hat
Efè a anomèr nan yon bag heterospiral vle di ke de atòm elèktron-pozitif oswa pè pè elektwon nan konformasyon an se nan direksyon opoze a diminye moman sa a dipol nan molekil la epi redwi enèji nan intramolekilè. Nan 1968, ekip la rechèch Descotes premye pwopoze yon efè anòmik. Lè yo etidye asetik bicyclic yo, yo te jwenn ke de konpoze yo nan figi ki anba a ki genyen 57 nan izomè a cis ak 43 nan izomè trans a nan melanj la ekilib nan 80 C. Transfòmatè a izomè trans trans isomèr a te estab ak yon enèji diferans nan 0.71 kJ / mol. Paske nan efè a anomèr nan izomèr a cis, izomèr a trans pa gen okenn efè sa yo.
eng
The anomeric effect of a heterospiral ring means that two electron-positive atoms or lone pairs of electrons in the conformation are in the opposite direction to reduce the dipole moment of the molecule and reduce the intramolecular energy. In 1968, the Descotes research team first proposed an anomeric effect. When they studied the bicyclic acetal, they found that the two compounds in the figure below contained 57% of the cis isomer and 43% of the trans isomer in the equilibrium mixture at 80 C. The cis isomer ratio trans The isomer was stable with an energy difference of 0.71 kJ/mol. Because of the anomeric effect of the cis isomer, the trans isomer has no such effect.