Chemistry of gossypol

Summary

Various methods of extracting gossypol from cotton-seed meal have been examined: (1) removal of the oil with petroleum ether and then extraction of gossypol with ether, (2) same as (1) but moistening the seed meal before ether extraction, (3) precipitation of gossypol as the acetic acid compound, (4) precipitation of gossypol as the aniline compound and (5) use of other solvents particularly chloroform not so far investigated. It has been confirmed that moistening of the meal is necessary for complete extraction with ether and when this is done only aniline works satisfactorily as the precipitant. The preliminary removal of the oil is not absolutely essential though desirable. With chloroform as the solvent, neither removal of the oil nor addition of moisture is necessary. Hence the use of chloroform as the solvent and aniline as the precipitant is most satisfactory. For recovering gossypol from the anilino compound decomposition using potash and sulphuric acid are not satisfactory. A new method has been evolved using acetic anhyride. Pure gossypol thus obtained melts at 189° and the solvent employed makes no difference. It gives no methoxyl values. A few other properties are described.