What is the structure of the molecule with the name (E)-3-benzyl-2,5-dichloro-4-methyl-3-hexene?

1 Answer
Ernest Z.
Jun 9, 2015

The structure of (E)-3-benzyl-2,5-dichloro-4-methylhex -3-ene is

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Explanation:

The real problem here is determining the (E,Z) configuration of the molecule.

You draw a hexane chain with the double bond between "C-3" and "C-4", "Cl" atoms at "C-2" and "C-5", a benzyl group at "C-3", and a methyl group at "C-4".

Determine the priorities of the groups on "C-3".

  • Benzyl. The atoms directly attached to the methylene carbon atom are ("C,H,H").
  • 1-Chloroethyl. The atoms directly attached to "C-1" are ("Cl,C,H").

1-Chloroethyl has higher priority than benzyl because color(lime)"Cl" has a higher atomic number than "C".

Determine the priorities of the groups on "C-4"

  • 1-Chloroethyl. The atoms directly attached to "C-1" are ("Cl,C,H").
  • Methyl. The atoms directly attached to the methyl carbon atom are ("H,H,H").
    1-Chloroethyl has higher priority than methyl because color(lime)"Cl" has a higher atomic number than "H".

In each case, the 1-chloroethyl group has the higher priority.

These groups must therefore be on opposite sides of the double bond (entgegen).

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