You have three bottles containing the three isomeric dibromobenzenes; they have the melting points \(+87^{\circ},+6^{\circ}\), and \(-7^{\circ} .\) By a great deal of work, you prepare six dibromonitrobenzenes \(\left(\mathrm{C}_{6} \mathrm{H}_{3} \mathrm{Br}_{2} \mathrm{NO}_{2}\right)\) and find that, of the six, one is related to (derived from or convertible into) the dibromobenzene of m.p. \(+87^{\circ}\), two to the isomer of m.p. \(+6^{\circ}\), and three to the isomer of m.p. \(-7^{\circ}\). Label each bottle with the correct name of ortho, meta, or' para. (This work was actually carried out by Wilhelm Körner, of the University of Milan, and was the first example of the Korner method of absolute orientation.)

Step by step solution

01

Ortho, Meta, and Para positions overview

These terms are used to describe the relative position of substituents on a benzene ring. The ortho position refers to two adjacent carbon atoms on the ring, the meta position describes a gap between two substituents, and the para position has the substituents directly opposite to one another on the benzene ring. Now we can analyze the effect of these positions on the number of possible dibromonitrobenzenes:

02

Ortho-dibromobenzene

In ortho-dibromobenzene, there are two bromine atoms located at adjacent carbon atoms. When we add a nitro group, there is only one possible position for it to be attached without being in direct contact with the adjacent bromine atoms. Therefore, there can only be one ortho-dibromonitrobenzene derivative.

03

Meta-dibromobenzene

In meta-dibromobenzene, there are two bromine atoms located on the benzene ring with one carbon atom separating them. When we add a nitro group to this isomer, there are actually two possible positions where the nitro group can be added, creating two distinct meta-dibromonitrobenzenes.

04

Para-dibromobenzene

In para-dibromobenzene, there are two bromine atoms located directly opposite each other on the benzene ring. When we add a nitro group to the para-dibromobenzene, there are three possible positions where the nitro group can be added, which leads to the formation of three distinct para-dibromonitrobenzenes. With this information, we can now confidently label the bottles:

05

Label the bottles

Based on the analysis, we can conclude that the bottle with the melting point of +87°C is the ortho-dibromobenzene, since one dibromonitrobenzene is related to it. The bottle with the melting point of +6°C is the meta-dibromobenzene, as two dibromonitrobenzenes are related to it. Finally, the bottle with the melting point of -7°C is the para-dibromobenzene, as three dibromonitrobenzenes are related to it.

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