The behaviour of some estrogens in nitration process - I. Estrone nitration with NaNO2 in the presence of crown ethers

Estrone 1 was nitrated in methylene chloride with sodium azotite (NaNO2, in solid state or solved in water) in the presence of crown ethers CE (12-cro wn-4, 15-crown-5, 18crown-6, dicyclohexyl-18-crown-6) yielding two isomers 2 and 3. Estrone 1 conversion in 2 and 3 nitroderivatives was 3-64%, depend ing on reactants ratio (1: NaNO2:CE), CE type, reaction time and biphasic s ystem. The nitroisomers ratio was 2:3 > 1 depending on reaction conditions. The process is of autocatalysis type as results from the HNO2 formed in an acid (1)-base (NO2-) reaction catalysed by CE (which transfer the NO2- ani on in the organic phase).