CS221001B1 - Process for producing sodium monomethyldithiocarbamate - Google Patents

Abstract

The essence of the invention entitled "Method for the production of sodium monomethyldithiocarbamate" is the improvement of the method of its production in the form of an aqueous solution consisting in the condensation of monomethylamine, sodium hydroxide and carbon disulfide preferably in an equimolar ratio of the reacting components at temperatures of + 5 to + 30 degrees Celsius, while carbon disulfide is dosed into an aqueous solution of monomethylamine and sodium hydroxide followed by further reaction of the reaction mixture. The invention can be used in the field of organic technology in the production of sodium monomethyldithiocarbamate.

Description

221001

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of sodium monomethyldithiocarbamate by condensation of monomethylamine, sodium hydroxide and carbon disulphide in equimolar dosages of reaction components.

BACKGROUND OF THE INVENTION The invention relates to an aqueous solution of sodium monomethyldithiocarbamate which is used as a fungicide preparation.

According to the diosial method, sodium monomethyldithiocarbamate is produced by aqueous condensation of monomethylamine, carbon disulphide and hydroxides in the form of an aqueous solution.

The condensation takes place in an aqueous medium at 20 to 40 ° C under normal pressure for 10 hours followed by 2 hours of unreacted CS2. CH 3 -NH 2 + NaOH + CS 2 -

-> CH 3 -NH — C — SNa + H 2 O

II p

According to the conventional method, carbon disulphide is added in a slight excess to mono-methylamine. Unreacted CS 2 was allowed to settle off condensation.

The sedimentation time is on average 2 hours.

A disadvantage of the process is the necessity of the CS2 sedimentation process, returning it to the production cycle, contaminated with reaction fumes and moisture. Another disadvantage of the conventional procedure is that excess NaOH is charged into the condensation of monomethylamine with CS2 and NaOH.

Excess sodium hydroxide remains unreacted from time to time and prevents the aqueous solution of sodium monomethyldithiocarbamate.

The above-mentioned drawbacks are overcome by the methods of the invention characterized in that a 35 to 45% aqueous solution of monethylamine, a 30 to 40% aqueous solution of sodium hydroxide and carbon disulfide are condensed, wherein the molar proportion of the reactants of monomethyl amine sodium hydroxide to carbon disulphide is 1.0 to 1.03 to 1.0 to 1.3, at 5 to 30 ° C, for 3 to 5 hours dosing the carbonate into an aqueous solution of monomethylamine and sodium hydroxide followed by reaction of the reaction mixture for 2-3 hours .

According to the process of the invention, the process is simplified by making the process of sedimentation and operation associated with returning CS2 to the production process unnecessary. Another advantage is the shortened addition of CS2 and response.

According to the invention, CS 2 does not get into the final product. Another advantage is that a sodium monomethyldiocarbamidate solution is prepared at a concentration of 30-40%, a substantially higher purity and low alkali, which is desirable from the application point of view. Example 1

Into a 1L three-necked flask equipped with a stirrer, a thermometer and a feed funnel, 25 mL of water was gradually added, and 228 mL of monomethylamine 41.28% aqueous solution was added, corresponding to 82.0 g of 100% monomethylamine, followed by 257 mL of 31.1% NaOH (107.1 g, 100% NaOH).

During the addition, the mixture was maintained at 20-30 ° C with a water bath. After the feeds were added, the mixture was stirred for 30 minutes at this temperature. CS2 was then added over 3 hours, adding 158 ml in total, corresponding to 200.7 g CS2. During the addition of CS 2, the reaction mixture was stirred and cooled with an aqueous bath to keep the temperature below 30 ° C.

After completion of CS2 dosing, the reaction mixture was stirred for 2 hours at 20-30 ° C. A sample was taken from the reaction mixture to determine: the sodium monomethyl dithiocarbamate concentration was 38.8% by weight, the solution density was 1.218 kg / m 3. The free NaOH was 0.2 g / l, the solution obtained was reddish-red colored, the mechanic content 0%. The reaction yield was consistent with the complete stoichiometric conversion of the raw materials into the desired product. Example 2

It was similarly treated as in Example 1, and 228 ml of monomethylamine of 41.28% aqueous solution was metered in sequentially, followed by 82.0 g of 100% monomethylamine, followed by the addition of 257 ml of a 31.1% aqueous solution of NaOH, which is 107%. 1 g of 100% NaOH. During the addition, the temperature was maintained at 20-30% C with an aqueous bath and stirred for 30 minutes. CS2 was added over 3 hours, adding 158 ml (200.7 gjCS2) in total.

During the addition of CS 2, the reaction mixture was stirred and cooled with a water bath so that the temperature did not exceed 30 ° C.

Upon completion of CS2 dosing, a sample was taken to determine: sodium monomethyldithiocarbamate concentration 40.10% by weight, free NaOH was 0.21 g / l, CS2 = 0, specific gravity 1.231 kg / m < 3 >

Claims (3)

SUBJECT A process for the production of sodium monomethyldithiocarbamate in the form of an aqueous solution by condensation of monomethylamine, sodium hydroxide and carbon disulphide, characterized by condensing 35 to 45% aqueous monomethylamine, 30 to 40% aqueous sodium hydroxide and carbon disulphide, wherein the molar ratio of monomethylamine reactants: sodium hydroxide: carbon disulfide is 1: 1.0 to 1.03: 1.0 to 1.03 at a temperature of 5 to 30 ° C, for 3 to 5 hrs. 2. The process of claim 1, wherein the monomethylamine, sodium hydroxide and carbon disulfide are condensed in a molar ratio. 1: 1: 1 3. Method according to claim 1 or 2, characterized in that the condensation is carried out for 5 hours without reaction.