A process for the manufacture of EN, N-diethyl-2-cyano-3- (3,4-dihydroxy-5-nitrophenyl) acrylamide, comprising: a) the reaction of 3,4-dihydroxy-5-nitrobenzaldehyde with N , N-diethyl-2-cyanoacetamide in the presence of a catalyst in a C4 to C8 alcohol under reduced pressure and at a temperature of at least 70 ° C； b) optionally cooling the mixture resulting from stage a)； c) optionally sowing the mixture resulting from stage a) or stage b) with N, N-diethyl-2-cyano-3- (3, 4-dihydroxy5 -nitrophenyl) acrylamide comprising at least 60% of the E-isomer by weight in the seed crystals； d) cooling the mixture resulting from stage a) or stage b) or stage c) to a temperature of 30 ° C or less； e) sow the cooled mixture from step d) with N, N-diethyl-2-cyano-3- (3, 4-dihydroxy-5-nitrophenyl) acrylamide comprising at least 10% of the Z isomer by weight in the crystals of sowing； f) cooling the mixture of step e) to a temperature of 5 ° C or less； g) isolate the product crystallized from the mixture； and h) the conversion of the mixture obtained from the E and Z isomers of N, N-diethyl-2-cyano-3- (3,4-dihydroxy-5-nitrophenyl) acrylamide into the E-isomer of N, N-diethyl- 2-cyano-3- (3, 4-dihydroxy-5-nitrophenyl) acrylamide.Un proceso para la fabricación de E-N, N-dietil-2-ciano-3- (3, 4-dihidroxi-5-nitrofenil) acrilamida, que comprende: a) la reacción de 3 , 4-dihidroxi-5-nitrobenzaldehído con N, N-dietil-2-cianoacetamida en presencia de un catalizador en un alcohol C4 a C8 a presión reducida ya una temperatura de al menos 70º C； b) opcionalmente enfriar la mezcla resultante de la etapa a)；c) opcionalmente sembrar la mezcla resultante de la etapa a) o de la etapa b) con N, N-dietil-2-ciano-3- (3, 4-dihidroxi5-nitrofenil) acrilamida que comprende al menos 60% del isómero E en peso en los cristales de siembra； d) enfriar la mezcla resultante de la etapa a) o la etapa b) o la etapa c) a una temperatura de 30º C o inferior； e) sembrar la mezcla enfriada de la etapa d) con N, N-die
