Chemsheets AS006 (Electron arrangement) 21/09/2018 www.CHEMSHEETS.co.uk GEOMETRIC ISOMERISM © www.chemsheets.co.uk AS 053 12-Jul-12
X GEOMETRIC ISOMERISM CANNOT ROTATE AROUND C=C © www.chemsheets.co.uk AS 053 12-Jul-12
GEOMETRIC ISOMERISM (E) but-2-ene (Z) but-2-ene E entgegen (opposite) Z zusammen (together) © www.chemsheets.co.uk AS 053 12-Jul-12
GEOMETRIC ISOMERISM PRIORITY: H < CH3 < CH2CH3 Look at atomic numbers of atoms attached to C=C (or subsequent atoms if the same). Highest values opposite = E Highest values together = Z 6 6, 6 6 6 6 E 2-bromo-3-fluorobut-2-ene E 3-methylpent-2-ene © www.chemsheets.co.uk AS 053 12-Jul-12
BOTH C ATOMS OF C=C MUST HAVE GEOMETRIC ISOMERISM trans but-2-ene (E) but-2-ene cis but-2-ene (Z) but-2-ene BOTH C ATOMS OF C=C MUST HAVE TWO DIFFERENT GROUPS © www.chemsheets.co.uk AS 053 12-Jul-12
TASK NO YES E Z methylpropene 1-chloropropene © www.chemsheets.co.uk AS 053 12-Jul-12
TASK NO NO 2-methylpent-2-ene 2-ethylpent-1-ene © www.chemsheets.co.uk AS 053 12-Jul-12
TASK YES E Z NO 3-methylpent-2-ene but-1-ene © www.chemsheets.co.uk AS 053 12-Jul-12
TASK YES Z E YES E Z 3,4-dimethylhex-3-ene 2-bromo-3-chlorobut-2-ene © www.chemsheets.co.uk AS 053 12-Jul-12