JPS61212575A - Production of high-purity uron ring compound - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high purity, by completing the dimethylolation in aqueous phase in the reaction of dialkylurea with formaldehyde in the presence of an acid catalyst, removing water by azeotropic distillation, and completing the cyclization with a dehydration agent. CONSTITUTION:A dialkylurea is made to react with formaldehyde in an aqueous phase in the presence of an acid catalyst such as hydrochloric acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid and/or their acid salt to complete the dimethylolation reaction. The water existing in the reaction system is re moved almost completely by azeotropic distillation, and the dimethylolated urea is completely dehydrated and cyclized by the addition of a dehydration agent such as phosphorus pentoxide, boric anhydride, etc., to obtain the objective compound of formula (R and R' are alkyl which may have branched chain) in high yield and purity with simple operation suppressing the side reactions. The compound is useful as a high-performance solvent, etc., used in electronic industries, pharmaceuticals, general chemical industry, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing a uron ring compound useful as a high-performance solvent used in the electronic industry, pharmaceutical field, and general chemical industry.

A uron ring compound is a tetrahydro-3,5-dialkyl-4) represented by the following structural formula:
A common name for -1,3,5-oxadiazin-4-one,
Hereinafter, this compound will be referred to as N,N'-dialkyluron.

Prior Art Conventionally, uron ring compounds have been useful as dyeing aids, and various manufacturing methods are known. For example, J, Org.

Chem, 2B, 1ll176-7 (1963),
Bul1, Chem, Soc.

Japan, 11.248-261 (1936), J
, Org, Chew.

29, 2777-g (1964), etc., the manufacturing method thereof is described.

Problems to be solved by the invention Conventional dehydration condensation reaction of dialkylurea and paraformaldehyde (J, Org, Chew, 29.27
77-8 (1964)), unreacted shea, '7rekyl chloride, and dimethylol of dialkyl urea remain. In addition, various by-products are generated because the reaction is not completely carried out, and it is difficult to separate and remove these by ordinary purification means such as distillation. especially,
It cannot be used for various purposes in the electronic industry where electrical properties are applied. Compounds of fairly high purity are required for use in medicine or as functional organic materials.

Means for Solving the Problems In order to solve the above problems, the present inventors completed the dimethylolation by reacting dialkylurea and formaldehyde in the presence of an acid catalyst, and then removed water by azeotropy. After that, a dehydrating agent was further added to dehydrate the dimethylolated urea, thereby completely dehydrating and cyclizing the dimethylolated urea, thereby successfully obtaining a highly pure uron ring compound.

That is, in the present invention, when a dialkylurea and formaldehyde are reacted in the presence of an acid catalyst, dimethylolization is completed in the aqueous phase, water is removed by azeotropy, and then a dehydrating agent is added to carry out cyclization. Provided is a method for producing a uron ring compound represented by the formula: [wherein R and R' are the same or different and represent an alkyl group that may have a branched chain].

The reaction between a dialkylurea and formaldehyde is carried out by dissolving the dialkylurea in an aqueous formaldehyde solution, for example, a 35% aqueous solution, and using an acidic catalyst such as hydrochloric acid, sulfuric acid, phosphoric acid,
This is carried out by adding para-toluenesulfonic acid and/or an acid salt thereof, and stirring at room temperature for 1 to 3 hours. This reaction yields a dimethylolated dialkyl urea. Formaldehyde is used in an amount of 2 mol or more, preferably 2.05 to 2.5 mol, per 1 mol of dialkylurea. The acidic catalyst is used in an amount of about 0.5% by weight of the raw material urea compound. After the reaction is completed, almost all of the water present in the reaction system is removed by heating azeotropically using an azeotropic solvent such as benzene, toluene, or xylene. Finally, in order to complete the reaction, a suitable dehydrating agent such as P t Os, boric anhydride, etc. is added to the azeotropic solvent solution of the dimethylol compound, preferably 5 to 20 parts by weight per 100 parts by weight of the dimethylol compound, and the mixture is heated under reflux. . The dehydrating agent can be removed by appropriate means such as filtration or centrifugation, and the azeotropic solvent can be distilled off to obtain the uron ring compound.

The dialkylurea that can be used in the present invention is a urea having two alkyl groups having the same or different linear or branched chains, and the number of carbon atoms in the alkyl group is not limited, but is preferably 4 or less.

Further, according to the method of the present invention, there are few side reactions, and a highly pure compound can be obtained in high yield with simple operations.

Examples will be described below.

Example! 88.11 g (1 mol) of 1,3-dimethylurea at 35%
The mixture was dissolved in 188 g (2.2 mol) of formalin solution, 0.5IIi of concentrated hydrochloric acid was added thereto, and the mixture was stirred at room temperature for 1 hour.

After confirming the disappearance of the raw material urea by TLC, add 20% benzene to it.
Add 0tai, add Dean Stark distiller,
The produced water and the water in the raw material formalin solution were removed from the system by azeotropy. After removing most of the free water, about 20 g of phosphorus pentoxide was added and heated under reflux for 1 hour to complete the cyclization reaction. After confirming the disappearance of the dimethylol compound by GLC, the reaction solution was cooled, then phosphorus pentoxide was removed by filtration, and neutralized with anhydrous potassium carbonate. After drying with magnesium sulfate and distilling off the benzene, 10%
A 1°C/3mmHg fraction was collected. The yield of 99% or higher purity was 98%.

Comparative example 1-1 The same reaction as in the example was carried out without the addition of phosphorus pentoxide.

Since dehydration was incomplete and dimethylol compounds remained, side reactions such as dehydration occurred during distillation, and the yield of 99% or higher purity was 66%.

Comparative Example If-1 88.11 g (1 mol) of 1,3-dimethylurea and 84 g (2.8 mol) of paraformaldehyde were mixed in 5001 g of
Ili was placed in a necked flask with a stirrer, the temperature of the oil bath was fixed at 122°C ± 2°C, and 0.3 mol of boric acid was added.
．． After adding 5g and reacting for 3 hours, distillation was performed to obtain 101
A fraction of °C/3 mmHg was obtained.

During the distillation, high purity products were not obtained due to the decomposition of residual paraformaldehyde, and complex by-products were observed as residues. In order to obtain a purity of 99% or more from this product, further purification was repeated, and the yield was 42%.

Examples 2 to I5, Comparative Examples 1-2 to 15, Comparative Example It-2
-15 are the compounds shown in Table 1 as dialkylureas (
Example 11 Comparative Example I-
It was carried out in the same manner as f and Comparative Example 11-1.

4. The experimental results are shown in Table-1.

Incidentally, in all of the even-numbered Examples, 20 g of boric anhydride was used instead of phosphorus pentoxide.

Procedural amendment (voluntary) May 8, 1985

Claims (1)

[Claims] 1. When dialkylurea and formaldehyde are reacted in the presence of an acid catalyst, dimethylolation is completed in the aqueous phase, and then water is removed by azeotropy, and then,
A method for producing a uron ring compound, which comprises adding a dehydrating agent to complete the cyclization. 2. The method according to item 1, wherein the dehydrating agent is phosphorus pentoxide or boric anhydride.