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Isomers Isomers are compounds with the same molecular formula but different structures and properties.Prepared by Prof. Dr. Hilal Zaid 10/24/2024 22 Prepared by Prof. Dr. Hilal Zaid 10/24/2024 Structural Isomers: Structural isomers differ in the connectivity of their atoms.o Example: Ethanol (C2H5OH) and dimethyl ether (C2H6O) have the same molecular formula but different functional groups (alcohol vs. ether).o Example: In but-2-ene, the cis isomer has the two methyl groups on the same side of the double bond, while the trans isomer has them on opposite sides.Types: oChain Isomers: Variations in the carbon chain (e.g., straight-chain vs. branched).Stereoisomers Stereoisomers have the same connectivity but differ in the spatial arrangement of atoms.

Isomers
Isomers are compounds with the same molecular formula but different
structures and properties.
Prepared by Prof. Dr. Hilal Zaid 10/24/2024
22 Prepared by Prof. Dr. Hilal Zaid 10/24/2024
Structural Isomers:
Structural isomers differ in the connectivity of their atoms.
Types:
•Chain Isomers: Variations in the carbon chain (e.g., straight-chain vs.
branched).
• Example: Butane (C₄H₁₀) has two chain isomers: n-butane (a
straight chain) and isobutane (a branched chain).
•Position Isomers: Differ in the position of a functional group on the
carbon chain.
• Example: 1-bromopropane and 2-bromopropane (the bromine is in
different positions).
•Functional Group Isomers: Differ in the functional groups present.
• Example: Ethanol (C₂H₅OH) and dimethyl ether (C₂H₆O) have the
same molecular formula but different functional groups (alcohol
vs. ether).
23 Prepared by Prof. Dr. Hilal Zaid 10/24/2024
24 Prepared by Prof. Dr. Hilal Zaid 10/24/2024
2. Stereoisomers
Stereoisomers have the same connectivity but differ in the spatial
arrangement of atoms. There are two main types:
•Geometric Isomers (Cis-Trans Isomers): Differ in the arrangement of
groups around a double bond or a ring structure.
• Example: In but-2-ene, the cis isomer has the two methyl groups on
the same side of the double bond, while the trans isomer has them on
opposite sides.
•Optical Isomers (Enantiomers): Non-superimposable mirror images of
each other. They typically involve chiral centers (atoms with four different
groups attached).
• Example: Lactic acid has two enantiomers, D-lactic acid and L-lactic
acid, which are mirror images of each other.
25 Prepared by Prof. Dr. Hilal Zai