COMPOSITIONS OF 1,l-DICHLORO-2,2,2-TRIFLUOROETHANE

AND HYDROGEN-CONTRIBUTING COMPOUNDS

BACKGROUND OF THE INVENTION

The present invention relates to stabilizers useful with l,l-dichloro-2,2,2-trifluoroethane (known in the art as HCFC-123) and hydrogen-contributing compounds. HCFC-123 may replace trichlorofluoromethane (known in the art as CFC-11) in many applications because environmental concerns over the use of CFC-11 exist.

CFC-11 is currently used as a refrigerant in closed loop refrigeration systems; many of these systems are air-conditioning systems. HCFC-123 has properties similar to those of CFC-11 so that it is possible to substitute HCFC-123 for CFC-11 in refrigeration applications with minimal changes in equipment being required.

A problem arises in such a substitution. Refrigeration systems which use CFC-11 generally use mineral oils to lubricate the compressor. We have found that the use of HCFC-123 and mineral oil results in the formation of l-chloro-2,2,2-trifluoroethane (known in the art as HCFC-133a); in the absence of mineral oil, the use of HCFC-123 does not result in the formation of HCFC-133a. E. Long et al., Toxicol. Appl.

Pharmacl. 72. 15 (1984) report that HCFC-133a is an animal carcinogen. Understandably, the potential presence of a known animal carcinogen is unacceptable in any commercial system.

CFC-11 is also currently used as an auxiliary blowing agent for the preparation of flexible foams and as a primary blowing agent for rigid foams. Polyurethane foams are manufactured by reacting and foaming a mixture of ingredients comprising in general an organic isocyanate, such as pure or crude toluene diisocyanate or a polymeric diisocyanate, with an appropriate amount of polyol or mixture of polyols, in the presence of a volatile liquid blowing agent, which vaporizes during the reaction, causing the polymerizing mixture to foam. Because HCFC-123 has properties similar to those of CFC-11, it is known to substitute HCFC-123 for CFC-11 in blowing agent applications.

In some blowing agent applications, a premix of polyol and HCFC-123 is used as taught by U.S. Patent 4,076,644. We have found that the use of a premix of HCFC-123 and polyol also results in the formation of HCFC-133a.

Thus, an object of this invention is to substantially reduce or even eliminate the formation of HCFC-133a in HCFC-123/lubricant systems.

Kokai Patent Publication 128,943 published May 22, 1989 teaches a method for stabilizing a hydrogen-containing furon such as

1,l-dichloro-2,2,2-trifluoroethane against alcoholic hydroxyl groups. The reference teaches that a three-component stabilizer system of a styrenic compound, a phenol, and an epoxy can be used for the

storage stability of polyol which contains the hydrogen-containing furon as the foaming agent. The reference does not recognize the problem addressed by the present invention or suggest the present solution as set forth below. Further, the reference lists chlorotrifluoroethane as a useful hydrogen-containing furon.

Kokai Patent Publication 128,944 published May 22, 1989 teaches a method for stabilizing a hydrogen-containing furon such as

1,l-dichloro-2,2,2-trifluoroethane against alcoholic hydroxyl groups. The reference teaches that a stabilizer of a nitro-containing hydrocarbon such as nitromethane, 1-nitropropane, 2-nitropropane, or nitrobenzene can be used for the storage stability of polyol which contains the hydrogen-containing furon as the foaming agent. The reference does not recognize the problem addressed by the present invention or suggest the present solution as set forth below. Further, the reference lists chlorotrifluoroethane as a useful hydrogen-containing furon.

Kokai Patent Publication 128,945 published May 22, 1989 teaches a method for stabilizing a hydrogen-containing furon such as

1,l-dichloro-2,2,2-trifluoroethane against alcoholic hydroxyl groups. The reference teaches that a two-component stabilizer system of a nitro-containing hydrocarbon and an epoxy compound can be used for the storage stability of polyol which contains the hydrogen-containing furon as the foaming agent. The reference does not reocgnize the problem addressed by the present invention or suggest the present solution as set forth below. Further, the reference lists chlorotrifluoroethane as a useful hydrogen-containing furon.

Summary Of The Invention

The present invention provides a novel solution to the foregoing problem. The present invention provides a composition comprising:

(a) 1,l-dichloro-2,2,2-trifluoroethane;

(b) a hydrogen-contributing compound; and

(c) a sufficient amount of a compound which substantially reduces the formation of l-chloro-2,2,2-trifluoroethane. The term "sufficient amount" as used herein means that amount of the compound which upon combination with 1,l-dichloro-2,2,2-trifluoroethane and the hydrogen-contributing compound, results in a substantial reduction in the formation of l-chloro-2,2,2-trifluoroethane.

As those skilled in the art know, l-chloro-2,2,2-trifluoroethane has one less chlorine atom and one more hydrogen atom than l,l-dichloro-2, 2 ,2-trifluoroethane. Although we do not fully understand the mechanism as to the formation of l-chloro-2,2,2-trifluoroethane from a combination of l,l-dichloro-2,2,2-trifluoroethane and a compound such as mineral oil or polyol, we believe that the mineral oil or polyol must be contributing a hydrogen. As such, the phrase "hydrogen-contributing compound" as used herein means any compound which contributes a hydrogen. Examples of preferred hydrogen-contributing compounds which are useful in the present invention include mineral oil, polyol, silicones, alcohols, esters, and ethers.

We have discovered a class of compounds which substantially reduce the formation of l-chloro-2,2,2-trifluoroethane in a system having 1,l-dichloro-2,2,2-trifluoroethane and a hydrogen-contributing compound therein. The prior art does not teach or suggest the present three-component compositions which solve the foregoing problem.

Other advantages of the present invention will become apparent from the following description and appended claims.

Detailed Description of the Preferred Embodiments

The l,l-dichloro-2,2,2-trifluoroethane used in the present invention may be prepared by any known method including that taught by commonly assigned U.S. Patent 4,145,368 which is incorporated herein by reference to the extent necessary to complete this disclosure.

Examples of preferred mineral oils are commercially available mineral oils such as Witco LP 250 (registered trademark) from Witco, Zerol 300 (registered trademark) from Shrieve Chemical, Sunisco 3GS from Witco, and Calumet R015 from Calumet.

A wide variety of polyols may be employed as disclosed in the prior art, such as polyether polyols and polyester polyols. Illustrative suitable polyether polyols are polyoxypropylene diols having a molecular weight of between about 300 and 3,000, glycerol based polyoxypropylene triols having a molecular weight of between about 300 and 3,000, trimethylolpropane-based triols having a a molecular weight of between about 300 and 3,000, sorbitol-based hexol having a molecular weight of between about 300 and 3,000, and sucrose-based octols having a molecular weight of between about 300 and 3,000. Illustrative suitable polyester polyols are the reaction products of polyfunctional organic carboxylic acids such as succinic acid, adipic acid, phthalic acid and terephthalic acid with monomeric polyhydric alcohols such as glycerol, ethylene glycol, trimethylol propane, and the like. A preferred polyol is Pluracol 1114 (420-OH#) from BASF Wyandotte Corporation.

Examples of preferred alcohols include methanol, ethanol, propanol, butanol, and pentanol.

Examples of preferred esters include phosphate esters, dibasic acid esters, fluoroesters, and neopentyl polyol esters.

An example of a preferred ether is polyphenyl ethers.

Examples of preferred compounds which substantially reduce the formation of l-chloro-2,2,2-trifluoroethane include benzene derivatives, metal-containing compounds, and phosphites. Preferred benzene derivatives include alpha-methyl styrene, butylated hydroxytoluene, N-phenylbenzinamine, octadecyl

3,5-di-tert-butyl-4-hydroxy-hydrocinnamate, and tetrakis (methylene 3,5-di-tert-butyl-4-hydroxycinnamate) which are commercially available materials. Preferred metal-containing compounds include zinc dithio dialkyl phosphate such as zinc dithio ethyl hexyl phosphate, zinc dialkyl dithio carbamates, zinc alkyl xanthates such as zinc isopropylxanthate which are commercially available materials. Preferred phosphites include isooctyl diphenyl phosphite and triisodecyl phosphite which are commercially available materials.

As those skilled in the art will appreciate, the amount of the compound which substantially reduces the formation of l-chloro-2,2,2-trifluoroethane will vary depending upon the compound selected. Preferably, about 0.0001 to about 5 weight percent of the compound based on the total weight of

1,l-dichloro-2,2,2-trifluoroethane and the hydrogen-contributing compound is used. More preferably, about 0.001 to about 5 weight percent of

the compound, and most preferably, about 0.01 to about 2 weight percent of the compound based on the total weight of 1,l-dichloro-2,2,2-trifluoroethane and the hydrogen-containing compound is used.

The present composition may be used in applications such as compression refrigeration and air-conditioning equipment, as a premix in the preparation of foams, and as a solvent in a variety of vapor degreasing, cold cleaning and solvent cleaning applications including defluxing and dry cleaning.

As such, the present invention also provides a method for substantially reducing the formation of l-chloro-2,2,2-trifluoroethane in compression refrigeration and air-conditioning equipment using l,l-dichloro-2,2,2-trifluoroethane as a refrigerant and mineral oil as a lubricant. The method comprises the step of: employing a compound which substantially reduces the formation of l-chloro-2,2,2-trifluoroethane.

The present invention is more fully illustrated by the following non-limiting Examples.

COMPARATIVES

These Comparatives address the preparation of a composition of HCFC-123 with mineral oil and testing the composition for the formation of l-chloro-2,2,2-trifluoroethane.

2.5 grams of HCFC-123 and 0.25 gram of mineral oil known as Witco LP 250 (registered trademark) which is available from Witco were sealed in heavy walled glass tube. Steel, copper, and aluminum pieces were also sealed in the tube. The tubes were put into an oven for 14 and 28 days at 149°C.

The tubes were opened after each exposure and examined using gas chromatography and also gas chromatography combined with mass spectrometry; at 14 days, two measurements were taken and the results were averaged. The results are shown m Table I below.

The above was repeated with 2.5 grams of HCFC-123, 0.25 gram of mineral oil, and 0.012 gram of an inhibitor. These results are also in Table I below.

TABLE l

Wt. % of HCFC-133a

Inhibitor Type 14 days 28 davs

no inhibitor 0.90 2.1

2,6-dimethyl- 1.80 2.8

2,4,6-octatriene

Fluoroepoxy- 0.96 2.8 diglycidylether

Tricresyl Phosphate 0.90 1.1

The 2,6-dimethyl-2,4,6-octatriene is currently used as an acid scavenger for premixes of HCFC-123 and polyol. The fluoroepoxydiglycidylether is currently used as an acid scavenger. Tricresyl phosphate is a commonly used lubricant additive. The results indicate that the use of 2,6-dimethyl-2,4,6-octatriene almost seems to promote the formation of l-chloro-2,2,2-trifluoroethane. Also, the use of fluoroepoxydiglycidylether at 28 days almost seems to promote the formation of

l-chloro-2,2,2-trifluoroethane. These results indicate that the use of inhibitors known for scavenging acid is not necessarily useful in inhibiting the formation of l-chloro-2,2,2-trifluoroethane.

EXAMPLE 1

This Example illustrates the preparation of a composition of l,l-dichloro-2,2,2-trifluoroethane, mineral oil, and alpha methyl styrene and testing the composition for the formation of l-chloro-2,2,2-trifluoroethane.

A mineral oil known as Witco LP 250 (registered trademark) from Witco was used. Alpha-methyl styrene from Allied-Signal Inc. was used. 2.5 grams of l,l-dichloro-2,2,2-trifluoroethane, 0.25 gram of mineral oil, and 0.012 gram of alpha-methyl styrene were sealed in a heavy walled glass tube. Steel, copper, and aluminum pieces were also sealed in the tube. The tubes were placed in an oven for 14 and 28 days at 149°C.

The tubes were opened after each exposure and examined using gas chromatography and also gas chromatography combined with mass spectrometry; at 14 days, two measurements were taken and the results were averaged. The results are shown in Table II below.

EXAMPLE 2

This Example illustrates the preparation of a composition of l,l-dichloro-2,2,2-trifluoroethane, mineral oil, and zinc dithio dialkyl phosphate and testing the composition for the formation of l-chloro-2,2,2-trifluoroethane.

A mineral oil known as Witco LP 250 (registered trademark) from Witco was used. Zinc dithio ethyl hexyl phosphate from Chevron was used. 2.5 grams of l,l-dichloro-2,2,2-trifluoroethane, 0.25 gram of mineral oil, and 0.012 gram of zinc dithio dialkyl phosphate were sealed in a heavy walled glass tube.

Steel, copper, and aluminum pieces were also sealed in the tube. The tubes were placed in an oven for 14 and

28 days at 149°C.

The tubes were opened after each exposure and examined using gas chromatography and also gas chromatography combined with mass spectrometry; at 14 days, two measurements were taken and the results were averaged. The results are shown in Table II below.

TABLE II

Wt. % of HCFC-133a Inhibitor Type 14 days 28 days

Example 1 0.17 0.67

Example 2 0.06 0.15

These results indicate that alpha-methyl styrene is effective in reducing the formation of l-chloro-2,2,2-trifluoroethane by a factor of 5 and zinc dithio dialkyl phosphate is effective in reducing the formation of l-chloro-2, 2 ,2-trifluoroethane by a factor of 10. We were surprised at these results in view of the Comparative inhibitors which were ineffective in substantially reducing the formation of l-chloro-2,2,2-trifluoroethane.

EXAMPLES 3-47

The following compositions are prepared with l,l-dichloro-2,2,2-trifluoroethane and tested for the formation of l-chloro-2,2,2-trifluoroethane as set forth in Example 1 above.

EX Component (b) Component (c)

3 mineral oil butylated hydroxytoluene

4 mineral oil N-phenylbenzinamine

5 mineral oil octadecyl 3,5-di-tert-butyl- 4-hydroxy-hydrocinnamate

6 mineral oil tetrakis (methylene 3,5-di- tert-butyl-4-hydroxycinnamate zinc dialkyl dithio carbamate zinc alkyl xanthate zinc isopropylxanthate isooctyl diphenyl phosphite triisodecyl phosphite butylated hydroxytoluene N-phenylbenzinamine octadecyl 3,5-di-tert-butyl- 4-hydroxy-hydrocinnamate 15 polyol tetrakis (methylene 3,5-di- tert-butyl-4-hydroxycinnamate zinc dialkyl dithio carbamate zinc alkyl xanthate zinc isopropylxanthate isooctyl diphenyl phosphite triisodecyl phosphite butylated hydroxytoluene N-phenylbenzinamine octadecyl 3,5-di-tert-butyl- 4-hydroxy-hydrocinnamate tetrakis (methylene 3,5-di- tert-butyl-4-hydroxycinnamate

Component (c)

zinc dialkyl dithio carbamate zinc alkyl xanthate zinc isopropylxanthate isooctyl diphenyl phosphite triisodecyl phosphite butylated hydroxytoluene N-phenylbenzinamine octadecyl 3,5-di-tert-butyl- 4-hydroxy-hydrocinnamate tetrakis (methylene 3,5-di- tert-butyl-4-hydroxycinnamate zinc dialkyl dithio carbamate zinc alkyl xanthate zinc isopropylxanthate isooctyl diphenyl phosphite triisodecyl phosphite butylated hydroxytoluene N-phenylbenzinamine octadecyl 3,5-di-tert-butyl- 4-hydroxy-hydrocinnamate

42 ester tetrakis (methylene 3,5-di- tert-butyl-4-hydroxycinnamate zinc dialkyl dithio carbamate zinc alkyl xanthate zinc isopropylxanthate isooctyl diphenyl phosphite triisodecyl phosphite

Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.