These questions are regarding to the Aromaticity and its reactions, I appreciate
ID: 538164 • Letter: T
Question
These questions are regarding to the Aromaticity and its reactions, I appreciate the help, thanks. Question 1 1 pts Which of the following statements is not true regarding electrophilic aromatic substitution? O Benzene acts as the nucleophile and its strength is affected by substituents on the ring. The rate determining step is the deprotonation of the intermediate because a base is not present. O A non-aromatic intermediate is formed that contains an sp hybridized carbon. O The electrophile is involved in breaking aromaticity
Explanation / Answer
Q1- the option B is wrong.
The rate determination step is the first, that is the electrophile forms a sigma-bond to the benzene ring and generating a positively charged benzenonium intermediate. This step is slow and rate-determining, step. The deprotonation step is fast and not rate determination step
Q2 - ans is option A
Because, rate of electrophilic substitution reactios depends on the nucleophilic nature of benzene ring. If benzene substituted with electron doonating groups like OR, NR2, the rate of reaction is more than benzene. At the same time, if the benzene ring is substituted with electron withdrawing groups like halogens/ Cl, Esters or amdes/CO2R, or positively charged quaternary amines/ +NR3, the rate of reaction is less than benzen.
Q3 - ans is opt A, All positions are possible. The reagent having both electron donating and withdrawaing groups on benzene ring but Both are orhto/para directing groups. strength of Br and Alkyl groups on directing abilities is Almost equal. So o and p positiions for both the groups will be participated, that means remaing 4 postions are active.
Q4 - ans is option b, at meta position to ketone
In this reagent, both electron withdrawing groups are present. Cl is ortho/para directing group but keto group is meta directing group. The effect of keto is more than Cl. So the substitution takes place at meta positioin to the keto group
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