JPH0363239A - Method for purifying diisopropyl ether - Google Patents

Abstract

PURPOSE:To continuously obtain high purity diisopropyl ether with excellent economic efficiency by adding isopropyl alcohol or acetonitrile to diisopropyl ether and carrying out purification and distillation of the diisopropyl ether. CONSTITUTION:Isopropyl alcohol(IPA) or acetonitrile in an amount of 0.5-20vol.% based on diisopropyl ether(IPE) prepared in a synthetic system is added thereto to carry out distillation preferably by a two-column method and afford high purity IPE. A mixture solution of the raw material IPE with an azeotropic solvent is fed to an intermediate plate 4 of the first distillation column having 35-40 actual number of plates and distilled at 65-67 deg.C column top temperature, 70-72 deg.C column bottom temperature and 20-30 reflex ratio to distill hexenes which are impurities as an azeotropic mixture solution from a line 5. The IPE and high boiling substances are then fed from a line 6 to an intermediate plate of the second distillation column to afford the high purity IPE from a line 10. The IPE containing the high boiling substances is obtained from a line 11, redistilled and subsequently recrycled to the synthetic system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the purification distillation of isopropyl ether in its production.

[Prior art]

Diisopropyl ether (hereinafter referred to as IPI!) is known to be obtained industrially by separating and purifying IPE obtained as a by-product when producing isopropyl alcohol, or by subjecting isopropyl alcohol and propylene to a contact reaction using raw materials. It is being

In the purification of rPH, impurities are generally separated by atmospheric distillation to obtain purified IP[l of 99% or more.

[Problem to be solved by the invention]

However, in the synthesis of IPE, the production of hexenes as impurities cannot be avoided.

However, some hexenes are known to have boiling points very close to IPH (TPf! boiling point of 68.4"C); for example, 2-methyl-2-pentene has a boiling point of 67"C. Therefore, if these impurities are generated, it is very difficult to separate them from IPE by ordinary distillation.Therefore, there are cases where it is not possible to increase the purity of purified IPH to 992 or higher.

(Means for Solving Problem t1) The present inventors conducted intensive research on the above-mentioned problems, and as a result, they arrived at the present invention.

That is, in the method for purifying diisopropyl ether of the present invention, in purifying distillation of diisopropyl ether, isopropyl alcohol or acetonitrile is added in an amount of 0.5 to 20 vol per diisopropyl ether! It is characterized in that it is added and distilled.

The raw material IPH in the present invention may be synthesized by any of the above-mentioned conventional methods.IPA or acetonitrile may be added and mixed in advance to the distillation raw material IPH before distillation, or it may be fed into the distillation column at the same time as IPE. The amount added may be 0.5 to 20 volX relative to IPH, and more preferably 0.5 to 10 volX. The distillation method can be either batch distillation or continuous method, but batch distillation is uneconomical, inefficient, and has large losses.

Continuous distillation is possible with one distillation column, but a two-column system is even better.A method using two columns will be described below.

The first distillation column is used as an azeotropic distillation column for light boiling impurities.
The actual number of stages may be about 35 to 40, and the raw material IP is placed approximately in the middle stage.
Supply a mixture of B and IPA or acetonitrile.

Distillation was carried out under normal pressure, with a top temperature of 65-67°C and a bottom temperature of 70°C.
It is carried out at a temperature of ~72°C and a reflux ratio of 20 to 30 degrees, and the impurity hexene is removed from the top of the column by IPA or acetonitrile and IPA.
It is distilled out as an azeotropic mixture with PE, and IP [! The high-boiling components are extracted as bottoms and supplied to the next second distillation column.

In addition, the top distillate is separately circulated to the reaction system and IP[! and IP
Collect A.

The second distillation column may have about 25 to 30 plates, and the bottom liquid from the first distillation column is supplied to approximately the intermediate stage. Distillation conditions are the first
Similar to the distillation column, in normal pressure distillation, the temperature at the top of the column is 68 to 70°C, the temperature at the base is about 70 to 75°C, and the reflux ratio is about 4 to 6. High-purity IPE is obtained from the top of the column, and high-boiling substances including IPB are extracted as bottoms from the bottom of the column.

FIG. 1 shows an embodiment of the process of the present invention.

The mixed liquid of the raw material IPE and the azeotropic solvent is supplied from line 4 to the intermediate stage of the first distillation column 1, and the impurity hexene is
It is distilled out of line 5 as an azeotropic mixture with A or acetonitrile. On the other hand, IPE on the bottom side of the column is supplied to the intermediate stage of the second distillation column through line 6 together with high-boiling substances. IPII containing high boilers is canned out, which after redistillation is recycled to the synthesis group and processed into IPE.
Collect.

〔Example〕

A more specific explanation will be given below with reference to Examples.

Example 1 Crude IP [!] containing about 1.8 wtX of 2-methyl-2-pentene and about 0.4 wtX of other hexenes.
(purity about 97.5 wtX) and 3. OvolX
In addition, the process shown in Figure 1 was distilled under the following conditions.

First distillation column Second distillation column feed (kg/Hr) 400 Column top temperature ('(:) 66-67℃ 68-6
9℃ tower bottom temperature ("C) TG~71"C70~7
2°C pressure Normal pressure Normal pressure reflux ratio 204 As a result, purified IPB with purity 99.5 wtX was 240
The total content of hexenes in this IPB, obtained at a rate of kg/Hr, was less than 0.4 wt%.

Example 2 Using the same raw materials as in Example 1, only the amount of IPA added was changed to 9. Distillation was performed by changing to OvolX.

As a result, purified IPE with a purity of 99.7 wtX was
The total content of hexenes in this IPB, obtained at a rate of kg/Hr, was less than 0.2 wt%.

Example 3 In Example 1, acetonitrile was used in place of IPA.
Rough IPI under the same conditions except for OvolX! was distilled.

As a result, purified IPE with a purity of 99.5 wtX was
The total content of hexenes in this IPB, obtained at a rate of kg/Hr, was less than 0.4 wtX.

Comparative Example 1 Crude IPH was distilled under the same conditions as in Example 1 except that IPA was not added.

As a result, purified IPB with a purity of 98.5 wtX was 240
kg/Hr.

〔Effect of the invention〕

By combining the method of the present invention with a conventional IPE synthesis apparatus, high-purity IPII of 992 or higher can be obtained continuously, efficiently, and economically, which is extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an example of the method for purifying diisopropyl ether of the present invention. 1. First distillation column 2. Capacitor 3. reboiler 4
, raw material supply line 5. First distillation column distillation line 6, first
Distillation column bottom line 7. Second distillation column 8, condenser
9. Reboiler 10, second distillation column distillation line 11, second distillation column bottom line Figure 1

Claims (1)

[Claims] A method for purifying diisopropyl ether, which comprises adding 0.5 to 20 vol% of isopropyl alcohol or acetonitrile to diisopropyl ether in the purification distillation of diisopropyl ether.