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Questions tagged [rearrangements]

For questions about specific rearrangements within organic chemistry.

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What shold be the answer to the given reaction? [closed]

Q.75 The final product A, formed in the following reaction sequence is: $$\ce{ Ph-CH=CH2 ->[(i) BH3 (ii) H2O2,OH- (iii) HBr][(iv) Mg, ether, then HCHO/H3O+] A }$$ Options $\ce{Ph-CH2-CH2-CH2-OH}$ $...
Rock's user avatar
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5 votes
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Electrolytic reduction of nitrobenzene in differing media

In my lecture notes it is given that in a weakly acidic medium, nitrobenzene on electrolytic reduction gives aniline, which makes sense to me because there is ample H+ in the medium to continue adding ...
Gaurav Sai Maddipati's user avatar
2 votes
1 answer
164 views

Explain the mechanism of the following reaction, which involves a 1,2-alkyl migration with double inversion of configuration

I came across the following reaction, whose mechanism is said to involve a 1,2-alkyl migration with a double inversion in configuration. The reagents used were nitrous acid (generated in situ) ...
Cyclopropanol's user avatar
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1 answer
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What nucleophilic reaction takes place in case of bad leaving group as well as 1* alpha carbon?

If we add HI to a substrate Ph-C-C-OH what will be the major product and what reaction mechn. will be followed? My attempt: as -OH is bad Leaving Group, we cannot just simply proceed with Sn2 and ...
Ash_Tag's user avatar
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5 votes
1 answer
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Does boric acid really rearrange phenols?

This reaction was on prepchem.com and I want to know whether it could work. Most of their reactions are well sourced but this is rather scant (and can't find the patent referenced). It is possible ...
TWiz's user avatar
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-3 votes
1 answer
137 views

Carbocation rearrangement in dehydration of an alcohol [closed]

In this problem, I know that initially a positive charge is formed at the carbon bearing the hydroxyl group , yielding a secondary carbocation. But, I can't go any further with that. What kind of ring ...
Rishi Shekher's user avatar
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1 answer
718 views

Carbocation rearrangement with ring expansion

I was solving a particular question which landed me to a position where I have to decide whether the following ring expansion would take place or not by carbocation rearrangement: If the expansion ...
Shekhar Dangi's user avatar
-1 votes
1 answer
48 views

Sigmatropic Rearrangement along with oxidation [closed]

I was going through an organic chemistry book I came along this question it's solution used sigmatropic rearrangement along with oxidation in Jones reagent, how does this rearrangement work??
Awadhesh Prajapati's user avatar
6 votes
0 answers
85 views

3-Step Transformation to Humulone

I have some ideas on how this transformation may occur. We're currently studying Ch. 3 (Polar Rxn's under Acidic Conditions) from Grossman's book. I've found some data online that shows we can perform ...
PhDeezNutz's user avatar
7 votes
1 answer
183 views

Reaction between 1,2-bis(buta-1,3-dien-1-yl)cyclohexan-1-ol and potassium hydride in THF

Which product is formed in the following reaction? I am quite certain that we deal with an oxy-Cope rearrangement that works at room temperature, but I don’t know how to draw the product given the ...
Mäßige's user avatar
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Acidification of a vicinal diol [duplicate]

The following is a question from Advanced problems in organic chemistry by MS Chouhan: The options given are: My initial thought was that this could be a pinacol–pinacolone rearrangement. However ...
Lost Anisole's user avatar
-5 votes
1 answer
56 views

Mechanism of terpene alcohol rearrangement [closed]

I thought about all kinds of hydride shifts that could be possible here, but I still could not figure out how the mechanism would work.
John Tan's user avatar
3 votes
4 answers
3k views

Hydride shift or Methyl shift

For the carbocation (A) given in the reaction, first we can rearrange it by ring expansion (4 to 5) then we have two choices either H-shift or methyl-shift. My teacher told me that Hydrogen is the ...
Spencer's user avatar
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6 votes
1 answer
216 views

Does the Oxy or Alkoxy Claisen Rearrangement Exist?

@Waylander's cogent Comment to the query of @Random Guy inspired me to post a problem in synthesis to test a question I have pondered for some time. The activation energy (AE) for the Cope ...
user55119's user avatar
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1 vote
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Why doesn't the protonated propyne rearrange? [closed]

In the reaction of propyne with $\ce{HBr}$ this cation (prop-1-en-2-ylium) was mentioned by my teacher: $$\ce{H3C-\overset{+}{C}=CH2}$$ He told me that the carbocation will not rearrange as it will ...
Ankit's user avatar
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7 votes
3 answers
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What is abnormal Beckmann rearrangement?

What is abnormal Beckmann rearrangement? I read this term in one of my solution papers but I am not able to find relevant literature for the same. Answers linking to some source, or giving the ...
Ashish's user avatar
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9 votes
1 answer
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Weerman degradation on alpha-hydroxy amides

I came across this reaction scheme in the solutions of a test paper: I understand the formation of isocyanate intermediate as the first step. In the second step, I realized that hydrolysis will be ...
TRC's user avatar
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3 votes
0 answers
178 views

Migratory aptitude of chlorobenzene vs nitrobenzene in pinacol-pinacolone

I do know the basic order of migratory aptitude in pinacol-pinacolone rearrangement, which is usually said as subject to reaction conditions. However, I wanted to know how can I compare the migratory ...
Ashish's user avatar
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-4 votes
1 answer
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Does rearrangement occur in schmidt reaction? [closed]

I recently read about schmidt reaction in which a carboxylic acid is converted to an amine. While forming this, acyl carbocation $(\ce{RCO+})$ is formed, so does rearrangement takes place or reaction ...
Praneeth's user avatar
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0 answers
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Why is there a phenyl shift in this reaction?

Why is there a phenyl shift in this reaction. I believe that the +R effect by 2 phenyl groups would be better than the +R effect by oxygen because of its lone pair. Can somebody please confirm?
Ritvish's user avatar
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Why and how does ring expansion occur in the dehydration of (cyclobut-3-ene-1,2-diyl)dimethanol?

Can someone explain how does this ring expansion occur with the mechanism? I do understand that the hydride shift occurred because of carbocation stability but why did the ring expand? Can you please ...
Ritvish's user avatar
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5 votes
0 answers
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Why does this carbocation undergo further rearrangement? [duplicate]

I am trying to figure out the product of this reaction. I initially thought that a carbocation would be formed at where the chlorine leaves from: But according to the answer stated by the textbook,...
lazearoundallday's user avatar
8 votes
1 answer
280 views

Does a reaction proceed through SN1 if rearrangement results in a stable carbocation?

While going through my book I came across the following problem: I thought it was safe to assume that the secondary alcohol would give SN1(although secondary alcohols give significant amount of both ...
Prajwal Tiwari's user avatar
5 votes
3 answers
332 views

Possible carbocation rearrangement in substitution reaction to give two different products

In the following substitution reaction, is compound I formed by $\mathrm{S_N}$2 and compound II formed by $\mathrm{S_N}$1 and carbocation rearrangement? Or is there some rearrangement I'm not aware ...
sam's user avatar
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4 votes
0 answers
127 views

Beckmann Rearrangement in cyclic compounds

Consider 1-indanone: I am supposed to find the rearrangement product on treating this with hydroxylamine (which gives an oxime) and then $\ce{H+}$ (with heat). I am aware of the mechanism of Beckmann ...
lazearoundallday's user avatar
2 votes
0 answers
122 views

Products of the reaction between cyclohexanone and N-bromosuccinimide

Problem Treating cyclohexanone with N-bromosuccinimide in the presence of carbon tetrachloride gives A. A on treatment with aqueous KOH gives B. Deduce the structures of A and B. Solution Questions ...
lazearoundallday's user avatar
1 vote
1 answer
113 views

How does temperature and other factors affect sigmatropic rearrangements?

The image below shows a [3,3] sigmatropic rearrangement. My question is why does the increased temperature favour the right side? The arrangement is technically the same except for the methyl groups ...
M.L's user avatar
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2 votes
0 answers
61 views

Show the mechanism of the Pinacol-Pinacolone Rearrangement reaction [duplicate]

In the reactant, due to $\ce{H+}$ ion, a positive charge will be created by removing water in place of the rightmost $-\ce{OH}$. But then how will it give such a product. I cant see any way to make ...
Soham Chatterjee's user avatar
0 votes
1 answer
90 views

Carbocation rearrangement

I am dealing with some basic reactions in organic chemistry. One of these is the acid reflux of alcohols. Something I came across was hydride shifts. I know how and why they occur, but I don't ...
Ambica Govind's user avatar
1 vote
0 answers
139 views

Hydrogen isotope effect on methyl shift

Consider this typical 1,2 methanide shift in a carbocation: Which isotopic form of methanide ($\ce{CH3, CD3, or CT3}$) would migrate from secondary carbocation to form more stable tertiary ...
Apurvium's user avatar
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1 vote
1 answer
335 views

Baeyer-Villiger Oxidation restricted to Ketones

According to Wikipedia, Baeyer Villiger oxidation occurs at the electron deficient oxygen site, with elimination of the carboxylate ion, and migration of an R group. But it is restricted to ketones ...
Solid - NMR's user avatar
11 votes
1 answer
307 views

Mechanism for the addition of hydrogen iodide to 3,3‐dimethylbut‐1‐yne

The following reaction mechanism was given as a solution to a solved problem in my textbook1 for the addition of hydrogen iodide to 3,3‐dimethylbut‐1‐yne: It can be seen that that 2,2-diiodo-3,3-...
Vishnu's user avatar
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0 votes
0 answers
388 views

Extent of multiple hydride shifts in a carbocation

Take this example: Multiple hydride shifts are possible only if in each step, the formed intermediate is more stable than the previous one. (1) to (2) converts $2^\circ$ carbocation to $3^\circ$ ...
Apurvium's user avatar
  • 1,272
2 votes
1 answer
357 views

Acid catalysed dehydration of alcohol with a bicyclo group

Pathway 1: Rate determining step is the formation of carbocation. In this pathway, a conjugated tertiary carbocation is generated as an intermediate. Pathway 2: One of the resonance form of ...
Apurvium's user avatar
  • 1,272
0 votes
1 answer
97 views

Acid catalysed dehydration of 5-methylidenecyclopent-2-en-1-ol [closed]

I think the following reaction is NOT possible. I could not find a mechanism for ring expansion. Is ring expansion possible in any way? Is the following mechanism correct?
Apurvium's user avatar
  • 1,272
1 vote
2 answers
133 views

Dehydration of primary alcohol with a cyclobutadiene substituent [closed]

Note: Primary alcohol will follow E2 mechanism, therefore, removal of protonated water and proton (RDS) shall proceed in a single step in the above mechanism. My questions are: 1- According to ...
Apurvium's user avatar
  • 1,272
3 votes
1 answer
3k views

Beckmann rearrangement v/s dehydration of Oximes

In the above question, A is an oxime, which is then reacted with phosphorus pentoxide. Now, phosphorus pentoxide is both a dehydrating reagent and a reagent used for Beckmenn rearrangement, but which ...
user avatar
1 vote
1 answer
332 views

Ring expansion in cyclo compounds

In the following reaction, why does ring expansion not take place? Mechanism that was the correct one: In the second step when there is a protonated carbon the ring should expand to become 6 ...
Shaurya Goyal's user avatar
0 votes
1 answer
655 views

Preparation of Grignard reagent. Free radical rearrangement

Mechanism of formation of Grignard Reagent $$\ce{R-X + ^.Mg^. ->[\text{r.d.s.}] R^. + ^.Mg+X-} $$ $$\ce{R^. + ^.Mg+X- -> R-Mg+X-} $$ As the mechanism of preparation of Grignard reagent suggests,...
Cubehacks's user avatar
1 vote
0 answers
100 views

What the product of this reaction?

The reaction is as follows, with (i) being my answer, and (ii) being the correct answer in the book. My question is why is the product (ii) formed here and elimination not favoured here? I think that ...
TheQuestioner's user avatar
7 votes
1 answer
807 views

Hydrolysis of (chloromethyl)cyclopropane: Is but-3-en-1-ol a possible product?

This is from one of the practice papers for the JEE , asks for possible hydrolysis products of (chloromethyl)cyclopropane . Product A happens to be due to stability of cyclopropyl methyl carbocation. ...
Fallen Grenade's user avatar
1 vote
0 answers
296 views

Predict the products of the following reactions with Mechanism [closed]

1 My Attempt : The correct answer is C. I tried rearranging similar to claisen rearrangement but I have no clue how to go forward. I know that option A is wrong and that the product is pretty easily ...
Anand Maneesh's user avatar
2 votes
1 answer
297 views

Why does ring contraction take place in Wagner–Meerwein rearrangement?

An example of Wagner–Meerwein rearrangement given in my textbook is substitution by $\ce{AgNO2}$ in iodocyclohexane. One of the product, cyclopentylnitromethane is through ring contraction. I don't ...
ba-13's user avatar
  • 421
-1 votes
1 answer
67 views

Rearrangement of 1,1-Dichloro-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene on heating

Due to angle strain , the three membered ring is not stable. So i think it would break and kick out one of the chlorine atoms resulting in the formation of a carbene. But i don't know how to proceed ...
booma vijay's user avatar
4 votes
1 answer
186 views

Is the Beckmann Rearrangement technically an "SN2" reaction at an "sp2" center?

Below is the mechanism from this link of the Beckmann Rearrangement. In the alkyl migration step, the alkyl group migrates simultaneously as the $\ce{H2O}$ leaving group is expelled. This seems as ...
Cyclopropane's user avatar
  • 2,069
9 votes
2 answers
790 views

Photochemical rearrangement of 4,4‐diphenylcyclohexa‐2,5‐dien‐1‐one

I can see how the option A and B are correct as it is just a standard dienone–phenol type reaction which involves a phenyl shift. However, the given answer is A, B, C and D. I do not see how C and D ...
booma vijay's user avatar
7 votes
1 answer
284 views

Does the nitrogen atom move with in the molecule in an ammonia maser, or does the molecule flip?

This intriguing answer to Can reactions produce microwave or radio wave radiation? says (in part): An ammonia maser qualifies as an inorganic RF-emitting reaction. As the nitrogen changes position in ...
uhoh's user avatar
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0 votes
0 answers
93 views

Which of the following compound will undergo rearangement?

Question Attempt I believe the answer should be B,C and D. In C and D the oxyge(or Nitrogen in D) can rearange by donating lone pair to carbocation. But the books answer says B. Where am I wrong. ...
Aditya suresh's user avatar
7 votes
1 answer
714 views

Elimination of bromine with sodium iodide and electrocyclization

I've been trying to solve the following reaction scheme for a while now and I am having trouble especially with the products E and F. For product D I got the following, but I'm unsure about ...
Pöytä Laatikko's user avatar
2 votes
2 answers
777 views

Anti-Markovnikov addition of HCl

The following reaction has been troubling me for a while now. Since peroxides won't give the anti-Markovnikov product when used with HCl, I cannot think of any reagents that would result in the ...
Pöytä Laatikko's user avatar