JPH0514707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized by catalytic reduction of 2-imidazolidinone and formaldehyde or paraformaldehyde using a hydrogenation catalyst in the presence of a solid acid. The present invention relates to a method for producing 1,3-dimethyl-2-imidazolidinone. 1,3-dimethyl-2-imidazolidinone is
It occupies an important position as a polar aprotic solvent, and has a wide range of uses such as solvents for organic synthesis reactions, solvents for polymer compounds, and extraction solvents for aromatic hydrocarbons and unsaturated hydrocarbons during petroleum refining. It is an extremely useful compound. The following methods are known as conventional methods for producing 1,3-dimethyl-2-imidazolidinone. (1) Method described in U.S. Patent No. 2,422,400 (a) Step of producing and separating methylol intermediate from 2-imidazolidinone and formaldehyde in a basic atmosphere, (b) After adjusting the pH of the reaction solvent , a step of catalytic reduction using a catalyst, Part 2
Requires a process. (2) Method described in JP-A-52-71419 2-imidazolidinone and formaldehyde
Hydrogenate in an acidic atmosphere with pH 3 to 5 to produce 1,3
A method for producing -dimethyl-2-imidazolidinone in one step has been developed. Unexamined Japanese Patent Publication 1972-
Although the substance for making the reaction solution acidic is not specified in Publication No. 71419 and is unclear, Example 1 describes a method for adjusting the reaction solution to pH 3 by adding phosphoric acid. In order to carry out this method, a corrosion-resistant reactor is required, and furthermore, after the reaction is completed, salts are generated by neutralizing the reaction solution and are difficult to separate. (3) Method described in JP-A-53-98965 In the presence of an acidic substance, 1,3-bis(hydroxymethyl)- or 1,3-bis(alkoxymethyl)-2-imidazolidinone is hydrogenated as a catalyst. A method for catalytic reduction using
However, in order to produce the raw material 1,3-bis(hydroxymethyl)- or 1,3-bis(alkoxymethyl)-2-imidazolidinone, 2-imidazolidinone and A methylolization process must be performed from formaldehyde, which is essentially a two-stage reaction. Furthermore, since the catalytic reduction is carried out in the presence of an acidic substance at a pH of 3 or less, a corrosion-resistant device is required as in JP-A-52-71419, and there is the problem of separation of salts produced by neutralization after the reaction is completed. occurs. As mentioned above, the conventional method is 1,3-dimethyl-
This method was not satisfactory as an industrial method for producing 2-imidazolidinone. The present inventors have conducted extensive research to establish a method for producing 1,3-dimethyl-2-imidazolidinone from 2-imidazolidinone in one step and under mild conditions that are industrially possible. They discovered that a specific solid acid was effective and completed the present invention. That is, in the present invention, 2-
The present invention relates to a method for producing 1,3-dimethyl-2-imidazolidinone, which comprises catalytically reducing imidazolidinone and formaldehyde or paraformaldehyde using a hydrogenation catalyst. The solid acid used in the present invention is obtained by firing sulfate ions and alumina, or sulfate ions, phosphate ions, and alumina. The ratio of each atom constituting the solid acid is: in the case of sulfate ions and alumina, S/Al is 0.01 to 0.06; in the case of sulfate ions, phosphate ions, and alumina,
(P+S)/Al is 0.2 without 0.02, S/P is 0.02
or 0.8. If the atoms constituting the solid acid are within this range, a solid acid with good activity and selectivity can be obtained. To prepare the solid acid of the present invention, alumina is added to an aqueous solution containing sulfate ions or sulfate ions and phosphate ions, which is obtained by dissolving sulfuric acid, phosphoric acid, or their aluminum or ammonium salts in water. Mix well, dry, and then bake.
In addition to the above method, to prepare a solid acid from sulfate ions and alumina, alumina may be brought into contact with an aqueous solution containing sulfate ions, followed by filtration, and the resulting solid may be calcined. The calcination temperature when preparing the solid acid of the present invention is
300°C or higher, preferably 500 to 900°C,
The firing time is suitably 1 to 10 hours, preferably 2 to 4 hours. The obtained solid acid can be used as is or after boiling with 2 to 10 times the amount of water.
Filter, wash with water and use for reaction. Although the alumina used for the solid acid is not particularly limited, powdered or beaded γ-alumina is preferred for practical purposes. Formaldehyde or paraformaldehyde, which is one of the raw materials of the present invention, is reacted and provided as an aqueous solution or a methanol solution, and the amount used is 2
A suitable amount is 2 to 4 times the molar amount of -imidazolidinone. The hydrogenation catalyst in the method of the present invention is not particularly limited as long as it is a hydrogenation catalyst obtained from palladium, nickel, or platinum, but is preferably at least one selected from palladium carbon, Raney nickel, and platinum carbon catalysts, and particularly preferably It is palladium on carbon. The amount used is preferably 0.1 to 10% by weight based on the 2-imidazolidinone. The amount of solid acid used is suitably 1 to 10% by weight based on the raw material 2-imidazolidinone, and the reaction solvent is suitably water or an alcoholic solvent. The reaction temperature is 100 to 200°C, preferably 140 to 170°C, and the hydrogen pressure during catalytic reduction is 20°C.
from 150Kg/cm ² , preferably from 40 to 100Kg/cm ²
It is. The solid acid of the present invention does not generate any sulfur compounds during firing, and it is confirmed from the weight of the fired product that sulfur compounds and phosphorus compounds are incorporated into the solid acid composition. Moreover, even if this solid acid was boiled with 4 times the amount of water for 2 hours, filtered and washed with water 5 times, and then calcined at a high temperature of 900°C for 3 hours, the activity in this reaction remained. It was possible to reuse this solid acid in the reaction of the present invention five times without deterioration. That is,
It is thought that there is almost no desorption of sulfur and phosphorus compounds from the solid acid due to heat, water washing, etc. A characteristic effect of the present invention is that the reaction is carried out in a neutral state with a pH of 6 to 7.
Since the pH of the reaction solution during and after the reaction is near neutral, there is no fear of corrosion of the reaction equipment, and there is no need to neutralize after the reaction. Therefore, after the completion of the reaction, high purity 1,3-dimethyl-2-imidazolidinone can be obtained by a simple operation of filtering out the solid acid and hydrogenation catalyst from the reaction solution and distilling them. After the reaction, the solid acid and hydrogenation catalyst recovered by filtration can be reused as they are in the next reaction without being separated, so the method of the present invention is industrially very advantageous. Production example 1 (Preparation of solid acid) Add 5 g of 98% sulfuric acid to 100 ml of water so that the atomic ratio S/Al is 0.03, add 100 g of γ-alumina powder to this solution with stirring, and then add it to the solution using an evaporator. The solid acid was evaporated to dryness under reduced pressure using a vacuum cleaner, and further calcined at 500°C for 3 hours in an air atmosphere to obtain 102 g of a solid acid. This solid acid had many acid sites exhibiting an acid strength of Hammett's acidity function (hereinafter referred to as "Ho") -8.2 or less. Further, no generation of sulfur compounds was observed during firing in the above operation. Production example 2 (Preparation of solid acid) 100 g of γ-alumina powder in 500 ml of 1N sulfuric acid aqueous solution
was added and stirred for 10 minutes, then filtered. After drying the separated γ-alumina powder,
It was calcined at 500°C for 3 hours to obtain 102g of solid acid. On the other hand, the filtrate was adjusted and the sulfate ion concentration in the filtrate was measured. The decrease in sulfate ions was determined from the sulfate ions contained in the filtrate, and the atomic ratio of the obtained solid acid was calculated, and S/Al was 0.03. This solid acid had many acid sites exhibiting an acid strength of Ho<-8.2. Furthermore, no generation of sulfur compounds was observed during firing. Production example 3 (Preparation of solid acid) The atomic ratio (S+P)/Al is 0.11, and S/P is
0.41, add 5 g of 98% sulfuric acid to 100 ml of water.
After dissolving 12.5 g of 80% phosphoric acid and adding 100 g of γ-alumina to this solution with stirring, it was evaporated to dryness under reduced pressure using an evaporator, and then calcined in an air atmosphere at 500°C for 3 hours to form a solid acid. Obtained 108g. This product had many acid sites showing an acid strength of Ho<-8.2. Further, no generation of sulfur compounds was observed during firing. Production example 4 (Preparation of solid acid) The atomic ratio (S+P)/Al is 0.09, and S/P is
0.16, add 2 g of 98% sulfuric acid to 100 ml of water.
After dissolving 12.5 g of 80% phosphoric acid and adding 100 g of γ-alumina to the solution with stirring, 107 g of solid acid was obtained according to Production Example 3. This one is Ho<-
It had many acid sites showing an acid strength of 8.2. Also,
No generation of sulfur compounds was observed during firing. Production Example 5 (Preparation of Solid Acid) 300 ml of water was added to 100 g of the solid acid obtained in Production Example 3, and after boiling for 2 hours, it was washed separately with water. The same operation was repeated four more times, followed by drying and calcining at 900° C. for 3 hours in an air atmosphere to obtain 99 g of solid acid.
This product had Ho<-8.2, and no sulfur compounds were observed to be generated during firing. Example 1 2-imidazolidinone (purity 86.3%, water content
13.5%) was dissolved in 40 ml of methanol, 0.7 g of activated carbon was added thereto, and the mixture was stirred at 40 to 50°C for 30 minutes. After separating the activated carbon, 47.8 g of a 46% formaldehyde solution (44% methanol, 10% water), 2 g of the solid acid obtained in Production Example 1, and 1 gram of 5% palladium on carbon were added.
After hydrogen substitution, hydrogen was introduced into the autoclave, and the mixture was reacted at 140 to 150°C and 40 to 80 kg/cm ² for 4 hours. After the reaction was completed, the contents were taken out, the catalyst and solid acid were filtered out, and the pH of the filtrate was measured with a PH meter, and it was found to be 6.1. After water and methanol are distilled off from this filtrate, vacuum distillation is performed.
At 120°C/25mmHg, 32.3g of 1,3-dimethyl-2-imidazolidinone was obtained. This product has a yield of 85.0% and a purity determined by gas chromatography.
It was 99%. Examples 2 to 5 Using the solid acids obtained in Production Examples 2 to 5, reactions and treatments were performed according to Example 1. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1. In the presence of sulfate ions and alumina, or a solid acid obtained by calcining sulfate ions, phosphate ions and alumina, 2-imidazolidinone and formaldehyde or paraformaldehyde are combined using a hydrogenation catalyst. A method for producing 1,3-dimethyl-2-imidazolidinone, which comprises carrying out catalytic reduction. 2 When the atomic ratio constituting the solid acid is sulfate ion and alumina, S/Al is 0.01 to 0.06, and when sulfate ion, phosphate ion and alumina are used,
(S+P)/Al is 0.02 to 0.2 and S/P is 0.02
The method according to claim 1, wherein the solid acid has a concentration of 0.8 to 0.8. 3. Claim 1, wherein the solid acid is a solid acid obtained by drying a mixture of alumina and an aqueous solution containing sulfate ions or sulfate ions and phosphate ions, and then calcining the mixture at 300°C or higher. the method of. 4. The method according to claim 1, wherein the hydrogenation catalyst is at least one hydrogenation catalyst obtained from palladium, nickel or platinum.