TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The reaction is carried out in a non-polar or poorly polar solvent, preferably in dichloromethane, at less than or equal to 70 degrees C, preferably less than or equal to 40 degrees C, especially -30 degrees C to 40 degrees C. The molar ratio between tertiary alkyl hydroperoxide and valencene varies from 2:1 to 3:1, preferably 2.2:1 to 2.5:1. The manganese dioxide is used in a molar ratio with respect to the valencene variable of 6:1 to 12:1. The process involves: a) preparing a suspension of manganese dioxide and valencene in molar ratio of 6:1 to 12:1 in dichloromethane; b) adding, to this suspension, tert-butyl hydroperoxide in a molar ratio with respect to the valencene variable of 2:1 to 3:1, at -30 degrees C to -10 degrees C; c) maintaining the obtained mixture under stirring at -20 degrees C to -10 degrees C for 5-8 hours; d) gradually raising the temperature to bring the mixture to reflux temperature and keeping it at that temperature for at least 2 hours. In the step (b), the tert-butyl hydroperoxide is added to the suspension in a molar ratio with respect to the valencene variable of 2.2:1 to 2.5:1 and in the step (d), the mixture is kept at reflux temperature for 2.5-4 hours. The raw nootkatone obtained from the reaction is purified by conversion into semicarbazone and subsequent acidic hydrolysis of the latter. Preferred Component: The tertiary alkyl hydroperoxide is selected from tert-butyl hydroperoxide, tert-amyl hydroperoxide and di-tert-amyl hydroperoxide (preferably tert-butyl hydroperoxide). EXAMPLE - 50 g Valencene and 350 ml dichloromethane were introduced into one litre three-necked flask to obtain a solution. 180 g Manganese dioxide was then added and the whole mixture was cooled down to -25 degrees C. At this point, over 30 minutes, 75 ml Luperox (RTM: tert-butyl hydroperoxide solution in water) was slowly added under vigorous stirring. Once the addition finished, the temperature was allowed to rise to -10 degrees C and the stirring was continued for around 6 hours. Subsequently, the temperature was allowed to rise and the mixture was refluxed for around 3 hours. A brief evolution of gas was noted, which is an indication of the decomposition of the non-reacted hydroperoxide. The final reaction mixture was then filtered and washed. The filtered organic phase was concentrated at the rotary evaporator and the residue obtained was distilled under low pressure. A single fraction (40.5 g) of distillate was obtained, consisting of nootkatone with titer of around 52%, equal to 97 mmols, corresponding to a yield of 56% considering the titer of around 70% of the initial valencene, and an undistillable residue, which still contained small amounts of nootkatone. 30 g Distillate was dissolved in 250 ml aqueous ethanol (60%) and treated with 16 g semicarbazide chloride and 18 g sodium acetate. The mixture was refluxed for around 20 minutes and cooled down in a refrigerator for one night. The precipitated nootkatone semicarbazone was separated by filtration (24 g) and then recrystallized from pure ethanol. The crystalline solid (18.5 g) was suspended in ethyl ether (150 mL) and subjected to hydrolysis with sulfuric acid diluted to 8 wt.% (150 mL), stirring vigorously for around 4 days. Once the hydrolysis was finished, the organic phase was separated from the aqueous phase, which was re-extracted twice with 60 ml ethyl ether. The combined organic phases were then washed with saturated bicarbonate solution and with brine. Through low-pressure concentration, highly pure nootkatone (titer GC-MS greater than 95%) in an amount equal to 13.1 g was obtained, with an overall yield of 83%.