US2415971A - Stabilization of organic peroxides - Google Patents

Description

PatentedFeb. 18, 1947 UNITED STATES PATENT orrie STABILIZATION OF ORGANIC PEROXIDES Henry 0. Stevens, Akron, Ohio, assignor to Pittsburgh Plate Glass Company, litts burgh,1a., a corporatioin of Pennsylvania No Drawing. Application February 4,

Serial No. 521,147

' pounds. Accordingly, one of the purposes of this invention is to provide a method of preventing the spontaneous decomposition of liquid. organic peroxy compounds and thereby permit storage for long period of time without the danger of loss. A further purpose of this invention is to eliminate the danger of explosions and fires in the use, storage, and shipment of liquid organic peroxy compounds.

I have invented a method of stabilizing liquid peroxy compounds which otherwise would decompose spontaneously within a very few minutes under ordinary conditions. By my method it is possible to completely avoid all danger of rapid decomposition or explosion over long periods" of time. Many of the peroxy compounds, particularly the low molecular weight percarbonates, are very explosive and must be prepared at very low temperatures to prevent immediate decomposition. In such cases, the use of my invention is particularly advantageous.

Many liquid peroxy compounds decompose more slowly and do not present a serious explosion problem. Such compounds decompose at an appreciable rate, however, and this invention 'has substantial utility in preventing such loss, thereby greatly lengthening the active life of the compounds.

I'have found that by adding a small proportion of iodine to a liquid peroxy compound the normal in solid form and dissolved by stirring or agitating the liquid. Normally, colorless liquid peroxy compounds willbe colored yellow, orange, or deep red by the dissolved iodine,- the coloring depending upon the solubility of iodine in the particular peroxy compound.

The iodine stabilization treatment of the invention is particularly advantageous in that it does not impair the utility of the peroxy compound. Although the presence of iodine may temporarily affect the color of the preparation, it is removed before use, thereby regenerating the pure colorless liquid peroxide compound.

My invention is useful in inhibiting the decomposition of any liquid compound containing peroxy oxygen, for example:

Diperoxy carbonates Many peroxy compounds are solid not subject to spontaneous decomposition. Hence, the in-' vention is particularly adapted to treatment of liquid .peroxy compounds and especially those in.

the above classes.

The new stabilization method may be practiced 'by adding solid iodine to a freshly prepared and purified liquid peroxy compound or the same peroxy compound may be prepared in the presence of iodine. The stabilization method although greatly inhibiting the decomposition frequently does not entirely prevent it. Decomposition proceeds at a'very slow rate becoming almost imperceptible at low temperatures. Accordingly, it is desirable to store the stabilized solutions in a refrigerator. This is especially advantageous if the solution is stored in a. closed container. Such containers should be vented to the atmosphere to prevent increased pressures within, due to the slow decomposition.

Frequently, the'iodine may be onlyslightly ol-- uble in peroxy compounds or is but slowly -dis-.

and adding such solutions to the peroxy com-v poimd.

Before use of the stabilized peroxy compounds for most purposes it is necessary to remove the iodine. The stabilized solution is first filtered to remove all traces of solid iodine. The filtered solution is then washed with a dilute water solution of-a strong oxidizing agent such as hypochlorous acidand subsequently with water. Frequently it is desirable to follow the hypochlorous acid with a very dilute caustic soda washin which may in turn be followed by a wash of dilute acetic acid. In all instances, the peroxy compounds are ultimately washed with water until neutral to litmus. All washing should be performed with the wash solutions at approximately C. The washed peroxy compounds again become very unstable and should be stored at temperatures of 0 C. or lower. The use of solid carbon dioxide, as a cooling medium, is preferred.

Other methods of removing the iodine will be apparent to the skilled chemist. For example, a very effective removal can be obtained by blowing the filtered stabilized solution with a jet of air for a period of several hours. This will cause turn until the air circulation is interrupted. Ac-

cordingly, the same equipment used to remove iodine may be used a a temporary storage vessel for the purified peroxy compound prior to use.

Further details of the practice of the invention are set forth in detail in the following examples:

Example I Approximately one pound of colorless isopropyl percarbonate analyzing 99.4 percent pure was stabilized by adding 4 g. of iodine and shaking until most of the iodine was dissolved. After storage for ten days the stabilized solution was filtered and cooled to approximately 0 C. It was washed with two volumes of water to which was added about 0.1 percent of sodium sulfate for the purpose of facilitating the separation into two liquid phases. The solution was then washed with 1 percent hypochlorous acid which removed practically all of the iodine and left the solution with a faint yellow color which was subsequently removed by washing with water. The colorless solution was then washed successively with 1 percent sodium hydroxide, 1 percent acetic acid, and ultimately with water until neutral to litmus. The colorless isopropyl percarbonate thus produced assayed at 99.6 percent.

A 10 g. sample of the original unstabilized isopropyl percarbonate was permitted to stand at room temperature. In 12 minutes it decomposed with a rapid evolution of gas.

' oxygen which comprises adding up to 1 percent 4 Example If A sample of ethyl percarbonate containing 1 percent of iodine was stored at room temperature (25 to 30 C.) and analyzed periodically for two weeks. The following results were obtained:

Time, hours per out n 98.4 72 am 114 82.2 200 14.5 258 67.4 330 62.8

A sample of the identical compound except nine minutes.

Although the invention has been described with respect to certain specific examples it is not intended that the details thereof shall be regarded as limitations upon the scope of the invention except to the extent incorporated in the following claims.

I claim:

1. A method of preventing the decomposition of liquid organic compounds containing peroxy oxygen which comprises adding a small proportion of iodine to the organic peroxy compound.

2. A method of preventing the decomposition of liquid organic compoundscontaining peroxy of iodine to the organic peroxy compound.

3. A method of preventing the decomposition of liquid organic compounds containing peroxy oxygenwhich comprises dissolving iodine in'the peroxy compound. a

4. A method of preventing the decomposition of liquid organic compounds containing peroxy oxygen which comprises dissolving up to 1% of iodine in theperoxy compound.

5. A stabilized liquid organic compound containing peroxy oxygen which comprises a liquid organic peroxy compound and iodine.

6.A stabilized liquid organic compound containing peroxy oxygen which comprises a liquid organic peroxy compound and up to 1 percent of iodine.

7. A method of preventing the decomposition of liquid percarbonates which comprises dissolving iodine in said percarbonates.

8. A method of preventing the decompositionof isopropyl percarbonate which comprises dissolving iodine in the isopropyl percarbonate.

9. A stable liquid percarbonate comprising a liquid percarbonate and iodine.

10. A stable isopropyl percarbonate comprising isopropyl percarbonate and iodine. v

HENRY C. STEVENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 7 446, pgs. 46, 4'1 (copy in Patent Oflice Library, 260-610).