• Journal of the Korean Chemical Society
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• v.46 no.4
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• pp.323-330
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• 2002

The protonation equilibrium of 5-substituted 2-furaldehydes is investigated spectrophotometrically in aqueous sulfuric acid at $25^{\circ}C$ and the basicity constants(p$K_{BH+}$) of the substrates is calculated by means of the excess acidity method. The basicity constant of 5-metyl-2-furaldehyde having electron donating group is larger than that of 5- nitro-2-furaldehyde having electron withdrawing group. Difference between the basicity constants(p$K_{BH+}$) of these two compounds was about 3.25 pK unit. The m value which is the degree of solvation of the protonated substrate is similar to that of acetophenone having same protonation site. The dependence of p$K_{BH+}$ on m value shows good linear cor-relation.

• Korean Journal of Microbiology
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• v.12 no.2
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• pp.77-84
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• 1974

In order to study 5-nitro-2-furaldehyde derivatives having more effective antibacterial activity, four new $N^4$-(5-nitro-2-furfurylidene)-$N^1$-substituted sulfanilamides$N^1$-3,4-dimethyl-5-isoxazoyl-$N^4$-5-nitro-2-furfurylidene sulfanilamide, $N^1$-4,6-dimethyl-2-pyrimidyl-$N^4$-5-isoxazoyl-$N^4$-5-nitro-2-furfurylidene sulfanilamide, $N^1$-6-methoxy-3-pyridazinyl-$N^4$-5-nitro-2-furaldehyde with sulfa drugs such as sulfisoxazole, sulfamethazine, sulfamethoxypyridazine, and sulfadimethoxine. All compounds were tested for antibacterial activity in vitro on the following micro-organisms : Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Proteus vulgaris. Each compound exhibited a fair bacteriostatic activity against each microorganism. Above all, sulfisoxazole derivatives showed higher activity than the others. Each compound was most active against Staphylococcus aureus, whereas least active against proteus vulgaris.