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Questions tagged [c-x-addition]

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Steriochemistry of 1,4-addition reaction of Trans buta -1,3-diene [duplicate]

I had learnt that in 1,4 addition (on reacting butadiene with HBr) the product formed will be trans isomer of 1- bromobut-2-ene .But in a question I saw that it gives both cis and trans isomer of of 1-...
4
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1answer
153 views

Can enamines be formed from α,β-unsaturated ketones?

This question was a result of discussion form here: α,β-unsaturated carbonyl compounds and alkyl addition The reaction below (condensation of cyclohexenone with a secondary amine) does not yield any ...
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1answer
311 views

difference between elimination reactions and oxidation reactions [closed]

I know that oxidation reactions involve the loss of hydrogen. But is the mechanism the same
5
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1answer
557 views

In the addition of HBr to isoprene why does the less stable carbocation form? [duplicate]

According to me, the answer is B as the tertiary allylic carbocation should be more stable. But the answer given is D and in the given solution, the tertiary allylic carbocation rearranges to primary ...
0
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1answer
221 views

Carbocation Stability: Tertiary versus Secondary Benzyl for Hydrobromic Acid Addition

I haven't been able to find anything concrete or consistent on this topic. For the following reactions, which product would be favored, assuming that they both have to go through a carbocation ...
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93 views

Steric hindrance during Hydroboration

In response to this diagram (Organic Chemistry By David Klein 3rd Edition Page 364): The textbook stated A comparison of the transition states for hydroboration via Markovnikov addition or anti-...
4
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2answers
2k views

Why does NOCl dissociate as +NO and Cl-?

$\ce{N}$ is more electronegative than $\ce{Cl}$ (albeit by a very small difference) but it should ideally dissociate as $\ce{Cl+}$ and $\ce{-NO}$ (similar to the dissociation of $\ce{Cl}$ in $\ce{HOCl}...
2
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0answers
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Addition Reaction

Why does the following addition reaction use radicals rather than using the normal transfer of hydrogen (seen in last picture)? I would think that because the reaction has no light to indicate ...
4
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1answer
367 views

Isocyanides undergo addition reactions, but cyanides do not. Why?

My book mentions addition reactions of isocyanides with halogens, ozone, sulphur, etc. but it doesn't mention any such reaction for cyanides. Instead, it bluntly states: "Cyanides do not undergo ...
7
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2answers
470 views

What is the driving force for imine formation?

I know this that when a primary amine is reacted with a carbonyl compound, an imine is formed: I'm wondering why the position of this equilibrium lies to the product side / right-hand side. Why is ...
0
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1answer
146 views

Mechanism for cyclic enamine formation after N-Boc deprotection

In this reaction taken from Snyder's total syntheses of Coccinellid alkaloids,1 how does the Boc deprotection lead to ring closure? I understand that the $\ce{PBr3}$ step simply converts the alcohol ...
5
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1answer
2k views

Cram's rule for nucleophilic addition to carbonyl groups

I recently heard about Cram's rule for predicting the stereoselectivity in nucleophilic additions to carbonyl groups. Can anybody explain what this is and whether it is an accurate rule?
5
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3answers
439 views

Effect of protecting group on diastereoselectivity of LiAlH4 reduction of α-hydroxyketones

In the reactions above, taken from Tetrahedron Lett. 1982, 23 (23), 2355–2358, the choice of protecting group on the α-hydroxyl group has a large influence on the diastereoselectivity of reduction. ...
4
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1answer
3k views

What is the major product formed on addition of Hydrogen Iodide to Pent-2-ene?

Orginal question: (1) One of the carbocations formed (CC on the right) is only slightly more stable than the other (both are 2°). (2) Iodine ion ($\ce{I-}$) is a slightly bigger ion and ...
9
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1answer
7k views

Order of reactivity of carbonyl compounds to Nucleophilic addition reaction

One of the questions in my textbook was to arrange the following in order of their reactivity for nucleophilic addition reaction. $\ce{(p-NO2Ph)_2CO}$ $\ce{(CH3)_2CO}$ $\ce{(p-NO2Ph)COH}$ $\...