The Catalysis of Maghemite and Hematite on the Aldol and the Retro-Aldol Condensation of Acetone

• Published in: Bulletin of the Chemical Society of Japan Vol. 64; no. 8; pp. 2411 - 2415
• Main Authors: Watanabe, Haruo, Seto, Jun’etsu
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 01.08.1991; Chemical Society of Japan
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Hematite; Catalytic reaction; Temperature; Aliphatic compound; Transition metal Compounds; Reverse reaction; Metal Oxides; Experimental study; Ketone; Aldol condensation; Alpha form; Heterogeneous catalysis; Gamma form; Medium effect; Acidobasicity; Tertiary alcohol; Preparation; Surface properties; Iron III Oxides; Catalyst activity; Catalyst; Maghemite; Acetone
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.64.2411

The catalytic activities of maghemite on the aldol condensation of acetone and on the retro-aldol condensation of diacetone alcohol are found to be higher than those of hematite. Further, the catalytic activity of maghemite on the formation of mesityl oxide is significantly higher than that of hematite. The active sites are considered to be surface hydroxyl groups which behave as a Brønsted base and acid points. Maghemite has more basic surface hydroxyl groups than does hematite, and far more acidic surface hydroxyl groups than does hematite they are sufficiently strong to make its average surface acidity greater than that of hematite. The basic surface hydroxyl groups of maghemite are speculated to be those which bond to the iron ions of the octahedral sites the acidic ones are those of the tetrahedral sites of the spinel lattice of the surface.