Portal de Periódicos da CAPES

The conformation of non-aromatic ring compounds. XXIII: Some halogenated 1,4-dithianes

1966; Royal Netherlands Chemical Society; Volume: 85; Issue: 6 Linguagem: Inglês

10.1002/recl.19660850615

1878-7096

H. T. Kalff, E. Havinga,

Organic and Inorganic Chemical Reactions

Abstract Several 2,3‐ and 2,5‐disubstituted halogeno‐1,4‐dithianes have been prepared and their conformational features have been investigated by means of dipole moments and infrared spectra. The NMR spectra, described elsewhere 2 , support the results presented in this paper. The crystal structures of trans ‐2,3‐dichloro‐1,4‐dithiane 3 and trans‐2,5‐dibromo‐1,4‐dithiane 1 , determined by X‐ray analysis, provide us with a basis for the conformational analysis. In both compounds the halogen atoms are in axial positions. For the 2,3‐compounds (dichloro‐, dibromo‐, and 2‐bromo‐3‐chloro‐) the dipole moments remain constant on changing the solvent; the infrared spectra in the solid state (KBr discs) and in solution (CS 2 ) are practically identical. The 2,5‐compounds, however, show additional peaks in solution in carbon disulfide, indicating a shift from the conformation with two axial halogen atoms to that with two equatorial halogen atoms in solution. The tetrachloro‐1,4‐dithiane, described by Varvoglis and Tsatsaronis 4 , is proved to be 2,2,3,3‐tetrachloro‐1,4‐dithiane. No trace of mono‐substituted, cis ‐2,3‐ or cis ‐2,5‐disubstituted products could be detected in our synthetic experiments.