TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The base is preferably ammonia, sodium methoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium bicarbonate, potassium carbonate or sodium bicarbonate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: In the process: the step (a) results in a salt of (-)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and the chiral tartaric acid derivative, and step (b) comprises separating the salt from the (+)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and reacting the salt with a base to obtain (I); or the step (a) results in a salt of (+)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and the chiral tartaric acid derivative, and step (b) comprises separating (I) from the salt. The step (a) is carried out in the presence of a solvent. The conversion to levosimendan comprises reacting the (-)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone with sodium nitrite and malononitrile. Preferred Components: The chiral tartaric acid derivative is D- or L- isomer of di-p-anisoyl-tartaric acid, di-p-tolyl-tartaric acid or O, O'-dibenzoyl-tartaric acid. The chiral tartaric acid derivative is the D-isomer of the tartaric acid derivative. The chiral tartaric acid derivative is preferably di-p-anisoyl-D-tartaric acid. The solvent is a mixture of water and a polar solvent. The polar solvent is methanol, ethanol (preferred), isopropanol, n-butanol, acetone or acetonitrile. The base is an organic or inorganic base. ACTIVITY - None given.    MECHANISM OF ACTION - None given.    EXAMPLE - Racemic 6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone (50 g) and ethanol (500 ml) were added to a flask and stirred at 65 degrees C for 30 minutes. Further di-p-anisoyl-D-tartaric acid (113.3 g) and water (500 ml) were added and stirring was continued for 1 hour. The reaction mass was cooled to 15 degrees C and stirred for another 30 minutes. Then the mass was filtered, washed with water and dried under vacuum at 55 degrees C to obtain the corresponding diastereomeric salt. The obtained salt and water (500 ml) were added to a reaction vessel and stirred at 25-30 degrees C for 30 minutes. The pH of the resulting solution was adjusted to 8-9 by adding ammonia solution and stirring was continued for 30 minutes. After completion of reaction, the contents were filtered and dried under vacuum at 55 degrees C to obtain solid (-)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone (24 g, purity of 99.6%).