IL28073A - Production of concentratable solutions and concentrated solutions of organic peroxides - Google Patents

Description

Patents Form No. 3 PATENTS AND DESIGNS ORDINANCE.

SPECIFICATION.

"PRODUCTION OP CONCENTRATABLE SOLUTIONS AND CONCENTRATED SOLUTIONS OP ORGANIC PEROXIDES" I / WE , ..CHARBONNAGES ..DE .PRANCE, ¾ Frenc public Institution, of.9», avenue P-e£ci^ «i*4© θ, France, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described aud ascertained in and by the following s tatement : - The present invention relates to the production of concentratable solutions of organic peroxides. It also relates to the production of concentrated solutions of such peroxides.

It is well known that certain organic peroxides, especially peroxides of cyclic alcohols such as cyclopentanol, cyclohexanol and cycloheptanol obtained by contacting said alcohols with oxygen or oxygen-containing gas at at least 100°C, are difficult or even impossible to concentrate. Peroxides of this kind may be employed as starting materials for a large number of syntheses. Thus, diacids are obtained by the reductive dimerization of these peroxides by means of ferrous ions.

It is therefore a great advantage to have solutions of organic peroxides which can be sufficiently concentrated, when this is necessary in industrial syntheses.

It is accordingly an object of the present invention to provide a method by which this result may be obtained.

This method consists essentially in putting the starting peroxide solution into contact with an ion-exchange resin of the stron acid type at a temperature substantially in the vicinity of room temperature or slightly higher than this temperature, then to remove the said resin and to recover a concentratable peroxide solution.

To the best knowledge of the applicant there is no satisfactory method for concentrating peroxide solutions obtained from a cyclo-alkanol which has been oxidated with oxygen or air (See Brown et al, J.A.C.S. Vol. 77 - 1956, pages 1756-1761).

It is also known to produce a peroxide from cyclo-hexanone by reaction with hydrogen peroxide. The actual structure of the final peroxides resulting from the two above processes is proposed the most probably formulae for these peroxides.

In any case, until now it has been necessary when ' using these peroxides as starting materials in syntheses either to handle dilute solutions which necessitates recycling and purification operations on large quantities of liquids, or to use methods operating with costly hydrogen peroxide to obtain concentratable or concentrated products.

Now, in accordance with the present invention, it is possible to obtain concentratable solutions of peroxides from dilute solutions, by subjecting the latter to the acidic treatment described above.

The exact mechanism resulting in these concentratable solutions is not fully understood. Brown et al have shown that a conversion and/or an equilibrium may take place between the different possible formulae of peroxides. In any case the resulting concentrated peroxide solutions in accordance with this invention have the same behaviour and uses as the initial diluted solutions and yield diacids by reductive coupling with ferrous ions either as concentratable or as concentrated solutions.

The method of concentration of a dilute solution of .... previously treated peroxide may be carried out by one of the known conventional methods.

In accordance with preferred embodiments, this concentration is effected by evaporation under vacuum or by rapid evaporation in the presence of a flow of oxygen or of a gaseous mixture containing a large proportion of oxygen.

According to *an advantageous method of procedure, this evaporation can be effected in a rotary evaporator, a thin film evaporator, a flash evaporator, etc., or any other apparatus time ensuring good contact between the oxygen and the solution and rapid removal of the concentrated product. — Thus, the present invention covers a method of production of concentrated solutions of peroxides characterized by the fact that it consists in subjecting a dilute solution of a peroxide to an ion exchange treatment, and then concentrating the dilute solution thus treated by one of the means indicated above. This method may be carried out continuously or ,by batch.

The term, ion exchange resins of the strong acid type, is meant to include crosslinked polystyrenes, usually with , divinylbenzene as the crosslinking agent, containing sulfonic acid groups which are usually introduced after polymerization by treatment with concentrated sulfuric acid or chlorosulfonic acid. The nominal DVB content is used to indicate the degree of crosslinking and refers to mole per cent of pure divinylbenzene in the polymerization mixture. A more complete description,; of this type of ion exchange resin will be found in the text entitled "Ion Exchange" by Helfferich (1962).

The best results are obtained with resins of the above type containing no more than 8 and preferably no more than 5° of DVB.

Other characteristic features and advantages of the invention will become more clearly apparent from the description which follows below, illustrating its application to the case of cyclo-hexanol peroxide taken as an example of a cyclic peroxide. This description will be made with reference to the accompanying drawings, wherein : Figs. 1 -3- represent flow sheets of three alternative ": forms of carrying out the invention.

The followin specific examples are illustrative only and should not be construed as limiting the scope of the invention.

EXAMPLE 1 A cyclohexanol peroxide solution is prepared by oxidation of cyclohexanol by atmospheric oxygen, following a known method. The solution containing 5.5 mg. of active oxygen per gram, of , which 0$ is in the- form of hydrogen peroxide, is stirred for minutes at 50°C. with 10$ of its volume of acid ion-exchange resin (Dowex 50). The product obtained has a content of active oxygen of 4.42 mg. per gram, of which only 8% is in the form of hydrogen peroxide. The percentage was determined by partition , r between water and ether after calibration (method of DAMKOHLER and EGGERGLUSS , Z. Physikal. Chem. (B) $ (1942) 165, 171).

The mixture thus treated is introduced for concentration, at a rate of 53 cu. cm. per hour, together with 52 normal litres per hour of oxygen, into the apparatus shown diagrammatically in Fig. 1, comprising the following units: introduced by means of the conduits G- and E; - A vaporizer V in which the partial vaporization of the pre-heated mixture is effected. The non-vaporized products are discharged by the conduit L; - A cooler R; - A separator S in which the distillate evacuated through D settles, while the non-condensed gas is discharged through P.

The temperature of the pre-heater and the vaporizer being 100°C, there is collected through L, 12. of the feed containing 20.1 mg. per gram of oxygen without hydrogen peroxide and through D, 87.6$ of the feed containing 1.3 mg. per gram of active oxygen, of which 53$ is in the form of hydrogen peroxide. The concentration of organic peroxides in the solution has .thus been multiplied by a factor of 4.5* without the loss of active oxygen exceeding 16$.

EXAMPLE 2 The solution of cyclohexanol peroxide obtained is sent into the evaporator without having been subjected to. the stabilization treatment (mixing with resin) described in Example Under these conditions, no enrichment of the non-vaporized fraction can be observed.

EXAMPLE 5 The same treatment is carried out as in Example 1 , except that 62.2 normal litres of oxygen are introduced per hour instead of 52. There is collected through L, 5.5$ of the feed containing 53.8 mg. per gram of active oxygen, or 11 times the content of the initial solution. This solution EXAMPLE 4 The same operation is carried out as in Example 1 , but the oxygen in the vaporizer is replaced by nitrogen (conduit G) . Under these conditions, there is obtained through L, 10.5$ of the feed containing 20 mg. per gram of active oxygen, but the loss of active oxygen is 40 .

EXAMPLE 5 ·' Oxidized cyclohexanol containing 5.0 mg. of active oxygen per gram, of which 2 is in the form of hydrogen · .·,,. peroxide, is stirred for 45 minutes at 35°C with 10% of its volume of acid ion-exchange resin (Dowex 50) . The product treated has then a content of active oxygen of 4.75 mg. per gram, of which only 8% is in the form of hydrogen peroxide.

The mixture thus treated is concentrated by introducing it at a rate of 50 cu. cm. per hour into the apparatus shown diagrammatically in Fig. 2 and comprising : - A pre-heater P into which the product to be concentrated passes through E; - A vaporizer V kept under vacuum, in which the vaporization of the cyclohexanol is effected, the non-vaporized products, passing out through L; - A cooler R; - A receiver S, from which the distillate is withdrawn through D.

The pre-heater is kept at 80°C, while the pressure in the vaporizer, which is also heated to 80°C, is held at about 16 mm. of mercury (16 Torr). There is collected through L, 13% with respect to the feed of non-vaporized products containing 28.5 mg. per gram of active oxygen, which corresponds to a the conduit D contains 1.2 mg. per gram of active oxygen, of which about 50$ is in the form of hydrogen peroxide.

An oxidized mixture has thus been concentrated 6 times without the total loss of active oxygen exceeding 5 in the stabilization and concentration treatments.

EXAMPLE 6 The oxidation is effected at 110°C. in the reactor 0 (Fig. 3). The oxygen passes in at G and passes through the liquid in the dispersed state. The reactor is fed with recycled cyclohexanol through the conduit D, the topping-up with fresh cyclohexanol being effected at A. The oxidized products pass through the column Cf kept at 35°C. and containing the acid ion-exchange resin, and then enter the pre-heater P, in which they are brought-up to 80°G .

In the vaporizer V, in which are maintained a temperature of 80°C. and an absolute pressure of 16 mm. Hg (Torr), is effected the separation of the non-vaporized products evacuated through L and of the distillate which is condensed in the cooler R and sent through the conduit D into the reactor.

From the oxidation products passing out of the reactor, which contain 2.7 mg. per gram of active oxygen there is thus obtained a solution of peroxide which contains 13 -8 mg. per gram of active oxygen, or 5 times more than the initial oxide.

It will be obvious to those skilled in the art that various changes ma be made without departing from the scope of the invention and the invention is not to be considered' " limited to what is shown in the drawings and described in the specification.

Claims (9)

HkVXNG NOW particularly described and ascertained our eaid invention and in what manner the same ie o e e orm }^^0^0Q^^3§gCXX we declare that what we claim is t

1. A method of treating organic peroxide solutions to render them concentratable , comprising contacting an organic peroxide solution with an ion exchange resin of the strong acid type at approximately room temperature, said peroxide being selected from the group consisting of peroxides of cyclic alcohols, then removing said resin and recovering said peroxide.

2. A method according to claim 1 wherein the .... peroxide is selected, from the group consisting of peroxides of cyclopentanol, cyclohexanol and cycloneptanol.

3. The product obtained by the process of claim 2.

4. A method according to claim 2 followed by concentrating the peroxide obtained.

5. A; method according to claim 2 followed by concentrating the peroxide by vacuum distillation.

6. A method according to claim 2 followed by concentrating the peroxide by rapid evaporation in the presence of an oxygen containing gas. ;

7. A process of preparation of a concentratable solution of an organic peroxide selected from the group consisting of peroxides of cyclopentanol, cyclohexanol and cyclic alcohol / cycloheptanol comprising contacting said oyoloalooho /with oxygen in a reactor maintained at at least 100°C. passing the oxidized products obtained into contact with an ion exchange resin of the strong acid type at approximately 35°C.,.and recovering said oxidized products.

8. A process according to claim 7 followed by vacuum distillation of said^ products to obtain a concentrated organic peroxide solution.

9. The product obtained by the process of claim 8.