Section Bank Spoiler!!! C/P 29

[Chelsea FC]

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Hey can anyone help be identify why 2b has more conjugations than 2a.. I am having problems counting them effectively and this has basically bugged me so much it has stalled my studying

 

[Mr. otcoD]

Conjugation is dealing with double bonds. In Compound 2a, yes there is the additional ring closure from the carboxylic acid but there is no double bonds in the actual ring. Think of conjugation as like a ladder. Each double bond is a rung and a single bond is the space between the rungs.

 

[Chelsea FC]

Conjugation is dealing with double bonds. In Compound 2a, yes there is the additional ring closure from the carboxylic acid but there is no double bonds in the actual ring. Think of conjugation as like a ladder. Each double bond is a rung and a single bond is the space between the rungs.

Wouldnt the O and the C=O lead to a conjugation ? And if not I still cant see why 2b has more conjugation

 

[Hospitalized]

2b has a one bond between each double bond. And also consider the quinone ring -- similar conjugated system as benzene. For 2a, if you look at the central carbon, it has no double bond on either side of it. This upsets the conjugation.