JPS61275239A - Method for purifying methylal - Google Patents

Abstract

PURPOSE:To economically obtain the titled substance which is an important intermediate for various medicines, agricultural chemicals and industrial chemicals, particularly important to fine chemical fields in high purity without requiring troublesome operation steps, by bringing crude mthylal containing a lower alcohol into contact with zeolite. CONSTITUTION:Crude methylal containing a lower alcohol is brought into contact with a naturally occurring and/or synthetic zeolite at ordinary temperature to adsorb the lower alcohol in the zeolite and obtain the aimed pure methylal. Any one of zeolite having the molecular sieve ability may be used as the zeolite, and molecular sieves, e.g. analcite group, faujasite group, zeolite A, X, etc., or others may be suitably used. Particularly, molecular sieves 3A or 4A, etc., are effective as the molecular sieves. The amount thereof to be used is not particularly limited, but >=1g, zeolite of the type 4A based on 0.11g methyl alcohol may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying methylal.

Methylal is a very important compound as an intermediate for various pharmaceuticals, agricultural chemicals, and industrial chemicals, and is required to be highly pure. The present invention is in response to such industry demands, and is applicable to the chemical field.

It is particularly important in the field of fine chemistry.

Methyral CH, 0CH20CH.

has conventionally been synthesized by the first-order method.

■ A method in which paraformaldehyde and methyl alcohol are reacted in the presence of hydrogen chloride, sulfuric acid, anhydrous ferric chloride, calcium chloride and ferric chloride, etc.

■ A method in which formaldehyde and methyl alcohol are reacted in the presence of hydrochloric acid and calcium chloride.

■ A method in which methylene chloride and methyl alcohol are reacted in the presence of sodium hydroxide.

As mentioned above, in all of the methods, methyl alcohol is used as a raw material, so that the product methylal is always accompanied by the raw material methyl alcohol, and therefore it is necessary to separate the methyl alcohol.

However, it is known that methylal azeotropes with methyl alcohol, water, etc., and it has been industrially extremely difficult to obtain pure methylal from crude methylal by simple rectification.

Therefore, in order to separate methyl alcohol which cannot be separated by simple rectification, various physical or chemical methods have been tried. for example.

Vysokomolek (Vysokomolek)
ul.

5 oedindan (8>1459-61 (1966) and Vynokurov (Nauch, Doklady V
ysekeishkoly.

Lesoinzhener, Delo, 1958
, No. 4, 193-195) purify metral by chemically reacting the methyl alcohol present with sodium metal.

The methyl alcohol may be removed by shaking out with a concentrated aqueous solution of calcium chloride and then drying the methylal. (Encyclopedia of Industrial Chemistry, edited by Ullman, No. 5
(Refer to Volume 6, page 15).

Further, various auxiliary agents for separating methyl alcohol and methylal include the following. :water(
JP-A-56-1477! +9. German Patent No. 1.0
02,305, U.S. Pat. No. 2,545, and 889), alkaline aqueous solution (U.S. Pat.
No. 90.340, Vinocro 7. Gidrolis Le
sokhim+prom, 12+ No5, pp
, 4-6 (1959)), and dimethylformamide (see German Patent No. 1,172,677).

Furthermore, it is described that methanol is reacted with excess aldehyde to form an acetal (USSR patent @12
1,445).

Vysehikh 7 (Izvest, Vysehikh
Ucheb.

ZuvedeniL Lesnor Zhvr, 2
, No. 2, 155-159 (1959)) compares three different methods of separating methyl alcohol and methylal. : Reaction of methyl alcohol with paraformaldehyde, treatment of an azeotrope of methyl alcohol and methylal with sodium hydroxide and distillation, and rectification in the presence of an excess of formalin solution.

A method of rectifying under high pressure using two rectification columns is also known (see JP-A-58-105331).

However, these known methods require addition of other substances for purification, large equipment, special equipment, and complicated operations. Methyral is denatured and destroyed during purification.

It has the disadvantage that the yield of methylal is low due to the upflow.

Until now, there have been no known examples of successful large-scale purification of methylal.

The present invention has been made to solve these drawbacks, and is to obtain highly pure methylal without causing loss of methylal when separating and purifying crude methylal containing methyl alcohol. The aim is to develop an economical method.

As mentioned above, methylal is a raw material or intermediate that is often used in the field of fine chemistry, such as pharmaceuticals and agricultural chemicals, so it must be free of impurities such as methyl alcohol and other lower alcohols that are by-products or mixed in during the manufacturing process. It has been a technical challenge in the industry to establish an industrial production method for separating such impurities and purifying methylal on an industrial scale without using delicate operations. Its purpose is to solve this technical problem.

With conventional methods, it has been industrially impossible to completely remove methyl alcohol and other lower alcohols from methylal. However, considering that methylal is frequently used in the field of 71 ink mistry, we have developed a method for purifying methylal. It was concluded that chemical purification methods using chemicals are inappropriate in this case.

Therefore, we focused on physical or mechanical purification methods, and examined the extremely large number of purification methods that exist, such as ability to remove lower alcohols, denaturation of methylal, possibility of industrial large-scale processing, presence of delicate operations, cost aspects, and pollution. As a result of screening in terms of prevention, yield, and other aspects, we found that the method using molecular sieves is effective here, and that the method using zeolite is the best way to achieve this industrially. We have learned that there is.

The present invention has been further developed based on this new knowledge.

It was completed as a result of research, and as a result of researching the adsorption mechanism and systematic screening, the zeolite method was found among numerous purification methods, and its effects will be described later. As such, the present invention is not simply a matter of simply selecting one of the purification methods, but rather has an extremely high degree of inventive step.

That is, the present invention relates to a method for purifying methylal by bringing crude methylal into contact with zeolite, thereby causing the zeolite to adsorb a lower alcohol such as methyl alcohol.

As zeolite, if it has molecular sieving ability,
As well as natural zeolites, synthetic zeolites can also be used advantageously. For example, boraxite group, faujasite group, chamesite group, soda heptasite group, shukuji 7
Zeolite group, mordenite group, zeolite 10X, 13X, etc. are effective.

The amount of zeolite used is not particularly limited,
This method is particularly excellent as an industrial large-scale processing method because there is no inconvenience when using it in large quantities, and delicate operations regarding the amount used are not required. For example, the amount of zeolite used is 4A type and methyl alcohol is 0.
It is sufficient to use zeolite iy or more for 111I. The used zeolite can be regenerated by flowing dry air at 250°C and can be used repeatedly.

According to the present invention, methylal can be purified by simply bringing the zeolite and the crude methylal solution into contact at room temperature, and is therefore particularly suitable as an industrial purification method. The two may be simply brought into contact with each other. For example, after mixing the two, the zeolite may be removed by filtration, centrifugation, decantation, etc., or by passing the crude methylal liquid through a column packed with zeolite. You may. It is also possible to repeat the process if necessary.

According to the present invention, first, there is an advantage that completely pure methylal containing 0% of methyl alcohol and other lower alcohols can be obtained.

The significance of this effect is quite obvious, considering that by conventional rectification methods and other physical or chemical methods, it was completely impossible to obtain pure methylal with a methyl alcohol content of Ols. It is.

Furthermore, the method of the present invention does not require complicated operations or processes, and can be processed in large quantities, so it is not only extremely easy to automate and save labor, but also causes no pollution. Because there is.

It is especially outstanding as an industrial refining method.

Moreover, since it has almost no effect on the yield of methylal, the present invention can be said to be an outstanding industrial purification method capable of obtaining completely purified methylal in high yield.

Furthermore, the present invention not only allows the use of relatively low-cost zeolite, but also allows for the reuse of zeolite, making it very economical and causing no pollution. This is a particularly advantageous aspect as an industrial purification method.

Next, examples of the present invention will be shown.

Example 1 Molecular sieves (registered trademark: Wako Tsumugi Co., Ltd.) 4A 1/1 (S 1001i) was mixed with 1002.8 g of crude methylal containing 1.2% by weight of methyl alcohol and left overnight. The molecular sieves were filtered. Pure methylal (methyl alcohol content: 0% by weight) was obtained by removing the sieves.The recovery rate of methylal was 94%, and the molecular sieves were regenerated by flowing dry air at 250°C. went.

Example Z Crude methylal 10 containing 8 weight percent methyl alcohol
Molecular sieves 4A 1/1<S on 00.9
727. F was mixed in and left overnight. Pure methylal (methyl alcohol content 0.1 wt es) is obtained by removing the molecular sieves by filtration.
I got it.

Example & 1000 g of crude methylal containing 1.2% by weight of methyl alcohol and Bilyt (manufactured by Kurita Industries) 4AT-144
1001i was mixed in and left overnight.

Purified methylal (content of methyl alcohol 0% by weight) was obtained by removing the bilite by filtration.

Example 4 Methyral 9 containing 1.1% by weight of methyl alcohol
115,498 g of pilot liquid was added to 80I and left overnight. The pilots are divided door to door, and the methyl alcohol weight it% is determined.
911 g of methylal containing .

Example 5 Zikrite 5GW (manufactured by Zikrite KK), a naturally produced zeolite, was activated at 650°C for 4 hours to produce a
Zeekrite on 0.9! 9GW50.9 was added and left overnight.

Sickle siglite from house to house and add methyl alcohol α86 weight f%
Methyral 915II containing was obtained.

Example & To 1,000 g of methylal K pilot containing 0.71% by weight of ethyl alcohol, 100 g of -154 was added and left overnight.

Bailit is sent door to door, ethyl alcohol 0.041f%
Methyral 9451 containing was obtained.

Example Z 154102 g of methylal 102017 containing 0.60% by weight of n-propyl alcohol
was added and left overnight.

The pilot is sent door to door, and n-propyl alcohol 0.23
967 g of methylal containing % by weight were obtained.

Example 8゜Methyl alcohol 0.35% by weight, ethyl alcohol 1
．． 26 weight it%, n-propyl alcohol/l/0,
-154,147 g of pyrite was added to 980 g of methylal containing 39% by weight and left overnight.

0.0% by weight of methyl alcohol,
907 g of methylal containing 0.23ii% of ethyl alcohol and 0.19% by weight of n-propyl alcohol was obtained.

Example 9 Methyral i containing 1.1% by weight of methyl alcohol
, oooy was placed in a 21"J eggplant-shaped flask with a Shijimrote cooling tube attached, and the experiment was conducted while maintaining the internal temperature of 40°C in a 43°C water bath. Bairit T-144100.9 was added and left at 40°C for 7 hours. After that, it was cooled and the bilit was distributed from door to door at room temperature.

960 g of methylal containing 0.58% by weight of methyl alcohol was obtained.

Example 10 985 g of methylalcohol containing 1.1 and [i%] of 2! The experiment was carried out by placing the flask in an eggplant-shaped flask and keeping the internal temperature at 3 to 5°C in an ice water bath.

Byrit T-144999 was added and left to stand while cooling for 7 hours, and then Byrit was distributed from house to house.

Methyral 9211 containing 0.69% by weight of methyl alcohol was obtained.

Claims (1)

[Claims] A method for purifying methylal, which comprises bringing crude methylal containing a lower alcohol into contact with a naturally occurring and/or synthetic zeolite, and adsorbing the lower alcohol onto the zeolite to obtain pure methylal.