CA1203371A

CA1203371A - Process for producing anhydrous organic hydrogen peroxide solutions

Info

Publication number: CA1203371A
Application number: CA000431876A
Authority: CA
Inventors: Karlheinz Drauz; Axel Kleemann; Rolf Wirthwein
Original assignee: Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 1982-07-07
Filing date: 1983-07-06
Publication date: 1986-04-22
Also published as: FI72707C; EP0098427B1; FI72707B; IL69155A0; ES523454A0; EP0098427A1; FI831933A0; ES8403833A1; DE3362532D1; JPS598604A; DE3225307A1; FI831933L; ATE18533T1; BR8303573A; IL69155A

Abstract

ABSTRACT OF THE DISCLOSURE
The production of organic hydrogen peroxide solutions which were practically anhydrous failed heretofore due either to a water content of the solutions which was too high or to an excessive loss of hydrogen peroxide by decomposition and when passing over as a distillate during the distillative drying operation. By selecting specific esters in combination with relatively high pressures in the azeotropic dehydration these disadvantages are avoided.

Description

~3~7~

~he present invention relates to a process for theproduction of an anhydrous organic hydrogen peroxide solution and the solutions produced thereby.
It is known that the water content of hydrogen peroxide solutions has an inhibiting effect in many reactions, for example, in oxidations or epoxidations (see, for example, Org.
Reactions 7, 395(1953). Thus, experiments in which purely aqeuous solutions of hydrogen peroxide were replaced by organic solutions have already been carried out. However, difficulties were encountered in the production of these solutions.
In the production of organic hydrogen per~xide solutions aqueous solutions of hydrogen peroxide are usually used as the starting material and either only mixed with the desired oryanic compound and subsequently dehydrated by distillation or the aqueous solutions are extracted with the organic compound and dehydrated when required.
In both cases organic solut:ions of hydrogen peroxide w~re actually obtained but their water content always was 1%
~y w~ight or more (see, for example, German Patent Nos.

2,038,319 and 2,038,320, U.S. Patent 3,7~3,706, British Patent 931,119).
In the processes according to the German Patents Nos.
2,038,319 and 2,038,320 it was attempted to remove the water present in the organic solutions by distillation at reduced pressure or followed by azeotropic distilla-tion with an additional entraining agent.
In the process of the U.S. Patent No. 3,743,706 it was supposed to be possible to use the extracting agent itself as entraining agent for an azeotropic distillation.
E~owever, details are lacking.
In the British Paten-t 931,119 the oo- component of the mixture was used for azeotropically distilling off the water.

~ lowever, in the production of organic hydrogen peroxide solutions from a~ueous solutions a further subs-tantial disad-vantage became apparent in addition to the frequently too high water con~ent. At -the pressures applied during the removal of the water a specific percentage of hydrogen peroxide was discharged with the distillate~ On a large industrial scale this resulted in real losses of hydrogen peroxide. Further losses were sustained by decomposition in the sump.
~ n the processes of the German Patent Nos. 2 r 038 ~ 319 and 2,038,320 organic phosphorus compounds and heterocyclic nitrogen compounds were applied and in the processe~ of the British Patent No. 931,119 and of the U.S. Patent No. 3,743~706 aliphatic or cycloaliphatic esters.
While the U.S. Patent No. 3~743~706 contains no data on the manner of carryiny out the azeotropic distillation, in the processes of the other three clted patents pressures suhstantially below 100 mbars are used (see the examples).
Ilowever, in the two German paten-ts a pressure range w~s quite generally mentioned, it was below 400 mbars, but in the after treatment with triethyl phosphate and N-methyl pyrrolidone at pressures at 400 and 100 mbars, respectively, h~drogen peroxide was found in amounts of 0.28 and 0. 6~ by weight and 0.26 and 0.8% by weight in the distillate, ln both cases relative to the distillate. Furthermore, an additional loss of hydrogen peroxide was sustained, i.e., 7.5 and 4.1%
by weight and 4. 7 and 3.9% by weight respectively, relative to hydrogen peroxide used. When adding up the amount of hydro-gen peroxide discharged wlth the distillate and the amount of hydrogen peroxide lost be decomposition, -the total losses at 400 and 1000 mbars were at least 7 to 8% by weight of the hydrogen peroxide used. However, when the distillation is carried out at substantially lower pressures i.e., far below ~2~33~

:L~0 mbars, i-~ is clear that the distillate still contains substantially larger amounts of hydroyen peroxide which can exceed 1 percent by weight relative to the distillate.
The examples are carried out these pressures which are regarded as preferred pressure (loc.cit.).
When using aliphatic esters as solvents for hydroge~
peroxide the azeotropic dehydration was carried out at pressures far below 100 mbars (see Bri-tish Patent No. 931,119, Example 1).
~ hen reproducing the production of a solution of lQ hydrogen peroxide in n-propyl acetate and the azeotropic dehydration of this solution it became apparent thal the distillate contained more than 0.5% by weight of hydrogen per-oxide at a pressure of 65 mm.
Therefore, according to the prior art it appeared that drying of organic hydrogen peroxide solu-tions by distil-lation at a reduced pressure necessaxily resulted in substantial losses of hydrogen perox:ide when carried out on a larcJe industrial scale.
However, not only is the loss o~ hydrogen peroxide a substantial disadvantage of the conventional processes but the fact that the residues from distillation were not free from wa-ter by any means is an additional disadvantage. Thus, for example, the organo-phosphorus solutions had residual water contents ranging from 0.97 to 9.5% by weight. However, these solutions cannot be used for the oxidation or epoxidation.
Even in the only examply of German Patent No.
2,Q38,320 the water content was 11.4% by weight in the organic phase.
Therefore, the present invention provides a process 3Q for produciny a solution of hydrogen peroxide in an organic solvent in which no appreciable loss of the hydrogen peroxide used occurs and whose water content is lower than 0.5~ by 337~
wei-Jhk ~
I-t has now been found that substantially anhydrous organic solutions of hydrogen peroxide can be obtained from aqueous solutions of hydrogen peroxide by mixing the a~ueous 5 solutions with carboxylic esters, when the aqueous hydrogen peroxide solutions are mixed with alkyl or cycloalkyl esters of saturated aliphatic carboxylic acids having a total carbon num-ber of 4 to 8 and forming azeotropes with water and the azeo-tropic dehydration is carried out at pressures between 160 to lO 1000 ~bars.

'rhe distillation is preferably carried out at 200 tc lO00 mbars.
The following carboxylic esters are preferred.
of acetic acid: the ethyl esters to hexyl ester, of propionic acic: the methyl esters to pentyl ester, 15 of butyric acid: the methyl esters to butyl ester, of valeric acid: the methyl esters to propyl ester, of c~proic acid: the methyl ester and ethyl ester as well as pivalic methyl and ethyl ester.

This also includes all the isomeric branched-chain 20 esters.

It is also possible to use mixtures of these esters.

Since in the production of practically anhydrous organic hydrogen peroxide solutions in accordance with the present invention the water is always removed by forming azeo-25 tropes with the solvent the end point of the dehydration canbe easily determined.
~ s soon as disintegration of the condensate into water and solYent no longer occurs in the water separato~, which is connected in series to the distilling column, b-~t on]y pure 30 solvent goes oYer the dehydration is completed.
By the combination according to the present invention which comprises the use of the esters referred to heretofore 37~

which Form a ]ow-boiling azeotrope with wa-ter as solvents and the azeotropic dehydration at the pressures specified hereto-fore hydrogen peroxide is reliably prevented from going over into -the distillate. This is the great advantage over the process according to German Patent Nos. 2,038,319 and 2,038,320 which relate to a homogeneous a~ueous organic solution.
The amounts of carboxylic esters which are mixed with the aqeuous hydrogen peroxide solution are optional per se and depend on the desired content of hydrogen peroxide in the organic solution and on the safe handling of these solutions.
Since said esters boil below the boiling ~oint of hydrogen peroxide, it is also possible to further concentrate the solutions obtained after the azeotropic dehydration by distilling off the solvent. Even solutions whose water content has possibly increased due to decomposition of the hydrogen peroxide can be dehydrated as such Ol- dehydrated again and reconcentrated.
However, this kind of reconcentration by simply distilling the solvent off is not possible in the organic hydrogen peroxide solutions according to German Patent Nos~
2,038,319 and 2,~38,320 because of the boiling point of the solvent.
This concentration is carried out at pressures of 200 to 1000 mbars.
The aqueous hydroyen peroxide to be applied normally contains the usual stabilizers (see ULLMANN, Enzyklopadic der technischen Chemie, Vol. 17, fourth edition, page 70~).
However, the process according to the present invention operates without any additional entraining agent. The azeotrope 3Q obtained from water and the solvent to be used according to the present invention disintegrates without difficulties so that the solvent obtained can be immediately reused. This is ~B33~

particularly favourable when the process is carried ou-t con-tinously. Costly aftertreatment processes can thus be dis-pensed with.
This is a further advance in -the art over the pro-cesses of German Patent Nos. 2,038,319 and 2,038,320.
The process according to the present invention can be carried out in conventional distilling apparatuses such as packed tower columns and plate-type columns. Any material which is inert with respect to hydrogen peroxide, as for example, glass, enamel, aluminium, passivated refined s-teel and specific plastics, is suitable for this purpose.
The advance in the art lies in that organic solutions havirlg a water content smaller than 0.5% by weight, can be produced in a simple manner, for exarnple, without adding further material.
Furthermore, these solutions can be concentrated without loss due to decomposition while a dehydration occurs when re~{uired.
~gain substantially no losses of hydrogen peroxide are incurred in the production of these organic hydrogen peroxide solutions.
The solutions produced according to the present invention also are remarkably stable.
The process will be illustrated by way of the following Examples.
Example 1 890.0 g of acetic-n-propyl ester having a water content of 0.5~ by weight (corresponding to 4.45 g of H2O) are added to a solution of 539.8 g of H2O2 in 230.2 g of H2O (corres-ponding to a 70.1~6 by weight a~ueous H2O2 solution) and a total of 234.0 ~ of water and 431.5 g of ester are distilled off at a vacuum of 250 mbars over a glass column provided with ~ ~33~
~f~

tJlass tower packing and water separator and having a length of 80 cm.
The bottom temperature increases from an initial ~alue of 62C to 76C and the temperature at the top reaches a maximal value of 47C.
The water distilled off has an H2O2 content of 0.02% by weight. ~ hydrogen peroxide content in the distilled-off ester is not detectable.
997.5 g of a 53.95% by weight solution of H202 in acetic-n-propyl ester are obtained as residue. The residual water content is 1.65 g corresponding to 0.16% by weight.
The aqeuous condensate is rejected and the distilled-off acetic-n-propyl ester is recovered.
Exarnple 2 , _ _ At 250 mbars 124.5 g of pure acetic--n-propyl ester are distilled off from 600.0 g of a 53.9% by weight anhydrous H202 in acetic-n-propyl ester produced according to Example 1.
A solution of 323.0 g of H202 in 152 g of ester corresponding to a 68.0% by weight anhydrous solution of H202 in acetic-n-propyl ester remains in the distillation sump.
Example 2 thus shows that low-concentration organic solutions of hydrogen peroxide can be reconcentrated in a simple manner.
Example 3 1500 g of acetic isopropyl ester having a water content of 0.05% by weight (corresponding to 0.75 g of water) are added to a solution of 819.0 g of H2O2 in 351 g of water (corresponding to a 70% by weight aqeuous H202 solutlon) and a total of 351.2 g of H2O and 552.2 g of ester are distil]ed off at a vacuum of 300 to 280 mbars analogousl~ to Example 1.
The bottom temperature was between 60 and 62C and the temperature at the top reached a maximal value of 44C.

337~

The water distilled off had an H2O2 content of <0.01% by weight.
The ester distilled off contained no H2O2.
1777 g of a 46.09% by weight solution of H2O2 in acetic isopropyl ester are obtained as residue. The residual water content is 0.559 g correspondiny to 0.031% by weight.
Example 4 667.5 g of acetic ethyl ester having a water content of 0.02% by weight (corresponding 0.13 g of H2O) are added to a solution of 406.7 g of H2O2 in 172.6 g of H2O (corresponding to a 70.2% by weight aqueous H2O2 solution) and 172.0 g of H2O
are distilled off at a vacuum of 600 mbars analogously to Example 1. Duxing the azeotropic distillation another 348.0 g of acetic ethyl ester containing 0.07 g of H2O are added and the pressure is reduced to 400 mbars. At this pressure the final temperature at the bottom was 73C and the temperature at the top was 40C. A total of 558.3 g of acetic ethyl ester was distilled off.
The water distilled off had an H2O~ content of <0.01%
by weight and the ester distilled off was free from hydrogen 2D ~eroxide.
~ 64.g g of a 42.1% by weight solution of H2O2 in acetic ethyl ester are obtained as residue. The residual wa-ter content is 0.8 g corresponding to 0.83% by weight.
Example 5 _._ ___ At 400 mbars 178.0 g of pure acetic ethyl es-ter are distilled off from 550.5 g of a 42.1% by weight anhydrous solution of H2O2 in acetic ethyl ester produced according to Example 4O
231.7 g of H2O2 in 140.7 g of ester ~corresponding to 3Q ~ 62~2% by weight anhydrous solution of H2O2 in acetic ethyl ester~ remain in the distillation sump. This low-concentration hydrogen peroxide solution could also be recollcentrated in a 333~7 s 1 mpl e ~nanner.
Fxamp~e 6 879.5 g of propionic methyl ester having a water con-tent of 1.78% by weight (correspondin~ to 15.7 g of H2O) are added to a solution of 406.6 g of H2O2 in 172.6 g of H2O
(corresponding to a 70.2% by weight aqueous H2O2 solution~
and a total of 188.0 g of H2O and 361.8 y of ester are distilled off at a vacuum of 600 to 400 mbars.
The bottom temperature increases from an initial value of 56C to 73C. The azeotrope goes over at 39 to 44C. The water distilled off had an H2O2 content of <0.01% by weight.
The ester distilled off was free from hydrogen peroxide.
920.7 g of a 43.78% by weight solution of H2O2 in proplonic methyl are obtained as resiclue.
The residual water content was 0.3 g corresponding to 0.03% by weight.
~xa ple 7 1157.7 g of propionic ethyl ester having a water content of 0.085% by weight (corresponding to 0.98 g of H2O2 ) are added to a solution oE 406.5 g of H2O2 in 171.4~ by weight aqueous H2O2 solution) and a total of 172.0 g of H2O
and 70~.2 g of estex are distilled off at a pressure of 200 mbars.
The bottom temperature increases from an initial value of 56.5C to 66.5C. The water distilled off has an H2O2 content of0.01% b~ weight. No hydrogen peroxide could be detected in the ester distilled off.
850.8 g of a 47.3% by weight solution of H2O2 in propionic ethyl ester are obtained as residue. The residual water content is 0.38 g corresponding to 0.04% by weight.
E~ample 8 666.7 g of pivalic ethyl ester and 520.0 g of acetic ~33~

ethyl es-ter are added to a solution of 405.9 g of H2O2 in 174.0 c~ of H~O (correspondiny to a 70% by weight aqueous H2P2 solution). The ester mlxture has a water content of 0.05%
by weight (corresponding to 0.59 g of H2O). At a vacuum of 6ao mbars 173.5 g of H2O and 273.7 g of ester are distilled off analogously to Example 4.
The bottom temperature reaches 72C and the temper-ature at the top reaches 39C.
The water distilled off had an H2O2 content of <0.01%
lQ by weight. The ester distilled off was free from hydrogen peroxide.
1314.0 g of a 30.8% by weight solution of H2O2 in a mixture of acetic ethyl ester and pivalic ethyl ester are obtained as residue.
The residual water content is 1.1 g corresponding to 0. 08% by weight.
Example 9 440.0 g of acetic-n-butyl ester and 622.6 g of ace-tlc-n-propyl ester are added to a solution of 406.9 g of H2O2 in 172.8 g of H2O (corresponding to a 70.2% by weight aqueous H2O2 solution). The ester m:ixture has a water content of a.06% by weight (corresponding to 0.5 g of H2O).
At 250 mbars 314.1 g of ester and 172.5 g of H2O
are distilled off analogously to Example 1.
The bottom temperature reaches 78.5C and the temperature at the top 46.5~C. The H2O distilled off had an H2O content of < 0.01% by weight. The organic phase distilled off was free from hydrogen peroxide.
1155 g of a 35.12% by weight solution of H2O2 in a mixture of acetic-n-propyl ester and acetic-n-butyl ester are obtained as residue.

The residual water content is 0.8 g corresponding to 37:~

0~07% by weight.
Example 10 Stability Test in a Storage Test~
Anhydrous solutions of H2O2 in satura-ted carboxylic esters are stored for 3 and 6 months.
In each case 500 ml of a solution of H2O2 in the ester are stored in a 2-litre plastic bot-tle (polyethylene) at temperatures between 20 and 25C.
The H2O2 content is determined potentiometrically at the beginniny and at the end of the storage time.

6 Month Storage Test -Solutlons of H2O2 concen- H2O2 concen- Decrease 2 2 n tration at trati.on at the begin- the end ning ~
~ by weight) (~ by weight) _ _ _ acetic ethyl ester 25.58 25~12 0.46 ~c~tic propyl ester 28.00 27.63 0.37 ac~tic-n-butyl ester/
acetic-n-propyl ester 23.16 22.88 0.28 propionic methyl ester 31.10 30.59 0.51 propionic ethyl ester 29.59 29.11 0.46 ~;3 3~

3 Month Stoxage Tes-t Solutions of H22 concen- H22 concen- Decrease H22 in tration at tration at the begin- the end ning (% by weight) (% by weight) (% by weight) acetic ethyl ester 42.12 41.68 0.46 acetic propyl ester 53.39 5~.91 0.48 acetic-n-butyl ester/
acetic-n-propyl ester 35.12 34.71 0.41 propionic methyl ester 43.73 43.25 0.53 propionic e-thyl ester ~7.28 46 89 ~.3~

Fundamentally any aqeuous hydrogen peroxide'solution cclrl be applied in the process accordlng to the present invention. However, lt has been found that solu-tions of applixinlately 35 to 70% by weight are favourable.
In solutions of lower concentrations too much water must be distilled off and in hydrogen peroxide solutions of higher concentrations safety aspects might have to be considered.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for producing substantially anhydrous organic solutions of hydrogen peroxide from aqueous solutions of hydrogen peroxide by mixing them with carboxylic esters, the aqueous hydrogen peroxide solutions being mixed with alkyl or cycloalkyl esters of saturated aliphatic carboxylic acids which have a total carbon number of 4 to 8 and form azeotropes with water and the azeotropic, dehydration being carried out at pressures between 160 and 1000 mbars.

2. A process according to claim 1, in which the azeotropic dehydration is carried out at 200 to 1000 mbars.

3. A process according to claim 1, in which the organic solutions of hydrogen peroxide obtained after the azeotropic distillation are reconcentrated by distilling the solvent off at 200 to 1000 mbars.

4. Organic hydrogen peroxide solutions in alkyl or cycloalkyl esters of saturated aliphatic carboxylic esters having a total carbon number of 4 to 8 and a water content of less than 0.5% by weight.

5. A process according to claim 1, 2 or 3, in which the carboxylic esters are selected from the ethyl to hexyl esters of acetic acid, the methyl to pentyl esters of prop onic acid, the methyl to butyl esters of butyric acid, the methyl to propyl esters of valeric acid, the methyl to ethyl esters of eaproic acid and the methyl to ethyl esters of peralic acid.