DE1935297A1 - Diaroyl and diacylperoxide preparation - Google Patents

Abstract

Aliphatic or aromatic acid chlorides are reacted with aq. solns. of H2O2 or alkali metal peroxides in alkaline medium. Before the reacting begins, anhydrous non-ionising halogen cpds. of Gp 3 to 6 elements are added to the acid chlorides. Preferably, 0.1 to 10 wt.% (relative to acid chloride) halogen cpd. is added. Preferably 0.5-4 wt.%. Advantages lie in the increased speed and safety of the process, in the high yields and purity of the prod.

Description

Process for the preparation of diaroyl and diacyl peroxides The invention relates to the reduction of the required reaction times in the production of Diaroyl or diacyl peroxides from acid chlorides, alkali and hydrogen peroxide through the use of catalysts.

In the production of diaroyl and diacyl peroxides by the method von Schotten / Baumann from the relevant acid chlorides and alkaline hydrogen peroxide solution respectively.

aqueous solutions of alkali salts of hydrogen peroxide occur often significant reaction inhibitions. Because of the strong exotherm of such Reactions on the one hand (e.g.

the enthalpy of formation of the dibenzoyl peroxide is approx.

240 kcal / kg and that of dilauroyl peroxide approx. 230 kcal / kg) and because of the well-known great sensitivity of organic peroxides to thermal On the other hand, such a reaction inhibition can pose a considerable safety risk represent.

To distribute the amount of heat released over a longer period of time and to be able to dissipate more easily in this way, one proceeds in practice usually in such a way that the acid chloride in question is gradually poured into the running in alkaline hydrogen peroxide solution.

In this way of working, it can often be observed that the acid chloride not reacting at first, even with intensive mixing, but rather in larger ones Amount as a lighter upper phase accumulates floating on the aqueous solution, until at some point the reaction suddenly occurred starts. In the process, the entire, until then, settles in the reaction vessel within a very short time existing acid chloride around what such a strong heating of the reaction mixture can cause dangerous uncontrollable decomposition to occur. It is difficult to predict whether and to what extent such a reaction inhibition will occur and probably depends, among other things. on the purity of the substances used.

There is one way to reduce the security risk described in that the acid chloride is allowed to drip in very slowly and in this way the proportion present in each case in the reaction mixture also in the case of the inhibition of the reaction leaves enough time to react. For example, in publications and patents dealing with the manufacture of dibenzoyl peroxide, sometimes called extremely long response times.

According to GDR patent specification No. 32 853, the appropriate reaction time is at 200 ° C. for 6 hours; in Polish patent specification No. 53,450 are at temperatures reaction times of more than 2 hours given below 150 C; J. D'Ans, J. Mattner and W. Busse recommend in the Z.f. Angew. Chem.

65 (1953) p. 59, also dropping times at temperatures around Oo C. of 2 hours, and B. Raskai et. al. let react at 200 C for 3 - 4 hours (cited after C.A. 54, 7635).

These long response times are not just from an economic standpoint made unsustainable, but they also affect the yields because of the increased Occurrence of secondary reactions in a negative way. The relatively high alkali content, which is necessary for the reaction to proceed, namely simultaneously causes a gradual saponification of the peroxides formed, if this lasts for a long time in the reaction solution is left. For example, after 15 minutes of stirring a suspension of dibenzoyl peroxide in 1% sodium hydroxide solution at 50 ° C. is a loss found by 11%; analogous observations can be found in the German explanatory document No. 1 192 181, column 4, for dilauroyl peroxide.

In order to shorten the response time, z. T. suggested to work at elevated temperature. In the already quoted DAS No. 1 192 181 is made using a benzoyl chloride with hydrogen peroxide and caustic soda organic solvent reacted at temperatures of 55 - 60 ° C within 15 min. However, this reaction time is still relatively long in view of the high temperature fear that a significant amount of thermal cleavage of the peroxide he follows; in addition, the side reaction occurring in this procedure endothermic saponification of the acid chloride to the carboxylic acid more favored than with low temperatures, which in turn affects the yield and purity of the product.

It has now been found that the reaction times during production of diaryl and diacyl peroxides from aromatic and aliphatic acid chlorides with any number of 'carbon atoms and aqueous solutions of hydrogen peroxide or alkali metal peroxides in an alkaline medium, if the acid chlorides before the start of the reaction, anhydrous, non-halogenated halogen compounds of elements of groups 3 - 6 of the periodic table are added, whereupon the implementation is carried out in a manner known per se.

These halogen compounds include BCl3, BBr3, 3 4, , SnC1 ,, P0l3 POC13, P3r3, SOCl2, SO? SO2 C12 They can be used individually or as a mixture are used together.

While all possible boron, sulfur and phosphorus compounds were very suitable for the production of diaroyl peroxides, turned out to be for the production of diacyl peroxides as particularly favorable: Bs13, S02C12, SOC12, PC15 and POOl3.

The technical progress of the measure according to the invention lies in that the reaction is accelerated considerably.

This acceleration takes place neither at the expense of security, nor the yield and purity of the product.

The reaction is carried out at temperatures such that neither a strong thermal cleavage of the per compound, another significant one Saponification of the acid chloride occurs.

Since the substances to be added according to the invention are highly sensitive to hydrolysis and lose their catalytic effect in aqueous solutions, they must dem Acid chloride can be added, in which they are due to their non-ionic nature generally solve well. Their presence causes even in relatively low concentrations, that when mixing the acid chloride with the alkaline hydrogen peroxide solution the reaction gets under way immediately.

Catalyst concentrations in the acid chloride proved to be effective from 0.1% by weight upwards. In principle, there is no upper limit concentration, but the amount added is not too large for economic reasons, d. H. do not choose greater than 10% by weight, otherwise not only the costs for the catalyst, but also the increased alkali consumption due to its hydrolysis would fall. The acid chloride is preferably used 0.5 to 4 total% of such a catalytically active substance, its hydrolysis products are water-soluble and therefore do not affect the purity of the resulting peroxide.

The peroxo component is preferably H202 and the basic component an alkali hydroxide or carbonate is used. However, alkali metal peroxides are also suitable, and that alone or in admixture with an alkali hydroxide or carbonate. As cheap molar ratios of acid chloride to H2 ° 2 to alkali of 1: 0.5: 1 have been found 1: 1.5: 1.5.

The reaction temperature should then be more favored because of the Side reactions do not exceed 40OC during the reaction time Peroxide and the chosen reaction temperature is to be adjusted; Times of more than However, 40 minutes is never required.

Concentrations of the alkaline hydrogen peroxide solution have proven to be advantageous 2 - 10% of H202 (or alkali peroxide) and 5 - 15% of alkali.

The invention is illustrated by the following examples: Example 1 In the course of a series of tests, 840 ml an aqueous solution that contains 0.6 moles of hydrogen peroxide and 0.8 moles of soda as well - small amounts of sodium pyrophosphate (to stabilize the H202) and a commercially available one Wetting agent contained as an emulsifier, 0.6 moles of benzoyl chloride within 20 minutes added dropwise, the temperature in the reaction mixture by a thermostat '300C was held. In a comparative experiment, distilled benzoyl chloride was used used without addition, while in the other experiments each 1 g of different Halides of elements of groups 3 - 6 of the periodic table were added. When the feed had ended, the precipitate was filtered off with suction on the suction filter, with a lot washed with distilled water and dried at 250C. The one in the individual attempts he targeted yields, based on the benzoyl chloride used, and the dibenzoyl peroxide content of the product is shown in the following table: Art of the additive purity yield in%, based on (1 g in% by weight based on bensoyl chloride - 96.5 53.0 A1C1 88.0 68.5 SnC14 97.9 87.4 PCl3 98.3 91.1, PC15 98.4 91.2 POC13 98.0 91.8 PBr3 98.7 86.1 SOCl2 980 89.3 S02Cl2 98.2- 90.6 While thus under the described Conditions the reaction time of 20 minutes without the use of an additive sufficient to convert a little more than half of the benzoyl chloride used to the peroxide implement, show the significantly higher yields in the experiments with Katalyeatorzusätze, that in this way a substantial shortening of the reaction times is achieved.

Example 2: In 420 ml of an aqueous solution containing 0.3 moles of hydrogen peroxide, 0.38 moles of soda, containing a few drops of emulsifier, and 0.5 g of Na4P207 were taken under Stir within 5 minutes a mixture of 0.3 mol of benzoyl chloride and 0.004 mol Phosphorus chloride was added dropwise, the temperature of the reaction mixture increasing to 40.degree was held. After the addition had ended, the mixture was stirred for a further 3 min, filtered off with suction and Worked up as described in Example 1. There were 31.5 g of 98.7% strength dibenzoyl peroxide obtained, corresponding to a yield of 85.5%.

Example 3 400 ml of an aqueous solution containing 0.32 moles of hydrogen peroxide, Containing 0.52 moles of sodium hydroxide and 0.5 g of 1a4P207 were brought to -5 ° C. in the cooling bath brought. las tUhlbad was removed and taken within 15-min Stir a mixture of 0.4 moles of distilled lauroyl chloride and 0.01 moles of thionyl chloride added dropwise, the reaction mixture heated to 330C. After that the encore Was finished, it was suction filtered with 1% sodium hydroxide solution and a lot of distilled water washed. After drying at 4500, 75.5 g of 98.4% strength dilauroyl peroxide were obtained, corresponding to a yield of 93.5%.

Example 4: In a corresponding experiment without thionyl chloride, it increased the temperature in the course of the dropping, which lasted 15 minutes, only increased to + 6 ° C. One reaction had apparently not happened: the lauroyl chloride floated as slightly cloudy Upper phase on the aqueous solution without the formation of a precipitate was. The experiment was then repeated at an initial temperature of 10 ° C.

The relatively small increase in temperature to 21011 already showed that here, too, the reaction was not complete. The precipitate had a greasy consistency and was very difficult to filter. After washing and drying, 68 g of a substance consisting of hard lumps were obtained, their peroxide content was 49.5 "; Yield 42.3%.

Claims (3)

Paten t a n 8 p r ü c h e 1) Process for the preparation of diaroyl and diacyl peroxides by Reaction of aliphatic or aromatic acid chlorides with aqueous solutions of hydrogen peroxide or alkali metal peroxides in an alkaline medium, thereby characterized in that the acid chlorides anhydrous, non-ionic before the start of the reaction Halogen compounds of groups 3 to 6 of the Periodic Table are added, after which the reaction is carried out in a manner known per se. 2) Method according to claim 1, characterized in that the anhydrous nonionic halogen compounds in amounts of 0.1 to 10 percent by weight, based on the acid chloride. 3) Method according to claim 1 and 2, characterized in that the anhydrous non-ionic halogen compounds in amounts of 0.5 - 4 percent by weight, based on the acid chloride, are used.