Q15-15-23E - Organic Chemistry (Mcmurry)

Question

Propose structures for aromatic hydrocarbons that meet the following descriptions:

 (a) C₉H₁₂; gives only one C₉H₁₁Br product on substitution of hydrogen on the aromatic ring with bromine 

(b)C₁₀ H₁₄ ; gives only one C₁₀H₁₃Cl product on substitution of hydrogen on the aromatic ring with chlorine 

(c) C₈H₁₀; gives three C₈H₉Br  products on substitution of hydrogen on the aromatic ring with bromine 

(d)C₁₀ H₁₄  ; gives two C₁₀H₁₃Cl products on substitution of hydrogen on the aromatic ring with chlorine

Step-by-Step Solution

Answer

(a)

                   Structure of the molecule

                                        Brominated product from the C₉H₁₂

(b)

                   Structure of the molecule

Chlorinated product from the C₁₀H₁₄ 

(c)

 

Structure of the molecule

                          Three brominated products from the C₈H₁₀

(d)

Structure of the molecule

                                  Two chlorinated products

Given is compound A

In the provided compound A,, there are nine carbon atoms that suggest that on parent hydrocarbon, i.e., (benzene) three methyl group is present. The remaining three positions on the benzene ring are with -CH₂ . By relacing one hydrogen with Br produces C₉H₁₁Br. Thus, the given compound produces only one product on substitution as there is only one kind of -C-H bond.

Product formed

The structure of the molecule with the formula C₉H₁₂ is

                   Structure of the molecule

 

The only brominated product from the C₉H₁₂  is shown as follows:

Brominated product from the C₉H₁₂ 

Given is compound B

In the provided compound B,  there are 10 carbon atoms that suggest that on parent hydrocarbon, i.e., (benzene) four methyl group or two ethyl group is present. The remaining three positions on the benzene ring are with -CH₂ . By relacing one hydrogen with Cl produces C₁₀H₁₃Cl. Thus, the given compound produces only one product on substitution as there is only one kind of -C-H bond. 

Product formed

The structure of the molecule with the formula is C₁₀H₁₄

Structure of the molecule

The only chlorinated product from the  C₁₀H₁₄ is shown as follows:

Chlorinated product from the C₁₀H₁₄

Given is compound C

In the provided compound C,  there are eight carbon atoms that suggest that on parent hydrocarbon, i.e., (benzene) two methyl group is present. The remaining three positions on the benzene ring are with -CH₂ . By relacing one hydrogen with Br produces C8H9Br. Thus, the given compound produces three product on substitution as there is three different kind of -C-H bond.

Product formed

The structure of the molecule with the formula C₈H₁₀ is 

The three brominated products from the C₈H₁₀   is shown as follows:

                           Three brominated products from the C₈H₁₀ 

Given is compound D

In the provided compound D,  there are 10 carbon atoms that suggest that on parent hydrocarbon, i.e., (benzene) two ethyl group is present. The remaining four positions on the benzene ring are with CH. By relacing one hydrogen with Cl produces C₁₀H₁₃Cl. Thus, the given compound produces two product on substitution as there is two different kind of -C-H bond.

Product formed

The structure of the molecule with the formula isC₁₀H14: