Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

Beteiligte Stoffe

Reaktionsschritte

2.20 g of a mixture of 80% of EDT-methanol and 20% of hydroxy-PDT (corresponding to 12.9 mmol; 10.3 mmol based on the main component EDT-methanol), 2.10 g (10.2 mmol) of N,N′-dicyclohexylcarbodiimide and 1 spatula tip of 4-(dimethylamino)pyridine are dissolved in 80 ml of CH2Cl2 and cooled in an ice bath. 3.00 g (10.2 mmol) of [(4′-cyano-1,1′-biphenyl-4-yl)oxy]valeric acid (see formula) are added a spatula at a time to the cold (0° C.) solution while stirring. Remaining [(4′-cyano-1,1′-biphenyl-4-yl)oxy]valeric acid is dissolved in 20 ml of CH2Cl2 and added to the reaction. After 1 hour, the reaction is continued at room temperature. After a further 48 hours, the colourless precipitate formed (N,N′-dicyclohexylurea) is filtered off. The clear, colourless solution is washed in succession with 3×75 ml of 1 N HCl, 3×75 ml of saturated NaHCO3 solution and 3×75 ml of saturated NaCl solution. The organic phase is dried over MgSO4, the desiccant is filtered off and the solvent is removed on a rotary evaporator. This gives 4.70 g of crude product.

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