Four-Membered Heterocyles

The chalcogenolysis of the disilene 721 with N20, S, Se, and Te results in formation of the three- and four-membered heterocyles 748-752 (Scheme 98). The addition of the isonitrile /-BuNC to the disilene 721 affords... 

A few measurements have been reported for ethylene carbonate, propylene carbonate, 4-butyrolactone and 4-valerolactone. ° These compounds are aprotic 5-membered heterocylic ring structures with unusually large dipole moments. Dielectric constants range from 36 for valerolactone to 89.6 for ethylene carbonate. All appear to be normal polar liquids. In all four solvents a capacity hump is observed on the positive side of the pzc (Fig. 7.2.5). The temperature coefficient of capacity at the hump in the butyrolactone solution is only one third of its value in DMSO and sulpholane, and less than one tenth of the water value. Anions appear to be specifically adsorbed as in other solvents. Strong specific adsorption of CIO4 anions from propylene carbonate has been reported. Butyrolactone is strongly adsorbed from aqueous solutions. ... 

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