O vs P ChloroNitroBenzene Polarity

[Hockeystar]

I'm having trouble understanding the difference in polarity between O and P ChloroNitroBenzene for my lab. One group is telling me the O isomer is less polar because the nitro group and chloro group do intramolecular bonding preventing intermolecular bonding. Another group is telling me the O isomer is more polar because the electron withdrawing groups are together creating more of a charge. The melting point of the O isomer is less than P but the P goes up the TLC further. Boiling points are almost identical. Thanks in advance.

David

 

[jbsteele]

's answer: The O-isomer is less polar because the nitro and chloro groups are located on the same side of the molecule, preventing intermolecular interactions. This results in weaker intermolecular attractions, resulting in a lower boiling point and melting point. On the other hand, the P-isomer has the nitro and chloro groups on opposite sides, allowing for stronger intermolecular interactions and thus stronger intermolecular attractions, resulting in a higher boiling point and melting point. The P-isomer also moves up the TLC further because it has more surface area available for interaction with the TLC plate.