DE1153026B - Process for the separation of diisopropylamine or triaethylamine from mixtures - Google Patents

Description

GERMAN

PATENT OFFICE

P24284IVb / 12q

REPORTING DATE: JANUARY 20, 1960

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL: AUGUST 22, 1963

The invention relates to a method for separation of diisopropylamine from a mixture with aqueous isopropanol and γοη triethylamine a mixture with aqueous ethanol.

The crude alkylamine in question to which the process of the invention is applied is obtained from the synthesis of diisopropylamine or triethylamine. The preparation of these alkylamines is characterized by the reaction of the corresponding alcohol with ammonia over a dehydrating or hydrogenating catalyst, by the reaction of dialkylamine with an alcohol or by the reaction of an alkylamine with an aldehyde or a ketone. In all of these reactions, a mixture of alkyl amines, unreacted alkylating agent ₅ ammonia and water is formed. ;

When separating the alkylamine from the reaction mixture, ammonia and lower-boiling alkylamines, ie those which boil below about 60 ° C., are separated from the higher-boiling components by distillation without difficulty, since the corresponding boiling points are far apart. The separation of the higher-boiling alkylamine from the rest of the mixture is, however, a physically difficult task because of the azeotropic mixtures that are formed. When diisopropylamine is separated off, for example, ammonia and isopropylamine have been distilled off from the reaction mixture, leaving a mixture consisting of diisopropylamine (boiling point 83.86 ° C.), isopropyl alcohol (boiling point 82.3 ° C.) and water. When this mixture is distilled, an azeotropic mixture of alkylamine and water is formed, which boils at 74.6 ° C. at a pressure of 760 mm of mercury and contains about 90% diiso-- ,, - propylamine. When the water content in the boiling liquid has decreased to a certain amount, a ternary mixture of diisopropylamine, isopropanol and water distills from the system. After all the water has been distilled off, is at a pressure of 760 mm of mercury at 80 ° C on a binary azeotropic mixture of diisopropylamine and ■■ isopropanol containing about 64 ° / "diisopropylamine.

Similarly, the distillation gives one consisting of triethylamine, ethanol and water System initially a ternary azeotropic mixture of 78.3% triethylamine, 11.1 «/ 0 ethanol and 10.6% Water boiling at about 75 ° C, then either an azeotropic mixture of triethylamine and water, which contains about 90% triethylamine and at 76.3 ° C process for separation

of diisopropylamine or triethylamine

from mixtures

Applicant:

Pennsalt Chemicals Corporation,
Philadelphia, Pa. (V. St. A.)

Representative: Dr. W. Beil

and A. Hoeppener, lawyers,

Frankfurt / M.-Hochstj-Antoniterstr. 36

Claimed priority:
V. St. v. America January 20, 1959 (No. 787 817)

Leslie Allen Gillette, Trenton, Mich.,

and LeRoy Martin, Wyandotte, Mich. (V. St. A.),

have been named as inventors

boils, or an azeotropic mixture of triethylamine and ethanol, which contains about 47% triethylamine and boils at 77.4 ° C, depending on the composition of the output mixture in the still:

The separation of very pure triethylamine or diisopropylamine from: the respective crude product mixtures Much attention has been paid to technology, especially economic The importance of the two amines has increased. Different - These separation methods have been developed up to now and are described in the patents given below described. Because of the formation of azeotropic mixtures, direct distillation could be up to now- cannot be carried out with success. In general, the mixtures of the crude are treated Alkylamines with water to remove a large part of the alcohol by washing. With A water-saturated oil layer containing the essentially alcohol-free alkylamine then usually becomes subjected to various modified distillation processes to remove the remaining alcohol or the to remove dissolved water from the alkylamine.

According to the method of US Pat. No. 2237 628, triethylamine is washed with hot water from his. Reaction mixture won. This separation is based on the different solubility of the different components, des

309 668/324

Mixture in water at elevated temperatures. The hydrous triethylamine obtained must be treated further. The method of US Pat. No. 2,348,683 gives diisopropylamine from the mixture with isopropanol by adding enough water that during the Distillation with all of the diisopropylamine in the alembic forms a binary azeotropic mixture. The water is then chemically or physically separated from the alkylamine. The amine mixtures are separated according to the method of the USA patent specification 2411802, that the crude reaction mixture is mixed with an aqueous solution of alkali metal hydroxides and that the amines are then distilled off from the resulting aqueous solution. Isopropanol is separated from diisopropylamine according to the process of US Pat. No. 2,512,584, by adding an inert hydrocarbon with water to the mixture and thereafter the isopropanol is distilled off azeotropically from the amine. According to the method of the USA patent specification 2,512,585 becomes isopropanol azeotrope with diisopropylamine distilled by adding an inert organic liquid containing isopropanol able to form azeotropic mixture, which is below the boiling point of the inert organic liquid, des Isopropanol, diisopropylamine and isopropanol-diisopropylamine azeotrope, boils. The method of U.S. Patent 2,695,267 uses a mixture of diisopropylamine, water and isopropanol distilled in the presence of a hydrocarbon fraction to give the diisopropylamine in pure form to win. According to the method of U.S. Patent No. 2,713,597, a mixture, diisopropylamine and contains isopropanol, washed with water at a temperature between 28 and 78 ° C; thereafter the isopropanol separates from the diisopropylamine, and the separated, washed Oil layer is distilled several times to obtain anhydrous diisopropylamine.

From the patents cited above it appears that one is dealing with the problem of deposition who has already dealt extensively with alkylamines from their respective mixtures. It is obvious that the known processes include multiple washes and distillations, what means a great deal of time and energy and taking up because of the repeated treatment the alkylamine-containing liquid layer reduced yields and impurities due to the added Azeotrope formers can result in ...

There has now been an improved method for recovering pure diisopropylamine from the mixture with isopropanol and water and to obtain pure triethylamine from the. Mixture with Ethanol and water found. It has been observed that during the distillation of such crude alkylamine mixtures at a pressure below. Atmospheric pressure the alkylamine in the distilling off Alkylamine-water azeotrope is enriched, while the remaining alcohol is enriched in alkylamine. impoverished. It was also observed that when these mixtures are distilled above atmospheric pressure, a ternary Mixture of alkylamine, alcohol and water changes in proportion to the pressure increases, gradually accumulate alcohol and water, while the desired alkylamine is in the residue enriches accordingly. Because of. dfesET observations are now reaction mixtures that contain diisopropylamine, isopropanol and water (and similarly mixtures of triethylamine, ethanol and water), initially at a pressure, which is under atmospheric pressure, distilled, whereby the alkylamine in a distillate, which in the Mainly consists of alkylamine and water, is enriched. After that this DestüHai will be converted into a Pressure-tight distillation column passed, where the alkylamine is enriched and as alcohol and anhydrous Residue product of techniselier quality is separated.

The process according to the invention has significant economic advantages inasmuch as none Washer, no water or azeotrope-forming liquids or dehydrating liquids added Chemicals are required. Alky / lamin losses because of the lengthy treatment are also diminished. In addition, the implementation a continuous process and facilitates the direct production of technically pure Alkylamine simplified and enhanced.

The vapor-liquid composition of the two systems used according to the invention and the effects of pressure on these systems are shown in the tables below. For comparison the vapor-liquid data for some diisopropylamine-isopropanol-water systems are in table 1 specified. Similar values for some triethylamine-ethanol-water systems can be found in Table II.

Table I.
Diisopropylamine-isopropanol-water-vapor-liquid equilibrium

component

Composition in percent by weight
Experiment 1 I Experiment 2 I Experiment 3

Diisopropylamine

Isopropanol

water

Diisopropylamine

Isopropanol

water

Vapor temperature, ° C / 760mm mercury
* Composition above a single-bottom Othmer column.

fluid 40.1 fluid 45.3 fluid 14.6 1 [ 52.1 \ vaporous * ^ 36.4 I I 11.5 78.2

50.1
30.0
19.9
64.2
23.8
12.0

77.2

85.2

10.3

4.5

83.2

7.5

9.3

75.6

Table II Triethylamine-ethanol-water-vapor-liquid equilibrium

component

phase

Composition in percent by weight
Experiment 1 I Experiment 2 I Experiment 3

Triethylamine

Ethanol

water

Triethylamine

Ethanol

water

Vapor temperature, ° C / 760 mm of mercury
* Composition above a single-bottom Othmer column.

fluid I. 40.3 50.5 85.2 fluid vapor * \ 49.5 33.6 10.0 fluid 1 10.2 15.6 4.8 78.4 75.3 82.6 10.6 10.6 10.2 11.0 14.1 7.2 75.2 75.4 75.3

The similarity between the vapor-liquid compositions and the boiling points of the two Alkylamine-alcohol-water systems at higher concentrations are based on a comparison of the tests 3 in the two tables. Due to this similarity, our inventive Procedures can be applied to both systems.

The effect of pressure on the vapor composition of the alkylamine-alcohol-water system goes (a) from table III (diisopropylamine-isopropanol-water system) and (b) from Table IV (triethylamine-ethanol-water system). In both systems, the results were achieved by that a synthetic mixture of crude alkylamine through a laboratory column using eighteen theoretical plates was distilled. It should be noted that in each table the alkylamine content in the vapor phase at an absolute pressure of less than 760 mm of mercury progressively higher and progressively lower at a pressure of over 760 mm.

Table III

Diisopropylamine-isopropanol-water system
Effect of pressure on vapor composition

Table IV

^a 5 triethylamine-ethanol-water system

Effect of pressure on vapor composition

Pressure in mm
Mercury column

155

445

760

1650

2862

temperature
in ⁰ C

37.7
60.8
74.6
97.3
115.4

Vapor composition

in percent by weight
Diiso- I
propyl

94.6
91.0
90.0
75.0
60.0

Iso-

propanol

0.0
0.0
0.0
9.0
25.0

water

5.4

9.0

10.0

16.0

15.0

Note: Composition of the liquid starting mixture in percent by weight: 55% diisopropylamine, 30% Isopropanol and 15% water.

Pressure in mm
mercury
pillar temperature
in ⁰ C Damp
in C
Tri
ethyl
amine E together
Weight prc
Ethanol Settlement
) cent
water 35 150 34.6 92.0 7.4 0.6 200 41.0 89.1 7.5 3.3 300 52.0 84.3 8.6 7.1 + o 760 76.3 78.3 11.1 10.6 1613 96.7 71.5 17.2 11.3 3000 116.0 66.6 20.4 13.1

Note: Composition of the liquid starting mixture for the distillations at a pressure of 150 to 760 mm of mercury in percent by weight: 12.0% triethylamine, 46.6% ethanol and 41.4% water. Composition of the liquid for the distillations at 1613 and 3000 mm mercury pressure: 76.3% triethylamine,

11.1% ethanol and 10.6% water.

In a preferred embodiment of the invention, crude alkylamine, i. H. the mixture of an alkylamine synthesis process, from which previously the bulk of ammonia and other lower boiling Constituents have been withdrawn continuously at a corresponding theoretical Number of plates (can be determined by the molar composition of the raw alkylamine feed mixture), z. B. about the fifth tray from below, introduced into a distillation column whose Height corresponds to at least about seven theoretical plates and that at a vacuum of about 150 mm of mercury works; the soil temperature must be high enough for adequate reflux and satisfactory distillation speed

to maintain chains without "drowning" the column. The residue fraction from the distillation plant becomes essentially alkylamine-free alcohol won. The distillate from the column is then continuously at a corresponding theoretical Number of plates, e.g. B. about two thirds from above, introduced into a distillation column, the height of at least corresponds to about four theoretical plates and which operates at a pressure of about 4.2 at; the bottom nothing otherwise indicated, mean percentages by weight.

example 1

The process according to the invention can be carried out either continuously or batchwise will; however, the continuous process is preferred.

The composition of the crude mixture that the still working at negative pressure supplied depends, of course, on the particular process used in the manufacture of the concerned

A mixture of about 20% triethylamine, 40% water and 40% ethanol is continuously about on the fifth tray (calculated from the bottom) of a fractionation column with a theoretical number of plates

temperature is essentially introduced by the boiling point of seven. The distillation plant works of the pure alkylamine determined and sufficient tet at a vacuum of about 150 mm Mercury, the water and the remaining alcohol as a silver column, a bottom temperature of 60 ° C and Remove distillate. The alkylamine is considered to have a head temperature of about 50 ° C. The reverse is practical anhydrous and alcohol-free product. According to the analysis, the fraction contains about 85% obtained, the purity of which corresponds to the commercial quality of ethanol, the remainder being essentially triethyl. is amine-free water. You win a distillate

the analysis of which shows about 82% triethylamine, 8% water and 10% ethyl alcohol. The distillate will continuously at about the third "tray of a pressure-tight fractionation column with four theoretical Soils introduced. This system works at a pressure of about 4.2 at, a bottom temperature of about 140 ° C and a head temperature of about 115 ° C. A bottom product is obtained whose ana-

Alkylamine, from the subsequent pretreatment 25 analysis results in about 99% triethylamine. The distillate is from the mixture, e.g. B. on the amount and the Ab- a mixture of ethyl alcohol and water and is separation process of ammonia, the unreacted alkylating agents and the lower alkylamines
and on the composition of the raw starting mixtures from various experiments and frac- 30
options. A crude mixture can contain about 10 to 90 percent by weight alkylamine, about 5 to 90 percent water
and contain about 5 to 90% alcohol. A particularly suitable mixture for the treatment according to the invention contains 10 to 60% alkylamine, 35 layer works at a vacuum of about 150 mm, 15 to 50% alcohol and 15 to 50% water (mercury column, a bottom temperature of 64 ° C weight percent). and a head temperature of about 50 ° C. A

The vacuum distillation of the crude, alkylamine residue fraction is obtained, its analysis containing mixture is under 600 mm of mercury about 85% isopropanol, with the remainder water column carried out. A suitable printer is 40; i.e., the residue is practically free from range is between 25 and 600 mm mercury diisopropylamine. You win a distillate, its pillar. Each vapor pressure in the still analysis is about 85% diisopropylamine, 7% water however, atmospheric pressure is advantageous and results in 8% isopropanol. The distillate becomes konkann be used. When using a crude mixture continuously in a pressure-tight fractionating column from diisopropylamine of the distillation at negative pressure 45 four theoretical plates about the second plate it is preferable to use an inserted one. The system works at a pressure of Pressure from 100 to 200 mm of mercury. In about 4.2 at, a floor temperature of about 135 ° C A similar way is used with triethylamine and a head temperature of about 115 ° C. Man preferably a pressure of 100 to 200 mm wins a residue product, its analysis Mercury column. In either case, however, a 50% will give about 98% diisopropylamine. The distillate is Vacuum of 150 mm of mercury, especially a mixture of isopropanol and water, which is in the preferred. is substantially free of diisopropylamine.

The overpressure distillation of the azeotropic mixture of alkylamine and water is at a Pressure of at least about 2.1 at is carried out. Any overpressure that is under the critical pressure of the constituents is necessary for the successful performance of the separation process of the invention advantageous. A suitable pressure range is between 2.1 and 10.5 at; a pressure of 4.2 at. These printing conditions can be used in the same

essentially free from triethylamine.

Example 2

A mixture of about 40% diisopropylamine, 35% isopropanol, and 25% water becomes continuous introduced about the fifth tray of a fractionating column with seven theoretical trays. The arrival

Claims (5)

PATENT CLAIMS: Ways to be applied to the mixture of diisopropylamine, isopropanol and water and to the mixture of triethylamine, ethanol and water. The invention and its practical implementation are illustrated by the following examples in which the percentages, if 1. A process for separating diisopropylamine or triethylamine from mixtures containing the alkylamine, the corresponding alcohol and water, characterized in that the mixture is first distilled under reduced pressure, the resulting distillate, which is richer in alkylamine than the feed mixture, then at overpressure distilled and a substantially anhydrous and alcohol-free alkylamine is separated off as a residue fraction. 2. The method according to claim 1, characterized in that there is a negative pressure of 9 ίο at most about 600 mm of mercury, prior 4. The method according to claim 1 to 3, characterized preferably 25 to 600 mm of mercury, characterized in that a negative pressure of turns. about 150 mm of mercury and an over- 3. The method according to claim 1, wherein pressure of about 4.2 ata applies, indicates that an overpressure of 5 5. The method according to claim 1 to 4, characterized at least about 2.1 ata, preferably characterized by 2.1, that the method is con- up to 10.5 ata. performs continuously. © 309 668/324 8.63