrope evolves and is removed. When about 250 parts
of the azeotrope has been removed, 584 parts (4 moles) of
adipic acid are added and the reaction continues to
produce an additional 450 parts of distillate. At this
time, 65 parts of trimethylol- propane are added to the
mixture and additional water is removed. The residue is
filtered and the filtrate is the desired ester.
-23- 2~7~ 7
Example 21
Esters are prepared by reacting mixtures ~f
isononanoic acid (1) and adipic acid (2) with
trimethylolpropane (3), in the presence of a
tetraisopropoxy orthotitanate catalyst. The reactants
are charged to a flask and heated until reaction ceases,
as indicated by termination of water collection in a
distillation trap, at which point the reaction mixture
has reached about 220C. A vacuum is applied to remove
volatile components, and the flask contents are cooled
and filtered to produce the liquid ester product.
Properties of the products are as follows:
MolesCatalyst. Viscosity.cSt Molecular
Product (1) (2) (3) qrams 40C 100C Weiqht _
A 44 2 1613 76.6 9.1 611
B 40 4 1612 116 12.3 694
C 16 2 6.75 141 13.9 723
As can be seen, increasing the fraction of dicarboxylic
acid results in a higher viscosity, higher average
molecular weight (as measured by vapor phase osmometry)
ester material.
Example 22
The procedure of Example 21 is used to prepare
esters from isononanoic acid (1), adipic acid (2) and
neopentylglycol (3), giving the following product
properties:
MolesCatalvst. viscosi~Y~cst Molecular
Product (1) (2~ l~L qrams 40'C lQ0C Weight
A 2 1 2 2 80 10.5 588
B 10.7 6.7 125 106 13.2 665
C 8.3 8.3 12.5 8 220 22.1 758
2~87~4~
-24-
Example 23
The procedure of Example 21 is used to prepare
est~rs from isononanoic acid (1), isooctanoic acid (2),
isobutanoic acid (3), adipic acid (4) and pentaerythry-
tol (5), giving the following product properties:
Moles Catalvst,
Product (1~ (2~ (3) (4) (S) _grams
A 7 7 7 1.5 6 5
B 7.2 7.2 6 1.8 6 5
Product Viscosity. cSt ~olecular
40-C lOO-C Weiqht
A 149.5 14.0 733
B 194 16.9 802
Example 24
The procedure of Example 21 is used to prepare the
ester in Table 3.
The organic lubricants according to the present
invention preferably contain branched alkyl groups and
generally are free of acetylenic and aromatic
unsaturation. Some compounds which contain such
unsaturation may be insoluble in the fluorine- containing
hydrocarbons. The soluble lubricz~nt5 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 carboxylic ester5 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 deter-
mined 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
208~94~
-25-
grams) is condensed into the cooled (-400C) 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 conduct-
ed with several examples of the carboxylic ester lubri-
cants of the present invention are summarized in the
following Table II.
TABLE 3
Moles
Adipic IS0 Nonanoic
Exam~le TMP~1) Acid Acid~2)
Comparative
Example 1 0 3
24A 1 0.1 2.8
24B 1 0.125 2.75
24C 1 0.25 2.45
24D 1 0.30 2.4
24E 1 0.35 2.3
ViScositY
Q40C Q100C
Exam~le 52.25 7.25
24A 69.4 8.65
24B 76.6 9.14
24C 119 12.3
24D 140 14
24E 185 16.8
(l) TMP - Trimethylol propane
(2) Available from Exxon Chemical Company
As can be seen from Table 3, as the level of
dicarboxylic acid is increased, the viscosity of the
ester increases.
~0~7~7
-26
T~BTE II
Liquid ContainingSolubility
Product of ExamPle~C ~pt.
6 -45
~50
11 ~40
12 ~50
13 -15
-30
16 10
17 -25
19 -10
21(A) ~35
21(~3) ~30
21(C) -30
The liquid compositions of the present invention
comprise a major amount of a fluorine-containing hydro-
carbon and a minor amount of at least one soluble organic
lubricant comprising at least one carboxylic ester. By
"major amount" is meant an amount equal to or 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%, ~0%, 30% and up to 49.9%. In one
embodiment, the liquid composition~3 of the present inven-
tion 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. The liquid
compositions have beneficial viscosity properties.
2~879~7
-27-
Preferably the liquid compositions have a viscosity of
50-250 centistokes ~cst) measured at 400c.
Liquid compositions containing carboxylic esters
derived from polyols such as neGpentylglycol, trimethylol
propane and pentaerythritol, ha~e beneficial thermal and
hydrolytic stability. Liquid compositions containing
carboxylic esters derived from branched acids, such as
iso or neo acids preferably neo acid, have improved
thermal and hydrolytic stability. In a preferred embodi-
ment, the carboxylic esters are derived from the above
polyols, a polycarboxylic acid and an iso or neo acid.
The liquid composition may contain one carboxylic ester
reaction product or in another embodiment, the liquid
compositions may contain a blend of two or more car-
boxylic ester reaction products. A liquid composition of
a desired viscosity may be prepared by blending a higher
viscosity carboxylic ester with a ~ower viscosity carbox-
ylic ester. 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.
~ he additives whLch may be included in the liquid
compositions of the present invention to enhance the
performance of the liquids include extreme-pressure and
anti-wear aqents, oxidation and thermal-stability improv-
ers, corrosion-inhibitors, viscosity-index improvers,
pour point and/or floc point depressants, detergents,
dispersants, anti-foaming agents, viscosity adjusters,
metal deactivators, etc. As noted above, these supple-
mentary additives must be soluble in the liquid composi-
tions of the invention. Included among the materials
which may be used as extreme-pressure and anti-wear
2 ~ ~ 7 9 !~ 7
-28-
agents are phosphates, phosphate esters, phosphites,
thiophosphates such as zinc diorganodithiophosphates,
chlorinated waxes, sulfurized fats and olefins, organic
lead compounds, fatty acids, molybdenum complexes,
borates, halogen-substituted phosphorous compounds,
sulfurized Diels Alder adducts, organic sulfides, metal
salts of organic acids, etc. Sterically hindered phe-
nols, aromatic amines, dithiophosphates, phosphites,
sulfides and metal salts of dithioacids are useful
examples of oxidation and thermal stability improvers.
Compounds useful as corrosion-inhibitors include organic
acids, organic amines, organic phosphates, organic
alcohols, metal sulfonates, organic phosphites, etc. VI
improvers include polyolefins such as polyesterbutene,
polymethacrylate, polyalkyl styrenes, etc. Pour point
and floc point depressants include polymethacrylates,
ethylene-vinyl acetate copolymers, succinamic acid-olefin
copolymers, ethylene-alpha olefin copolymers, etc.
Detergents include sulfonates, long-chain alkyl-sub-
stituted aromatic sulfonic acids, phosphonates, phen-
ylates, metal salts of alkyl phenols, alkyl phenol-alde-
hyde condensation products, metal salts of substituted
salicylates, etc. Silicone polymers are a well known
type of anti-foam agent. Viscosity adjusters are ex-
emplified by polyisobutylene, polymethacrylates, poly-
alkyl styrenes, naphthenic oils, alkyl benzene oils,
polyesters, polyvinyl chloride, polyphosphate~, etc.
Examples of useful metal deactlvators include dimercapto-
thiadiazoles and derivative~ thereof, ~ubstituted and
unsubstituted triazoles (e.g., benzotriazole, tolyltri-
azole, octylbenzotriazole, and the like), mercaptobenzo-
thiazoles, etc.
The following examples (TABLE 1) relate to formula-
tions which are useful as organic lubricant (B) in the
present invention.
20879~7
--29--
o o ,
X . ~
r-- ooooo
o~
X . . .
~ C~ o o
H a~ 1
H . ~
r o
a~
H 0 rl O
H ~
:'~O O O
0
0 ~ O
H ~
O O
~1 0 ~
~ ~ ~ O O
m
E~
:> . . .
H O~ O O
O
OD
H ~ .
H ~O O
H
~ Ul
H 0~ O
1`
H O~
0
x u
O ~ ~
.C Ul O O
~1, 0 N N
o ~1 .1 0 ~
o ~ m ~
_1 0
~ ~ 0
O
~ r1 0
m o u~
2087~7
-30-
The liquid compositions of the present invention are
particularly useful as refrigerants in various refrigera-
tion systems which are compression-type systems such as
refrigerators, freezers, and air-conditioners including
automotive, home and industrial air-conditioners. The
following examples are illustrative of the liquid com-
positions of the present invention.
Parts bv Wt.
Exam~le A
1,1,1,2-tetrafluoroethane (HCFC-134a) 90
Lubricant of Example 2 10
Exam~le B
1,1,2,2-tetrafluoroethane 85
Lubricant of Example 4 15
Example C
HCFC-134a 95
Lubricant of Example 6 5
Exam~le D
HCFC-134a 80
Product of Example 1 20
Exam~le E
HCFC-134a 85
Product of Example 4 15
Table 2 contains further examples of the liquid
compositions of the present invention.
Table 2
F ~ _ I J
HCFC 134a 80 85 90 90 85
Lubricant of
Example:
I 20
V 15 10
VII 10 15
~087947
-31-
While the invention has been explained in relation to its
preferred embodiments, it is to be understood that various
modifications thereof will become apparent to those skilled in
the art upon reading the specification. Therefore, it is to be
understood that the invention disclosed herein is intended to
cover such modifications as fall within the scope of the appended
claims.
