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Lance Crayon

Order of reactivity of carbonyl compounds towards nucleophilic addition

Doctor Lee  Follow

Carbocation doesn't come into the picture at all, when we are discussing about nucleophilic addition reactions. Steric hindrance will also not play a role because the compounds are planar (attack is going to take place on $sp^2$ hybridised carbon). The nucleophile is going to attack only from the top and bottom* as shown:

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The only factors that come into picture in the options are the electron withdrawing or releasing nature of the groups attached to the carbonyl carbon. If the group is $e^-$ withdrawing in nature, the deficiency on the carbon atom increases, making it susceptible to nucleophilic attack.

So, the correct order is : B > A > C > E > D

P.S.:* Since the attack is from top and bottom, both of which are equally likely, the resulting product is a racemic mixture (if the carbon on which attack happens is chiral after the attack).

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John Willis  Follow
chemistry.stackexchange.com/questions/7412/…More
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Erik Bergstr?m  Follow
And read this answer by Greg: More
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Goran Savic  Follow
Also, you modify those arrows showing nucleophilic attack since its not exactly perpendicular to the x-z plane. Due to repulsions from the filled $\pi$ orbitals of carbon, the nucleophile approaches at an obtuse angle. You can read about it by searching Burgi-Dunitz angle on Google.More
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Gail Fisher  Follow
google.co.in/url?sa=t&source=web&rct=j&url=http://…More
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Jonathan Belsey  Follow
Read this: More
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