Question

For each horizontal row of substituted benzenes, indicate

1. the one that is the most reactive in an electrophilic aromatic substitution reaction.
2. the one that is the least reactive in an electrophilic aromatic substitution reaction.
3. the one that yields the highest percentage of meta product in an electrophilic aromatic substitution reaction

1.

2.

3.

Short answer

1. 
   

Most reactive Least reactive

2.

Least reactive most reactive

3.

Most reactive least reactive

Step-by-step solution

Reactivity of row 1 in electrophilic aromatic substituent

In the first horizontal row, toluene is more reactive.

Because toluene is an electron-donating group due to the presence of an alkyl group that is methyl and the rest have an electron-withdrawing group which makes it least reactive.

In the first horizontal row, benzal fluoride is less reactive.

Because the compound contains two fluorine atoms and fluorine is an electron-withdrawing in nature and due to the presence of two atoms it becomes the least reactive.

Most reactive least reactive

Reactivity of row 2 in electrophilic aromatic substituent

In the second horizontal row N, N ethyl, tert-butyl aniline is more reactive.

The electron-donating groups are more reactive toward electrophilic aromatic substitution reaction and the alkyl group shows an electron-donating effect more the alkyl group will be electron-donating effect and the more reactive the substance is.

In the second horizontal row N, N tert-butyl aniline is less reactive.

Reactivity depends upon the electron-donating group more the presence of the electron-donating group is the reactivity and the N-tert butyl have fewer alkyl group than other least reactive.

Least reactive most reactive

Reactivity of row 3 in electrophilic aromatic substituent

In the third horizontal row,ethoxy benzene is more reactive.

Due to the presence of oxygen having lone pair act as an electron-donating group and make the compound more reactive.

In the third horizontal row, methyl is less reactive

Due to the presence of carbonyl which acts as an electron-withdrawinggroup and makes the compound least reactive.

Most reactive least reactive

High percentage of meta product

The compound which has an electron-withdrawing effect are meta directing because they deactivate the ortho and para position for substitution and those compounds are least reactive in electrophilic aromatic substitution so,

The compound has a high percentage of meta product in row 1: benzal fluoride

The compoundhasa high percentage of meta product in row 2: N, N tert-butyl aniline

The compoundhasa high percentage of meta product in row 3: methyl benzoate