Chemical examination of plant insecticides. Part V. A comparative study of scandenin, lonchocarpic acid and robustic acid

Abstract

A more detailed study of scandenin is made and its important properties compared with those of lonchocarpic and robustic acids. The three non-rotenoids show marked resemblance. They do not give the Durham test, and are definitely acids owing this property not to carboxyl groups but to specially active hydroxyl groups. They are quite stable to aqueous and alcoholic alkali. The fully methylated ethers have three methoxy groups in all the three cases and these ethers undergo decomposition readily in alcoholic alkali in the presence of zinc, the main products being neutral in nature. The three compounds do not give chemical tests for the presence of carbonyl groups, exhibit definite toxicity to fish and have very similar ultra-violet absorption spectra. The toxicity and the spectra indicate the presence of carbonyl groups in conjugation with ethylenic bonds. Oxidation with alkaline hydrogen peroxide yields p-hydroxy-benzoic acid with all the three compounds. In acetic acid solution scandenin and lonchocarpic acid add on two atoms of bromine; whereas robustic acid takes up 4 bromine atoms.