why 1bromobutane is optically inactive while 2 bromobutane is optically active?

Dear Student,

Please find below the solution to the asked query:


A substance is said to be optically active which can rotate a plane polarized light. Such substance chiral molecules. The reverse is true for optically inactive compounds.



If you look at the carbon center in 1-bromobutane it has two hydrogens attached to it and hence it has a plane which can divide the molecule in equal half, i.e. plane containing C3H7 - C - Br, hence the carbon center is achiral and is optically inactive. On the other hand, the carbon center in 2-bromobutane has four different groups attached to it and hence do not possess a mirror plane, so we can say that it is chiral or optically active.



Hope this information will clear your doubts about Haloalkanes and Haloarenes.

Best Wishes !

  • 8
In 1-bromobutane the carbon which has bromine attached to it has two H atoms attached to it....but in 2-bromobutane second carbon has four different groups attached they r 1) bromine 2) methyl group 3) H-atom 4) and a C2H5 group So as the carbon in 2-bromobutane has four different groups attached so its optically active whereas in 1 -bromobutane there r two same groups that is two H-atoms attached therefore it is not optically active
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