DE1290142B - Process for the preparation of a mixture of ª ‡, ª ‡ '-Bis- (di-tert.-butylperoxy) -1, 3-diisopropylbenzene and ª ‡, ª ‡' -Bis- (di-tert.-butylperoxy) -1, 4-diisopropylbenzene - Google Patents

Description

one for the preparation of diperoxides of the general formula

R ₁ -COOCACOOCR ₁

• ι ι ■ ι ι

3 ** 5

R ₇

R ₃ (I)

in which the groups R> to R7 are lower alkyl radicals are, the hydrogen atoms of which can be partially substituted by halogen atoms, the group Ri one Represents an alkyl radical with 1 to 6 carbon atoms,

German Patent 1,228,259 suggests that the valuable and relatively expensive processes for the production of organic diper substances glacial acetic acid and perchloric acid are lost, oxides by converting an organic hydro- because their recovery is uneconomical, peroxides with a tertiary alcohol in the presence In addition, the diperoxide crystals are mixed with an acidic condensation agent in water, in which ₅ insoluble di-tertiary butyl peroxide remain mixed, a further operation is necessary in order to remove the latter and to purify the diperoxide. Normally, for this purpose, the solid residue is dissolved in methanol, from which the pure diperoxide crystals separate out on cooling. But this way of working is quite cumbersome.

The invention relates to a simple and effective process for the preparation of a mixture of a, a'-bis- (di-tert-butylperoxy) -l, 3-diisopropylbenzene and a, a -bis- (di-tert-butylperoxy) -1,4-diisopropylbenzene. The production of just such a mixture that, for example, 60 to 70%, preferably 65%, of the m-isomer and 40 to 30%,

whose hydrogen atoms partially by halogen ₂ o preferably 35%, contains of the p-isomer, represents an atom can be substituted, or an aromatic technical and economic "matic radical means 6 to 20 carbon atoms advantage compared to the previous operation and the hydrogen atoms thereof, which precedes the actual condensation between the hydroperoxide and the tertiary alcohol or halogen atoms, likewise substituted by alkyl, aryl, cycloalkyl groups, and precedes.

A a phenylene, diphenylene, naphthylene, an These precursors consist of the alkylation

thracenylene-, diphenylenbenzene- or tetrahydro- of benzene with propylene (which is known to be a naphthylene radical, which can be substituted by two alkyl groups sub- - a mixture of m- and p-diisopropylbenzenes in the, is formed at a temperature ratio of about 65:35 is), between 0 and 120 ⁰ C, expediently with stirring, 30 oxidation of this product to the corresponding a hydroperoxide of the formula hydroperoxides and the final reduction

to the respective dialcohols. By using

R _{2 of} the mixture of the two m- and p-isomers as

The rectification of the isomers is superfluous as the starting material in the process according to the invention. According to the invention, these disadvantages become apparent in the preparation of a, a'-bis (di-tert-butylperoxy) -l, 3-diisopropylbenzene and «, a'-bis (di-tert-butylperoxy) -1,4-diisopropylbenzene by reacting tertiary butyl hydroperoxide with the α, α'-dioxydiisopropylbenzenes avoided by a process which is characterized in that the condensation in Presence of di-tertiary butyl peroxide as solvent and sulfuric acid as catalyst carries out, the solvent is then continuously removed in countercurrent with steam.

OOH

(Π)

in which R ₁ , R ₂ and R _{3 have} the aforementioned meaning and a carbinol of the general formula

OH-C-A-C-OH

(III)

R ₇

grazes and the pure mixture of the m- and p-isomers of the diperoxide by crystallization or a other processing method wins.

The di-tertiary butyl peroxide is available in commercial tertiary butyl hydroperoxide in quantities of about 25% and can be used as a solvent with good success. You can in the pure state or as a component of the commercial

in which R4 to R7 and A have the aforementioned meaning, dissolves in a strong organic acid or suspended and an acidic condensing agent added to the solution or suspension, with at least 2 moles of hydroperoxide (II) per mole of carbinol (III) must be present.

For example, the condensation reaction

between tertiary butyl hydroperoxide and α, α'-di- 55 conventional tertiary butyl hydroperoxide. oxy-1,4-diisopropylbenzene with formation of α, α'-bis- The diperoxide formed is in di-tertiary butyl-

(Di-tert-butylperoxy) -l, 4-diisopropylbenzene dissolved in ice peroxide, which helps it against degradation vinegar and in the presence of perchloric acid than to protect by acid. The mixture is with Catalyst carried out. Part of the diluted in this water, whereby two layers are formed The diperoxide formed in this way precipitates and will be in 60: the upper layer, which the diperoxide in separated crystalline form. A part, however, remains dissolved and contains di-tertiary butyl peroxide

lower aqueous layer, which contains H2SO4, while the excess hydroperoxide is divided between the two phases. The lower layer is removed, while the upper organic layer through a column filled with Raschig rings in countercurrent to water vapor of 100 "C trickles, whereby the steam the di-tertiary butyl peroxide with-

as a result of the action of di-tertiary butyl peroxide, which is always usually in amounts of around 25% in the commercially available tertiary butyl hydroperoxide is present in solution.

If you want to facilitate the separation of the diperoxide, you have to filter the mixture dilute with water. In diluted maternal

which is then recycled without any purification. The diperoxide is obtained in pure form.
This new method has the following advantages:

a) Use of di-tertiary butyl peroxide instead of glacial acetic acid. In contrast to the as Acetic acid used as a solvent, di-tertiary butyl peroxide can easily be recovered and recirculate it as a solvent to the condensation stage.

b) The possibility of continuous separation and purification of the diperoxide.

c) The possibility of purifying the isomer mixture from m- and p-a, a'-bis- (di-tert-butylperoxide) -diisopropylbenzene without product loss, with the original percentage remaining unchanged. (In this context note that the m-isomer is much more soluble in methanol than the p-isomer. Purification in methanol would therefore not only be unsatisfactory Yields of m-isomers lead, but also the 65:35 ratio of the two isomers Change shapes in favor of the p-isomer.)

d) The greater simplicity and economy in the conduct of the reaction, in which a stage less is required for cleaning the diperoxide, since the diperoxide is immediate from the solution in di-tertiary butyl peroxide by the action of the countercurrent Water vapor is separated.

e) The use of the cheaper sulfuric acid instead of perchloric acid as a catalyst.

In the method according to the invention is further the contact time of a, a'-bis (di-tert-butylperoxy) -diisopropylbenzols and di-tertiary Butylperoxyds with the water vapor (100 ⁰ C) for the continuously performed step of the solvent removal on a Shortened minimum. This avoids harmful heating of large quantities of products which, although they have a relatively high stability, are of a peroxidic nature and can therefore decompose violently.

The process is expediently carried out as follows: 456 g of a 62.5% H ₂ SO ₄ and 256 g of di-tertiary butyl peroxide from ongoing operations are placed in a 2-1 flask which is equipped with a high-speed propeller stirrer, an immersion thermometer, a hydraulic shut-off valve, a non-immersing gas inlet pipe and a socket for the introduction of the reactants and is immersed in a brine (-8 to -12 ° C.) serving as a cooling bath. The temperature of the mixture is adjusted to 0 ⁰ C, whereupon 123 g of 75% tertiary butyl hydroperoxide and 101 g, a'-Dioxydiisopropylbenzol be added to a. The mixture is stirred for about 1 hour at a temperature of 0 to 3 ° C. under an inert CCV atmosphere. Rapid introduction of 400 g of water at from 85 to 90 ^° C. results in immediate separation into two phases, namely a lower aqueous and an upper organic layer. The lower layer is discarded. The upper layer is washed, neutralized with NaOH and washed again. After this treatment, the organic solution weighs 422 g. It consists of a 35% solution of a, a- bis- (di-tert-butylperoxy) -1,3-1,4-diisopropylbenzene in di-tertiary butyl peroxide. This solution is placed on top of a glass column (height about 90 cm, diameter 2.8 cm) which is filled with Raschig rings and provided with an outer jacket in which water vapor at 100 ° C. circulates. From below, water vapor at 100 ^° C. is introduced into the column in such an amount that the volume ratio of distilled steam to the organic solution introduced is 1: 1. Under these conditions, the distillation with steam in countercurrent is ended after one hour and 8 minutes.

Di-tertiary butyl peroxide is obtained from the distillate, while a mixture of condensed water and α, α'-bis- (di-tert-butylperoxy) -1,3-1,4-diisopropylbenzene collects at the foot of the column. The mixture, which is ^{heated to 55 °} C. until it melts completely, is carefully separated, 153 g of a mixture of α, α'-bis- (di-tert-butylperoxy) -1,3-diisopropylbenzene and a, a '-Bis- (di-tert-butylperoxy) -1, 4-diisopropylbenzene (H ₂ O content about 4.25%) and 154.5 g of aqueous layer, which is to be discarded, are obtained.

Claims (1)

Claim: Process for the preparation of a mixture of a, a -bis- (di-tert-butylperoxy) -1,3-diisopropylbenzene and a, a'-bis- (di-tert-butylperoxy) -l, 4-diisopropylbenzene Reaction of tertiary butyl hydroperoxide with the a, a '; dioxydiisopropylbenzenes, characterized in that the condensation is carried out in the presence of di-tertiary butyl peroxide as the solvent and sulfuric acid as the catalyst, the solvent is then continuously stripped off in countercurrent with steam and the pure mixture of the m- and p-isomers of diperoxide obtained by crystallization or another work-up method.