In this pa per, eigh teen aryl sub sti tuted semicarbazide un der went ef fi cient ox i da tion to aryl azo com - pounds us ing NaNO2/NaHSO4·H2O/SiO2 un der mild con di tions with ex cel lent yields. ... Azo com pounds have caused great in ter est in or ganic syn the sis. They are widely used as dyes and an a lyt i cal re - agents.1 Op ti cal-switching and im age stor age can be made by azo ben zene liq uid crys tal film.2,3 Re cently, many note wor thy stud ies have shown ...
