2 4 dihydroxybenzoic acid pka July 8, 2019 16 32 64 128 Pka value of 2 4 dihydroxybenzoic acid 2 4-dihydroxybenzoic acid 2 6-dihydroxybenzoic acid 2 4-dihydroxy-6-methylbenzoic acid 2 5-dihydroxybenzoic acid pka