Isomer

same molecular formula, different structural formula

Structural isomer/constitutional • Different functional group (functional group isomerism) • Same functional group • chain isomer • position isomers -Tautomerism Stereoisomers • cis-trans isomers (geometric isomers) • optical (configurational) isomers • conformational isomers

-aka Structural isomerism -Molecules that contain the same atoms but connected in different ways so they contain different functional groups and / or bonding patterns. They have different physical and chemical properites.

• Chain isomerism • Postition isomerism • Functional group isomerism • Tautomerism

Isomers arise because of the possibility of branching in carbon chains

The basic carbon skeleton remains unchanged, but important groups are moved around on that skeleton.

Isomers contain same molecular formula, but different functional groups

The atoms making up the isomers are joined up in the same order/connectivity, but still manage to have a different spatial arrangement.

• Conformational isomerism • Configurational isomerism • Geometric isomers (E/Z or cis/trans) • optical isomerism

• Stereoisomers produced by rotation about the sigma bonds • Typically can interconvert at room temperatrure • represented by newman progection

stereoisomers that can cannot be converted into one another by rotation around a single bond.

• Geometric isomerism • Optical isomerism

Stereoisomers whose substituents are arranged differently relative to each other around a double bond or ring.

• cis-trans isomerism • E-Z isomerism

Geometrical isomers in which two identical substituents (or two pairs of two identical substituents) are bonded differently to carbon atoms participating in a double bond or ring bond.

higher atomic number, higher priority If the higher-priority substituents (“1” and “2”) are on the same side of the double bond, then the substituents are arranged in Z configuration; if the higher-priority substituents are on opposite sides of the double bond, then they are arranged in E configuration.

aka. chiral isomer Optical isomers are named like this because of their effect on plane polarised light. mirror image=enantiomers

• a pair of enantiomer shows similar reactivity with achiral molecule • can show completely opposite behavior with other molecules • Thus a pair of enantiomers may react differently with a receptor site