Name: SN2 Reaction
Uploaded: 2019-07-19
Duration: 1 min 59 s
Description: In the SN2 reaction, nucleophiles attack from the back side of the carbon. So the product assumes a stereochemical position opposite to the leaving group.

Question

Arrange the isomeric dichlorobenzene in the increasing order of their boiling point and melting points.

Accepted Answer

The arrangement of the isomeric dichlorobenzene in the increasing order of their boiling point and melting points is:

m-dicholrobenzene $<$ o-dicholrobenzene $<$ p-dicholrobenzene

The boiling points of isomeric (o-, m- and p-) dihalobenzenes are very nearly the same due to the absence of hydrogen bonding. But, the melting points of these compounds show a considerable variation. Among isomeric dihalobenzenes, the para isomer has a much higher melting point (about $70 - 100$ degree) as compared to that of ortho or meta isomer. For example,

The higher melting point of para isomer is due to its symmetrical structure. Due to symmetrical structure, the molecules of p-isomer can pack more closely in the crystal lattice as compared to those of o- and m-isomers. Consequently, the intermolecular forces of attraction in p-isomer are stronger and a greater energy is required to break the lattice. This is why p-isomer melts at a much higher temperature than the corresponding o- and m-isomers. The ortho isomer has a stronger dipole-dipole interaction as compared to the meta isomer.

Arrange the isomeric dichlorobenzene in the increasing order of their boiling point and melting points.

Important Questions on Haloalkanes and Haloarenes

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