CS209578B1 - A process for producing sodium dimethyldithiocarbamidate - Google Patents

Abstract

A method for producing sodium dimethyldithiocarbamate in the form of an aqueous solution by condensation of dimethylamine, sodium hydroxide and carbon disulfide, characterized in that a 36 to 14% aqueous solution of diethylamine, a 30 to 45% aqueous solution of sodium hydroxide and carbon disulfide are condensed, the molar ratio of the reacting components dimethylamine: sodium hydroxide and carbon disulfide being 1:1:1.0 to 1.03, at a temperature of 5 to 25 °C, during 1 to 3 h of dosing carbon disulfide into an aqueous solution of dimethylamine and sodium hydroxide, with subsequent reaction of the reaction mixture for 1 h.

Description

The present invention relates to a process for the production of sodium dimethyldithiocarbamidate by codification of dimethylamine, ground hydroxide and carbon monoxide in equimolar dosing of reaction components.

. An aqueous solution of sodium dimethyldithiocarbamidate is used in the polymerization of rubber.

According to the conventional production process, sodium dimethyldithiocarbamidate is produced in the form of an aqueous solution, condensation of dimethylamine, carbon disulphide and sodium hydroxide.

Condensation is carried out in an aqueous medium at a temperature of + 15 ° C to + 20 ° C under normal pressure for 8 hours of reaction.

CH,

CH

NH + CS ₂ + NaOH

N - C - S - Na + H ₂ 0 ch ₃

CH,

According to the current production process, carbon disulfide is added in a molar ratio to dimethylamine of 1.09 to 1.2 to 1.

The unreacted carbon disulfide after condensation was allowed to settle after stirring was stopped.

Sedimentation time is in average 2 h. The disadvantage of the process is the necessary process of sedimentation® of unreacted CSg, its separation, returning to the production cycle, being contaminated with flue gases, moisture and the like.

Sedimented carbon disulphide together with soluble reactants and part. the water is returned to the CS storage tank, which increases its contamination, which is a disadvantage, but a big disadvantage is that the aqueous solution of the desired sodium dimethyldithiocarbamidate alone contains free unreacted carbon disulfide, sometimes up to 2.0 kg / m 2, raw material in the product, but also worsens the processing conditions of the aqueous solution of sodium dimethyldithiocarbamidate due to the generally known toxic conditions of CSg,

A disadvantage of the current production process is that condensation of dimethylamine with carbon disulphide and NaOH feeds sodium hydroxide in excess.

The molar ratio of dimethylamine to sodium hydroxide used so far is 1 to 1.02.

Excess sodium hydroxide remains partially unreacted and passes into the aqueous solution of sodium dithiocarbamate, in some cases up to 4.0 kg / nr.

Unreacted NaOH represents a loss of raw material in the product, but also a deterioration in the processing conditions of the aqueous solution of sodium dimethyldithiocarbamidan.

Another disadvantage of the conventional production method is related to the overdose of carbon disulphide and sodium hydroxide against dimethylamine during censification, thus creating conditions for their mutual reaction. Reaction of excess carbon disulphide and sodium hydroxide gives rise to the undesired NagCSy sodium tritiocarbamate, which causes a deterioration in the quality of sodium dimethyldithiocarbamidate.

As a by-product and undesirable product of the reaction, it deteriorates the coloring of the sodium dimethyldithiocarbamide solution.

The above-mentioned disadvantages are eliminated by the process for the preparation of sodium dimethyldithiocarbamidate in the form of an aqueous solution by the condensation of dimethylamine, sodium hydroxide and carbon disulfide according to the invention, which consists in condensing an aqueous solution of 36-41% by weight aqueous dimethylamine solution. % by weight and carbon disulphide, wherein the molar ratio of the reactants, dimethylamine: sodium hydroxide and carbon disulphide is 1: 1: 1.0 to 1.03, at 5 to 25 ° C for 1 to 3 hours of dosing of the carbon disulphide into an aqueous solution of dimethylamine and hydroxide. of sodium, followed by reaction of the reaction mixture for 1 h.

The process according to the invention simplifies the technological production process in that the process of edimentation and the operations associated with returning the CS to the manufacturing process are eliminated.

Furthermore, in the process according to the invention, CS 2 does not enter the final product.

If a slight excess of CSg for condensation (0.01 to 0.03 ml excess) is used, this is partly a handling bag and few of it is soluble in the sodium dimethyldithiocarbamidate solution.

Sodium hydroxide is metered in an equimolar ratio to the dimethylamine resp. even with respect to carbon disulfide, free KaOH does not enter the final product.

In the process according to the invention, sodium hydroxide is not overdosed and the carbon disulfide to dimethylamine thereby avoiding the formation of undesirable sodium tri- thiocarbamate, thereby substantially improving. purely the desired product, but also the color of the solution.

This procedure avoids orange-red coloration of the solution to give a clear, colorless sodium dithiocarbamidate sodium solution.

Example 1

To a 1 L three-necked flask equipped with a stirrer and thermometer, a feed funnel, 47 mL of water was gradually added, followed by 93.7 g of 100% KaOH as an aqueous solution, 104.3 g of dimethylamine 100% as a 40% aqueous solution.

The temperature was maintained between + 15 ° C and + 20 ° C with the water bath.

After the feed of these raw materials, the mixture was stirred for 30 min. at the indicated temperature.

Next, CSg was added over 3 hours, while a total of 183g CSg was added at 0 ° C, ^and the reaction mixture was stirred and cooled with a water bath so that the temperature did not rise above +20 ° C.

After the addition of CSg was complete, the sodium dimethyldithiocarbamidate solution was stirred for about 1.5 h and 53 mL of water was added.

A sample was taken from the solution and found to have a sodium dimethyldithiocarbamidate concentration of 40.35 wt%.

voealealcals expressed as NaOH 0% CSg content 0,75 g / 1 mechanical impurities trace clear and colorless solution

Example 2

To a 1 L three-necked flask equipped with a stirrer and thermometer, a raw material dosing funnel, 47 ml of water was successively dispensed, followed by 92.7 g (2.32 liters) / 100% NaOH in the form of an aqueous solution, 104.3 g / 2. 32 mol / dimethylamine 100% as a 40% aqueous solution.

The temperature was maintained between +15 and 20 ° C with the water bath.

After the feed of these raw materials, the mixture was stirred for 30 minutes at this temperature.

The addition of CSg was started for 1 hour, with a total of 183 g CSg (2.4 mol) added. During the addition, the reaction mixture was stirred and cooled, with an aqueous bath, such that the temperature did not exceed +20 θθ.

For further use, the sodium dimethyldithiocarbamidate solution was diluted with 53 ml of water. After sampling, the concentration of sodium dimethyldithiocarbamad was found to be 40.33% by weight.

% free alkali in the form of NaOH ψ wt.

content CSg 0,64 g / l mechanical impurities trace clear colorless solution

Example 3

47 ml of water was successively dispensed into a 1 L 3-necked flask equipped with a stirrer, a thermometer, and a feed funnel.

Further, 92.7 g (2.32 mol) of 100% NaOH was added as an aqueous solution.

The temperature was maintained at +8 to +20 ° C with a water bath during the addition.

After dosing of these / raw materials, the mixture was stirred for 20 minutes at this temperature.

CSg was then added over 1 hour, with a total of 178.3 g. (2.32 mol) CSg. During the addition, the reaction mixture was stirred and cooled with a water bath such that the temperature did not exceed +20 ° C.

Further, the solution was diluted with 53 mL of water and a sample was taken to determine the concentration of dimethyldithiocarbamidan.

sodium hydroxide was · 40.57% free alkali in the form of NaOH 0 content CSg traces solution was clear colorless

Claims (3)

47 ml of water were successively metered in, followed by the addition of 92.7 g (2.32 .mu.mol / 100% NaOH) of an aqueous solution, 104.3 g (2.32 mol) of dimethylamine 100% in the form of 40% aqueous solution. flow. During the addition, the temperature of the water bath was maintained at +15 to 20 ° C. After dispensing these raw materials, the mixture was stirred for 30 minutes at that temperature. CSg was added slowly for 1 hour, adding 183 g of CSg (2.4 mol) in total. During the addition, the reaction mixture was stirred and cooled, with an aqueous bath, so that the temperature did not exceed +20 ° C. For further use, the sodium dimethyldithiocarbamidate solution was diluted with 53 ml of water. After sample collection, sodium dimethyldithiocarbamate was found to be 40.33% by weight. free alkali in the form of NaOH 0 wt. content CSg 0.64 g / l mechanical impurities traces clear color solution Example 3 47 ml of water were gradually metered into a 1 liter three-necked flask fitted with a stirrer, thermometer and feed funnel. violet was added 92.7 g (2.32 mol) of 100% NaOH as an aqueous solution. During the addition, the temperature was maintained at +8 to +20 ° C with a water bath. After the addition of these raw materials, the mixture was stirred for 20 minutes at the same temperature, CSI was added for 1 hour, adding 178.3 g (2.32 mol) CSg overall. stirred and cooled with a water bath so that the temperature did not exceed +20 ° C. The solution was diluted with 53 ml of water and a sample was taken to determine the concentration of dimethyldithiocarbamidate. the sodium hydroxide was 40.57% free alkali in the form of NaOH 0, the content of the CSg trace was clear, colorless. A process for the preparation of sodium dimethyldithiocarbamidate in the form of an aqueous solution by condensing dimethylamine, sodium hydroxide and carbon disulphide characterized in that a 36 to 14% aqueous solution of dimethylamine, a 30 to 45% aqueous sodium hydroxide solution and a sieve are condensed, wherein the molar ratio of dimethylamine reactants is with sodium hydroxide: sulfur carbon is 1: 1: 1.0 to 1.03, 4 at 5 to 25 ° C, for 1 to 3 hours of carbon disulphide in an aqueous solution of dimethylamine and sodium hydroxide followed by reaction reaction mixture for 1 h. 2. A process according to claim 1, wherein the dimethylamine, sodium hydroxide and carbon disulphide are 1: 1: 1 molar. 3. Process according to claim 1 or 2, characterized in that the condensation is carried out for 1 hour without reacting. · '-