JPS62190135A - Treatment of halogenoacetaldehyde dialkyl acetal reaction liquid - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield, by reacting vinyl acetate with a halogen and an alcohol and neutralizing the resultant reaction liquid of halogenoacetaldehyde alkyl acetal at a low temperature with a hydroxide of a group IIa metal of the periodic table. CONSTITUTION:A reaction liquid containing a halogenoacetaldehyde dialkyl acetal produced from vinyl acetate, halogen and alcohol is treated by adding preferably 1.0-1.2mol (based on 1mol of vinyl acetate) of a hydroxide of a group IIa metal (especially calcium hydroxide, magnesium hydroxide, etc.) while maintaining the system at <=20 deg.C. EFFECT:The treatment can be carried out absolutely without using a compound requiring prudent care in handling and operation and the efficiency of treatment can be maintained even by lowering the treatment temperature. USE:An intermediate for pharmaceuticals, agricultural chemicals, etc. An intermediate raw material for reducing agent or modifying agent of water-soluble polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for treating a reaction solution containing a halogenoacetaldehyde dialkyl acetal produced using vinyl acetate, a halogen, and an alcohol as raw materials.

[Prior art 1] Halogenoacetaldehyde dialkyl acetals (hereinafter abbreviated as HADAA) are used as intermediate raw materials for pharmaceuticals and agricultural chemicals, or as modifiers and modifiers for water-soluble polymers such as polyvinyl alcohol and starch. It is a very useful compound as a raw material.

As a typical method for producing the compound, it has been known that vinyl acetate and a halogen are reacted in alcohol. Kroll 7
A method for obtaining cetaldehyde dimethyl acetal in high yield is described. The feature of this method is that the reaction liquid (residue) after distilling off the low-boiling point components is mixed with a solid substance selected from the group consisting of metal oxides and carbonates of Ha group of the periodic table.
The point is that it neutralizes while maintaining the temperature of ℃. Excellent results with an overall yield of over 90% have been obtained by the darning method.

[Problems to be Solved by the Invention] However, when the present inventors attempted to produce chlor7cetaldehyde dimethyl acecool based on the description in the above publication, they found that the method had the following drawbacks. There was found. That is, (1) Metal oxides of Group IIa of the periodic table are substances that should not be immersed in water or similar substances that belong to the third class of dangerous substances, and must be stored and handled with extreme caution.

■When using a metal carbonate of Group IIa of the periodic table, the problem described in (■) disappears, but the carbon dioxide gas may bump when used (=neutralized), which is dangerous on an industrial scale. It may happen.

■Set the temperature during neutralization to the low temperature side (30℃ or less as a practical matter)
If it is set at 1, the rate of progress of neutralization becomes extremely slow, and neutralization tends to be insufficient, resulting in the production of high-boiling by-products during distillation.

For this reason, it is actually desirable to carry out neutralization at a temperature of 40°C or higher, but in such a case, vapors of various compounds such as hydrochloric acid, methyl alcohol, and methyl acetate are generated from the reaction solution, and the neutralization process This results in problems.

Problems such as these were pointed out.

Under these circumstances, it is recommended to use a safer compound that does not have to worry about problems such as (1) and (2), and that the neutralization rate will not decrease even if the neutralization temperature with the compound is low.
Furthermore, the absence of generation of by-products is considered to be a more desirable condition for industrial implementation. Therefore, the present inventors investigated neutralization using calcium hydroxide, that is, a hydroxide of Group IIa of the periodic table, in place of the metal oxide or carbonate of Group Na of the periodic table. However, with this method, a new problem occurred in that the liquid after neutralization did not separate into two phases as clearly as when using the above compound, and it was found that this greatly depended on the temperature at the time of neutralization. It is. That is, this phenomenon is unavoidable at temperatures of 30 to 50°C, which is considered particularly desirable in the prior art, and moreover, at temperatures above 40°C, where it is considered practical to increase the progress of neutralization, the reaction solution An unexpected problem occurred that even led to discoloration. As a matter of course, this fact brings about an unexpected drop in the yield and quality of the product, and it is considered that it cannot be adopted in reality.

Means for Solving Problem 1] However, the present inventors have attempted various studies to solve the above problems. As a result, it was quite surprising that conventional neutralization methods using metal oxides or carbonates could not be carried out at low temperatures, that is, below 20°C, which had been thought to be disadvantageous in terms of yield and efficiency. only if
It was discovered that the above-mentioned problem was successfully solved, and of course the neutralization rate was not reduced (the desired purpose could be successfully achieved).
The present invention has now been completed.

That is, the present invention involves adding a metal hydroxide of Group IIa of the periodic table to a reaction solution of halogenoacetaldehyde dialkyl acetal obtained by reacting vinyl acetate, a halogen, and an alcohol while maintaining the temperature at 20° C. or lower. It is characterized by:

As can be easily understood from the above-mentioned circumstances, the present invention cannot achieve the lateral bottom simply by substituting the hydroxide of the Ha group metal oxide or carbonate of the Itn Law; The temperature setting of neutralization below 20°C to make it usable is an extremely original idea that cannot be imagined from the common sense of the technical field to which this application belongs, that is, the idea that higher temperatures are better. It is based on an idea.

In order to explain the treatment method of the present invention in detail, the steps of raw materials and reactions thereof will be described in order.

First, in the present invention, a reaction solution containing H/DAA obtained by reacting vinyl acetate, a halogen, and an alcohol is treated. As the halogen, chlorine and bromine are usually used, and as the alcohol, lower alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, flobyl alcohol, butyl alcohol, and glycol M, example i1? Ethylene glycol, propylene glycol, etc. are optionally used, but in the present invention, chlorine, methyl alcohol, and ethyl alcohol are most preferably used.The reaction itself is described in JP-A-58-1059.
As described in Publication No. 33, vinyl acetate and a halogen are simultaneously added to excess alcohol, or vinyl acetate and alcohol are mixed in advance (mixing molar ratio 1:3).
~1:~10, preferably 1:3.5~1:6), and the mixed solution and halogen are continuously charged for an appropriate residence time (0.1~10 hours, preferably 0.5 hours). A method of continuously taking out this after 5 hours) may also be optionally adopted. Of course, the preparation method and reaction method are not limited to those mentioned above, and vinyl acetate, halogen, and alcohol can be used as raw materials) l A
It goes without saying that the method of the present invention described later can be applied to all systems for producing DΔA. The total amount of raw materials to be charged during the reaction is usually 0.9 to 1.2 mol, preferably 1.0 to 1.1 mol, and 3 to 10 mol, preferably 3.0 mol, of halogen to 1 mol of vinyl acetate. 5-6
It is a molar ratio. The reaction temperature is not particularly limited, but due to the physical properties of the raw materials, it is usually -20 to 4
After the completion of the C1 charging, the reaction is often promoted by raising the temperature to below the boiling point of the target compound, preferably 30 to 65°C.

Depending on the type of alcohol used as a raw material, the resulting reaction solution contains various HADAA, such as halogenoacetaldehyde dibutyl acetal, halogenoacetaldehyde dibutyl acetal, halogenoacetaldehyde dipropyl acetal, and halogenoacetaldehyde dibutyl acetal.

After removing low-boiling components from the resulting reaction solution by distillation if necessary, it is treated by adding a metal hydroxide of Group 1Ia of the Periodic Table while maintaining the temperature at 20°C or less according to the method of the present invention. .

When the treatment temperature is in the range of 20 to 30 °C, the yield decreases, although it somehow separates into two layers, and especially when the temperature exceeds 3 o °C, as mentioned earlier, the hydroxide is added (including The interface becomes unclear, which is thought to be caused by the formation of by-products, making the operation difficult and resulting in a decrease in the yield of the target product.A particularly preferred temperature range is -5 to 15 degrees Celsius.
is within the range of Practical examples of metal hydroxides in Group IIa of the periodic table include calcium hydroxide, magnesium hydroxide, and barium hydroxide. Calcium and magnesium hydroxide are preferred. Such metal hydroxides can be used either as such or in aqueous solution. Only when the metal hydroxide is used, the neutralization reaction in the above temperature range can be carried out efficiently, and if either the temperature condition or the metal hydroxide deviates from the specifications of the present invention, it is possible to carry out the neutralization reaction efficiently in the above temperature range. It is inevitable that the reaction solution will be successfully processed. The above metal hydroxide may be added in the amount necessary to neutralize the solution, preferably with stirring, but usually 1.0 to 1.2 mol based on the amount of vinyl acetate used as the raw material. It is best to use approximately the same amount as a guide.

After the addition is complete, stir thoroughly and let the liquid stand for a while, and it will separate into RWIC (upper layer) containing HADAA and an aqueous (alcohol) layer (lower layer) containing neutralized salts and others.
Separate the liquids according to the usual method. A small amount of HAD contained in the lower layer
In order to recover AA, it is extracted using an extractant, generally an acetic acid ester, such as methyl acetate or ethyl acetate, in an amount equivalent to that of the lower layer liquid. The upper layer is distilled as is or together with the organic solvent solution containing a small amount of HADAA obtained by extraction, preferably under reduced pressure.

If necessary, further purification may be performed by known means.

1 Effect] Thus, by adopting the method of the present invention, there is no need to use compounds that require careful handling and work as in the past, and there is no need to use compounds that require extreme care during handling and work, and there is no need to reduce efficiency even at low processing temperatures. This is a very effective method when implemented on an industrial scale.

[Example] Hereinafter, the processing method of the present invention will be explained in more detail by way of an example.

Note that all yields of HADAA are based on the charged vinyl acetate.

Example 1 Methyl alcohol 154 ml under stirring. (4.8 mol), vinyl acetate 1048 (1.2 mol) and chlorine gas 91
g (1.28 mol) were simultaneously charged over 2.5 hours while maintaining the temperature in the system at about θ°C. After charging the entire amount, middle distillate 208 obtained in the same manner as the distillation operation described later was added, the temperature was raised to 60°C, and an aging reaction was carried out for 15 minutes, and the reaction solution was cooled to about 10°C.

While stirring the liquid at 10° C. or lower, 45 g of calcium hydroxide was added over 30 minutes. After charging, continue at the same temperature for 30 minutes.
After stirring for several minutes and allowing the mixture to stand still, a two-layer liquid was immediately obtained.

After separating the layers, the lower layer was extracted twice with 501Il of methyl acetate, and the extract was extracted from the upper M! i (organic WI) and distilled.

After removing methyl acetate and methyl alcohol as the first distillation,
Middle distillate (contains a small amount of target product and reaction intermediate product) 2
Finally, 145g of the target material (53-54°C/
5 (l Torr, colorless) was obtained.

Analysis of the vaginal fluid by gas chromatography revealed that chloroacetaldehyde dimethyl acetal was obtained with a purity of 95%.

Yield: 92.1% Example 2 An experiment was conducted using 35 g of magnesium hydroxide instead of calcium hydroxide in Example 1, and the treatment proceeded successfully in the same manner.

Yield: 91.8% Control Example 1 An experiment was conducted under the same conditions as in Example II except that calcium carbonate was used instead of calcium hydroxide. It was found that neutralization was not completed even when a molar amount (equimolar amount) was added, and it could not be put to practical use.

Comparative Example 2 In Example 1, the holding temperature at the time of calcium hydroxide addition was changed to 25 to 30°C, and the treatment was carried out.

Although the processing progressed with almost no difference from Example 1, the yield of the target product decreased to about 80%.

Further, when the temperature at the time of charging was 40 to 45°C, the interface of the liquid became unclear, the separation operation was not successful, and the yield further decreased to about 75%.

Example 3 The same procedure as in Example 1 was carried out except that the holding temperature at the time of calcium hydroxide addition was changed to 12 to 17°C.

Yield: 90.5% Example 4 Except for using 221 g (4.8 mol) of ethyl alcohol instead of the raw material methylfurfur in Example 1, and using ethyl acetate as the extractant during extraction after the reaction. The reaction and post-treatment were carried out in the same manner as for rotation.

Both the reaction and post-treatment proceeded successfully without any problems, and 162 g of a colorless liquid was obtained.

Chloracetaldehyde diethyl acetal is (53~
The purity was 96% (54°C, 716 Torr).

Yield: 85.1% [Effect 1 As understood from the above examples, the present invention allows the treatment to be carried out using cheaper and safer compounds, and the desired product can be obtained in high yield with extremely easy operation. This treatment method is much superior to conventional methods in that it can recover the following from the reaction solution.

Patent applicant Nippon Gosei Kagaku Kogyo Co., Ltd.
0 January 30, 1988 2, Name of the invention: Process for treating halogenoacetaldehyde dialkyl acetal reaction solution 3, Related to the @Correction case Patent applicant address: 9-6 Nozaki-cho, Kita-ku, Osaka ( Postal code 530)
4. In Column 5 of Detailed Description of the Invention of the Specification Subject to Amendment, line 911 of the Specification of Contents of Amendment, [molar equivalent] is corrected to "equivalent".

Claims (1)

[Claims] 1. A metal hydroxide of group IIa of the periodic table is added to a reaction solution of halogenoacetaldehyde dialkyl acetal obtained by reacting vinyl acetate, a halogen, and an alcohol while maintaining the temperature at 20°C or less. A method for treating a halogenoacetaldehyde dialkyl acetal reaction solution, characterized by adding. 2. The treatment method according to claim 1, wherein the metal hydroxide of Group IIa of the periodic table is calcium hydroxide or magnesium hydroxide.