JPS5998028A - Separation of anisole - Google Patents

Abstract

PURPOSE:To obtain anisole, by distilling a mixture of anisole, methanol, water, and a specific organic compound, separating methanol as a liquid at the top of a column, taking out a solution having a weight ratio of methanol/water in a specified range at the concentrating part of the column as a side flow solution, subjecting it to separation of oil and water. CONSTITUTION:A mixture of anisole, methanol, water, and an organic compound (e.g., phenols, or cresols) to form the minimum azeotropic mixture from it and water, having an azeotropic point higher than a boiling point of an azeotropic mixture of anisole and water is distilled, methanol is continuously distilled and separated as a liquid at the top of a column, a solution having a weight ratio of methanol/water of <=4 at the concentration part of the column is taken out (taking part is equipped on the distillation plate at 1/4-3/4 part from the top of the concentrating part of the column) as a side stream solution, and the side stream solution is subjected to separation of oil and water to give anisole. The weight ratio changes depending upon anisole concentration, it is <=4 at 50wt%, <=1.5 at >=10wt%, <=3/7 at >=1wt%, and anisole can be separated by the separation of oil and water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an organic compound which forms the lowest azeotrope with anisole, methanol, water and water and whose azeotropic point is higher than the boiling point of the azeotrope of anisole and water. The present invention relates to a method for separating anineol in a mixture of at least/species of compounds.

Water and anisole have low mutual solubility, and this mixture can be almost completely separated into oil and water into aninole and water at temperatures below θ°C. However, when methanol is added to this system, their mutual solubility increases. For example, if anisole is less than /0 weight and methanol is more than SS weight, a homogeneous solution is formed, making oil-water separation impossible. Therefore, separating anisole from such a three-component system requires a separation operation such as distillation, and requires complicated equipment.

In the case of a three-component system of anisole, water and methanol,
It is also possible to isolate aninole by subjecting the liquid after removing methanol by distillation to an oil-water separation operation,
In a normal industrial reaction product liquid, for example, a reaction product liquid from catalytic alkylation of phenol or anisole with methanol, the above three component mixture Valuable components are often mixed in a mixed liquid containing the ninth or higher component (called a component system). In particular, if one of these valuable components forms the lowest azeotrope with water, anisole also forms an azeotrope with water, so even if you simply distill it, the No. 1 component will be mixed with anisole and water from the top of the column. An added mixture is obtained, and if this is a homogeneous solution, separation of the anisole by oil/water separation is not possible. Furthermore, even if oil and water separation were possible, separation of anisole would be accompanied by many difficulties, such as the need for complicated wastewater treatment if the No. 3 component is soluble in water. For example, even if water in a liquid obtained by removing methanol from the above-mentioned component system by distillation can be separated from toluene by azeotropic distillation, it is necessary to further separate the alcohol. That is, in order to separate anisole from the above-mentioned component system, at least three separation operations are required.

An object of the present invention is to provide an improved method by which anisole can be easily separated from the above-mentioned component system.

Furthermore, an object of the present invention is to provide a method in which anisole in the above-mentioned ingredient system can be separated by simply seven consecutive distillation operations and seven oil-water separation operations.

The method of the present invention is characterized by subjecting the mixed liquid of the above-mentioned components to continuous distillation to separate methanol as an overhead liquid, and in the concentrating section of the distillation column, a liquid having a methanol/water weight ratio of less than The purpose is to take out the side stream liquid and separate the oil and water from this side stream liquid to obtain anisole.

The present inventors have investigated various methods for efficiently separating anisole from a component system having the above-mentioned problems, and have discovered the following facts and arrived at the present invention. That is, the amount and azeotropic temperature of water in the azeotropic mixtures of water-anisole, water-phenol, and water-cresol at normal pressure are the weight coefficient of θj and 93.3, respectively.
℃, 9θ and weight ratio and 22j℃ and and weight ratio and 22℃
Although it is considered extremely difficult to separate anisole from phenol or cresol in the presence of water, the concentration distribution of each component in the column concentrating section is as shown below. A side stream liquid extraction port is provided, and depending on the operating conditions, a side cut is performed from a place where the anisole concentration is high and the methanol concentration is low. After cooling the obtained side stream liquid, oil and water separation is performed, and anisole and water are separated. It has been found that separation can be carried out.

Regarding the concentration distribution of each of the above components, although there is some variation depending on the distillation operating conditions, high purity methanol is accumulated in the area above the top of the concentrating section. At the bottom, the methanol concentration decreases rapidly. On the other hand, anisole has a low concentration in the upper and lower parts of the column concentration section (near the supply section), but is concentrated to a high concentration in the middle section.

Water is almost undetectable at the top of the tower, but reaches a high concentration by the middle part, and is distributed at a constant concentration from then on to the bottom of the tower. ! The concentration of phenol or orcincresol decreases rapidly above the feed section, and is almost non-existent at about 37 g from the top of the column to the column concentration section.

Namely, anisole.

Despite the fact that phenol or orthocresol independently forms an azeotropic mixture with water under almost the same conditions, in the above-mentioned gaseous component system, a high concentration of water exists below the middle part of the condensing section of the methanol distillation column. However, it was revealed that there are parts where almost no phenol or orthocresol exists.The reason for this is unknown, but the vapor partial pressure of methanol is relatively high in the condensing part. It is assumed that the mixture composition has changed.

In this way, anisole has a high concentration in the middle of the concentration section, while methanol has a low concentration, so by extracting this liquid as a side stream and cooling it, phenolmataha ortho-cresol can be extracted. It is possible to separate anisole from water by oil-water separation without substantially containing anisole.

For organic compounds whose No. separation could be achieved.

Examples of organic compounds used in the present invention that form the lowest azeotrope with water and whose azeotropic point is higher than the boiling point of the azeotrope of anisole and water include phenol, cresols, and xylenols.

ρ, 3-dichlororo/-propatool, heptatool,
Aliphatic and aromatic compounds such as benzyl alcohol 7/l
/ Coles and their derivatives, aniline.

Amine compounds and their derivatives such as N-ethylaniline and tributylamine, acids such as crotonic acid and valeric acid, esters such as ethyl benzoate and dimethyl phthalate, as well as nitrohenzene and acetophe/7. Includes =con, etc. If the content of water in the azeotropic mixture of these compounds with water is high, they are likely to be separated, and those having an azeotropic composition above the water f0 weight plate are particularly preferred.

For continuous distillation in the present invention, ordinary pressure, reduced pressure, or pressurized distillation equipment can be used. Although there is no particular restriction on the concentration of the da component system serving as the feed liquid, it is preferable that the anisole concentration is 805% by weight or more. If less than this,
In order to clearly separate the high-concentration anisole portion from the low-concentration methanol portion, a distillation column with an extremely high number of plates is required, or an extremely large amount of methanol must be refluxed. Also,
The method of side cutting is to cut from the top of the column concentrating section to 3/'
It is best to provide a withdrawal part in each distillation stage (or distillation section) of 1, and select a withdrawal part that can separate oil and water from the liquid after cooling and provides a side stream liquid from which as much anisole as possible can be separated. It's a method.

The conditions that enable oil-water separation in the present invention are such that most of the methanol and the primary component are almost completely removed by the distillation operation.

The determination may be made based on the mutual solubility of the three-component system of water and anisole. Specifically, ■If the anisole concentration is 50% by weight, the methanol/water weight ratio is less than /j; ■If the anisole concentration is on a 70% weight board, the methanol/water weight ratio is less than /j. - If the following conditions are established: the concentration of anisole is above the /weight ratio, and the weight ratio of methanol/water is below 3/7, anisole can be separated from the three-component system of anisole, water, and methanol by oil-water separation.

The temperature for oil/water separation varies depending on the composition of the three-component system, but is generally 90°C or lower, and preferably 0°C or lower. The oil/water separation operation can be carried out under increased pressure or reduced pressure, if necessary.

As the above-mentioned component system, one derived from a gas phase catalytic alkylation reaction product of phenol with methanol is used. However, the method of the present invention is not limited to this, and can be applied to all component systems that satisfy the above conditions.

According to the present invention, anisole can be easily isolated from the above-mentioned component system. That is, anisole can be isolated from the above-mentioned component system by simply seven consecutive distillation operations and seven oil/water separation operations.

The present invention will be further explained below by showing examples of actual plants.

In the examples, percentages are by weight.

Example/ Using a perforated plate distillation column with an inner diameter of 20 mm and an actual number of plates θ, methanol 7.5%, water 10 mL, anisole θ/3%
A homogeneous solution consisting of 1, 7% phenol θ, 3 parts orthocresol, and 2, 2, and dimethylphenol was fed to the 37th stage from the top of the column at a rate of 7/hr to carry out demethanol distillation. The pressure at the top of the column is atmospheric pressure, and the distillate volume is /
, 2.3 kg/'hr to obtain methanol with a purity of 99, &%. The side cut was made at the 0th stage of the 3rd bow at the top of the tower, using 37% methanol.

A composition solution of 3S% water, anisole, 2% θ3 j;
I was able to extract it at a rate of kg/hr. The other components were below 00%. By cooling this liquid to 0°C,
! Phase separation occurred and 9j% pure anisole was separated.

The separation rate with respect to the anisole fed to the distillation column was 7.

Example methanol 3/7%, water 1173t4. Aninrug/%, orthocresol/response, metacresol,! The mixed liquid of 2-gudimethylphenol θ7 and 2-gudimethylphenol θ7 was a heterogeneous liquid with a trace amount of oil layer at room temperature, but it was subjected to de-methynol distillation in the distillation column of Example. and 'l ky/hr from the top of the column to the 37th stage, and from the top of the column c/9. ．． Five-purity methanol was obtained. A side cut was carried out at the 125th stage from the top of the column, and a solution of methanol/S%, )c3s% and anine-sida 0 parts was extracted at a rate of kp/hr. Other ingredients are 99
It was less than 7%. This liquid was cooled to 0°C and separated into oil and water, allowing anisole to be separated at a purity level of 2.

The recovery rate relative to the amount of anisole fed to the distillation column reached 9%.

Example 3 Methanol 392%, water, 2 and 3 parts, aninol 3 parts, benzyl alcohol 10%, dimethyl phthalate 7
A mixed solution of 0% and nicotine g, g%, diameter, 23
mm, 23rd stage from the top of a 75-stage glass Aldershaw distillation column / 00? /hr. The pressure at the top of the column is normal pressure, and the pressure at the top of the column is 99%. ．． 2% pure methanol was obtained.

Perform the side cut at the 77th step from the top, and add methanol
A solution of 7% water J] and anisole was obtained. The second component is benzyl alcohol θ0.2%,
The other components were 907% or less. This liquid. :zs℃
The mixture was cooled to 50%, separated into two phases, and 90% pure anisole was separated. The separation rate of anisole with respect to the amount of anisole supplied was ff, 2%. The loss of benzyl alcohol was less than θ03.

Comparative Example/Example/The same methanol distillation was performed using the same distillation column and solution of the same composition without side cutting. The raw material liquid was delivered to the 37th stage at a rate of 1 kg/hr.
g/hr. The amount of anisole mixed in was θθ/% or less, and the other impurities were water.The bottom residue from which methanol was removed was distilled again in the above-mentioned distillation column. The top liquid was mostly water, but almost all of the supplied anisole and phenol and a small amount of orthocresol were dissolved.
One of these O Comparative example that could not be separated! .

The bottom liquid from which methanol was removed in the first distillation operation of Comparative Example/ is distilled again in the above distillation column, and toluene is supplied to the top/stage of the column to achieve azeotropic distillation, which results in azeotropic distillation. Obtained toluene. Of this fraction? Separation of highly purified water based on mountain water flesh color.Because the crab and anisole that were obtained were dissolved in toluene, it was not possible to separate 1fJ, and further separation operations were required.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd. Same as above Mitsui Petrochemical Industries Co., Ltd.

Claims (1)

[Scope of Claims] / At least / species of organic compound that forms the lowest azeotrope with aninur, methanol, water, and water, and whose azeotropic point is higher than the boiling point of the azeotrope of anisole and water. When separating anisole in a mixture consisting of the A method for separating anisole, which comprises taking it out and separating the side stream liquid into oil and water to obtain anisole. evening. If the organic compound is phenol, cresols and/or
or dimethylphenols, Claim No./
The method described in section.