JP2691020B2 - Method for producing Nt-butyl acrylamide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing Nt-butylacrylamide, which is an intermediate of a mono-tertiary alkylamine useful as a raw material for organic rubber chemicals and pharmaceuticals. is there.

(Prior Art and Problems to be Solved by the Invention) Conventionally, as a method for producing Nt-butylacrylamide, a method of reacting acrylonitrile and t-butyl alcohol in an acetic acid solvent at 40 ° C. in the presence of concentrated sulfuric acid (J Amer. Chem. Soc. 73 , (9), 4076 (1951)) or acrylonitrile and t-butyl alcohol in a methanol or ethanol solvent at 40 to 60 ° C in the presence of concentrated sulfuric acid (JP-B-47). -51329) etc. are known.

However, in these methods, reaction at high temperature,
Alternatively, the temperature rises because it is difficult to control the temperature because the reaction is non-uniform and the heat generation is sudden. for that reason,
The modified substance and the polymer substance produced by the side reaction are mixed in the product, and the quality of the obtained Nt-butylacrylamide is not preferable.

An object of the present invention is to produce a high-quality Nt-butyl acrylamide by suppressing such a heterogeneous and sudden heat generation reaction and reacting at a low temperature.

(Means for Solving the Problem) The present invention is a method for producing Nt-butylacrylamide by reacting t-butyl alcohol and acrylonitrile in the presence of sulfuric acid, and a mixed solvent of acetic acid-water is used as a solvent. As well as using, the molar concentration of water in the reaction system
N characterized by being 0.7 to 4.5 mol / l (liter)
A method for producing -t-butyl acrylamide is provided. If the molar concentration of water is higher than this range, the reaction rate tends to be low and the economy tends to be poor. On the other hand, when the amount is less than this range, the viscosity of the reaction system increases and the heat generation suddenly occurs, so that it becomes difficult to control the reaction temperature and the quality of the obtained Nt-butylacrylamide deteriorates. The amount of the mixed solvent is usually 0.4 to 1.0 times (weight ratio) of the raw material system (total of acrylonitrile and t-butyl alcohol), but the present invention can be carried out even if it is out of this range. The amount of sulfuric acid added is usually 0.5 times or more, and preferably about 1.0 times the molar ratio of acrylonitrile.

The preferable amount of t-butyl alcohol used is such that the molar ratio to acrylonitrile is 0.9 or more, and particularly 0.9 to 1.3.
Double molar is preferred. When the amount of t-butyl alcohol used is more than this range, there is no particular inconvenience, but the economical efficiency is deteriorated, which is not preferable. On the other hand, if the amount of t-butyl alcohol used is less than this range, the modification reaction of acrylonitrile will accompany and the resulting modified substance will be mixed into Nt-butyl acrylamide, which is not preferable.

The reaction temperature is -30 to 40 ° C, particularly preferably -10 to 30 ° C. When the reaction temperature is higher than this range, the modifying substance and the polymer substance generated by the side reaction are mixed in Nt-butylacrylamide, which is not preferable. or,
When the reaction temperature is lower than this range, there is no particular inconvenience, but the reaction rate becomes small and the economy becomes poor.

As the reaction system of the reaction in the present invention, either the batch system or the continuous system can be used to achieve the object.

(Action) Although the reaction mechanism of this reaction is not completely clear, it is estimated as shown below.

The reason why the reaction is non-uniform and the heat generation suddenly occurs or is often violent is that the viscosity of the reaction system becomes extremely viscous due to the formation of a sulfuric acid adduct of N-t-butylacrylamide. It is extremely difficult to control the concentration of the complex of t-butyl alcohol sulfuric acid.
Therefore, it is considered that the effect of the solvent occupies an important cause. From this finding, the reaction in a mixed solvent of acetic acid-water suppresses the formation of a sulfuric acid adduct of Nt-butylacrylamide, so that the viscosity of the reaction system does not increase, and further, the reaction of (2) It is considered that the control of the reaction became extremely easy because of the equilibrium reaction.

(Effects and Examples of the Invention) According to the method of the present invention, the temperature control in the reaction can be performed very easily, and further, the reaction can be performed at a low temperature, so that the modified substance and the polymer substance due to the side reaction are unlikely to occur. for that reason,
Since the target Nt-butylacrylamide can be obtained in high quality, the method of the present invention is industrially very useful.

The high-quality Nt-butylacrylamide referred to herein means that the purity thereof is 99.6% or more when analyzed by high performance liquid chromatography, and 99.9% or more is particularly preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A glass container having an inner volume of 3 l was charged with 531 g (10 mol) of acrylonitrile, 743 g (10 mol) of t-butyl alcohol, 741 g of acetic acid and 101 g (2.4 mol / l) of water. In this, 1010 g of 98% sulfuric acid was added to about 10 while keeping the reaction temperature at 25 ° C.
The solution was gradually added dropwise with stirring over time. The viscosity of the reaction solution after the dropping was measured at 20 ° C. and found to be 48 cps.
The reaction liquid was analyzed by high performance liquid chromatography and the reaction yield was calculated.
95%. The reaction solution was gradually poured into a large amount of ice water and stirred to precipitate Nt-butylacrylamide. The precipitated crystals were filtered and washed with water. Next, when the obtained crystals were analyzed by high performance liquid chromatography, the purity was 99.9%, which was a very high quality.

Example 2 Example 1 was repeated except that 140 g (3.7 mol / l) was added instead of 101 g water.

Results: As shown in Table 1. Example 3 The procedure of Example 1 was repeated, except that 584 g (11 mol) was used instead of 531 g of acrylonitrile.

Results: described in Table 1 Example 4 The same procedure as in Example 1 was carried out except that the reaction temperature was -10 ° C instead of 25 ° C.

Result: As shown in Table 1. Example 5 483 g (9.1 mol) was used instead of 531 g of acrylonitrile, 42 g (1.0 mol / l) was added instead of 101 g of water, and the reaction temperature was 35 ° C instead of 25 ° C. Otherwise, the same procedure as in Example 1 was carried out.

Results: As shown in Table 1. Example 6 The same procedure as in Example 1 was carried out except that the reaction temperature was 50 ° C instead of 25 ° C.

Results: As shown in Table 1. Example 7 The same procedure as in Example 1 was carried out except that 605 g (11.4 mol) was used instead of 531 g of acrylonitrile.

Results: As shown in Table 1 Comparative Example 1 The same procedure as in Example 1 was carried out without adding water and using 842 g of acetic acid instead of 741 g of acetic acid. However, the reaction temperature could not be controlled at 25 ℃ because the reaction suddenly occurred during the addition of sulfuric acid.

Comparative Example 2 The procedure of Example 1 was repeated except that water was not added and the reaction temperature was 40 ° C instead of 25 ° C.

Results: described in Table 1 Comparative Example 3 The procedure of Example 1 was repeated except that water was not added and the reaction temperature was 50 ° C instead of 25 ° C.

Results: described in Table 1 Comparative Example 4 The same procedure as in Example 1 was carried out except that 501 g of ethyl alcohol was used instead of 741 g of acetic acid without adding water.

Results: described in Table 1 Comparative Example 5 The same procedure as in Example 1 was repeated except that 501 g of ethyl alcohol was used instead of 741 g of acetic acid and the reaction temperature was 50 ° C. instead of 25 ° C. without adding water. .

Results: As shown in Table 1 Comparative Example 6 Acrylonitrile (1115 g, 21 mol), t-butyl alcohol (520 g, 7 mol) and 98% sulfuric acid (140 g) were charged and reacted at a reaction temperature of 80 ° C. for 3 hours while stirring.

Results: described in Table 1 Comparative Example 7 The same procedure as in Example 1 was performed except that 8 g (0.2 mol / l) was added instead of 101 g of water.

Results: described in Table 1 Comparative Example 8 483 g (9.1 mol) of acrylonitrile instead of 531 g
21.0 g (0.5 mol / l) of water was added instead of 101 g,
Example 1 was repeated except that the reaction temperature was 35 ° C instead of 25 ° C.

Results: Listed in Table 1 Table 1 is a list of Examples (7 cases) and Comparative Examples (8 cases).

The results of Examples 1 to 7 and Comparative Examples 1 to 8 prove the effect of the acetic acid-water mixed solvent of the present invention. In the case of an acetic acid solvent, it is difficult to control the reaction temperature in a low temperature reaction (reaction runaway), and in the case of an ethanol solvent, the reaction rate becomes extremely slow in a low temperature reaction, both of which are not industrially practical. The low temperature reaction mentioned here refers to a reaction at about 30 ° C. or lower.

Claims (3)

(57) [Claims] 1. A method for producing N-t-butylacrylamide by reacting t-butyl alcohol with acrylonitrile in the presence of sulfuric acid, wherein a mixed solvent of acetic acid-water is used as a solvent, and The molarity of water
N characterized by being 0.7 to 4.5 mol / l (liter)
-Method for producing t-butyl acrylamide. 2. The Nt according to claim 1, wherein the molar ratio of t-butyl alcohol to acrylonitrile is 0.9 or more.
-Method for producing butyl acrylamide. 3. The method for producing Nt-butylacrylamide according to claim 1 or 2, wherein the reaction temperature is -30 to 40 ° C.