DE1210777B - Process for the production of epichlorohydrin - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07d

German: 12 ο-5/05

Number: File number: Filing date:
Display day:

1210777
C31353IVb / 12o
November 8, 1963
17th February 1966

In the known production of epichlorohydrin by treating dichlorohydrin with alkali hydroxides, Alkali carbonates or alkaline earth hydroxides easily saponify some of the epichlorohydrin to glycerin, whereby the yield of epichlorohydrin is noticeably deteriorated. Even if you use the alkaline agents in low concentration and the epichlorohydrin formed removed from the reaction mass immediately after its formation, result from side reactions numerous by-products, which require a complex purification of the resulting epichlorohydrin require.

To avoid these disadvantages, it is preferably 3- previously went from 3 to 10, up to 6 ° / ₀ by weight of Dichlorhydrinlösungen, as obtained in the Chlorhydrinierung of allyl chloride, which is preferably 1,3-dichloropropanol (2) next l , 2-dichloropropanol (3) and by-products such as trichloropropane and higher chlorine-containing ethers. Such a procedure has the disadvantage that the work-up requires a lot of energy, especially steam, and that such solutions contain not inconsiderable amounts of hydrogen chloride from their preparation, which requires additional alkali for neutralization and thus the work-up and removal of the resulting salts due to the increased salt formation Wastewater difficult.

There has now been a process for the preparation of epichlorohydrin by dehydrochlorination of 1,2-dichloropropanol- (3) found with alkaline agents in aqueous medium at elevated temperature, which is characterized in that 1,2-dichloropropanol (3) in an amount of 30 to 60 percent by weight, based on the reaction mixture in which Reaction mixture emulsified. Surprisingly, this relatively high concentration of dichloropropanol occurs no increased saponification of the epichlorohydrin formed. Besides, there won't be any Increase in side reactions observed. 1,2-dichloropropanol- (3) is obtained by chlorinating allyl alcohol, ζ. B. by the method of German Patent 1170 923, in excellent yield and accessible to great purity. 1,2-dichloropropanol- (3) can be used in pure form; just as can the undistilled crude product, like it z. B. accruing according to the method of the aforementioned patent can be used. As an alkaline agent the alkali hydroxides or alkali carbonates or alkaline earth hydroxides or oxides are suitable, for example Sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, caldum hydroxide Process for the production of epichlorohydrin

Applicant:

Chemical works Hüls Aktiengesellschaft, Mari

Named as inventor:
Dr. Georg Boehm, Mari

or calcium oxide, but the inexpensive calcium oxide or calcium hydroxide is preferably used. The compounds mentioned are used in at least stoichiometric amounts, preferably in an excess of 5 to 15 percent by weight,

zö applied. The 1,2-dichloropropanol (3) is preferred used in such an amount that in the reaction mixture of water, alkaline agent and 1,2-dichloropropanol- (3) the alcohol is present in a concentration of 35 to 45 percent by weight.

The 1,2-dichloropropanol- (3) is preferably obtained by mechanical agitation of the mixture, e.g. B. by stirring, but emulsifiers known per se such as alkylarylsulfonates, alkoxylated alkylphenols or oxethylated fatty alcohols or acids can also be used. The reaction can be carried out either under normal or under reduced pressure. The reaction temperature is set so that the distilling mixture of epichlorohydrin, water and a little unreacted dichloropropanol at the top of the separating column a temperature about 89-98 ⁰ C, preferably from 92 to 93 ° C possesses. In general, it will therefore heat the reaction mixture to 100 to 110 ⁰ C. When carrying out the process, the reflux ratio on the separating column will expediently be set so that the mixture distilling off at the top of the column has approximately the composition of the epichlorohydrin-water azeotrope. The water and the crude epichlorohydrin are separated in a downstream separator and the water is expediently recirculated into the reactor. The crude epichlorohydrin can then be worked up further in a rectification column. However, the method is advantageously carried out

5 "Connection of several stirred vessels in series or by combining a stirred reactor with one Make thin film evaporator continuous.

Epichlorohydrin can ζ. B. on glycerine, further worked or can be used as a starting product for glycidyl ethers or esters. Furthermore, it can too Epoxy resins or polyethers are implemented.

Example 1 ^: "

In a stirred vessel, * the v'erseheiiist with feed, Rektifizieräufsatz and dephlegmator and separators, to be 290 parts by weight of water, 51 parts by weight of calcium oxide and 2œ6 parts by weight, '^ - submitted dichloropropanol (3) (Kp _2O 84 to 86 ° C.) and heated to 102 to 105 ^{° C. by external heating with vigorous stirring.} The head temperature is adjusted by the reflux so that it does not exceed ^{92 to 93 0 C.} At the same time, the aqueous phase in the separator is returned to the stirred vessel and the crude epichlorohydrin obtained is separated off as the lower phase.

The reaction is complete when no more epichlorohydrin separates out at the top. The rectification of the crude epichlorohydrin over a 20-soil column yields 133 parts by weight of pure product, bp. 115-116 ⁰ C next to 6 parts of unreacted dichloropropanol. This corresponds to a conversion of 97.1% and a yield based on the conversion of 92.7% of theory. _ _:.

Example 2

The apparatus described in Example 1, which is additionally provided with a floor drain and a downstream thin-film evaporator, are charged every hour with vigorous stirring with 221 parts by weight of crude 1,2-dichloropropanol (3) freed from hydrogen chloride, as is obtained in the chlorination of allyl alcohol and (3) contains 92.5 weight percent 1,2-dichloropropanol, and fed to 365 parts by weight of 20 ° / ₀ strength milk of lime.

"Def" downstream thin-film evaporator heated by steam is acted upon by the outlet in such a way that the contents of the stirred vessel remain constant. _r ......

The condensed head product of the Dünnschichtverdamp'fers ^"is lor ^the; 'Ruhr vessel''zurückgefüfirt the CaCl ₂ and some excess Ca (OH) ₂ containing waste water of the evaporator is substantially free of epichlorohydrin and unreacted dichloropropanol..

In the separator behind the agitator vessel, 140 parts by weight of crude epichlorohydrin with an analytically determined content of 93.5 percent by weight of epichlorohydrin, 4.6 percent by weight of unreacted dichloropropanol and 1.9 percent by weight of dissolved water are obtained every hour in the deployed product "contained dichloropropanol) of 96.8% and a yield of ^1% 92.3. . -

Claims (2)

Patent claims: 1. Process for the preparation of epichlorohydrin by dehydrochlorination of 1,2-dichloropropanol- (3) with alkaline agents in an aqueous medium at elevated temperature, thereby characterized in that 1,2-dichloropropanol (3) emulsified in an amount of 30 to 60 percent by weight in the reaction mixture. ■ 2. The method according to claim 1, characterized in that that crude 1,2-dichloropropanol (3), as obtained in the chlorination of allyl alcohol, used. 3. The method according to claim 1 or 2, characterized in that the l, 2-dichloropropanol (3) is emulsified by mechanical agitation of the reaction mixture. 609 508/275 2.66 © Bundesdruckerei Berlin