JPS6327339B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing 1,1,3,3-tetramethyl guanidine salt, and specifically, by reacting cyanogen halide and dimethylamine in the presence of a solvent to produce 1,1,3,3-tetramethyl guanidine salt. The present invention relates to a new method for producing guanidine salts in which an aqueous solvent is used as the solvent. In recent years, 1,1,3,3-tetramethyl guanidine has been expected to find many uses, including as a curing agent for epoxy resins, an etching agent, a raw material for polyurethane resins, and an intermediate raw material for pharmaceuticals. Conventionally, 1, 1,
A method for producing 3,3-tetramethyl guanidine and its salt is a method in which dimethyl cyanamide and dimethylamine hydrochloride are melted at 140 to 150°C (Rec.trav.chim., Bd.66, S.343 [1947 ]), a method of reacting dimethyl cyanamide and dimethylamine hydrochloride in a specific organic solvent such as nitrobenzene at 185 to 200°C [US Pat. No. 3,551,490 (hereinafter sometimes abbreviated as USP 3,551,490)], and is a method in which chlorocyan and dimethylamine are reacted at 140 to 150°C in a specific organic solvent such as toluene [West German Published Patent Application No. 1958095 (hereinafter referred to as
(sometimes abbreviated as DOS1958095)] etc. have been proposed. However, none of these conventionally proposed techniques have been industrially satisfactory. That is, in the above melting method, the yield of 1,1,3,3-tetramethyl guanidine is approximately
Although the methods of USP3551490 and DOS1958095 are both solution reactions, organic solvents such as nitrobenzene and toluene are essential, so there are problems in managing the working environment and recovering the organic solvent after the reaction. Furthermore, since the reaction is carried out under pressure because it requires a relatively high temperature to complete the reaction, it has many problems such as large restrictions on the reactor, and for this reason it has not been widely adopted industrially. Ta. The present inventors discovered that 1,1,3,3-tetramethyl guanidine has recently been found to be in promising demand for the above-mentioned uses, etc., and as a result of extensive research into its industrial production method, the halogenated When cyanide and dimethyl amine are reacted using an aqueous solvent, highly pure 1,1,3,
This was an unexpected discovery in which 3-tetramethyl guanidine can be obtained in high yield, leading to the present invention. Previously proposed USP3551490 and West German Publication No. 1958095 both use specific organic solvents that are incompatible with water, such as nitrobenzene and toluene, and only when the reaction is carried out at a relatively high temperature, that is, 130 to 195°C. , 1,3,3-tetramethyl guanidine is obtained in relatively good yield, but
When water or a water-miscible solvent is employed, the yield is 0% (USP 3551490, column 1, line 57);
The solvent used must be a water-immiscible solvent (“mit
Wasser nicht mischbaren Lo¨sungsmittel”;
DOS1958095, page 5, lines 3-4) is considered an essential requirement. It is not clear why these aqueous solvents, which were actively excluded in the prior art, are surprisingly very useful in the synthesis of 1,1,3,3-tetramethyl guanidine. The details of the present invention will be further explained below. The aqueous solvent used in the present invention refers to water and a mixed solvent containing water as a main component and one or more other solvents that are miscible with water. Examples include methanol, ethanol, isopropanol, etc. Further, the cyanogen halides used in the present invention include chlorcyan, bromcyan, iodocyan, etc., and preferably chlorcyan and bromcyan are used. The reaction method of cyanogen halide and dimethylamine in the present invention is not particularly limited,
There is a method in which either cyanogen halide or dimethylamine is suspended or dissolved in advance in an aqueous solvent, and the other reaction raw material, that is, dimethylamine or cyanogen halide, is successively added thereto. As for which method to use, it is best to choose one that is easy to carry out in actual work, but preferably when using bromic cyanide, a method in which BrCN is dissolved or suspended in a reaction solvent and dimethylamine is sequentially added, In Lucian's case, the opposite method is used. Regarding the molar ratio of dimethylamine and cyanogen halide to be added to the reaction, in general, when dimethylamine is in excess of more than 2 moles per mole of cyanogen halide, the 1,1,3,3-tetramethyl guanidine salt is It is preferred because of its high yield. The reaction temperature is preferably kept at a relatively low temperature during the sequential addition of cyanogen halide or dimethylamine; for example, the reaction system is kept at 30° C. or lower by cooling. In order to obtain the desired high yield of 1,1,3,3-tetramethyl guanidine salt, the reaction system may be kept as it is after the completion of the sequential addition until the reaction is completed, but it is possible to obtain a high yield in a relatively short time. In order to obtain
The temperature is maintained at 60°C to reflux temperature, more preferably 80°C to reflux temperature, particularly preferably 90°C to reflux temperature.
Here, the preference for temperatures below reflux temperature does not mean that heating the reaction system above reflux temperature must be particularly avoided; even below reflux temperature, high yields can be achieved at an industrially necessary speed. 1,
It is used in the sense that 1,3,3-tetramethyl guanidine salt can be obtained. In this manner, according to the present invention, the hydrohalide salt of 1,1,3,3-tetramethyl guanidine can be obtained industrially and very easily from cyanogen halide and dimethylamine. Furthermore, free 1,
1,3,3-Tetramethyl guanidine can be easily obtained from an aqueous solution of a hydrohalide according to a conventional method.
Add NaOH aqueous solution and release 1,1,3,3
- A method of fractionating and purifying tetramethyl guanidine is adopted. Specific examples of embodiments of the present invention will be described below with reference to Examples. Example 1 40.0 g of bromic cyanide (BrCN) was placed in a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a cooling tube.
(0.378 mol) and 20 ml of water were added and suspended, and 120 ml (1.097 mol) of a 50% aqueous dimethylamine solution was added dropwise over 30 minutes. During the first half of the reaction, especially until approximately 2/3 of the dropwise dimethylamine aqueous solution is added, there is a clear exotherm, so the whole is cooled in an ice-water bath and kept at 15-30°C. Immediately after the dropwise addition is completed, the temperature is raised and kept at 48-52°C for 20 hours to complete the reaction. Obtain a colorless and transparent liquid. Concentrate under reduced pressure and dry in a vacuum dryer kept at 60°C until constant temperature is reached. Yield 73.6g, yield 99.5%,
The melting point was 166.5-176.5°C. When this substance is recrystallized from hot ethanol, the melting point is 185.0-186.0℃.
The elemental analysis results were in good agreement with the measured value as tetramethyl guanidine hydrobromide.

[Table] Example 2 40.0 g of bromic cyanide (BrCN) was placed in a reaction vessel equipped with a stirrer, thermometer, gas introduction tube, and cooling tube.
(0.378 mol), 120 ml of water are added and, under suspension, dry dimethylamine gas is introduced until saturation. Since there is heat generation at the beginning of introduction, cool the whole thing in an ice water bath.
Keep the reaction temperature below 20°C. Absorption of dimethylamine ceases in approximately 1 hour and saturation occurs. The amount of dimethylamine fed was 144 g. 15~20℃ as is
Keep for 24 hours to complete the reaction. By concentrating and drying, the desired hydrobromide salt is obtained. Yield 74.0g,
The yield was 99.8%, and the melting point was 167-178°C. Example 3 900 ml of 50% dimethylamine aqueous solution was placed in a reaction vessel equipped with a stirrer, thermometer, gas introduction tube, and cooling tube.
(8.225 mol) was added, and while stirring, 180 g (2.928 mol) of newly synthesized chlorocyan (Cl.CN) was gently warmed and introduced into the reaction vessel through the gas introduction tube. White smoke is produced and a gradual fever is observed. Cool the whole thing in a cold water bath and keep it below 30℃. 2
Finish introducing Chlorcian in time. Immediately after completion of the reaction, raise the temperature and keep at 60℃ for 12 hours to complete the reaction. Excess dimethylamine was distilled off under reduced pressure, and the mixture was further concentrated. When 200 ml of water was distilled out, the concentration was stopped. Under cooling, 240 g of a 50% aqueous sodium hydroxide solution was added to 1000 ml of benzene, and the mixture was thoroughly stirred. After separating a small amount of precipitated sodium chloride, the aqueous layer is extracted repeatedly with a large amount of benzene. The benzene layers are combined, dried with anhydrous sodium carbonate, and then distilled under reduced pressure to collect a fraction at 70-78°C/22mmHg. yield
287.0g, yield 85.1%, purity 98.2%. Example 4 The reaction was started with the same composition as in Example 1, the temperature was raised immediately after the completion of the dropwise addition, and the temperature was kept at 90 to 95°C for 4 hours.
The reaction was completed. After the reaction is completed, excess dimethylamine is distilled off, and 50 ml of water is further distilled off under reduced pressure. Cooled 50% aqueous sodium hydroxide solution 34
g, add 200 ml of benzene, separate the precipitated sodium bromide, separate the layers, and repeat the extraction of the aqueous layer with a large amount of benzene. The benzene layers were combined, dried over anhydrous sodium carbonate, and then fractionally distilled. 50~52℃/11mm
Collect the Hg fraction. The yield was 37.0 g, yield 85.1%, and purity 99.0%.

Claims (1)

[Claims] 1. In a method for producing 1,1,3,3-tetramethyl guanidine salt by reacting cyanogen halide and dimethylamine in the presence of a solvent, it is possible to use an aqueous solvent as the reaction solvent. Features 1,
Method for producing 1,3,3-tetramethyl guanidine salt. 2. A method for producing 1,1,3,3-tetramethyl guanidine salt according to claim 1, characterized in that the reaction is carried out under non-pressurized conditions.