Abstract: Described herein is a process for preparing a hydroxyflavan compound which comprises reacting a polyhydric phenol compound represented by formula(2): ##STR1## wherein at least one of W, X, Y and Z is hydroxy; with a ketone in the presence of (i)an acid catalyst and (ii)water and/or a seed crystal, using an organic solvent which is insoluble in water, procuces the hydroxyflavan compounds in high yield and with high selectivity while maintaining high conversion of the polyhydric phenol.

Abstract: The present invention relates to a method for producing a vulcanized rubber by compounding in a kneading step at a relatively high temperature, a rubber and a flavan compound of the formula (I) ##STR1## wherein R.sup.1, R.sup.2, R.sup.4 and R.sup.5 independently of one another represent a hydrogen or an aliphatic group having 1-6 6 carbon atoms, or R.sup.1 and R.sup.2 together with the carbon atoms to which they are attached and/or R.sup.4 and R.sup.5 together with the carbon atom to which they are attached form an alicyclic ring having 4-10 carbon atoms, R.sup.

Abstract: A rubber composition (1) which comprises:a rubber (A) such as natural rubber, isoprene rubber and the like;a hydroxy flavan compound (B1) represented by the formula (I): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are hydrogen or an aliphatic group and X and Y are hydrogen hydroxy or an aliphatic group, such as 2,4,4-trimethyl-2',4',7-trihydroxyflavan (B2); and2,2,4-trimethyl-1,2-dihydroquinoline polymer (C1) containing 1% or less by weight of a primary amine, 3% or less by weight of the monomer and 30% or more by weight of the dimer based on the total weight of the polymer, or a cromane compound (C2) which may be a novel cromane compound.