No abstract

The U.V. absorption spectra of forty-one substituted coumarins have been studied in methanol and aqueous methanol over a pH range. The effect of the nature and position of the substituent in the coumarin nucleus is discussed. 7-OH-3-isopropyld-Me coumarin was prepared by the method of Chakravarti, * m.p. 230 "C. (Chakravarti reported 224 'C.) 7-OH-4,8-diMe coumarin was obtaincd from Professor Sethna's laboratory and the methyl ether was prepared by refluxing it (1 g) in acetone (75 ml) with nahydrous potassium carbonate (2 g) and dimcthyl sulphate (I ml) for 6 h. Thc acetone was removed by distillation and potassium carbonate dissolved in water. The residue crystallised from aqueous alcohol, m.p. 156 "C. AnalysisFound C = 70.50; H = 5.46 C,,H,,03 Requires C = 70.60; H = 5.88%. 331C 332