DE1212514B - Process for the preparation of 2-chlorobutene- (2) - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C07c

German class: 12 ο -19/02

Number:
File number:
Registration date:
Display day:

1212514
K53593IVb / 12o
29th June 1964
March 17, 1966

2-chlorobutene- (2) is an important starting product for the production of 2-chlorobutadiene- (1,3), butyne- (2), 2,2,3-trichlorobutene and various dichlorobutenes. ^ It also has in the form stabilized with isopropanol and chloroform as a solvent and intermediate found versatile use.

It is known that 2-chlorobutene- (2) can be prepared from 2,3-dichlorobutane or 2,2-dichlorobutane by splitting off HCl with alkalis. Of 2,3-dichlorobutane also can be (2) gain with the aid of activated carbon BaCla contacts at 200 to 250 ⁰ C 2-Chlorbuten-.

The disadvantage of this known method is based on the consumption of alkalis and the formation of, By-products that can no longer be used in the process.

It has been found that the yields in the dehydrochlorination of 2,3-dichlorobutane to BaCl ₂ -Aktivkohlekontakten, especially at longer reaction times, not more than 50 ° / ₀ are. As a result of the formation of polymerizing by-products, a resinification of the contacts and, in connection with this, a decrease in contact performance is observed. A regeneration of the contact by burning, such. B. with contacts on silicate carriers, is not possible with an activated carbon contact. However, the use of support material based on silicate or metal oxide is known to lead to butadiene (1,3) as the main product.

The invention now has a process for the preparation of 2-chlorobutene (2) by catalytic dehydrochlorination of dichlorobutane, which is characterized in that 2,2-dichlorobutane, which is optionally diluted with an inert gas, in the presence of a or more of the metals calcium, strontium, barium, magnesium, nickel, cobalt, iron, lead, zinc, cadmium, aluminum and copper, preferably in the form of acids or powder, and / or their chlorides and / or oxides, optionally on a carrier as catalysts at temperatures of 50 to 400, preferably 50 dehydrochlorinated to 25O ⁰ C and the resulting 2-Chlorbuten- (2) purified in a conventional manner by washing with water and / or distillation. As a carrier material you use z. B. kaolin, kieselguhr (SiO ₂ ), glass powder, porcelain, asbestos, pumice stone or activated carbon.

You can also use metal chips, e.g. B. iron powder, which is split off with the during the reaction React hydrogen chloride on their surface to the corresponding metal chloride and likewise act catalytically. Activated carbon is also suitable, but a process for the production of 2-chlorobutene- (2)

Applicant:

Knapsack Aktiengesellschaft, Huerth-Knapsack

Named as inventor:

Dipl.-Chem. Dr. Kurt Sennewald,

Dipl.-Chem. Dr. Wilhelm Vogt,

Dipl.-Chem. Dr. Herbert Baader, Hermülheim -

Because of the poor regenerability, such contacts have a limited service life.

When the catalysts are added, hydrogen chloride is split off at room temperature. In order to accelerate the reaction, it is convenient to operate at the reflux temperature or above approximately between 50 and 250 ⁰ C. Above 400 ⁰ C, the yields decrease already sharply.

The dehydrochlorination is carried out under normal pressure; but it can also be useful to work at reduced pressure or 2,2-dichlorobutane with an inert gas, ζ. Β. Nitrogen, carbon oxides or to dilute argon.

The split off hydrogen chloride gas can either be washed out by water or by 2-chlorobutene- (2) are distilled off.

Since with a longer reaction time a little resin or Soot deposits on the contact cannot be completely ruled out the contact can be regenerated from time to time with oxygen or air.

The method according to the invention has considerable advantages for technology. It gives better yields than that known dehydrochlorination of 2,3-dichlorobutane.

Butadiene- (1,3) could only be found in amounts of <0.1 percent by weight in the reaction product. The contact has a longer service life, and contact regeneration by burning off any soot deposits that may have formed is also possible when using silicate or metal oxide carriers. The significantly better contact performance also has an advantageous effect, which, according to the process according to the invention, with at least 325 g of 2-chlorobutene- (2) per liter of contact and hour is almost twice as large as with the dehydrochlorination of 2,3-dichlorobutane on BaCl ₂ - Activated carbon.

You can put the catalyst in a tube, ζ. Β. a quartz tube, fill and be within the specified Temperatures preferably vaporous 2,2-di-

609 538/416

pass through chlorobutane, whereby its residence time is about the catalyst is expediently between 10 and 50 seconds. However, it is cheaper if you 2,2-dichlorobutane boils under reflux with the catalyst and at the top of the fractionation or reflux column 2-chlorobutene- (2) decreases in addition to hydrogen chloride gas.

Example 11

In a 60 cm long quartz tube, which was filled with 210 ml of a 20 percent by weight magnesium chloride and 80 percent by weight pumice stone contact, 100 g of 2,2-dichlorobutane were introduced per hour and at a temperature of 240 to 260 ° C with elimination of hydrogen chloride in 2-chlorobutene- (2) transferred. The hot gases emerging from the reactor were introduced into water and the organic phase which separated out was separated off and dried. After distillation of the organic phase per hour 55.4 g of 2-Chlorbuten- (2) (cis-trans-Gemiseh a boiling range of 62 to 71 ⁰ C) was obtained. In addition, 13> 4 g of 2-chlorobutene- (l) were formed. The conversion of the 2,2-dichlorobutane was practically quantitative; the yield of 2-chlorobutene- (2) _r based on converted 2,2-dichlorobutane was 78.5%; the yield of 2-chlorobutene- (l) was 19%.

Example Γ 2

In the same reactor described in Example 1, a contact has been filled, the ₀ consisted of 20% BaCl ₂ and to 80 ° / of activated carbon. 100 g of 2,2-dichlorobutane were introduced every hour at 190 to 210 ^{° C.} The work-up of the reaction product according to Example 1 gave 59.8 g of 2-chlorobutene- (2) and 5.2 g of 2-chlorobutene- (1) per hour. The conversion was quantitative and the yield of 2-chlorobut- (2) was 84 ⁰ _{I 0} .

Example 3

A 250 ml flask was charged with 275 grams of 2,2-dichlorobutane and 10 grams of contact. The contact consisted of pumice stone prepared _{with 20 percent by weight ZnCl 2.} When the 2,2-dichlorobutane (boiling point 102 to 104 ° C.) was boiled under reflux, hydrogen chloride and 2-chlorobutene- (2) escaped through a 30 cm long column. On top of this column were in the course of 8 hours, 204 g of a fraction of 60 to 8O ⁰ C removed; 30 g of this were unreacted 2,2-diehlorbutane, 165.7 g consisted of a cistrans mixture of 2-chlorobutene- (2). The conversion was 89%, the yield of 2-chlorobutene- (2), based on converted 2,2-dichlorobutane, was 95%.
5

Example 4

In the experimental setup of Example 3, 2,2-dichlorobutane was treated with various catalysts. FeCl ₃ , NiCl ₂ , CoCl ₂ ,

ίο PbCl ₂ , CdCl ₂ , AlCl ₃ , CuCl ₂ , CaCl ₂ , BaCl ₂ , MgCl ₂ . The oxides of the corresponding metals could also be used in place of the chlorides. The use of a support material for the catalysts was not absolutely necessary. Metal filings, such as iron filings, were also effective. The latter obviously form chlorides on the surface, which catalyze the reaction. The yields of 2-chlorobutene- (2) were between 60 and 95%.

Claims (3)

Patent claims: 1. Process for the production of. 2-chlorobutene- (2) by catalytic dehydrochlorination of dichlorobutane, characterized in that 2,2-dichlorobutane, which is optionally diluted with an inert gas, in the presence of one or more of the metals calcium. Strontium, barium, magnesium, nickel, cobalt, iron, lead, zinc, cadmium, aluminum and copper, preferably in the form of chips or powder, and / or their chlorides and / or oxides, optionally on a support as catalysts at temperatures from 50 to 400, preferably 50 to 250 ⁰ C dehydrochlorinated and the resulting 2-Chlorbuten- (2) purified in a conventional manner by washing with water and / or distillation. 2. The method according to claim 1, characterized in that the carrier material used is kaolin, kieselguhr (SiO ₂ ), glass powder, porcelain, asbestos, pumice stone or activated carbon.
. 3. The method according to claim 1 or 2, characterized in that the residence time of the starting product over the catalyst is about 10 to 50 seconds. 4. The method according to any one of claims 1 to 3, characterized in that 2,2-dichlorobutane is refluxed with the catalyst. 609 538/416 3.66 © Bundesdruckerei Berlin