Hydrogenated Neem Oil: Preparation, Formulation and Appraisal

Neem oil (0.023% Aza-A) was hydrogenated employing Adams’ catalyst at 200 psi (13.6 atm) pressure of hydrogen gas to yield a 43% conversion of Aza-A to its 22, 23-dihydro derivative. Emulsifiable concentrates of neem oil/hydrogenated neem oil (25% w/w oil basis in solvent ceenine, employing 5% w/w of a 1:1 mixture of Tween-20 and IGSURF-6000 as emulsifier) complying with the various physico-chemical requirements (emulsion stability, flash point, acidity and low temperature stability) were developed. The insect growth inhibitory and antifeedant activity of the pre and post-heat stored neem oil/hydrogenated neem oil, and their formulations, against Spodoptera litura did not differ significantly. At 5 and 10 ml kg−1 seed treatment, both the formulations did not affect the seed germination in bottle gourd and sponge gourd, but reduced it in okra (34%) and green gram (5–10%). One per cent emulsions from the formulations showed no phytotoxicity against the 10 d old seedlings of green gram, bottle gourd and sponge gourd but 2 and 3% levels showed some burning symptoms as well as the stunted growth of seedlings. The treated seedlings recovered to normal after 10 d of spray.