Question

Compound prepared in lab was found to be 3,4 di-bromo hexane write all the possible structures of it and specify them as R and S. Give stereochemical relationship between all the isomers. Can the isomers of the above compound be separated based upon physical properties? 

Answer 1

The higher the atomic number of the immediate substituent atom, the higher the priority. For example, H– < C– < N– < O– < Cl–. (Different isotopes of the same element are assigned a priority according to their atomic mass.)

In the letter E, the horizontal strokes are all on the same side; in the E isomer, the higher priority groups are on opposite sides. In the letter Z, the horizontal strokes are on opposite sides; in the Z isomer, the groups are on the same side.

• Hexane, CH₃CH₂CH₂CH₂CH₂CH₃, a straight chain of six carbon atoms.
• 2-Methylpentane (Isohexane), CH₃CH(CH₃)CH₂CH₂CH₃, a five-carbon chain with one methyl branch on the second.
• 3-Methylpentane, CH₃CH₂CH(CH₃)CH₂CH₃, a five-carbon chain with one methyl branch on the third.