DE1101420B - Process for the production of catalytically active, anhydrous aluminum chloride suspensions for organic-chemical reactions - Google Patents

Description

GERMAN

It is known to use aluminum chloride as a catalyst to carry out known organic chemical reactions, such as. B. the Friedel-Craft synthesis or to use the Gattermann - Koch reaction, for the success of the reactions mentioned the perfect condition of the catalytic converter is of crucial importance. Usually the technically pure, anhydrous aluminum chloride is used, which is pulverized before use must be in order to have as fine a distribution as possible in the reaction solution, and thus a favorable one to achieve a catalytic effect. The production of such suspensions, however, encounters many things Difficulties caused mainly by the known properties of anhydrous aluminum chloride are conditional. For example, the anhydrous aluminum chloride is highly hygroscopic and decomposed rapidly in the normally humid air atmosphere with elimination of hydrogen chloride. This makes its handling very difficult and its catalytic activity uncontrollable Dimensions reduced. The reactions carried out with the partially decomposed aluminum chloride proceed imperfect and provide non-reproducible yields of reaction products. For partial To avoid the difficulties mentioned, solutions are occasionally used instead of suspensions Aluminum chloride used in nitrobenzene. This method is also unsatisfactory, especially with their execution on an industrial scale, since the separation and recovery of the nitrobenzene is tedious and cumbersome.

It has now been found that catalytically active, anhydrous aluminum chloride suspensions are obtained, if you replace the previously used technically pure, anhydrous and mechanically crushed Aluminum chloride uses such an aluminum chloride that is produced by reacting metallic Aluminum with dry hydrogen chloride in a solvent inert for the reaction, if appropriate is also obtained in a liquid reactant involved in the reaction, and the formed Aluminum chloride particles by suitable means, e.g. B. with the help of a stirrer, im Solvent suspended.

The catalytically highly active aluminum chloride suspensions obtained in this way do not have the aforementioned disadvantageous properties of technical aluminum chloride and unfold in their application, e.g. in the synthesis according to Gattermann - K och. their full effectiveness.

Any form of aluminum metal, e.g. B. foils, turnings, powder and semolina can be used. It's advantageous method of manufacture
of catalytically active, anhydrous

Aluminum chloride suspensions
for organic chemical reactions

Applicant:

Farbwerke Hoechst Aktiengesellschaft

formerly Master Lucius & Brüning,

Frankfurt / M., Brüningstr. 45

Dr. Hans Fernholz, Bad Soden (Taunus),

and Dr. Eberhard Mundlos, Frankfurt / M.-Höchst,

have been named as inventors

stick, the aluminum by adding a little bromine, iodine or especially by adding about 0.1 to activate up to about 20%, preferably about 1 to about 10% of its weight of mercury (II) chloride. In this way, the aluminum reacts smoothly with hydrogen chloride to form aluminum chloride achieved, operating at a temperature which is expediently between about 10 and about 50 ° C. As inert solvents or diluents are saturated paraffin hydrocarbons, such as z. B. cyclopentane, cyclohexane or gasoline mixtures with a boiling point of about 100 ° C suitable can be easily removed from the reaction mixture by distillation. They are particularly advantageous z. B. for the execution of the Gattermann-Koch aldehyde synthesis common solvents such as benzene and tetrachloroethane. Optionally, the reaction of the aluminum with hydrogen chloride, as already mentioned, also take place in a liquid reactant involved in the reaction.

The aluminum chloride suspensions produced by the process according to the invention have opposite the known suspension of commercially available, mechanically comminuted aluminum chloride in many advantages to an indifferent solvent. For example, the manufacture prepares and Handling of such suspensions no difficulties, and external influences such as moisture, which have a detrimental effect on the stability of the aluminum chloride are eliminated. The increased catalytic activity of the aluminum produced by the process according to the invention

109 529/731

nium chloride suspensions caused in reactions catalyzed by aluminum chloride, as from the following Examples in the case of a Gattermann-Kochschen synthesis, an increase in the yields can be seen End products. Since in the representation of aromatic aldehydes according to Gattermann - Koch the individual Reactants are involved in the reaction in molar amounts, the percentage was determined Yields in the examples described are based in each case on the reaction component present in the smallest amount based.

example 1

In a stirred mixture of 750 ecm of benzene, 50 g of crushed aluminum foil and 5 g of mercury (II) chloride are within 15 minutes 60 1 of hydrogen chloride and then at 25 to 30 ° C 90 1 each Introduced hour hydrogen chloride. After 3 hours, 10 g of p-toluene aldehyde and 36 g of copper (I) chloride are added added and with continued stirring with the simultaneous dropwise addition of 184 g of toluene 60 1 of hydrogen chloride and 1201 carbon monoxide within

Initiated 3 hours. The reaction product is poured onto ice and worked up in a known manner.

Yield: 168 g of p-toluene aldehyde or 75% of theory, based on Al Cl ₃ .

Example 2

In a stirred autoclave in a from 5 kg of tetrachloroethane, 1 kg of aluminum powder and 10 g Mercury (II) chloride existing mixture at 20 to 30 ° C 29001 hydrogen chloride within

4 hours initiated. After adding 5 kg of toluene and closing the autoclave, the mixture is flushed through with carbon oxide and stirring is continued under a carbon oxide pressure of 70 atmospheres at room temperature. During the reaction time of 2 hours, the temperature rises to 35 ° C. The reaction product is poured onto ice and separated in a manner known per se. Yield: 3.9 kg of p-toluene aldehyde or 87.9% of theory, based on Al Cl ₃ .

Example 3

5 kg of benzene, 450 g of crushed aluminum foil and 20 g of mercury are placed in a stirred autoclave (II) chloride and passes in 2400 liters of hydrogen chloride within 3 hours at 25 to 35 ° C. Of the The autoclave is then closed, flushed with carbon oxide, heated to 40 to 50 ° C and the contents stirred under a carbon dioxide pressure of 80 atmospheres. After 8 hours the reaction product becomes poured onto ice and worked up in a known manner.

Yield: 1.57 kg of benzaldehyde or 89.2% of theory, based on AlCl ₃ .

Example 4

In one consisting of 400 g of tetrachloroethane, 55 g of aluminum powder and 3 g of mercury (II) chloride Mixture are passed in 350 l of hydrogen chloride at room temperature over the course of 3 hours with stirring. After adding 55 g of hydrocyanic acid dissolved in 100 g of tetrachloroethane and 140 g of diphenyl at 0 ° C the mixture is heated to 75 ° C. over the course of one hour and hydrogen chloride for 4 hours at this temperature initiated. Working up is carried out in a manner known per se.

Yield: 142 g of diphenyl-4-aldehyde or 86% of the Theory based on diphenyl.

For comparison, those in Examples 1 to 4 according to known A ^ are experienced using the hitherto conventional catalyst suspensions obtained compounds prepared in the following yields:

yield
in weight
percent Reference p-ToluylaJdehvd 40 to 51 Organic Synthesis, Collective Volume II, 1950, p. 583 Benzaldehyde to 85 Methods of organic chemistry (Houben-Weyl),
4th edition, 1954, Vol. VII, Part 1, oxygen connection
gen II, p. 18, third paragraph from the bottom Diphenyl-4-aldehyde 75 Methods of organic chemistry (Houben-Weyl),
4th edition, 1954, Vol. VII, Part 1, oxygen connection
gen II, p. 24, table 2

Claims (3)

PATENT CLAIM: 1. Process for the production of catalytically active, anhydrous aluminum chloride suspensions for organic-chemical reactions, characterized in that aluminum metal, which has as large a surface as possible, with dry hydrogen chloride in one for the reaction inert liquid preferably at a temperature of about 10 to about 50 ° C in aluminum chloride transferred and the aluminum chloride particles formed suspended by suitable, known measures in the solvent. 2. The method according to claim 1, characterized in that the aluminum metal with about 0.1 to 20% of its weight activated mercury (H) chloride. 3. The method according to claim 1, characterized in that there is a liquid as the inert liquid organic compound is used, which is later used in the presence of the aluminum chloride formed is implemented. Considered publications:
German patent specifications No. 907 168, 914 129. © 109 52Ϊ / 731 2.61