Q37 of 66 Page 149

“Stability of carbocation depends upon the electron releasing inductive effect of groups adjacent to positively charged carbon atom involvement of neighbouring groups in hyper-conjugation and resonance.”

The structure of triphenylmethylcation is given below. This is very stable and some of its salts can be stored for months. Explain the cause of high stability of this cation.



The triphenylmethylcation is very stable because, it is a tertiary carbocation as well as the positive charge present on the carbon atom is being stabilised by three phenyl groups via resonance.

As we know that the phenomenon of resonance, leads to enormous stability of carbocation, as there is delocalisation of electron cloud, and the phenyl ring has great amount of delocalised electrons which are very potentially stabilising the positive charge lying on the carbon.


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35

“Stability of carbocation depends upon the electron releasing inductive effect of groups adjacent to positively charged carbon atom involvement of neighbouring groups in hyper-conjugation and resonance.”

Draw the possible resonance structures for and predict which of the structures is more stable. Give reason for your answer.


 36

“Stability of carbocation depends upon the electron releasing inductive effect of groups adjacent to positively charged carbon atom involvement of neighbouring groups in hyper-conjugation and resonance.”

Which of the following ions is more stable? Use resonance to explain your answer.



 38

“Stability of carbocation depends upon the electron releasing inductive effect of groups adjacent to positively charged carbon atom involvement of neighbouring groups in hyper-conjugation and resonance.”

Write structures of various carbocation that can be obtained from 2-methylbutane. Arrange these carbocation in order of increasing stability.


 39

Three students, Manish, Ramesh and Rajni were determining the extra elements present in an organic compound given by their teacher. They prepared the Lassaigne’s extract (L.E.) independently by the fusion of the compound with sodium metal. Then they added solid FeSO4 and dilute sulphuric acid to a part of Lassaigne’s extract. Manish and Rajni obtained Prussian blue colour but Ramesh got red colour. Ramesh repeated the test with the same Lassaigne’s extract, but again got red colour only. They were surprised and went to their teacher and told him about their observation. Teacher asked them to think over the reason for this. Can you help them by giving the reason for this observation. Also, write the chemical equations to explain the formation of compounds of different colours.