JPH0725539B2 - Method for producing dicyanamide metal salt - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improved method for producing a dicyanamide metal salt.

(Prior Art) Metal dicyanamide is a strong bactericidal disinfectant effective against both Gram-positive and Gram-negative bacteria, N, N "-bis (4-
Chlorophenyl) -3,12-diimino-2,4,11,13-tetraazatetradecanediimidamide (generic name, chlorhexidine) is a useful compound used as a starting material or an intermediate.

A method for producing a dicyanamide alkali metal salt by reacting ammonia, cyanogen halide and an alkali metal hydroxide in a water solvent system is known (US Pat. No. 342965).
8).

(Problems to be solved by the invention) However, in this method, approximately equivalent amounts of both cyanogen halide and alkali metal hydroxide are reacted with 1 equivalent of ammonia, and the dicyanamide alkali metal salt and alkali metal salt are reacted. In addition to halides, it has the drawback of producing ammonium halide as a by-product, and the purity of the resulting dicyanamide alkali metal salt is 50
It is as low as ~ 73%. Furthermore, the yield of the dicyanamide alkali metal salt is as low as 33 to 73%, which is not industrially satisfactory.

(Means for Solving Problems) The inventors of the present invention have earnestly studied to solve the problems found in the related art. As a result, ammonia, cyanogen halide and metal hydroxide in an aqueous solvent, approximately 1:
The present invention has been completed by finding that the dicyanamide metal salt can be industrially advantageously produced by reacting at an equivalent ratio of 2: 3.

That is, the present invention was selected from 1.8 to 2.2 equivalents of cyanogen halide and alkali metal hydroxide, alkaline earth metal hydroxide, copper hydroxide and zinc hydroxide with respect to 1 equivalent of ammonia in an aqueous solvent. Disclosed is a method for producing a dicyanamide metal salt, which comprises reacting 2.8 to 3.2 equivalents of a metal hydroxide.

Hereinafter, the method of the present invention will be described in more detail.

The chemical reaction formula for the production of dicyanamide metal salt by the method of the present invention is It is represented by. Here, X represents a halogen atom, M represents a metal atom, and n represents the valence of the metal atom.

The cyanogen halide used in the method of the present invention includes cyanogen chloride, cyanogen bromide, cyanogen iodide and the like, and cyanogen chloride is the cheapest and economically preferable. The form of cyanogen halide may be any of gas, liquid and solid, but it is usually preferable to use gas.

Examples of the metal hydroxide used in the present invention include alkali metal hydroxides, alkaline earth metal hydroxides, copper hydroxide and zinc hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, Zinc hydroxide and the like are industrially easily available, inexpensive, and economically preferable.

The amount of cyanogen halide used is 1.5 to ammonia.
The range of 2.5 equivalents, preferably 1.8 to 2.2 equivalents is good. When it is less than 1.5 equivalents or more than 2.5 equivalents, the formation of by-products and the decomposition of the product dicyanamide metal salt increase, and the yield and purity decrease.

The amount of the metal hydroxide used is 2.5 to 3.5 equivalents, preferably 2.8 to 3.2 equivalents, relative to ammonia. If it is less than 2.5 equivalents or more than 3.5 equivalents, the formation of by-products and the yield and purity of the product dicyanamide metal salt decrease.

The reaction is usually carried out by using a water solvent, and ammonia is charged at a concentration of 5 to 25% by weight, preferably 10 to 20% by weight, and at the same time, a metal halide or an aqueous solution thereof or a water solution thereof is added while adding a cyanogen halide. This is done by adding. The reaction is carried out under atmospheric pressure using a normal pressure vessel, but may be carried out under pressure using a pressure resistant vessel such as an autoclave.

The reaction temperature is 0 to 60 ° C, preferably 10 to 40 ° C. If the temperature is lower than 0 ° C, a large amount of unreacted raw material remains, while if the temperature exceeds 60 ° C, the formation of by-products and the decomposition of the product dicyanamide metal salt increase, and the yield and purity decrease.

Although the reaction time varies somewhat depending on the temperature, it is preferably 0.5 to 6 hours, and if it is long, decomposition of the dicyanamide metal salt and formation of by-products are unfavorable.

The dicyanamide metal salt can be isolated by filtering the reaction mixture after the reaction, or by precipitating the dicyanamide metal salt produced by concentrating a part of the reaction mixture and filtering it. The dicyanamide metal salt thus obtained can be purified by washing with cold water or an alcohol solvent such as methanol or ethanol or an aqueous solution containing a ketone solvent such as methyl ethyl ketone, if necessary. A high-purity dicyanamide metal salt can be obtained in a yield of 90% or more.

By this method, dicyanamide sodium salt, dicyanamide potassium salt, dicyanamide lithium salt, dicyanamide calcium salt, dicyanamide magnesium salt, dicyanamide barium salt, dicyanamide zinc salt, high-purity dicyanamide metal salt such as dicyanamide copper salt, Manufactured in high yield.

(Examples) Hereinafter, the present invention will be further described with reference to Examples. However, these are merely examples for description, and the present invention is not limited to these examples.

Example 1 Preparation of dicyanamide sodium salt 32.7 g of 25% aqueous ammonia and 100 ml of water in a 500 ml four-necked flask.
I put it in. While stirring, 61.5 g of cyanogen chloride was introduced into the reactor as a gas from the gas introduction pipe, and at the same time sodium hydroxide was added.
Addition of a solution consisting of 57.6 g and 60 g of water to the reactor was started. In 40 minutes, the dropping of the aqueous sodium hydroxide solution and the introduction of cyanogen chloride were completed. During this time, the reaction temperature is 20-
The pH was kept in the range of 8 to 9 at 30 ° C. Cool to 5 ℃ 30
After stirring for 1 minute, the reaction mixture was filtered off, washed with cold water and dried under reduced pressure. The obtained product was 41.0 g, the purity as dicyanamide sodium salt was 94.3%, and the yield from the used ammonia was 90.5%.

Example 2 Preparation of dicyanamide calcium salt 32.7 g of 25% ammonia water and 100 ml of water in a 500 ml four-necked flask.
I put it in. Cyanide 6 with stirring as in Example 1
While introducing 1.5 g, 53.4 g of calcium hydroxide was added little by little. 150 minutes after the start, the introduction of cyanogen chloride and the addition of calcium hydroxide were completed. During this period, the reaction temperature was kept at 15 to 25 ° C. and the pH was kept at 8 to 9. The reaction solution
After cooling to 10 ° C. and stirring for 1 hour, the reaction mixture was filtered to remove a small amount of insoluble matter that had precipitated. Concentrate the filtrate,
After cooling, the precipitate was filtered off, washed with cold water, and dried under reduced pressure. The obtained product was 43.3 g, the purity as a dicyanamide calcium salt was 90.1%, and the yield from the used ammonia was 94.4%.

Example 3 Production of potassium dicyanamide salt In a 500 ml four-necked flask, 32.7 g of 25% aqueous ammonia and 60 ml of water were added.
I put it in. A gas of 61.5 g of cyanogen chloride was introduced over 1 hour while stirring, and at the same time, a solution of 84 g of potassium hydroxide and 90 ml of water was added dropwise over 1 hour. Then cool to 10 ℃,
After stirring for a minute, the reaction mixture was filtered off and washed with cold water.
The product obtained after drying under reduced pressure was 49.6 g, the purity as a dicyanamide potassium salt was 92.5%, and the yield from the used ammonia was 91%.

Example 4 Preparation of dicyanamide zinc salt 3500 g of 25% aqueous ammonia and 100 ml of water in a 500 ml four-necked flask.
I put it in. While stirring, 56.1 g of cyanogen chloride was introduced as a gas over 2 hours, and simultaneously, 124 g of zinc hydroxide was added little by little over 2 hours. The reaction temperature at this time was 20 to 30 ° C. After the reaction, the mixture was cooled to 10 ° C., the precipitate was filtered off, washed with cold water, and dried under reduced pressure. The yield of the obtained dicyanamide zinc salt was 92.0%.

(Effect) According to the method of the present invention, the disadvantage of the low yield of the dicyanamide metal salt, which has been a problem in the conventional method, can be solved all at once, and in addition, a highly pure dicyanamide metal salt can be obtained.

Claims (1)

[Claims] 1. A metal selected from 1.8 to 2.2 equivalents of cyanogen halide and an alkali metal hydroxide, an alkaline earth metal hydroxide, copper hydroxide and zinc hydroxide with respect to 1 equivalent of ammonia in a water solvent. A method for producing a dicyanamide metal salt, which comprises reacting 2.8 to 3.3 equivalents of a hydroxide.