CS214397B1 - Method for the production of 1-methyl-4-methoxy-5-chlor-6-oxo-1h-pyridazine - Google Patents

Description

Preparation of 1-methyl-4-methoxy-5-chloro-6-oxo-1H-pyridazine

The present invention provides a novel process for the preparation of 1-methyl-4-methoxy-5-chloro-6-oxo-1H-pyridazine. The compound can be used as an intermediate in the synthesis of various organic compounds, while also being effective as a herbicide.

The preparation of 1-substituted-4-alkoxy-5-chloro-6-oxo-1H-pyridazines of formula (I) (I) is known from the literature.

N, N

I 2 (II) o

2 wherein R is alkyl, cycloalkyl, aralkyl, alkenyl, R is alkyl, cycloalkyl or aryl, by reaction of 4 »5-dichloro-1-substituted-6-oxo-1 H-pyridazines of formula (II) if a C ⁰¹

wherein R is as defined above with an alkali metal alcoholate in an alcohol medium, or by reaction of 4-hydroxy-5-chloro-1-substituted-6-oxo-1H-pyridazines of formula (III)

214 397

214 397

wherein R is as defined above with an alkyl halide. (British Pat. 917,849} US Pat. 2,628,181).

Now a new method of preparation of 1-methyl-4-methoxy-5-chloro-6-oxo-1H-pyridazine

I I

M-CH3 by reaction of dimethyl sulfate or methyl iodide with an alkaline salt of 4,5-dihalo-6-oxo-1H-pyridazine of the formula

wherein M is sodium or potassium in a medium of methanol at a temperature of -5 ° C to 25 ° C. Upon completion of the reaction, an equivalent amount of sodium or potassium hydroxide, sodium or potassium carbonate is added, and the reaction mixture is heated to reflux.

The following examples illustrate but do not limit the novel process for the preparation of 1-methyl-4-methoxy-5-chloro-6-oxo-1H-pyridazine,

Example 1

1400 ml of methanol and 42 g of sodium hydroxide (1.05 mol) were added to a 2 L three-necked flask and 165 g of 4,5-dichloro-6-oxo-1H-pyridazone (1 mol) was added in portions while stirring. 20 to 40 ° C. Then 132.5 g of dimethyl sulphate (1.05 mol) are added gradually over 90 min. and temperatures from 0 to 5 ° C. The reaction mixture is stirred for a further 2 hours at normal temperature, then 42 g of sodium hydroxide (1.05 mol) are added in one portion and the reaction mixture is heated to reflux with stirring for 1 hour. 1300 ml of methanol are then distilled off with stirring. The reaction mixture is cooled to 50-60 ° C. Then 500 ml of water are added, mixed and cooled to 5 ° C. The precipitated product is collected by filtration, washed on the filter with 150 ml of water. 130.4 g of a white crystalline solid are obtained with m.p. 152-154 ° C, which corresponds to a 74.7% yield. Calcd for 41θΗγΟΙΝ ^ Calc .: 41.18% C, 4.02% H, 20.31% Cl, 16.03% H / m-174.58 / Found »41.22% C, 4.14% H, 20.16% Cl, 16.21% N of the IR spectrum in CHCl3 ₃ -ty-0 /

1650 om ” ¹ _{y CC1} V / _G _ _C1 / 1675 om

UV in ethanol max.

^ / CN / ¹⁶¹⁰ ° “” ¹ / log £ /: 295 nm / 3.60 / 264 nm / 3.52 / 215 nm / 4.47 / '/ CN / ^{1610 cm 1}

214 397 ¹ H NMR in dimethylsulfoxide deuterated

- CH 8.38 ppm

CH 2 -N 3> 88 ppm

CH 2 -O 4> 28 ppm

Example 2

1400 ml of methanol and 59 g of potassium hydroxide (1.05 mol) were added to a 2 L three-necked flask, and after dissolution 165 g of 4,5-dihalo-6-oxo-1H-pyridazine (1 mol) was added portionwise at a temperature 20-40 ° C, then 149 g of methyl iodide (1.05 mol) are added gradually, the reaction mixture is stirred for 2 hours. at reflux. 145 g of potassium carbonate (1.05 mol) are then added, and the reaction mixture is heated to reflux, where it is stirred for a further 1 hour, distilling 1300 ml of methanol with stirring. To the distillation residue after cooling to 60 ° C was added 500 ml of water, mixed and cooled to 10 ° C. The precipitated product is collected by filtration and the filter is washed with water. 135.6 g of product with m.p. 153-155 ° C, which corresponds to a 77.7% yield.

Example 3

1400 ml of methanol and 42 g of sodium hydroxide (1.05 mol) were added to a 2 L flask, after dissolution, 165 g of 4,5-dichloro-6-oxo-1H-pyridazine (1 mol) were gradually added under stirring at 15 ° C. - 35 ° C. Then gradually in 60 min. 132.5 g of dimethyl sulfate (1.05 mol) are added at 5-10 ° C. The reaction mixture was stirred for 2 hours. at 20-25 ° C and 59 g of potassium hydroxide (1.05 mol) are added, then the reaction mixture is stirred at reflux for 1 hour, 1300 ml of methanol are distilled off. X of distillation residue is gradually added at 80 ° C to 500 ml of water, cooled to 15 ° C, the precipitated product is collected by filtration and washed on the filter with water. 138.2 g of crystalline substance are obtained, m.p. Mp = 152-154 ° C, which corresponds to 79%. výttažku.

Claims (1)

OBJECT OF THE INVENTION { A process for the preparation of 1-methyl-4-methoxy-5-chloro-6-oxo-1H-pyridazine having the formula: Wherein M is sodium or potassium in methanol at -5 ° C to 25 ° C, and after completion of the basic reaction, an equivalent amount of sodium or potassium hydroxide, sodium or potassium carbonate is subsequently added and the reaction mixture is heated to a temperature of reflux.