DE10247497B4 - Process for the continuous production of acyclic C4 to C6 mono- and di-chlorohydrocarbons - Google Patents

Abstract

Process for the continuous preparation of acyclic C ₄ - to C ₆ -mono- and di-chlorohydrocarbons with high purity by reacting the corresponding C ₄ -C ₆ -alcohols with hydrogen chloride in the presence of an amine hydrochloride, characterized in that additionally water vapor in the Column and / or fed into the reaction system of the apparatus used, wherein the additionally fed amount of steam from 0.8 to 25% by mass based on the alcohol feed.

Description

The present invention relates to a process for the continuous preparation of acyclic C ₄ - to C ₆ mono- and di-chlorohydrocarbons with high purities by reacting the corresponding C ₄ - to C ₆ mono- or dialcohols with hydrogen chloride in the presence of amine hydrochlorides and additional water feed into the column or in the reaction system of the apparatus used.

Acyclic C ₄ - to C ₆ -mono- and di-chlorinated hydrocarbons are, inter alia, valuable precursors for organometallic compounds, for crop protection agents or for pharmaceutical products. They are therefore often needed with high purities.

The Recovery of acyclic chlorinated hydrocarbons from the corresponding Alcohols by reaction with hydrogen chloride is one of the generally common Methods of organic chemistry and is already in the "Traitē de Chimie organique "by Grignard and Baud, Paris (1935), Vol. III, p. 249.

It is also quite common to carry out this reaction using catalysts. Next Lewis acids, especially in the form of the chlorides of iron, aluminum, arsenic, Antimons, tin or zinc are preferably amine hydrohalides used. In addition to the hydrobromides, these are in particular hydrochlorides the amines. The amines are, for example, primary, secondary or tertiary amines with unbranched or branched acyclic or cyclic carbon chains or also to amines with aromatic groups. In particular, it can also be heteroaromatic amines. Preferably the hydrochlorides of alkylpyridines used.

SU 706 391 describes a process for the preparation of butyl chloride by reacting butyl alcohol with hydrogen chloride in the presence of an aqueous solution of hydrochloric triethylamine acting as a catalyst. The reaction takes place in two successive reaction zones at temperatures of 85 to 110 ° C. The output of the product is 90 to 91%.

In SU 707 904 For example, the aforesaid invention is modified in such a way that the exhaust gas hydrogen chloride produced during the process is absorbed by the butanol used at a temperature of 5 to 20 ° C. and returned to the process. The output of butyl chloride is 92.8% (Example 2).

The European patent application EP-A-0 392 270 describes a process for working up the reaction product of the continuous reaction of C ₃ to C ₄ monoalcohols with hydrogen chloride at elevated temperature and optionally in the presence of a catalyst. In the examples for the preparation of n-butyl chloride, an aqueous zinc chloride solution is used as the catalyst. With an alcohol conversion of about 98%, a selectivity of about 80% is achieved.

In the European patent application EP-A-0 428 166 describes the preparation of methyl halides by reacting methanol with hydrogen halide in the liquid phase in the presence of amine hydrohalide in a special apparatus. The single-phase reaction is separated by partial condensation in a methyl chloride phase and a methanol / water phase and these streams are fed to a separate workup. This process can not be used for the preparation of acyclic C ₄ to C ₆ chlorohydrocarbons in which the reaction effluent is biphasic.

DE 21 49 822 describes a continuous process for the preparation of chlorinated in 1,4- or 1,5-position hydrocarbons by reacting a liquid reaction mixture of 1,4- or 1,5-diols and / or corresponding cyclic ethers and hydrogen chloride, if appropriate in the presence of a catalyst ,

A process for the preparation of haloalkanes having 1 to 4 carbon atoms describes DE 39 38 089 A1 wherein alcohols having 1 to 4 carbon atoms are reacted with hydrogen halide in the liquid phase in the presence of amine hydrochloride.

Also describes a process for the preparation of lower haloalkanes by the reaction of a lower alcohol with hydrogen halide EP 0 446 537 , Here, hydrogen halide and the lower alcohol is fed to the reactor continuously, the haloalkane and the water distilled off from the reactor, carried out a phase separation and recycling a portion of the distilled water in the distillation column.

The EP 0 352 799 B1 also describes a process for the preparation of haloalkanes by the reaction of hydrogen halide with a stoichiometric excess of the alcohol in a plug flow reactor, wherein pressure and temperature are selected to maintain a liquid, aqueous medium in the reactor.

In the patent US 6,245,954 describes the reaction of alcohols with phosgene or thionyl chloride using a nitrogen-containing catalyst. As shown in Examples 1-6, 96.6 to 98.6% alkyl chlorides are generated in the reaction of diols.

A significant improvement over the aforementioned methods is given in the European patent application EP-A-0 789 013 presented. There is described a process for the preparation of long-chain alkyl chlorides from alcohols and hydrogen chloride.

The Reaction becomes at a temperature below the boiling point of the Carried out alkyl chloride and the formed alkyl chloride with the aid of additionally fed hydrochloric acid overhead distilled off at the short path without column attachment. In this process become larger amounts of alcohol with the products (alkyl chloride, water of reaction) overhead discharged. In order to completely reduce the alcohol content in the alkyl chloride phase, is common a second reaction stage (cascade mode) is required.

The object of the invention was therefore to develop a process for the preparation of acyclic C ₄ - to C ₆ mono- and di-chlorohydrocarbons from the corresponding alcohols by means of hydrogen chloride, in which the target products without great expenditure on apparatus and in particular without subsequent complex, multistage, fractional distillation can be obtained directly with high purities.

Surprised mm was found that when using amine hydrochlorides as catalysts and additional Infeed of water or steam into the column or in the reaction system of the apparatus used, the purity of the target products especially by noticeable reduction of ether formation elevated is and by the supply of water or steam the operation the plant with different inlets and the targeted control of nearly ideal operating conditions possible is done.

The invention therefore relates to a process for the continuous preparation of acyclic C ₄ - to C ₆ -mono- and di-chlorohydrocarbons with high purity by reacting the corresponding C ₄ - to C ₆ -alcohols with hydrogen chloride in the presence of an amine hydrochloride, wherein additionally water vapor is fed into the column and / or in the reaction system of the apparatus used and the additionally fed amount of steam from 0.8 to 25% by mass, based on the alcohol feed.

The required separation efficiency of the column used depends significantly from the composition in the reactor. Therefore it is for high product purities at the top of the column useful, the alcohol concentrations in the reactor preferably to keep low.

One particular advantage of the method according to the invention is that water is introduced into the column system (vapor), with the corresponding mono- or di-chlorohydrocarbon azeotrope from can be withdrawn from the reactor. By controlling the amount of steam can in the reactor, even with changing feed quantities, a state be set on the one hand, in a rapid response to the mono or Di-chlorinated hydrocarbon and second, a low concentration of ether due to the Reactor set concentration ratios is achieved. The product removed at the top of the column is then extracted (for example, with water) and so on the required purity brought. The dissolved in the water Proportions of alcohol and mono- or di-chlorohydrocarbon can by Stripping recovered and particularly advantageous again in the Column be fed.

By the feeding of water (vapor) into the reactor or in the column will make it possible one optimal operating point, without the return of the column (impact on the separation efficiency), the reactant streams or the amount of extractant to change.

Without the extra Injection of water vapor sets in from the inlets, column return and the quality of contact more dependent Condition (pressure, temperature and composition), which in the Usually not desired Effects (separation of organic and aqueous phase in the reactor, ether formation, Increase in reactor levels) causes.

Next Mono can Di-alcohols are also used, so that in addition to mono- and di-chlorinated hydrocarbons can be produced. Preferably, however, mono-chlorohydrocarbons (acyclic Monoalkyl chlorides, alkyl chlorides). The after the procedure Chlorohydrocarbons produced can be linear or branched be. Examples of this are n-butyl chloride, isobutyl chloride, sec-butyl chloride, tert-butyl chloride, n-pentyl chloride, n-hexyl chloride, 1,5-dichloropentane and 1,6-dichlorohexane.

In in a known manner is in the continuous production the mono- or di-chlorohydrocarbons submitted the catalyst or the catalyst mixture, on the desired Adjusted reaction temperature and the corresponding alcohol and Hydrogen chloride retracted into the reactor. The resulting Reaction products become vaporous without or over an attached column withdrawn condensed, the forming Separate phases and fed to a separate workup.

at the method according to the invention are used as catalysts amine hydrochlorides. With the amines they are preferably primary, secondary or tertiary amines with unbranched or branched alkyl groups, cyclic, acyclic and aromatic amines whose hydrochlorides are water-soluble and boiling points or decomposition points of> 250 ° C have.

preferred Amines used in the invention Amine hydrochloride are the aromatic and heteroaromatic amines such as aniline, pyridines, quinolines, phenylenediamines and naphthylamines, wherein said compounds are one or more Alkyl groups or alkoxy groups preferably having 1 to 4 carbon atoms can carry.

Especially preferred amine hydrochlorides are the alkylpyridine hydrochlorides the methylpyridines, ethylpyridines, methyl-ethylpyridines or their Mixtures. But there are also other mixtures of amine hydrochlorides used.

The Amine hydrochlorides can for example, be introduced into the reactor in admixture with water or from the corresponding amines by reaction with Hydrogen chloride are produced.

To the method according to the invention the reactor temperature is chosen so that the reactor contents a water content of 3 to 50%, preferably from 5 to 30%, especially preferably from 7 to 25% and that in the continuous Synthesis of the reactor level remains almost constant. The reactor temperature is generally 80 to 170 ° C, preferably 90 to 150 ° C.

The additionally fed amount of water vapor is 0.8 to 25% by mass based on the Alcohol intake. In essence, the water is needed to the concentration ratios constant in the reaction system. Without the feed, the desired reaction conditions can not be safely adhered to.

at The reaction of, for example, n-butanol becomes the reactor temperature from 90 to 150 ° C, preferably from 95 to 135 ° C and more preferably adjusted from 105 to 117 ° C. The additionally fed steam or amount of water is 1 to 20 mass%, preferably 10 to 15 mass% based on the n-Butanolzulauf. The n-butanol content in the reactor is based on a content from 2 to 20%, preferably from 5 to 10%. The return on n-Butyl chloride, which is driven to the top of the column, is 2.5 to 7 times, preferably 3.5 to 5 times, the n-Butanolzulaufmenge.

The Process provides acyclic mono- and di-chlorohydrocarbons at high space / time yields with improved selectivity. The accumulation of residues, in particular the seizure of dialkyl ethers, is very low.

The The following examples are not intended to further explain the invention but limit the scope.

example 1

Continuous production of n-butyl chloride

The apparatus consists of a 1 L jacketed glass reactor with stirrer and dip tube for Eduktdosierung and N ₂ coverage, a 1 m long electrically heatable column with Glasraschigringen (4 × 4 mm), steam divider, condenser, intensive cooler and distillate receiver.

The Steam is supplied via a pre-evaporator in the middle part of the column (0.5 m).

Of the Alkylchloridrückfluss is installed above the column packing.

The liquid reactant streams be with suitable pumps (for example peristaltic pumps) promoted. The HCl supply takes place via a calibrated variable area flowmeter.

The process exhaust gases are passed through countercurrent scrubbers (alcohol scrubber, water scrubber) and the purified exhaust gas (mainly N ₂ ) fed into an exhaust manifold and fed to a suitable disposal.

450 g of alkylpyridine hydrochloride having a water content of 15% are introduced, adjusted to a reactor temperature of 115 ° C. while introducing HCl, and the following educt streams are metered in continuously: n-butanol: 50 g / h n-butyl chloride-reverse: 200 g / h Steam injection: 7 g / h HCl: 40 g / h

The two-phase distillate is separated and a separate work-up fed. The lower aqueous Phase is over a Stripper column freed from the organic Bestanteilen, this are again fed to the synthesis. The upper organic phase is partly as column reflux used, the remaining amount is extracted alkaline to remove residual n-butanol (<1%) and over caustic soda dried.

It is> 99.8% n-butyl chloride produced with a di-n-butyl ether content of 0.02%. The yield n-butyl chloride is> 97% of theory on the n-butanol use. The reactor contents remain after the initial one Adjustment of the balance, over a period of 30 days almost constant and indicates only slight enrichment of di-n-butyl ether out. (Increase = <1% based on the alkylpyridine hydrochloride used).

Comparative Example 1

Continuous production of n-butyl chloride

Corresponding Example 1, the reaction is carried out without additional steam feed. The di-n-butyl ether content in the target product rises opposite Example 1 to twice the value (0.04%). The reactor contents rises, after the initial one Adjustment of the balance, over a period of 30 days by 5%. In the alkylpyridine hydrochloride, enhanced di-n-butyl ether is analyzed.

Example 2a and Comparative Example 2b

Continuous production of n-hexyl chloride

In the apparatus described above, 450 g of alkylpyridine hydrochloride are presented with a water content of 7.5%, adjusted with introduction of HCl to 135 ° C and the following educt streams added: example 2a 2 B n-hexanol: 54 g / h 54 g / h n-hexyl-reverse: 200 g / h 200 g / h Steam injection: 9 g / h - HCl: 33 g / h 30 g / h

at These process conditions, the formed di-n-hexyl ether predominantly in the alkylpyridine hydrochloride phase. After a term of For 30 days, the reactor contents in Example 2a contained 1.6 g of di-n-hexyl ether and in Example 2b, 3.8 g of di-n-hexyl ether.

From the different ether formation can be seen that without additional steam feed the Catalyst phase must be cleaned more frequently.

Claims (9)

Process for the continuous preparation of acyclic C ₄ - to C ₆ -mono- and di-chlorohydrocarbons with high purity by reacting the corresponding C ₄ -C ₆ -alcohols with hydrogen chloride in the presence of an amine hydrochloride, characterized in that additionally water vapor in the Column and / or fed into the reaction system of the apparatus used, wherein the additionally fed amount of steam from 0.8 to 25% by mass based on the alcohol feed. Method according to claim 1, characterized in that that the withdrawn at the top of the column product is then extracted becomes. Method according to claim 1, characterized in that that the chlorinated hydrocarbons produced by the process are linear or branched. Method according to claim 1, characterized in that that it is in the prepared by the process mono- or Di-chlorinated hydrocarbons n-butyl chloride, isobutyl chloride, sec-butyl chloride, tert-butyl chloride, n-pentyl chloride, n-hexyl chloride, 1,5-dichloropentane or 1,6-dichlorohexane. Method according to one of the preceding claims, characterized characterized in that amine hydrochlorides of primary, secondary, tertiary, linear, cyclic, acyclic or aromatic amines. Method according to one of the preceding claims, characterized characterized in that used as catalysts amine hydrochlorides be whose hydrochlorides are water-soluble and a boiling point or decomposition point of> 250 ° C have. Method according to one of the preceding claims, characterized characterized in that hydrochlorides of anilines, Pyridines, quinolines, phenylenediamines and naphthylamines are used. Method according to one of the preceding claims, characterized characterized in that the catalyst is a mixture of Alkylpyridinhydrochloriden is used. Method according to one of the preceding claims, characterized in that the alkylpyridine hydrochlorides are hydrochlorides of 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 2,3-dimethylpyridine, 2,4-dimethylpyridine, 2,5-dimethylpyridine and 2,6-dimethylpyridine or mixtures thereof.