What is the Difference Between Symmetrical and Unsymmetrical Alkenes?

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The main difference between symmetrical and unsymmetrical alkenes lies in the substituents at each end of the double bond.

  • Symmetrical alkenes have the same substituents at each end of the double bond. These alkenes are characterized by having doubly bonded carbon atoms bearing the same ligands.
  • Unsymmetrical alkenes have different substituents at each end of the double bond. These alkenes are characterized by having doubly bonded carbon atoms bearing different ligands.

Alkenes are hydrocarbon compounds containing at least one carbon-carbon double bond. They are classified into two major types: terminal and internal alkenes, depending on the position of the double bond in the molecule. Symmetrical and unsymmetrical alkenes can be found in both terminal and internal alkene categories.

Comparative Table: Symmetrical vs Unsymmetrical Alkenes

The main difference between symmetrical and unsymmetrical alkenes is the arrangement of substituent groups on the carbon-carbon double bond. Here is a summary of their differences:

Symmetrical Alkenes Unsymmetrical Alkenes
Both substituent groups on the double bond are identical. The two substituent groups on the double bond are different.
Carbon-carbon double bond is in the terminal position. Carbon-carbon double bond can be in the terminal or internal position.
Examples include ethene (C₂H₄) and propene (C₃H₆). Examples include butene (C₄H₈) and pentene (C₅H₁₀).

In addition to these differences, the reactivity of symmetrical and unsymmetrical alkenes can also vary. For instance, when a symmetrical alkene reacts with hydrogen bromide, the result is the same regardless of whether the hydrogen from HBr is added to one end of the double bond or the other.