US2868851A - Stabilization of chlorinated hydrocarbons with acetylenic ethers - Google Patents

Description

ethylene containing them comes into contact.

United States Patent STABILIZATION OF CHLORINATED HYDRO- CARBONS WITH ACETYLE'NIC ETHERS Maxwell J. Skeeters, Painesville, Ohio, assignor to Diamond Alkali Company, Cleveland, Ohio, a corporation of Delaware No Drawing. Application July 26, 1954 Serial No. 445,922

Claims. (Cl. 260652.5)

This invention relates to inhibiting the decomposition of tetrachloroethylene catalyzed by light, air, heat, moisture, and metal surfaces and more particularly relates to a composition of matter consisting essentially of tetrachloroethylene and stabilizing amounts of an acetylenic ether.

It has heretofore been known that tetrachloroethylene (perchloroethylene) of a high degree of purity and containing only minute amounts of saturated, or other unsaturated, lower aliphatic chloro-hydrocarbons is very inert to the action of air, light, heat, moisture, and metal surfaces with which it comes into contact during storage and commercial use. However, the obtaining of such high purity tetrachlorethylene in commercial production is not generally feasible and it has been found that the impure material normally encountered incommerce decomposes when in contact with the substances noted above. Hence, means other than purification for preventing or inhibiting the decomposition of tetrachloroethylene and the lower chlorinated aliphatic hydrocarbons generally associated therewith must be had.

It is generally believed that tetrachloroethylene exposed to air, light, heat, moisture, etc., decomposes, especially in the presence of moisture, principally by way of. oxidative attack at the double bond involving a series of steps in which the ultimate products include phosgene, trichloroacetic acid, and hydrogen chloride. Itis also believed that the oxidative attack is catalyzed by light and by the products of oxidation, as a result of which, oxidative decomposition once initiated is self-catalyzing and self-sustaining. Other chloro-hydrocarbons generally associated with crude commercial tetrachloroethylene also are subject to oxidative attack and decompose to some of the same products as those formed by the oxidation of tetrachloroethylene, and at a somewhat accelerated rate, as compared to the oxidation of tetrachloroethylene. These products are then available to catalyze the decomposition of the tetrachloroethylene. For example, tetrachloroethylene obtained commercially from the crude products of chlorination and chlorinolysis of lower aliphatic hydrocarbons may contain small but appreciable amounts of saturated and unsaturated chlorinated hydrocarbons, such as dichloroethylene, trichloroethylene, trichloroethane, unsymmetrical tetrachloroethane, pentachloroethane, and the like. These lower chloro-hydrocarbons in themselves are relatively innocuous in solvent extraction processes in which the tetrachloroethylene is used, but the oxidation decomposition products thereof corrode metal surfaces'with which a body of tetrachloro- These less stable chloro-hydrocarbons are believed to be the principal initial source of chloro oxygen-containingimpurities, such as phosgene, chloroacetic acid, trichloroacetic acid, and the like, in the tetrachloroethylene, which imporities catalyze decomposition of the tetrachloroethylene.

The problem, therefore, is principally one of inhibiting theinitiation of the oxidation of the .chlorohydroearbons commonly associated with commercial tetrachloroethyllice 2 ene, as well as inhibiting the oxidation of tetra-chloroethylene itself.

One of the objects of the present invention is to provide means for inhibiting oxidation of tetrachloroethylene and lower aliphatic chloro-hydrocarbons generally asso- .ciated therewith during exposure to air, light, heat, moisture, and metal surfaces.

Many materials are known to be useful for the purpose of stabilizing chlorinated hydrocarbons, particularly, tetrachloroethylene, and, in general, they may be regarded as satisfactory in that they etfect stabilization sufficiently adequately, as determined by well-known tests, for most of the major uses of chlorinated solvents. However, the needs of industry for improved solvents meeting the requirements of specified operations is expanding constantly; hence, the quest continues for new stabilizers adapted to diverse uses.

In many instances of stabilizing chlorinated solvents, it has been found desirable to employ a pair of stabilizing ingredients, one for the general purpose of stabilizing the solvent against the effects of air, heat and moisture and another for the purpose of stabilizing against decomposition under the influence of light. This is because various stabilizers are to some extent deficient in their ability to effect the desired degree of light-stability. Accordingly, materials such as benzaldehyde, thymol, isoeugenol, ethyl alcohol, butyl alcohol, turpentine, benzene, toluene resorcinol, aniline, quinol, hydroquinone mono-methyl and monoethyl others have been employed in conjunction with the general-purpose stabilizers. Of this group, isoeugenol has been found to be unusually effective and it is especially effective when employed in combination with the new general-purpose stabilizers of this invention.

A further object of this invention, therefore, is to pro vide a new stabilizing composition of matter and a new solvent composition including the new stabilizing composition which will be especially stable under the influences of all of the several decomposing effects, and, particularly, the eif'ect of light.

These and other objects will be apparent to those skilled in the art from the discussion hereinafter.

Unstabilized chlorinated solvents, as obtained from the producer, including tetrachloroethylene, may be either in relatively pure or impure condition. For the most part, the purity of such tetrachloroethylene depends upon its age, that is, the length of time it has stood unstabilized after production withoutparticular effort being made to prevent decomposition. pure solvent is found to be of limited utility for many industrial needs, although further decomposition may be satisfactorily inhibited by using the stabilizers of this invention. On the other hand, some solvent is relatively fresh and is correspondingly pure and useable; such solvent requires only stabilization against further decomposition in order to be satisfactory for a number of its uses.

Where the initial percentage impurity is not tolerable, the solvent requires pre-treatment of a nature such that the major portion or substantially all of the impurities are removed, prior to the addition of stabilizers so as to provide a material having a good initial level of acceptability for industrial needs. As noted above, some solvent may not require such pre-treatment; however, those skilled in the art will understand that preferably, a solvent containing undesirable impurities is treated for the removal of any impurities prior to stabilization. Such purification may be effected as hereinafter taught.

The present. invention is described primarily in relation to solvent materials of relatively high initial purity; It should be understood, however, that the invention is not limited in applicability to substantially pure solvents but, rather, insofar as elfecting stabilization against fur- Accordingly, the relatively irnther decomposition is concerned, the present invention is effective substantially equally, in an impure or pure solvent.

It has been found that where the crude tetrachloroethylene, particularly that obtained from commercial processes involving the chlorinolysis of lower hydrocarbons or hydrocarbon chlorides, or the chlorination and simultaneous dehydrochlorination of hydrocarbon chlorides, such as ethylene dichloride, or of unsaturated hydrocarbons, such as acetylene, ethylene, and the like, contains appreciable amounts of lower chlorinated aliphatic hydrocarbons other than tetrachloroethylene as impurities, such crude product may initially be purified by wellknown means, such as by contact with an aqueous solution of an inorganic base or a high boiling point organic base in order to destroy the major portion of volatile acids and acid-forming impurities, and then combined with an acetylenic ether, decomposition of the tetrachloroethylene and other lower chlorinated aliphatic hydrocarbons is inhibited under the most adverse conditions of storage and commercial use.

In general, the present invention is directed to a composition comprising essentially tetrachloroethylene and stabilizing amounts of ethers which are characterized by the presence of at least one acetylenic bond in their structure. More particularly, the acetylenic ethers contemplated are those selected from the group consisting of hydrocarbon acetylenic ethers, halohydrocarbon acetylenic ethers and hydroxy hydrocarbon acetylenic ethers. Further, the invention is directed to such a composition including an additional ingredient effective to exert stabilizing action against the influences of light. It will be understood that the invention is not limited to a particular light stabilizer and that any of the well-known light stabilizers may be employed. Preferably, however, the invention contemplates the use of isoeugenol in combination with the new general purpose stabilizers.

The new class of general purpose stabilizers noted immediately above, namely, acetylenic ethers, have been found particularly effective in stabilizing tetrachloroethylene contaminated with minor amounts of other lower aliphatic chlorohydrocarbons, both in the liquid and in the vapor phase. For the most part, the stabilizing effect has been found to be most pronounced and prolonged where pre-treatments which destroy the greater part of the chloro-acids and acid chlorides have been resorted to prior to the addition of the stabilizing acetylenic ether. The initial treatment of the crude tetrachloroethylene may include adding an organic base of the amine type and having a boiling point higher than tetrachloroethylene, for example, aniline or morpholine, in an amount from approximately 0.22.0% by Weight to the crude product, and fractionally distilling the crude mass to recover substantially all of the tetrachloroethylene as an intermediate fraction in the distillation; additional treatments may include washing the tetrachloroethylene frac tion with a solution of an inorganic base, such as an alkali metal or alkaline earth metal base, for example, sodium hydroxide, sodium carbonate, calcium hydroxide, magnesium bicarbonate, and the like, drying the washed product and distilling the dried product to recover a more highly refined tetrachloroethylene fraction. The purpose in using an amine, such as aniline, is to allow for the reaction of such amine with acid chloride products contained in the crude product whereby an anilide or analogous compound may form during distillation and the undesired impurity is retained in the distillation residue. The purpose of washing the efiluent from the initial distillation with an alkali metal or alkaline earth metal base is to remove the more volatile of the acid chloride impurities, such as hydrogen chloride, phosgene, and the like, which may not have reacted with the amine. The crude product may also be washed initially with a solution of an inorganic base,'such as those noted above, dried, and combined with an amine having a boiling 4 point substantially higher than tetrachloroethylene, generally in an amount from 0.2T2.0% by weight, and the mixture thus obtained distilled as described above in order to recover the purified tetrachloroethylene substantially free from chloro oxygen-containing impurities.

Where such impurities as hydrogen chloride, phosgene, chloro-acids, and the like, are known to be extremely low in the crude product, this material may be combined with an amine, such as aniline, as noted hereinabove, and subjected to fractional distillation to recover the substantially pure tetrachloroethylene without the necessity of resorting to the treatment with a solution of an inorganic base. Moreover, the dilute alkaline wash may be omitted even where the chloro oxygen-containing compounds are present in appreciable quantities in the crude product, but it has been found that the amount of organic amine consumed and the volume of distillation residue accumulated is excessive.

After any one of the above-described initial treatments, the recovered tetrachloroethylene may be combined with a stabilizing amount of an acetylenic ether, as noted above, for example, in an amount from 0.01- 1.0% by weight of tetrachloroethylene, preferably, however, from 0.20.3% where the above pro-treatments or their equivalent have been used. The extremes within the above-noted broad range are preferred where the amount of chloro-hydrocarbon impurities associated with the tetrachloroethylene is unusually high or unusually low, while the amounts within the intermediate preferred range are generally sufficiently effective where the purified tetrachloroethylene contains not more than about 1-3% of the lower chlorinated aliphatic hydrocarbon impurities consisting essentially of trichloroethylene, the most common impurity obtained in commercial production.

- The beneficial effects of the present invention may also be realized where tetrachloroethylene has been purified in a commercial operation and stabilized either with a high boiling point stabilizer, i. e., a stabilizer such as one of the amine or of the ether type having a higher boiling point than that of tetrachloroethylene, or with stabilizers which are more volatile than tetrachloroethylene, by removing such stabilizer as by chemical reaction, azeotropic distillation, or the like; the thus-treated mass is then fractionally distilled to recover the tetrachloroethylene fraction, which may be combined with an acetylenic ether, as described above, in an amount sufficient to effect stabilization, whereby the tetrachloroethylene is rendered especially suitable, due to its stability, for, degreasing or dry cleaning operations.

The benefits which may be derived from this invention may be had by employing any one of a large number of acetylenic ethers. Ethers, as a topic of discussion, may be described as derivatives of alcohols. Accordingly, for convenience, in indicating the exemplary compounds that are suitable for use herein, mentioned immediately hereinafter is an exemplary group of alcohols and then thereafter there is mentioned a group of suitable organic materials which are to be taken in conjunction with the mentioned alcohols, as forming the derivatives thereof and, thus, the ethers for use herein as the new stabilizers. From this it will be understood that any of the suggested organic materials are contemplated as derivatives of any of the mentioned alcohols.

It is contemplated that for the purpose of forming acetylenic ethers for use according to this invention either mono or dihydric alcohols containing a triple bond wherein the hydroxyl groups of the compound are secured to carbon atoms which are substituted by three other substituents may be employed. Of this class of alcohols, both straight and branched chain compounds are suitable and, within the range expressed in the previous sentence, the relative'position of the triple bond and the hydroxyl groups is not pertinent.

'Of the straight chain mono-hydric compounds, there regard to the availability of particular chemicals.

may be mentioned propargyl alcohol, propargyl carbinol, methyl acetylenyl carbinol, ethyl acetylenyl carbinol, 2- butyne-l-ol, and higher homologues of this series, including the octyl and nonyl substituted compounds, as well as aryl substituted compounds. Of the branched chain mono-hydric compounds may be mentioned dimethyl acetylenyl carbinol and higher homologues, such as diethyl, dibutyl, diamyl and similiar substituted compounds, including those having two diiferent substituents, such as methyl, ethyl acetylenyl carbinol, and the like. Of special use in this group are methyl butynol and methyl pentynol, and of particular interest of the isomers of these compounds are respectively 2-methyl-3- butyne-Z-ol and 3-methyl-1-pentyne-3-ol. Any readily available .diol may be employed, especially attractive examples being 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyne-3-ol.

Among the suitable organic material that are to be taken as ether derivatives of the aforementioned alcohols are hydrocarbons, either acyclic, cyclic or substituted cyclic, saturated or unsaturated, including acetylenic unsaturation. Such materials may also be straight or branched chain; additionally, they may' contain functional groups such, for example, as halide and hydroxyl groups.

It is contemplated that such materials may contain as many as ten or more carbon atoms. Preferably, and in general, more suitable materials are those of lower molecular weight, particularly those numbering about eight or less carbon atoms. The selection of this portion of the ether as to molecular weight, in a great many instances of contemplated use for the stabilized solvent, is made quite agreeably in relation to the boiling point of the resulting ether that is produced. Thus, if an end product of a specified boiling point or one boiling within a permissible range, if desired, the derivative portion might well be selected after having determined the alcohol to be selected. For example, if a high boiling alcohol or other similar ether-forming material is selected for etherification and it requires only a small alteration in boiling point upwardly to a preferred figure, a low molecular weight hydrocarbon should be contemplated. Sometimes it is quite difiicult to procure particular desired Y chemical compounds in quantities that are needed for industrial operations. On the other hand, it may be possible to obtain a homologue of the desired material or a closely related chemical in large quantity. It will be seen that in this event, the present invention permits the use of such substitute chemical and the realization of the improved result of the invention substantially without In the present instance, it is to be expected that such difficulty would most likely arise in obtaining the basic acetylenic material as exemplified by the alcohols above mentioned since the group of organic materials above noted are generally very readily available in any quantitydesired.

More particularly illustrative of these organic materials which are suitable for use in the present invention are such compound as methane, ethane, propane, propene, propyne, butane, isobutane, butene, butadiene, pentane, hexane, hexene and all similar hydrocarbons in the homologous series, cyclohexane, methyl cyclohexane, cyclohexene, benzene, toluene, xylene and its isomers, and various substituted forms of all of such materials such, for example, as the chloro and hydroxy derivatives.

Particularly suitable among the ethers that are set forth above are the lower molecular weight ethers of the above-mentioned especially suitable acetylenic alcohols such as the methyl, ethyl, propyl butyl and isoamyl ethers of, for example, propargyl alcohol, and the methyl butynols and methyl pentynols, not only because of the remarkable stabilizing efiects that they have but also because of their conformity to'the desirable boiling range of the stabilizing materials.

. water and is 0 Those skilled in the art will appreciate that while all of the ethers derivable from the above-mentioned alcohols and hydrocarbons, and particularly, the ethers derivable from specifically mentioned alcohols and hydro carbons will be useful in the practice of the present in vention, those materials having boiling points in the same general range as that of tetrachloroethylene (B. P. 119- 122 C.) will be especially desirable as they may be expected to have the property of going into the vapor phase with the solvent and returning with it to the liquid phase. This is especially significant in vapor phase metal degreasing operations, as well as in the dry cleaning industry where solvents commonly are recovered by distillation and reused. It will be recognized that certain ethers are outstanding in this property, such for example, being the propyl, butyl, isobutyl, isoamyl ethers of propargyl alcohol, methyl, ethyl, propyl and ethers of the methyl butynols and methyl pentynols. As a general guide any of the ethers boiling between about and C. are regarded as especially suitable.

In order that no difficulty will be encountered in practicing the present invention, it is desired to illustrate in a detailed fashion, methods for preparing some of the ethers contemplated for use in the invention.

N-BUTYL ETHER OF METHYL BUTYNOL To 2.0 g. sodium hydroxide dissolved in 4 ml. water is added 5.5 g. 3-methyl-3-chloro-l-butyne and 30 ml. n-butyl alcohol and the resulting mixture boiled for five minutes. The mixture is allowed to cool, sodium chloride beginning to precipitate at once. When sodium chloride stops forming, 50 ml. water is added and the organic (upper) layer separated, dried, and distilled, the

fraction boiling at about the boiling range of the ether This fraction is shaken twice with recovered for analysis and testing. Analysis of the product reveals it to have the formula 2O-C4Hg.

PHENYL PROPARGYL ETHER To a solution of 16 g. sodium hydroxide in 30 ml. water is added 31.3 g. phenol and 100 ml. methanol and to the resulting homogeneous solution is added 25.3 g. (0.34 mol) propargyl chloride. Sodium chloride starts forming at once, and when it stops forming, the liquid is filtered off and distilled 55 ml. being collected which is mostly methanol. 150ml. H O is then added, which causes separation of an oily liquid. This liquid is extracted three times with ether, the ether extract dried and the ether evaporated off under vacuum. The remaining oily residue is distilled at about 45 mm. pressure, the fraction boilingat about l00-l05 C. being collected. Analysis reveals the product to be the phenyl ether of propargyl alcohol.

With the foregoing illustrative examples of the manner of preparation of certain of the ethers of this invention before them, it is not believed that those skilled in the art will have difiiculty in preparing any of the several materials.

In order that those skilled in the art may better understand the present invention and in what manner the same may be carried into efiecflspecific examples are provided below.

In all examples, stability is tested in accordance with the following procedure:

One hundred mls. of the tetrachloroethylene to be tested for stability are placed in a 300-ml. flask equipped with a ground glass joint. A copper strip 2.0 x 7.5 x 0.005 cm., which has been washed with concentrated hydrochloric acid, water, dried and weighed, is placed in the flask. Next, 0.2 ml. of water is added. The flask is attached to a small Soxhlet extractor equipped with a bottom ground glass joint and a top ground glass joint. A bulb type condenser with a bottom ground glass joint is attached to the Soxhlet. An acid washed, weighed copper strip (2.0 x 7.5 x 0.005 cm.) is placed being collected.

in the Soxhlet, and another acid washed and weighed copper strip of the same size is placed in the bottom part of the condenser, so that the condensing tetrachloroethylene condenses on the strip. The water scrubber (containing 150-200 mls. H O) absorbs any HCl that does not react with the copper during the stability run. To prevent the sucking back of water, two filter flasks, so arranged that water is pushed from one flask to the other with changes in pressure, are employed. The flask containing the tetrachloroethylene is heated on a heater controlled to adjust the boiling rate so that the Soxhlet extractor empties every 8-10 minutes. A 100-watt bulb is placed one inch from the vapor line of the-Soxhlet extractor to furnish light for the photochemical oxidation. The stability test is run for 72 hours.

The aggregate loss in weight of the copper strips is a measure of the stability of the tetrachloroethylene tested.

In general, material which shows a 45 mg. aggregate loss in weight in the 3 copper strips over the period of the test is acceptable for dry cleaning purposes (National Institute of Cleaning and Dyeing, Perchlorethylene (Drycleaning), Tentative Standard 3-50). 18 mg. loss is closer to industry standards, however, but naturally the more stable the material, the better.

In all of the following exemplary material, 100 ml. portions of samples are employed to which 0.25% by weight of the new stabilizers is added. Where isoeugenol is specified, the portion employed is 0.01% by weight.

Example I For this example, two 100 ml. samples of unstabilized tetrachloroethylene of about four weeks age are employed. This material, due to its age, contains a substantial quantity of impurity; nevertheless, the effectiveness of the stabilizer is clearly demonstrated.

Total loss in weight Sample: of 3 Cu strips, mg.

Containing ethyl-propargyl ether about 11.0 Control stabilized with a standard known stabilizer (including light-stabilizer) about 61.1

Example 11 A similar sample tested identically and concurrently with the above but containing 0.01% by weight isoeugenol in addition to the ether loses about 9.8 mg.

Example III Employing the same tetrachloroethylene stock as employed in Example I, a sample is prepared using phenyl propargyl ether as the stabilizer and tested concurrently with the Example I samples. The total weight loss is about 10.8 mg. I

Example IV A sample similar in all respects to that of Example 111, except that isoeugenol is present as a light stabilizer in addition to the ether, is prepared and tested concurrently with the Example I samples. The total weight loss is about 8.6 mg.

While the invention has been described in terms of its use in connection with tetrachloroethylene, it is desired to point out that it is not to be thus limited. The invention extends to the stabilization of other lower chlorinated aliphatic hydrocarbons, either saturated or unsaturated, such as dichloroethylene, trichloroethylene, trichloroethane, pentachlorocthane, chloroform, carbon tetrachloride and the like, in which a similar stability problem is encountered. In fact, it will be noted that the origin of the problem in connection with the tetrachloroethylene is in part attributable to the presence of such less stable chlorohydrocarbons and, as mentioned above, the new stabilizers or" the invention effectively prevent their decomposition.

While there have been described various embodiments of the invention, the methods and products described are not intended to beunderstood as limiting the scope of the invention as it is realized that changes therewithin are possible and it is further intended that each element recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner, it being intended to cover the invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. A composition of matter comprising a lower molecular weight chlorinated hydrocarbon and a stabilizing amount of an acetylenic ether selected from the group consisting of hydrocarbon acetylenic ethers, halohydrocarbon acetylenic ethers and hydroxy hydrocarbon acetylenic ethers.

2. A composition of matter comprising a lower molecular weight chlorinated hydrocarbon and a stabilizing amount of an acetylenic ether selected from the group consisting of hydrocarbon acetylenic ethers, halohydrocarbon acetylenic ethers and hydroxy hydrocarbon acetylenic ethers, the boiling point of which is within about 20 C. of the boiling point of the said chlorinated hydrocarbon.

3. A composition of matter as claimed in claim 1 which includes a light stabilizer.

4. A composition of matter as claimed in claim 1 which includes isoeugenol as a light stabilizer.

5. A composition of matter as claimed in claim 2 which includes isoeugenol as a light stabilizer.

6. A composition of 'matter comprising tetrachloroethylene and a stabilizing amount of an acetylenic ether selected from the group consisting of hydrocarbon acetylenic ethers, halohydrocarbon acetylenic ethers and hydroxy hydrocarbon acetylenic ethers.

7. A composition of matter comprising tetrachloroethylene and a stabilizing amount of an acetylenic ether selected from the group consisting of hydrocarbon acetylenic ethers, halohydrocarbon acetylenic ethers and hydroxy hydrocarbon acetylenic ethers, the boiling point of which ether falls within the range of about to about C.

8. A composition of matter asclaimed in claim 6 which includes a light stabilizer.

9. A composition of matter as claimed in claim 6 which includes an effective amount of isoeugenol as a light stabilizer.

10. A composition of matter as claimed in claim 7 which includes an effective amount of isoeugenol as a light stabilizer.

References Cited in the file of this patent UNITED STATES PATENTS 1,097,145 Snelling May 19, 1914 2,126,179 Duggan Aug. 9,, 1938 2,371,645 Aitchison et al Mar. 20, 1945 2,593,267 Church et al Apr. 15,1952

UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,868,851 January 13,1959 Maxwell J. Skeeters It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 68, for which imporities read which impurities-; column 5,

line 36, for range, it read -range, is; hne 60, for such compound read -such compounds; column 6, line 88, the formula should appear as shown below instead of as in the patent H3C-CEO(CHg)aO-C4HB Signed and sealed this 8th day of September 1959.

[SEAL] Attest KARL H. AXLINE, Attesti'ng Ofioer.

ROBERT C. WATSON, Comnm'ssz'oner of Patents.

Claims (1)

1. A COMPOSITION OF MATTER COMPRISING A LOWER MOLECULAR WEIGHT CHLORINATED HYDROCARBON AND A STABILIZING AMOUNT OF AN ACETYLENIC ETHER SELECTED FROM THE GROUP CONSISTING OF HYDROCARBON ACETYLENIC ETHERS, HALOHYDROCARBON ACETYLENIC ETHERS AND HYDROXY HYDROCARBON ACETYLENIC ETHERS.