Isomerism in organic compounds, Lecture notes of Chemistry

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What Is isomerism? lsomers are compounds that have the same molecular formula, but different arrangements of atoms. There are two main types of isomerism: structural isomerism and stereoisomerism. Structural isomerism OH OH om™ ® Instructural isomers, the chemical ANZ position formula remains the same but the structural formula changes. oon se SN functional ® Position isomerism occurs when the GfOuPp location of the functional group varies in each isomer. A YS ™ Ghali ® Functional group isomerism occurs when there are different functional groups present. ® Chain isomerism occurs when isomers differ in the structure of their carbon ‘skeleton’. Stereoisomerism H3C CH; H3C H =( = = ® Sterecisomers are compounds whose : 2 = molecules have the same atoms bonded to each other, but with different cis trans neither arrangements of the atoms in space. \ _/ a = *® Geometrical (cis/trans) isomerism occurs due to the restricted rotation about a C=C double bond. In cis Reflection . ; isomers, the substituents are on the H H same side of the double bond, while in trans isomers, they are on opposite sides. HN COOH : HOOC Nie R R ° Optical isomerism occurs when a A B molecule contains a carbon atom bonded to four different atoms or groups of atoms. This carbon atom is called a chiral centre. The two isomers, called enantiomers, are mirror images of each other and cannot be superimposed.