US3505415A - Process for stabilizing 1,1,1-trichlorethane - Google Patents

Description

United States Patent Int. Cl. con 17740; B01j 1/16 US. Cl. 260-652.5 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for stabilizing 1,1,1-trichlorethane, and more particularly to a process for stabilizing 1,1,l-trichlorethane by addition thereto of a compound containing an alkoxy group with 1 to 3 carbon atoms in the beta position in relation to a -C=O group, as stabilizing agent This application is a continuation of application Ser. No. 367,236 filed -May 13, 1964 and now abandoned.

It is known that halogenated hydrocarbons, such as vinyl chloride, vinylidene chloride, trichlorethane, trichlorethylene, perchlorethylene, as well as other aliphatic chlorinated hydrocarbons easily undergo decomposition. This decomposition usually takes place with the simultaneous formation of acids, and is caused by the presence of air, light and traces of water, among other causes. It is furthermore known that the evolution of acid is especially promoted by the presence of certain metals. For example, the decomposition of halogenated hydrocarbons is catalyzed by iron, aluminum, magnesium, and their alloys.

The decomposition reaction of some of the halogenated hydrocarbon compounds is so violent that the utilization and the processing of the above named halogenated hydrocarbons can be conducted in metal vessels only with the greatest of difficulties. Even the action of light promotes the decomposition. This tendency to decomposition is a serious disadvantage and is particularly evident in the case of 1,1,1-trichlorethane. It has been established that 1,1,1-trichlorethane substantially more readily undergoes decomposition evolving HCl and turning black than any above-mentioned chlorinated hydrocarbons. The decomposition can result in the complete resinification of the material. As a result 1,1,1-trichlorethane is used for industrial purposes only with a stabilizer .or stabilizers added thereto.

The stabilization of 1,1,1-trich1orethane has heretofore been provided by using dialkylsulfoxides, dialkylsulfites, dialkylsulfides, 1,4-dioxanes, 1,3-dioxolanes epoxides, monoketones, nitriles trialkylsilylethers, tetralkyl compounds of tin and lead, nitroalkanes, sec. or tert. alcohols in association with 1,4-dioxanes, nitriles, acetylene alcohols, oxazirines, thiazirines, oxaphosphirines, and thiaphosphorines. Unfortunately, however, these known stabilizing additives must generally be used in rather large amounts in order to achieve an adequate stabilizing effect, so that the 1,1,1-trichlorethane thus stabilized acquires the character of a mixture of solvents. This mixture, however, has only a limited field of application. Further the use of dioxane and a number of other compounds as set out above as stabilizers is impossible for many purposes because of the toxicity of these compounds. Other conventional stabilizers have proved undesirable because of their color, while others are ineffective because of their reactivity for example with the objects being degreased. This reactivity results in a gradual loss of the stabilizing effect whereupon the above-described decomposition phenomenon can be observed. Another group of known stabilizers is characterized by great sensitivity to hydrolysis and oxygen, and these, too, therefore, have limited application.

An object of this invention is a new improved method for the stabilization of 1,1,1-trichlorethane.

Another object of the present invention is the development of stabilized 1,1,1-trichlorethane.

The foregoing and other objects which will be manifest to the skilled in the art from the following description are realized in accordance with the invention wherein it has been found that these objects are accomplished, and stabilization of 1,1,1-trichlorethane obtained by addition to the 1,1,1-trichlorethane of an organic compound having in the beta position in relation to a C=O group, an alkoxy group with l to 3 carbon atoms. The stabilization is obtained using 0.1 to 10 weight percent and preferably 0.5 to 5 weight percent referred to the chlorinated hydrocarbon of the organic compound containing the group represented by the formula:

lame-(Iii wherein R represents an alkyl group containing 1 to 3 carbon atoms. The -C=O group of the stabilizing organic compound can be part of an acid], ester, aldehyde or ketone group, or part of a lactone ring.

The beta-position substituted acids or esters which are suitable as stabilizers can be produced in the known manner, as for example by the reaction of a B-propiolactone or a ,B-lactone with an alcohol. An example of the stabilizing compound, the C=O group of which is part of an aldehyde is B-methoxypropionaldehyde. Examples of stabilizers suitable for use in accordance with the invention the C=O group of which is part of the keto group are: 4-methoxybutanone-(2), 4-methyl-4-methoxypentanone- 2 4-methyl-4-ethoxy-pentanone- (2 etc.

The use of the stabilizers in accordance with the invention produces markedly superior results compared to the use of the conventional stabilizers and in particular as concerns the disadvantages associated with the conventional stabilizers.

The evaluation of the various stabilizers and their suitability for use can be carried out, for example, by simply boiling a given quantity of 1,1,1-trichlorethane with identical percentages of the stabilizing compounds in question in. the presence of a defined quantity of metal chips.

The stabilizing effect of the compounds of the invention can in most instances be enhanced by using the stabilizing compounds of the invention in combination with a prior art stabilizer, such as for instance, isopropanol, tert. butanol, 1,4-dioxane, 1,3-dioxolanes, methyl ethyl ketone, nitriles such as acetonitrile, acrylonitrile, etc. Mixtures of isopropanol, tert. butanol, 1,4-dioxane, 1,3- dioxolane, 22-dimethyl -1, 3- dioxalne, methyl ethyl ketone, nitromethane and acetonitrile with the compounds of the invention can also be used.

The stabilizers for use in the process .of the present invention can be added to the 1,1,1-trichlorethane in the various stages of the manufacture thereof. In certain instances, the presence of a stabilizer in the gaseous phase and in distillation may be particularly desirable. This can be readily accomplished according to the present invention.

The following examples are given as illustrative and as limitations of the invention:

EXAMPLES 1-31 The effect of a number of known stabilizers and a number of the novel stabilizers in accordance with the in- 3 vention of 1,1,1-trichlo-rethane was determined. In each case, the stated quantity of stabilizer of stabilizing mixture was added to 100 grams of 1,1,1-trichlorethane and the mixture was then refluxed over 5 grams of aluminum turnings until the chlorinated hydrocarbon had turned black or until the evolution of HCl had begun. The time taken for the occurrence of discoloration or for the evolution of HCl to commence was recorded and serves as a measure of the suitability of the tested compound as a stabilizing agent. The results of the experiments are set out in the table which follows: in the table the symbol designates that the experiment was discontinued after the noted time as a considerable difference in comparison with the blank test had been demonstrated.

In the table,

I represents the experiment conducted without any stabilizer;

II represents the experiments conducted with the conventional stabilizers used for the stabilization of 1,1,1- trichlorethane, and

III represents the stabilization experiments conducted with the stabilizing compounds of the invention.

Time for Quantity evolution added of H01 or (in wt. for black- Example Stab111zer percent) ening 1 20 sec. 2 Styrene oxide 0. 1. 9 min. 3 Propylene xide 0. 6 min. 4 Epichlorhydrin. 0. 4.5 min. 5 Allyl glycidyl ether 0. 7 min. 6a 0. 60 min. 6b hrs. 6c 1. 28 hrs. 7a... 0. 9 min. 7b 16 hrs. 8a.. 12 hrs. 81)... 25 hrs. 9- 0. 3 min. 10 0. 3 min. 11 Propargyl alcohol 0. 10 min. 12a Isopropanol 30 min.

90 min. 2.0 hrs. 4.5 hrs. 2.5 hrs. 12 hrs. 33 hrs.

2 hrs.

12 hrs. 36 hrs. 43 hrs. 80 hrs. 55 hrs. 144 hrs. 78 hrs.

19b do 120 hrs. 20 4-methyl-4-ethoxypenta- 80 hrs.

none-2. 21 fi-methoxyproplonie acid 80 hrs.

methyl ester. B-methoxypropronaldehyde O. 22 4methyl-4-meth0xy- 80 hrs. 4 pen{:1anor}1oe-t2. 2 0. 1

met oxy u anone- 23 "{liiproggnoLb t 9 80h1s. -me oxy u anone-- '"{2,2-dimethyl-1,3-dioxolane. 0. 5} 771115 Time for Quantity evolution added of H01 or (in wt. for black- Example Stabilizer percent) ening 4-methyli-methoxypenta- 1 25 none-2 hrs. ipropan0l. 1 4-methyl-4-methoxypenta- 1 26 none-2 48 his methyl ethyl ketone. 1 fl-Methoxypropionie acid 1 27 methyl ester 240 hrs.

nitromethane. 1 4-methoxybutanone-2, 0. 5

28 1,4-dioxane 0. 5 93 hrs.

1,3-dioxolane. 0. 5 4-meth3l-4-methoxy-penta- 1 none- 29 acetonitrile 0. 5 102 hrs t-butanol. O. 5 4-methsgl-4-methoxypenta- 1 none- 30 t-butanol 1 240 hrs methyl ethyl ketone. 1 t-methyzli-methoxypenta- 1 none- 31 1,4-dioxane 1 80 hrs methyl ethyl ketone. 1

We claim:

1. A stabilized mixture of 1,1,1-trichloroethane having therein a stabilizing amount of a stabilizer which is a mixture of methyl-B-methoxypropionate and at least one member of the group consisting of isopropanol, tert. butanol, 1,4,-dioxane, 1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane methyl ethyl ketone, nitromethane, and acetonitrile.

2. Mixture as claimed in claim 1, containing 0.1 to 10 weight-percent, based upon said trichlorethane of said stabilizer. 3. Mixture as claimed in claim 1, containing 0.5 to 5 weight-percent, based upon said trichlorethane of said stabilizer.

4. A stabilized mixture as claimed in claim 1, wherein said stabilizer contains nitromethane.

References Cited UNITED STATES PATENTS 2,999,886 10/1961 Crabb et al. 260-6525 2,371,645 3/1945 Aitchison 260-6525 2,818,446 12/ 1957 Stocks 260-6 525 3,060,125 10/1962 Sims 260-6525 2,947,792 8/1960 Skeeters 260-6525 FOREIGN PATENTS 912,118 12/1962 Great Britain.

LEON ZITVER, Primary Examiner H. T. MARS, Assistant Examiner US. Cl. X.R.