DD285092A5 - METHOD FOR INCREASING THE SELECTIVITY OF FRIEDEL-CRAFTS ALKYLATION OF FLAVORS WITH 1,2-DIHALOGENALCANES - Google Patents

Abstract

The invention relates to a process for increasing the selectivity of the FRIEDEL-CRAFTS alkylation of aromatics with 1,2-dihaloalkanes in the liquid phase by adding mixed aluminum chloride / stannous chloride catalysts in a molar ratio of AlCl3 to SnCl4 of 0.25: 1 to * a molar ratio * of 5: 1 to 10: 1 and a molar ratio * of 0.05: 1 to * The yields of 1,2-diarylalkanes can be increased to 65 to 90% (based on the halogenated hydrocarbon) . {diarylalkane be; Friedel-Crafts reaction; 1,2-dihaloalkane; 1,2-dichloroethane; 1,2-dichloropropane; Selectivity; Fluessigphasenreaktion; Aluminum chloride-tin chloride composite catalyst; benzene; toluene}

Description

embodiments Example, 1 (comparative example)

In a 2-liter four-necked flask with dropping funnel, KPG stirrer, cooler with drying tube and thermometer 15mol benzene and 0.2 mol AICI _{3 are} submitted. About 5 ml of 1,2-dichloropropane are added with stirring and warmed up until the reaction starts. The heat source is removed and at temperatures of 15 to 25 ⁰ C, the 1,2-dichloropropane (2 mol) slowly added dropwise. After completion of the dropwise addition is still stirred at room temperature until no more hydrogen chloride escapes. The reaction mixture is added to ice-water, washed with water, aqueous sodium bicarbonate solution and again with water and dried over magnesium sulfate. After distilling off the benzene, the reaction mixture has the following composition:

1,2-dichloropropane 0.002 kg / kg toluene 0.004 kg / kg Ethyl benzene track xylene track n-propylbenzene 0.08 kg / kg i-Propylbenzene (Cumen) 0.06 kg / kg 1,2-Dipheny! Propane 0.41 kg / kg 1,1-diphenyl 0.04 kg / kg 2,2-diphenyl track higher alkylated compounds 0.40 kg / kg

Example 2

In a test apparatus as in Example 1 15mol benzene, 0.2 mol of tin (IV) chloride and 0.1 mol of aluminum chloride are presented. About 5 ml of 1,2-dichloropropane are added and the mixture is warmed gently until the reaction starts. After a test procedure analogous to Example 1, the reaction mixture has the following composition (kg / kg):

1,2-dichloropropene 0 1,2-dichloropropane 0 toluene 0 ethylbenzene traces xylene 0 n-propylbenzene 0.01 i-propylbenzene traces 1,2-Dipheny! Propane 0.70 1,1-diphenyl 0.09 2,2-diphenylpropene 0 higher alkylated compounds 0.20

Table 1 contains the results of further mixing ratios. Table 1

Mixture Aromat: CKW

temperature

catalyst Yield

1,2-Diphenylalkanin%

1,2-dichloroalkane 2: 1 20 0.1 mol AICI ₃ mol SnCl ₄ 25 1,2-dichloropropane 5: 1 20 0.1 mol AICI ₃ mol AICI ₃ / 34 7.5: 1 20 0.1 mol AICI ₃ mol SnCl ₄ 41 10: 1 20 0.1 mol AICI ₃ mol SnCl ₄ 40 15: 1 20 0.1 mol AICI ₃ mol AICI ₃ 40 20: 1 20 0.1 mol AICI ₃ mol AICI ₃ / 38 7.5: 1 0 0.1 mol AICI ₃ mol SnCl ₄ 37 7.5: 1 30 0.1 mol AICI ₃ 41 7.5: 1 50 0.1 mol AICI ₃ 36 7.5: 1 20 0.2 mol AICI ₃ / 0.1 mol SnCl ₄ 48 7.5: 1 20 0.1 mol AICI ₃ / 0.1 mol SnCl ₄ 54 7.5: 1 20 0.05 mol AICI ₃ / 0.1 mol SnCl ₄ 70 7.5: 1 20 0.025 mol AICI ₃ / 0.1 76 7.5: 1 20 0.01 0.1 0 7.5: 1 20 0.1 0 1,2-dichloroethane 7.5: 1 20 0.1 49 7.5: 1 20 0.1 0.1 74

Claims (1)

Process for increasing the selectivity of FRIEDEL-CRAFTS alkylation of aromatics, especially benzene or toluene, with 1,2-dihaloalkanes, in particular 1,2-dichloroethane or 1,2-dichloropropane, in the liquid phase with the catalyst system AICI ₃ ZSnCU im Temperature range 0 to 5O ⁰ C and with a molar excess of the aromatic in relation to the 1,2-dihaloalkane, characterized in that a molar ratio AICI ₃ to SnCU of 0.25: 1 to 0.5: 1 at a concentration of the mixed catalyst is adjusted in the reaction mixture based on 1,2-dihaloalkane of 0.05 to 0.2 mol / mol. Field of application of the invention The invention relates to increasing the selectivity of the FRIEDEL-CRAFTS reaction of dihaloalkanes and aromatics. Diarylalkanes are very interesting intermediate and end products in technical organic chemistry. You can u. a. be used as a solvent and heat exchangers on a large scale. By sulfonation, nitration, halogenation, oxidation and hydrogenation of the diarylalkanes polyfunctional synthesis units are obtained. Characteristic of the known state of the art In 1877, the possibility was first described of obtaining alkylaromatics by reacting alkyl halides with aromatics in the presence of catalytic amounts of aluminum chloride. It is known that FRIEDEL-CRAFTS reactions proceed only with very low selectivity because of rearrangements, transalkylations, polyalkylations and dealkylations. For this reason, a variety of catalysts has already been tested. Boron trifluoride-carboxylic acid complexes (US Pat. No. 4,158,677), graphite / aluminum chloride / antimony chloride catalysts (US Pat. No. 4,111,023), phosphorus (V) fluoride / hydrogen fluoride (US Pat. No. 4,083,885), titanium (IV) fluoride can also be used instead of the aluminum chloride. Ether complexes (US Pat. No. 4,061,689, antimony (V) chloride (US Pat. No. 3,977,714), iron (III) chloride (US Pat. No. 3,759,040), iron (III) bromide (US Pat. No. 3657370), aluminum chloride / zinc chloride complex (US Pat. No. 3,655,797 ), Titanium (IV) chloride (US Pat. No. 3,641,778), zinc chloride / mercury (II) chloride (US Pat. No. 3,637,883), BismuKVD fluoride (US Pat. No. 3,154,223), aluminum fluoride (US Pat. No. 3,456,034), BismuM.sub.4 fluoride / alkylaluminum dichloride (US Pat. US Pat. No. 3,466,343), aluminum chloride / titanium chloride (US Pat. No. 3,370,101), molybdenum (V) chloride (US Pat. No. 3,131,822), aluminosilicates (DE-PS 1,133,706), aluminum organyls (DE-OS 1,443,543) and carbonyls or salts of the elements the 6th, 7th and 8th subgroup are used. German Pat. No. 699,607 uses aluminum chloride / antimony chloride / aluminum chloride / tin dichloride complexes for the alkylation of benzene with monohaloalkanes. By the addition of antimony (V) - or tin (IV) chloride, a better distribution of the catalyst should be achieved. Dihaloalkanes, especially 1,2-dichloroalkanes can only in the presence of the most effective catalysts, eg. For example, aluminum chloride (Ransley, J. Org. Chem. 31/1966 / 11,3595) or aluminum organyls (Alberola, Fernandez, A. Quim., 67/1971 / 6,643-650) can be reacted with aromatics. The selectivity of these reactions is correspondingly low, the Aunbouten of 1,2-diarylalkane are about 40% (DD-PS 107432). Object of the invention The aim of the invention is to modify the synthesis of diarylalkanes based on a FRIEDEL-CRAFTS reaction, that the forced addition of by-products can be reduced and the work-up of the reaction products can be simplified. Explanation of the essence of the invention The invention is based on the object, the selectivity of the FRIEDEL-CRAFTS alkylation of aromatics, in particular Berlin or Toluen with acyclic 1,2-dihaloalkanes, in particular 1,2-dichloroethane or 1,2-dichloropropane in the liquid phase riiii »the catalyst system AICI _3rd / SnCl ₄ in the temperature range 0 to 50 ° C with a molar excess of the aromatic in the ratio ζιτϊ: 1,2-Dihalogenalkan to increase so that yields based on dihaloalkane of more than 65% can be achieved. According to the invention the object is achieved in that in the reaction of the 1,2-dihalogenated acyclic hydrocarbon with the aromatic, a molar aluminum chloride-tin (IV) chloride ratio of 0.25 to 1 to 0.5 to 1 at a concentration of the mixed catalyst relative to Dichloroalkane is adjusted from 0.05 to 0.2 mol / mol in the reaction mixture. The excess of aromatics is 5: 1 to 10: 1 relative to dihalo-decane. Thereafter, it is worked up by known methods. Surprisingly, it has been found that in this way 65 to 80% of 1,2-diarylalkane (based on 1,2-dihaloalkane) can be isolated and the amount of by-products, in particular of the higher alkylated compounds, is greatly reduced. In particular, it was not to be expected that mixed catalysts with a predominant proportion of tin (IV) chloride would produce this advantageous effect, since tin (IV) chloride alone shows no catalytic effect in the context considered.