DD222302B1 - PROCESS FOR THE PREPARATION OF DICHLORAL UREA - Google Patents

Description

Field of application of the invention

The invention relates to a process for the preparation of dichlorourea, in particular for the preparation of highly concentrated herbicidal formulations.

Characteristic of the known technical solutions

It is known to produce dichlorourea by reacting urea with chloral hydrate; the reaction can be carried out both without solvent and in the presence of solvents. For example, technical chloral hydrate can be reacted directly with urea without solvent (DD-PS 131 646). However, this produces a solidified dichloroalurea, which includes considerable amounts of starting material as well as impurities. In the workup of the viscous, doughy reaction mass arise in particular on a technical scale significant problems. It is also known to prepare N, N'-bis (2,2,2-trichloro-1-hydroxyethyl) urea by reacting molar amounts of urea and chloral or chloralhydrate in the presence of mineral acids and optionally inorganic salts as catalyst. For example, ethanol or water can be used as solvent (HU-PS 156808).

When filtering off and washing the separating Dichloralharnstoffes result in large quantities of waste liquors, which contain mainly chloral, urea, and Dichloralharnstoff and the impurities. The work-up of these solutions causes considerable costs, but is necessary for reasons of environmental protection.

Object of the invention

The aim of the invention is to develop a simple process starting from technical chloral hydrate for the production of dichlorourea, which is particularly suitable for producing active ingredients for highly concentrated herbicidal formulations.

Explanation of the essence of the invention

The object of the invention is to avoid the disadvantages of the state of the art, which consist primarily in the need to work up large Ablaugemengen.

This task, Dichloralharnstoff by reaction of technical Chloralhydrat and urea at temperatures between 75 ° C and 85 ° C in the presence of water as a solvent and distillative Entfe / nung of water, unreacted chloral and volatile minor constituents from the reaction mixture after completion of the reaction and recycling of these To prepare components in a new reaction mixture, the invention is achieved in that the reaction in the presence of 0.2 to 2Gew .-% of a surfactant based on alkanesulfonic acid of chain length C ₁₃ -Ci ₈ , Na alkane sulfonates of chain length Ci ₂ -C ₂ O or Na dialkylnaphthylsulfonate is performed.

The advantage of the method according to the invention is mainly to be seen in the fact that the otherwise necessary work-up of considerable amounts of Ablaugemengen deleted and Chloralverluste can be significantly reduced. It is particularly advantageous to carry out the reaction and also the drying of the product contained in the same reactor. In this case, a dust-fine powder is obtained, which is suitable directly for the production of highly concentrated agents.

Technical Chlorohydrate is known to be obtained by chlorination of ethanol or acetaldehyde and contains between 75.

and 90% by weight of chloral, up to 5% by weight of HCl, and up to 10% by weight of other chlorinated aliphatic compounds. In this respect, it was not to be expected that a dichlorourea suitable for further processing would be obtained directly.

embodiments

Example 1 (comparative example)

In a 4 l sulfonating flask equipped with stirrer, thermometer and reflux condenser, 1 378 g of chloral hydrate (72%) = 6 mol, and 150 g of urea = 2.5 mol are added. To ensure good mixing, 600 ml of water are added.

The mixture is heated to 80 ⁰ C and stirred for 6 hrs. At this temperature. After cooling to 25 ^° C., the precipitated dichlorourea is filtered off with suction through a porcelain chute. It is then washed with water until neutral reaction of the filtrates. After drying at 80 ⁰ C in vacuo, 653,6g Dichloralharnstoff with a content of 98.8% 1.2% DCU next Monochloralharnstoff. The yield is 72.8% d. Theory based on urea used.

The mother liquor contains 23.7% chloral and weighs 732 g ^ 173.5 g chloral. Another 167.3g of chloral are contained in 4289g of washing water.

Example 2

92 g of 80% technical grade chlora hydrate (0.5 molar chloral) are mixed at 60 ⁰ C with a warm solution of 15 g urea (0.25 mol) in 20 ml water and 0.75 g techn. Alkylsulfonamidgemisch and 0.75 g techn. Na-Alkylsulfonatgemisch added and held in a vacuum rotary evaporator for 4 hours at 80-90 ⁰ C (this begins the first clear solution after about 15min reaction time to cloud and go into a white slurry). Subsequently, a weak stream of air is passed over the product, while the temperature is gradually increased to 110 ⁰ C. Unreacted chloral hydrate distils off together with water and volatile impurities. This distillate (46.3 g with a chloral content of 22.2% = 10.3 g) can be used as the starting material for a subsequent reaction mixture. The initially sticky, pulpy reaction mass on the flask undergoes a viscous pulpy state during the distillation and decomposes into a powder as the drying progresses. The end of drying can be easily recognized visually by dust in the cooler.

Yield: 79g F. 196 ° C dec. 203 ⁰ C

DCU content: 93.5% = 84.1% d. The theory continues

Urea: approx. 1.5%

NH ₄ Cl: 2.7%

Monochloroalurea (MCU): approx. 2%

Example 3

In a horizontally arranged, acid-solid lined, cylindrical reactor with about 9I nominal volume, equipped with a Wandgängigen agitator, temperature measurement and a reflux condenser were 3041 g of 75.8% technical chloral hydrate and

1 200g distillate containing 29.0% chloral hydrate and

69.1% water and 20g Na dibutyl naphthylsulfonat heated to 60 ⁰ C and 540g urea added with stirring.

The temperature rose to about 75 ⁰ C and was then gradually increased by heating to 85 ⁰ C. After stirring for 4.5 hours, the reflux condenser was replaced with a descending condenser and, after evacuating the system to a pressure of 130-25mbar (100 to 20 Torr), chloral, water and volatiles were distilled off, adjusting the heater so that a temperature of 100-105 ⁰ C was not exceeded. After about 2.5 hours of distillation, a flour-like powder was formed in the reactor, which was free of chloral. There were 1 402g distillate with a chloral content of 26.4% = 371.4g chloral obtained. The distillation was stopped and water was added to apparatus 41. After 15 minutes

Stirring the obtained Breiaufeiner porcelain drip was filtered off with suction and washed with 21 water. After drying the Nutscherückstandes in a paste fluidized bed dryer were

2718 g of DCU, which in addition to about 1.5% monochloroalurea (MCU) contained virtually no further impurities.

F _p : 198-202 ° C and Zers. = 83.3% d. theory

The Chloralbilanz results in a loss of 29.4g Chloral. This corresponds to a loss of 7.3% based on unreacted Chloral.

Example 4

In an acid-resistant vacuum paddle dryer were

638kg 77% techn. Chloral hydrate (3.33 kMol) and

1401 water heated to 6O ⁰ C and added at this temperature 100kg urea with stirring. Subsequently, 10 kg Al kylsu If о na mi dg em isch added and stirred at 80-85 ⁰ C under reflux for 5 hours. It was then switched to distillation and drying. For this purpose, the previously connected as a reflux condenser heat exchanger was operated as Brüdenerhitzer before the downstream dust filter with steam and then the vapors condensed in a further heat exchanger. The system was under a pressure of about 200mbar (150Torr).

After about 10 hours drying at a maximum product temperature of 95 ° C were 520kg DCU, F.: 194-96 ° C Zers. 204 ⁰ C with a content of 96% = 84.5% d. Theory obtained as a fine powder. The product contained as impurities:

Monochloroalurea (MCU) <1% urea: approx. 0.5%

NH ₄ Cl: 1.5%

The replaceable distillate was 338kg containing 68.8kg of chloral. The loss of chloral is 5.1% based on unreacted chloral.

Example 5

The approach described in Example 4 was repeated; as surfactant 4kg Na-alkylsulfonate were used. Under otherwise identical conditions, 512 kg of DCU are obtained as powder, with the same quality as described in Example 4.

Claims (1)

Invention claim: A process for the preparation of Dichloralharnstoff by reacting technical Chloralhydrat and urea at temperatures between 75 ° C and 85 ° C in the presence of water as solvent and with removal by distillation of water, unreacted chloral and volatile minor constituents from the reaction mixture after completion of the reaction and recycling of these components in a new reaction mixture, characterized in that the reaction in the presence of 0.2 to 2Gew .-% of a surfactant based on Alkansulfonsäureamiden the chain length C ₁₃ -C ₁ S, Na alkane sulfonates of the chain length C ₁₂ -C ₂ O or Na-dialkylnaphthylsulfonate is performed.