title: Humic substances as catalysts in condensation reactions.
abstract: Humic substances (HS) demonstrate appreciable impact on the rate of the condensation reactions as shown in the example of the reaction between hydrazine and 4-(dimethylamino)-benzaldhyde in an aquatic environment. The catalytic activity of HS has also been demonstrated in Knoevenagel and Claisen-Schmidt reactions for condensation of carbonyl compounds with CH acids. The aquatic fulvic acids are the most active in these reactions. The velocity of the studied reactions also depends on pH, temperature, the concentration and origin of HS used. A possible micellar and acid-base catalysis mechanism in aquatic media has been suggested.
authors.affiliation: Department of Environmental Science, University of Latvia, Riga. mklavins@lanet.lv
authors.forename: M
authors.initials: M
authors.lastname: Kļaviņs
authors.forename: J
authors.initials: J
authors.lastname: Dipane
authors.forename: K
authors.initials: K
authors.lastname: Babre
mesh_terms: D001578:Benzopyrans / Q000737:chemistry; D002384:Catalysis; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006812:Humic Substances / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D001578:Benzopyrans; D006812:Humic Substances; D014874:Water Pollutants, Chemical; C005023:fulvic acid