a variety of alcohols readily add to 3,4-dihydro-2h-pyran under solvent free conditions in the presence of catalytic amount of acidic ionic liquid [et3n(ch2)4so3h][ots] to afford the corresponding tetrahydropyranyl ethers in good to excellent yields at room temperature. the use of this procedure allows easy separation of the desired products from ionic liquid and recycling the ionic liquid. som...

h-point standard addition method (hpsam) with simultaneous addition of both analytes in nonaqueous solution was applied for determination of levonorgestrel (lev) and ethinyl estradiol (ee)  in ld and hd tablets. the results showed that, simultaneous determination could be performed with the ratio 1 to 5 of lev-ee. the lod for lev and ee were obtained 5.1×10 -7 and 9.6×10 -7 m, respectively, and...