1 .1-DICHLORO-1-FLUOROETHANE: DICHLOROMETHANE OR

DICHLOROETHYLENE: AND CHLOROPROPANE:

AND OPTIONALLY ALKANOL

BACKGROUND OF THE INVENTION

Vapor degreasing and solvent cleaning with fluorocarbon based solvents have found widespread use in industry for the degreasing and otherwise cleaning of solid surfaces, especially intricate parts and difficult to remove soils.

In its simplest form, vapor degreasing or solvent cleaning consists of exposing a room temperature object to be cleaned to the vapors of a boiling solvent. Vapors condensing on the object provide clean distilled solvent to wash away grease or other contamination. Final evaporation of solvent from the object leaves behind no residue as would be the case where the object is simply washed in liquid solvent.

For difficult to remove soils where elevated temperature is necessary to improve the cleaning action of the solvent, or for large volume assembly line operations where the cleaning of metal parts and assemblies must be done efficiently and quickly, the conventional operation of a vapor degreaser consists of immersing the part to be cleaned in a sump of boiling solvent which removes the bulk of the soil, thereafter immersing the part in a sump containing freshly distilled solvent near room temperature, and finally exposing the part

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to solvent vapors over the boiling sump which condense on the cleaned part. In addition, the part can also be sprayed with distilled solvent before final rinsing.

Vapor degreasers suitable in the above-described operations are well known in the art. For example, Sherliker et al. in U.S. Patent 3,085,918 disclose such suitable vapor degreasers comprising a boiling sump, a clean sump, a water separator, and other ancillary equipment.

Cold cleaning is another application where a number of solvents are used. In most cold cleaning applications, the soiled part is either immersed in the fluid or wiped with rags or similar objects soaked in solvents and allowed to air dry.

Fluorocarbon solvents, such as trichlorotrifluoroethane, have attained widespread use in recent years as effective, nontoxic, and nonflammable agents useful in degreasing applications and other solvent cleaning applications. Trichlorotrifluoroethane has been found to have satisfactory solvent power for greases, oils, waxes and the like. It has therefore found widespread use for cleaning electric motors, compressors, heavy metal parts, delicate precision metal parts, printed circuit boards, gyroscopes, guidance systems, aerospace and missile hardware, aluminum parts and the like.

The art has looked towards azeotrope or azeotrope-like compositions including the desired fluorocarbon components such as trichlorotrifluoroethane which include components which contribute additionally desired characteristics, such as polar functionality, increased solvency power, and stabilizers. Azeotropic or

azeotrope-like compositions are desired because they do not fractionate upon boiling. This behavior is desirable because in the previously described vapor degreasing equipment with which these solvents are employed, redistilled material is generated for final rinse-cleaning. Thus, the vapor degreasing system acts as a still. Unless the solvent composition exhibits a constant boiling point, i.e., is azeotrope-like, fractionation will occur and undesirable solvent distribution may act to upset the cleaning and safety of processing. Preferential evaporation of the more volatile components of the solvent mixtures, which would be the case if they were not azeotrope-like, would result in mixtures with changed compositions which may have less desirable properties, such as lower solvency towards soils, less inertness towards metal, plastic or elastomer components, and increased flammabiiity and toxicity.

The art is continually seeking new fluorocarbon based azeotrope-like mixtures which offer alternatives for new and special applications for vapor degreasing and other cleaning applications. Currently, of particular interest, are fluorocarbon based azeotrope-like mixtures which are considered to be stratospherically safe substitutes for presently used fully halogenated chlorofluorocarbons. The latter are suspected of causing environmental problems in connection with the earth's protective ozone layer. Mathematical models have substantiated that hydrochlorofiuorocarbons, such as 1 ,1-dichloro-1-fluoroethane (known in the art as HCFC-141b), will not adversely affect atmospheric chemistry, being negligible contributors to ozone depletion and to green-house global warming in comparison ■to the fully halogenated species. HCFC- 141 b is known to be useful as a solvent.

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Other advantages of the invention will become apparent from the following description.

DESCRIPTION OF THE INVENTION

In accordance with the invention, novel mixtures have been discovered comprising 1 ,1-dichloro-1-fluoroethane; dichloromethane; and chloropropane; and optionally alkanol. Also, novel azeotrope-like or constant-boiling compositions have been discovered comprising 1 ,1-dichloro-1-fluoroethane; dichloromethane or dichloroethylene; and chloropropane; and optionally alkanol. The chloropropane is selected from the group consisting of 1 -chloropropane; 2-chloropropane; and mixtures thereof.

Preferably, the novel azeotrope-like compositions comprise effective amounts of 1 ,1-dichloro-1-fiuoroethane; dichloromethane; and chloropropane; and optionally alkanol. The term "effective amounts" as used herein means the amount of each component which upon combination with the other component, results in the formation of the present azeotrope-like composition.

Novel azeotrope-like compositions preferably comprise 1 ,1-dichloro-1-fiuoroethane; dichloromethane; and 1 -chloropropane which boil at about 31.1 °C, and more preferably, about 31.1 °C ±_ about 0.5°C at 760 mm Hg (101 kPa).

Novel azeotrope-like compositions preferably comprise 1 ,1-dichloro-1-fluoroethane; dichloromethane; and 2-chloropropane which boil at about 31.5°C, and more preferably, about 31.5 °C _±_

about 0.5°C at 760 mm Hg (101 kPa).

The preferred azeotrope-like compositions of 1 , 1 -dichloro-1 - fluoroethane, dichloromethane, and chloropropane are in Table I below wherein the numerical ranges are understood to be prefaced by "about":

TABLE I

Novel azeotrope-like compositions preferably comprise

1 ,1-dichloro-1 -fluoroethane; dichloromethane; 1 -chloropropane; and methanoi which boil at about 30.3 °C, and more preferably, about 30.3°C ±. about 0.5°C at 760 mm Hg (101 kPa).

Novel azeotrope-like compositions preferably comprise

1 ,1-dichloro-1 -fluoroethane; dichloromethane; 2-chloropropane; and methanoi which boil at about 30.4°C, and more preferably, about 30.4°C about 0.5°C at 760 mm Hg (101 kPa).

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The preferred azeotrope-like compositions of 1 ,1-dichloro-1- fluoroethane, dichloromethane, methanoi, and chloropropane are in Table II below wherein the numerical ranges are understood to be prefaced by "about":

TABLE

Novel azeotrope-like compositions also preferably comprise 1,1-dichloro-1 -fluoroethane; dichloromethane; 1 -chloropropane; and ethanol which boil at about 31.1 °C and more preferably, about 31.1 °C s about 0.5°C at 760 mm Hg (101 kPa).

Novel azeotrope-like compositions also preferably comprise 1 ,1-dichloro-1 -fluoroethane; dichloromethane; 2-chloropropane; and ethaπol which boil at about 32.3°C and more preferably, at about 32.3°C _±_ about 0.5°C at 760 mm Hg (101 kPa).

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The preferred azeotrope-like compositions of 1 , 1-dichloro-1 - fluoroethane, dichloromethane, ethanol, and chloropropane are in Table III below wherein the numerical ranges are understood to be prefaced by "about":

TABLE In

All compositions within the indicated ranges, as well as certain compositions outside the indicated ranges, are azeotrope-like, as defined more particularly below.

The 1 ,1-dichloro-1 -fluoroethane component of the invention has good solvent properties. The dichloromethane, 1 -chloropropane, 2-chloropropane, methanoi, and ethaπol components also have good solvent capabilities. Thus, when these components are combined in effective amounts, an efficient azeotrope-like solvent results.

In accordance with the invention, novel mixtures have been discovered comprising 1,1-dichloro-1 -fluoroethane; dichloroethylene; and chloropropane; and optionally methanoi or ethanol. Also, novel azeotrope-like or constant-boiling compositions have been discovered comprising 1 , 1 -dichloro-1 -fluoroethane; dichloroethylene; and chloropropane; and optionally methanoi or ethanol. The dichloroethylene is selected from the group consisting of trans-1 ,2-dichloroethylene; cis-1 ,2-dichloroethylene; and mixtures thereof. The chloropropane is selected from the group consisting of 1 -chloropropane; 2-chloropropane; and mixtures thereof.

Preferably, the novel azeotrope-like compositions comprise effective amounts of 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene; and chloropropane; and optionally methanoi or ethanol. The term "effective amounts" as used herein means the amount of each component which upon combination with the other component, results in the formation of the present azeotrope-like composition.

Novel azeotrope-like compositions preferably comprise 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene selected from the group consisting of trans- 1 ,2-dichloroethylene, cis-1 , 2-dichloroethylene, and mixtures thereof; and 1 -chloropropane which boil at about 33°C, and more preferably, about 33°C ±. about 0.5°C at 760 mm Hg (101 kPa).

Novel azeotrope-like compositions also preferably comprise 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene selected from the group consisting of trans-1 , 2-dichloroethylene, cis-1 , 2-dichloroethylene, and mixtures thereof; and 2-chloropropane which boil at about 32.8 °C and more preferably, at about 32.8 ° C +_ about 0.5 °C at 760 mm Hg.

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The preferred azeotrope-like compositions of 1 , 1 -dichloro-1 - fluoroethane, dichloroethylene, and chloropropane are in Table IV below wherein the numerical ranges are understood to be prefaced by "about":

TABLE Iv

Novel azeotrope-like compositions preferably comprise 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene selected from the group consisting of trans-1 , 2-dichloroethylene, cis-1 , 2-dichloroethylene, and mixtures thereof; 1 -chloropropane; and methanoi which boil at about 29.6°C, and more preferably, about 29.6°C ±_ about 0.5°C at 760 mm Hg (101 kPa).

Novel azeotrope-like compositions also preferably comprise 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene selected from the group consisting of trans-1 ,2-dichloroethylene, cis-1 ,2-dichloroethylene, and mixtures thereof; 1 -chloropropane; and ethanol which boil at about 32.3 °C and more preferably, about 32.3 °C ±. about 0.5°C at 760 mm Hg (101 kPa).

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The preferred azeotrope-like compositions of 1 ,1 -dichloro-1 fluoroethane, dichloroethylene, chloropropane, and methanoi or ethanol are in Table V below wherein the numerical ranges are understood to be prefaced by "about":

TABLE V

Novel azeotrope-like compositions also preferably comprise 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene selected from the group consisting of trans-1, 2-dichloroethylene, cis-1 ,2-dichloroethylene, and mixtures thereof; 2-chloropropane; and methanoi which boil at about 30.3°C and more preferably, at about 30.3°C _ about 0.5°C at 760 mm Hg (101 kPa).

Novel azeotrope-like compositions preferably comprise 1 ,1 -dichloro-1 -fluoroethane; dichloroethylene selected from the group consisting of trans-1 , 2-dichloroethylene, cis-1 , 2-dichloroethylene, and mixtures thereof; 2-chloropropane; and ethanol which boil at about 30.5°C and more preferably, at about 30.5 °C ±_ about 0.7 °C at 760 mm Hg (101 kPa).

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The preferred azeotrope-like compositions of 1 , 1 -dichloro-1 - fluoroethane, dichloroethylene, 2-chloropropane, and methanoi or ethanol are in Table VI below wherein the numerical ranges are understood to be prefaced by "about":

TABLE Vi

All compositions within the indicated ranges, as well as certain compositions outside the indicated ranges, are azeotrope-like, as defined more particularly below.

The 1 ,1 -dichloro-1 -fluoroethane component of the invention has good solvent properties. The trans-1 , 2-dichloroethylene, cis-1 , 2-dichloroethylene, 1 -chloropropane, 2-chloropropane, methanoi, and ethanol components also have good solvent capabilities. Thus, when these components are combined in effective amounts, an efficient azeotrope-like solvent results.

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The precise azeotrope compositions have not been determined but have been ascertained to be within the above ranges. Regardless of where the true azeotropes lie, all compositions with the indicated ranges, as well as certain compositions outside the indicated ranges, are azeotrope-like, as defined more particularly below.

It has been found that these azeotrope-like compositions are on the whole nonflammable liquids, i.e. exhibit no flash point when tested by the Tag Open Cup test method - ASTM D 1310-86 and Tag Closed Cup Test Method - ASTM D 56-82.

From fundamental principles, the thermodynamic state of a fluid is defined by four variables: pressure, temperature, liquid composition and vapor composition, or P-T-X-Y, respectively. An azeotrope is a unique characteristic of a system of two or more components where X and Y are equal at the stated P and T. In practice, this means that the components of a mixture cannot be separated during distillation, and therefore are useful in vapor phase solvent cleaning as described above.

For the purpose of this discussion, azeotrope-like composition is intended to mean that the composition behaves like an azeotrope, i.e. has constant-boiling characteristics or a tendency not to fractionate upon boiling or evaporation. Thus, in such compositions, the composition of the vapor formed during boiling or evaporation is identical or substantially identical to the original liquid composition. Hence, during boiling or evaporation, the liquid composition, if it changes at all, changes only to a minimal or negligible extent. This is to be contrasted with non-azeotrope-like compositions in which during boiling or evaporation, the liquid composition changes to a substantial

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degree.

Thus, one way to determine whether a candidate mixture is "azeotrope-like" within the meaning of this invention, is to distill a sample thereof under conditions (i.e. resolution - number of plates) which would be expected to separate the mixture into its separate components. If the mixture is non-azeotrope-like, the mixture will fractionate, i.e. separate into its various components with the lowest boiling component distilling off first, and so on. If the mixture is azeotrope-like, some finite amount of a first distillation cut will be obtained which contains all of the mixture components and which is constant-boiling or behaves as a single substance. This phenomenon cannot occur if the mixture is not azeotrope-like, i.e. it does not behave like an azeotrope. Of course, upon distillation of an azeotrope-like composition such as in a vapor degreaser, the true azeotrope will form and tend to concentrate.

It follows from the above that another characteristic of azeotrope-like compositions is that there is a range of compositions containing the same components in varying proportions which are azeotrope-like or constant-boiling. All such compositions are intended to be covered by the term azeotrope-like or constant-boiling as used herein. As an example, it is well known that at differing pressures, the composition of a given azeotrope-like composition will vary at least slightly as does the boiling point of the composition. Thus, an azeotrope-like composition of A and B represents a unique type of relationship but with a variable composition depending on temperature and/or pressure.

As is readily understood by persons skilled in the art, the boiling

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point of the azeotrope-like composition will vary with the pressure.

The azeotrope-like compositions of the invention are useful as solvents in a variety of vapor degreasing, cold cleaning and solvent cleaning applications including defiuxing and dry cleaning and as blowing agents.

In one process embodiment of the invention, the azeotrope-like compositions of the invention may be used to clean solid surfaces by treating the surfaces with the compositions in any manner well known to the art such as by dipping or spraying or use of conventional degreasing apparatus.

The 1 ,1 -dichloro-1 -fluoroethane; dichloromethane; 1 -chloropropane; 2-chloropropane; methanoi; ethanol; trans-1 ,2- dichloroethylene; and cis-1 , 2-dichloroethylene components of the novel solvent azeotrope-like compositions of the invention are known materials and are commercially available. Commercially available trans-1 ,2-dichloroethylene may contain cis-1 ,2-dichloroethylene. Commercially available cis-1 ,2-dichloroethylene may contain trans-1 ,2-dichloroethylene.

It should be understood that the present compositions may include additional components so as to form new azeotrope-like or constant-boiling compositions. Any such compositions are considered to be within the scope of the present invention as long as the compositions are constant-boiling or essentially constant-boiling and contain all of the essential components described herein.

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

EXAMPLES 1 THROUGH 3

These examples confirm the existence of constant-boiling or azeotrope-like compositions of 1 ,1 -dichloro-1 -fluoroethane; dichloromethane; and 1 -chloropropane; and optionally methanoi or ethanol via the method of distillation. It also illustrates that these mixtures do not fractionate during distillation.

A 5-plate Oldershaw distillation column with a cold water condensed automatic liquid dividing head was used for these examples. The distillation column was charged with HCFC-141b, dichloromethane (hereafter DCM), and 1 -chloropropane (hereinafter 1-CP), and optionally methanoi (hereinafter MeOH) or ethanol (hereinafter EtOH) in the amounts indicated in Table VII below for the starting material. The composition was heated under total reflux for about an hour to ensure equilibration. A reflux ratio of 3:1 was employed for this particular distillation. Approximately 50 percent of the original charges were collected in four similar-sized overhead fractions. The compositions of these fractions were analyzed using gas chromatography. The averages of the distillate fractions and the overhead temperatures are quite constant within the uncertainty associated with determining the compositions, indicating that the mixture is constant-boiling or azeotrope-like.

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16 TABLE VII

Starting Material (wt. %)

Distillate Compositions (wt. %)

From the above example, it is readily apparent that additional constant-boiling or essentially constant-boiling mixtures of the same components can readily be identified by anyone of ordinary skill in this art by the method described. No attempt was made to fully characterize and define the outer limits of the composition ranges which are constant-boiling. Anyone skilled in the art can readily ascertain other constant-boiling or essentially constant-boiling mixtures containing the same components.

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EXAMPLES 4 THROUGH 6

These examples confirm the existence of constant-boiling or azeotrope-like compositions of 1 ,1 -dichloro-1 -fluoroethane; dichloromethane; and 2-chloropropane; and optionally methanoi or ethanol via the method of distillation. It also illustrates that these mixtures do not fractionate during distillation.

A 5-plate Oldershaw distillation column with a cold water condensed automatic liquid dividing head was used for these examples. The distillation column was charged with HCFC-141b, dichloromethane (hereinafter DCM), and 2-chloropropane (hereinafter 2-CP), and optionally methanoi (hereinafter MeOH) or ethanol (hereinafter EtOH) in the amounts indicated in Table VIII below for the starting material. Each composition was heated under total reflux for about an hour to ensure equilibration. A reflux ratio of 3:1 was employed for this particular distillation. Approximately 50 percent of the original charges were collected in four similar-sized overhead fractions. The compositions of these fractions were analyzed using gas chromatography. The averages of the distillate fractions and the overhead temperatures are quite constant within the uncertainty associated with determining the compositions, indicating that the mixtures are constant-boiling or azeotrope-like.

÷-i ml S _--u ft-u £

TABLE VIII

Starting Material (wt. %)

Distillate Compositions (wt. %)

From the above example, it is readily apparent that additional constant-boiling or essentially constant-boiling mixtures of the same components can readily be identified by anyone of ordinary skill in this art by the method described. No attempt was made to fully characterize and define the outer limits of the composition ranges which are constant-boiling. Anyone skilled in the art can readily ascertain other constant-boiling or essentially constant-boiling mixtures containing the same components.

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EXAMPLE 7

These example confirm the existence of constant-boiling or azeotrope-like compositions of 1 ,1 -dichloro-1 -fluoroethane; trans-1 , 2-dichloroethylene; and 1 -chloropropane via the method of distillation. It also illustrates that this mixture does not fractionate during distillation.

A 5-plate Oldershaw distillation column with a cold water condensed automatic liquid dividing head was used for these examples. The distillation column was charged with HCFC-141 b, trans-1 , 2-dichloroethylene (hereafter TDCE), and 1 -chloropropane (hereinafter 1-CP) in the amounts indicated in Table IX below for the starting material. The composition was heated under total reflux for about an hour to ensure equilibration. A reflux ratio of 3: 1 was employed for this particular distillation. Approximately 50 percent of the original charges were collected in four similar-sized overhead fractions. The compositions of these fractions were analyzed using gas chromatography. The averages of the distillate fractions and the overhead temperatures are quite constant within the uncertainty associated with determining the compositions, indicating that the mixture is constant-boiling or azeotrope-like.

TABLE IX

Starting Material (wt. %)

^■ *** ^■ -> T TUTB SHEET

Distillate Compositions (wt. %)

From the above example, it is readily apparent that additional constant-boiling or essentially constant-boiling mixtures of the same components can readily be identified by anyone of ordinary skill in this art by the method described. No attempt was made to fully characterize and define the outer limits of the composition ranges which are constant-boiling. Anyone skilled in the art can readily ascertain other constant-boiling or essentially constant-boiling mixtures containing the same components.

EXAMPLE 8

Example 7 is repeated except that cis-1, 2-dichloroethylene is used instead of trans-1, 2-dichloroethylene.

EXAMPLE 9

Example 7 is repeated except that a mixture of 90 weight percent trans-1 , 2-dichloroethylene and 10 weight percent cis-1 ,2-dichloroethylene is used instead of trans-1 ,2-dichloroethylene.

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21 EXAMPLE 10

This example confirms the existence of constant-boiling or azeotrope-like compositions of 1 , 1 -dichloro-1 -fluoroethane; trans-1 ,2-dichloroethylene; and 2-chloropropane via the method of distillation. It also illustrates that these mixtures do not fractionate during distillation.

Example 7 was repeated except that 2-chloropropane was used instead of 1 -chloropropane. The distillation column was charged with HCFC-141 b, trans-1 , 2-dichloroethylene (hereinafter TDCE), and 2-chloropropane (hereinafter 2-CP) in the amounts indicated in Table X below for the starting material.

TABLE X

EXAMPLE 11

Example 10 is repeated except that cis-1 ,2-dichloroethylene is used instead of trans-1 , 2-dichloroethylene.

EXAMPLE 12

Example 10 is repeated except that a mixture of 90 weight percent trans-1 ,2-dichloroethylene and 10 weight percent cis-1 , 2-dichloroethylene is used instead of trans-1, 2-dichloroethylene.

EXAMPLE 13

This example confirms the existence of constant-boiling or azeotrope-like compositions of 1 ,1 -dichloro-1 -fluoroethane; trans-1 ,2-dichloroethylene; 1 -chloropropane; and methanoi via the method of distillation. It also illustrates that this mixture does not fractionate during distillation.

Example 7 was repeated except that methanoi was added. The distillation column was charged with HCFC-141b, trans-1 , 2-dichloroethylene (hereafter TDCE), 1 -chloropropane (hereinafter 1-CP), and methanoi (hereinafter MeOH) in the amounts indicated in Table XI below for the starting material.

e eri'- T'

TABLE XI

Starting Material (wt. %)

Distillate Compositions (wt. %)

Example 13 is repeated except that cis-1 , 2-dichloroethylene is used instead of trans- 1 ,2-dichloroethylene.

EXAMPLE 15

Example 13 is repeated except that a mixture of 90 weight percent trans-1 ,2-dichloroethylene and 10 weight percent cis-1 , 2-dichloroethylene is used instead of trans- 1 ,2-dichloroethylene.

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24 EXAMPLE 16

This example confirms the existence of constant-boiling or azeotrope-like compositions of 1 ,1 -dichloro-1 -fluoroethane; trans-1 ,2-dichloroethylene; 1 -chloropropane; and ethanol via the method of distillation. It also illustrates that these mixtures do not fractionate during distillation.

Example 7 was repeated except that ethanol was added. The distillation column was charged with HCFC-141 b, trans-1 ,2-dichloroethylene (hereinafter TDCE), 1 -chloropropane (hereinafter 1-CP), and ethanol (hereinafter EtOH) in the amounts indicated in Table XII below for the starting material.

TABLE Xll Starting Material (wt. %)

Distillate Compositions (wt. %)

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EXAMPLE 17

Example 16 is repeated except that cis-1 , 2-dichloroethylene is used instead of trans-1 , 2-dichloroethylene.

EXAMPLE 18

Example 16 is repeated except that a mixture of 90 weight percent trans- 1 ,2-dichloroethylene and 10 weight percent cis-1 ,2-dichloroethylene is used instead of trans-1 ,2-dichloroethylene.

EXAMPLE 19

This example confirms the existence of constant-boiling or azeotrope-like compositions of 1 ,1 -dichloro-1 -fluoroethane; trans- 1 ,2-dichloroethylene; 2-chloropropane; and methanoi via the method of distillation. It also illustrates that these mixtures do not fractionate during distillation.

Example 10 was repeated except that methanoi was added. The distillation column was charged with HCFC-141 b, trans- 1 ,2-dichloroethylene (hereinafter TDCE), 2-chloropropane (hereinafter 2-CP), and methanoi (hereinafter MeOH) in the amounts indicated in Table XIII below for the starting material.

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26 TABLE XIII

Distillate Compositions (wt. %)

EXAMPLE 21

Example 20 is repeated except that cis-1 , 2-dichloroethylene is used instead of trans-1 ,2-dichloroethylene.

EXAMPLE 22

Example 20 is repeated except that a mixture of 90 weight percent trans-1 ,2-dichloroethylene and 10 weight percent cis-1 ,2-dichloroethylene is used instead of trans-1 ,2-dichloroethylene.

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27 EXAMPLE 23

This example confirms the existence of constant-boiling or azeotrope-like compositions of 1 , 1 -dichloro-1 -fluoroethane; trans-1 , 2-dichloroethyiene; 2-chloropropane; and ethanol via the method of distillation. It also illustrates that these mixtures do not fractionate during distillation.

Example 10 was repeated except that ethanol was added. The distillation column was charged with HCFC-141 b, trans- 1 ,2-dichloroethylene (hereinafter TDCE), 2-chloropropane (hereinafter 2-CP), and ethanol (hereinafter EtOH) in the amounts indicated in Table XIV below for the starting material.

TABLE XIV

Distillate Compositions (wt. %)

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EXAMPLE 24

Example 23 is repeated except that cis-1 , 2-dichloroethylene is used instead of trans-1 , 2-dichloroethylene.

EXAMPLE 25

Example 23 is repeated except that a mixture of 90 weight percent trans-1 , - 2-dichloroethylene and 10 weight percent cis-1 ,2-dichloroethylene is used instead of trans-1 ,2-dichloroethylene.

EXAMPLES 26 THROUGH 50

Performance studies are conducted wherein metal coupons are cleaned using the present azeotrope-like compositions as solvents. The metal coupons are soiled with various types of oils and heated to 93 °C so as to partially simulate the temperature attained while machining and grinding in the presence of these oils.

The metal coupons thus treated are degreased in a three-sump vapor phase degreaser machine. In this typical three-sump degreaser, condenser coils around the lip of the machine are used to condense the solvent vapor which is then collected in a sump. The condensate overflows into cascading sumps and eventually goes into the boiling sump.

The metal coupons are held in the solvent vapor and then vapor rinsed for a period of 15 seconds to 2 minutes depending upon the oils selected. The azeotrope-like compositions of Examples 1

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through 25 are used as the solvents. Cleanliness testing of coupons are done by measurement of the weight change of the coupons using an analytical balance to determine the total residual materials left after cleaning.

Mixtures of 1 -chloropropane and 2-chloropropane may be used in any proportions in the present invention as long as azeotrope-like compositions form.

Inhibitors may be added to the present azeotrope-like compositions to inhibit decomposition of the compositions; react with undesirable decomposition products of the compositions; and/or prevent corrosion of metal surfaces. Any or all of the following classes of inhibitors may be employed in the invention: alkanols having 4 to 7 carbon atoms, nitroalkanes having 1 to 3 carbon atoms, 1 ,2-epoxyaikanes having 2 to 7 carbon atoms, phosphite esters having 12 to 30 carbon atoms, ethers having 3 or 4 carbon atoms, unsaturated compounds having 4 to 6 carbon atoms, acetals having 4 to 7 carbon atoms, ketones having 3 to 5 carbon atoms, and amines having 6 to 8 carbon atoms. Other suitable inhibitors will readily occur to those skilled in the art.

Examples of useful alkanols having 4 to 7 carbon atoms are 2-methyl-2-propanol; 2-methyl-2-butanol; 1-pentanol; 2-pentanoi; 3-pentanol; and 3-ethyl-3-pentanol. The preferred alkanols are 2-methyl-2-propanol and 3-pentanol.

Examples of useful nitroalkanes having 1 to 3 carbon atoms include nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane. The preferred nitroalkanes are nitromethane and nitroethane.

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Examples of useful 1 ,2-epoxyalkanes having 2 to 7 carbon atoms include epoxyethane; 1 ,2-epoxypropane; 1 ,2-epoxy butane; 2,3-epoxybutane; 1 ,2-epoxypentane; 2,3-epoxypentane; 1 ,2-epoxy hexane; and 1 ,2-epoxyheptaπe. The preferred 1 ,2-epoxyalkanes are 1 ,2-epoxybutane and 1 ,2-epoxypropane.

Examples of useful phosphite esters having 12 to 30 carbon atoms include diphenyl phosphite; triphenyl phosphite; triisodecyl phosphite; triisooctγl phosphite; and diisooctyl phosphite. The preferred phosphite esters are triisodecyl phosphite (hereinafter TDP) and triisooctyl phosphite (hereinafter TOP).

Examples of useful ethers having 3 or 4 carbon atoms include diethylene oxide; 1 ,2-butylene oxide; 2,3-butylene oxide; and dimethoxymethane. The preferred ethers are diethylene oxide and dimethoxymethane.

Examples of useful unsaturated compounds having 4 to 6 carbon atoms include 1 ,4-butyne diol; 1 ,5-pentyne diol; and 1 ,6-hexyne diol. The preferred unsaturated compounds are 1 ,4-butyne diol and 1 ,5-pentyne diol.

Examples of useful acetals having 4 to 7 carbon atoms include dimethoxyethane; 1 ,1-diethyoxyethane; and dipropoxymethane. The preferred acetals are dimethoxyethane and dipropoxymethane.

Examples of useful ketones having 3 to 5 carbon atoms include 2-propanone; 2-butanone; and 3-peπtanone. The preferred ketones are 2-propanone and 2-butaπone.

SUBSTITUTE SHEET

Examples of useful amines having 6 to 8 carbon atoms include triethyl amine, dipropyl amine, and diisobutyl amine. The preferred amines are triethyl amine and dipropyl amine.

The inhibitors may be used alone or in mixtures thereof in any proportions. Typically, up to about 2 percent based on the total weight of the azeotrope-like composition of inhibitor might be used.

SUBSTITUTE SHEET