Helmut Huber-Emden

High Catalytic Activity of Rosindone and Related Compounds in Alkaline Pulping

Abstract The efficacies of phenazine, phenazone and rosindone derivatives as additives in alkaline pulping were investigated and compared. Phenazones and rosindones are superior to the phenazines described earlier. Equimolar charges of rosindone sulfonate stabilize carbohydrates more than anthraquinone (vM∼l.l) but the de-lignification effect is slightly inferior (rM = 0.72). Due to low solubility rosindone does not follow the square root relationship. Low rosindone charges (<0.1%) catalyze delignification as efficiently as anthraquinone (rM ∼1). The half-wave potentials (pH Ik, 90°C, IN NaOH, SCE, in the presence of wood) were measured. No correlation is to be found between pulping efficacies (rM-value) and redox potentials (Ey2). The differences of the pulping efficacies are mainly explained in terms of chemical stability.