Questions tagged [reaction-mechanism]

The detailed (and as complete as possible) description of plausible or observable pathways leading from reactants to products of a chemical process. This tag should be applied to questions about these processes. It may be applied to hypothetical and/or proposed mechanisms.

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61 views

How to Choose if a reaction will go elimination of substitution? [closed]

I want to know how to choose if a given reaction will prefer going substitution mechanism or elimination mechanism.Both elimination and substitution reactions have types like Sn1 ,Sn2 ,SnNGP,Sni and ...
5
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1answer
109 views

Aromatisation of a ring which includes nitrogen

Question Complete the following reaction sequence: Answer My solution I was able to complete all the steps except for the last one. This is what I ended up with: What I'm not getting is how the $\...
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How is elimination reaction (E1) possible without base and in presence of acid?

When learning about E1 we were taught that three things are important factors to judge if the reaction is E1 or E2 Substrate ( 3,2,1 favours E2 but only 3 favours E1 ) Base ( Stronger Base favours E2 ...
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91 views

Formation of methane using Kolbe's electrolysis reaction

I have read in my book that methane cannot be formed using Kolbe's reaction (mechanism — Organic Chemistry Portal). And honestly, I kinda think I get where they are coming from: that two radicals are ...
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Why can't methyl glycosides mutarotate?

I found this link trying to explain it: Why pyranosides do not mutarotate? however, I don't understand a step of the reasoning. Why is it that acetalisation needs a stronger acid than for hemi-...
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What mechanism is this? [closed]

I was solving problems in Organic Chemistry related to Substitution and Elimination. This was a question asked in JEE 2019 This was the solution for above. At last of solution, It has been mentioned ...
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1answer
97 views

How are diazonium salts prepared without self coupling

While preparing diazonium salts, what prevents the freshly formed diazonium salt from reacting with the still unreacted amines left in the solution and perform diazo coupling? If this happened then ...
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2answers
69 views

Inconsistency in Elementary Bi-Molecular Reaction Rate Expressions

Assume the following bi-molecular reaction is elementary as written with rate constant $k_\mathrm{f}$: $$\ce{A + A -> P}$$ This review, suggests to express the rate in terms of the production of ...
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91 views

Comparing nucleophilicity of oxygen and nitrogen in acetylation of 4-aminophenol

Here, the answer has $\ce{N}$ acting as a nucleophile making the answer (C). I thought that $\ce{O}$ would be more nucleophilic, considering the fact that $\ce{O}$ has two lone pairs, one in ...
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30 views

Why can't Grignard reagents react like Organolithium does (with acids)?

I'd read yesterday that Grignard reagents can't give ketones on reaction with carboxylic acids. It is because of the fact that Grignard reagent is a "super-base", and it will deprotonate the ...
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566 views

How to determine rate law for a reaction?

I am having trouble understanding this problem. A proposed mechanism for the decomposition of $\ce{N2O5}$ is as follows \begin{align} \ce{N2O5 &->[$k_1$]NO2 + NO3} &&\text{(...
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Reaction of a cyclic tertiary alcohol with chromic acid

We know that $\ce{H2CrO4}$ cannot oxidize tertiary alcohols. The mechanism is: Now the ${\alpha}$ carbon does not have any hydrogen to proceed to next step. Therefore, this reaction would not occur. ...
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Can a reaction have more than one rate determining step?

There are many organic reactions in which two steps have comparable rates. Can we say they are both RDS? For example, the rate of iodination of benzene and deuterated benzene is different even though ...
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510 views

Reaction of copper with nitric acid [duplicate]

When copper reacts with dilute nitric acid, $$\ce{3Cu + 8HNO3 -> 3Cu(NO3)2 + 2NO +4H2O}$$ while with concentrated nitric acid, $$\ce{Cu + 4HNO3 -> Cu(NO3)2 + 2NO2 + 2H2O}$$ As we see that with ...
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Three-membered ring pathway bromination of alkene

Bromination of alkene occurs by the mechanism as shown (source: Master Organic Chemistry — Bromination of Alkenes: The Mechanism): Here $\ce{Br^-}$ attacks bromonium ion from a side which is more ...
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2answers
295 views

What are the products formed in acidic hydrolysis of a tetrahydropyranyl ester?

Find the major product of the following reaction: My approach From my knowledge of reagents, I figured out that that the acid will protonate the oxygen(s) in the reactant and after that $\ce{C-O \...
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1answer
81 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 ...
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1answer
59 views

Predict the species formed by the reaction of mercury(II) chloride and iodine

$\ce{HgCl2}$ and $\ce{I2}$ both when dissolved in water containing $\ce{I-}$ ions the pair of species formed is A. $\ce{HgI2, I3-}$ B. $\ce{HgI2, I-}$ C. $\ce{HgI4^2-, I3-}$ D. $\ce{Hg2I2, I-}$ ...
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106 views

Reaction between Polyvinylpyrrolidone (PVP) and NaOH

I am using polyvinylpyrrolidone (PVP) as a dispersant in a reaction. The reaction contains concentrated NaOH (pH of the NaOH solution is 12 to which PVP is added). When I add the PVP, the solution ...
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1answer
64 views

Acidity of thiamine - how comes hydroxide anion with pK about 15 ionizes thiamine with pK about 18?

Textbooks say removing proton from thiamine's C atom will produce a resonance stabilized carbanion which is hence bioactive. That's OK, but how comes that 1) we abstract the acidic proton with the OH ...
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1answer
151 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-...
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Diazo coupling of α-naphthol [duplicate]

Why does coupling of α-naphthol take place at δ-position (para to $\ce{-OH}$) rather than the β-position (ortho to $\ce{-OH}$)? In the case of β-naphthol, we consider the aromaticity of the entire ...
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55 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 $3^\circ$ ...
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2answers
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Is the green product from Iodine reaction with Aluminium coated plastic, hydrated Aluminium Iodine

I found a package containing some Iodine I bought a while ago. It was contained in a plastic jar placed inside an Aluminium coated plastic pocket. The pocket had strange green worm like trails over ...
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Function of sodium amalgam and CO2 in formation of aldohexose

There is this following conversion in my book: $$\gamma-\text{Lactone}\ce{->[Na/Hg +CO2]}\text{Aldohexose}$$ I'm not sure how this reaction takes place. I searched for mechanisms and couldn't ...
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1answer
35 views

Chemical reaction of radicals with different multiplicity

I am studying the chemical reaction of radicals by computational chemistry software. I just want to know what is the rules for multiplicity. I have two radicals for which, the ground state of one is a ...
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1answer
137 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 ...
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1answer
79 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?
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1answer
80 views

Acids used in Friedel-Crafts alkylation

I am learning adding alkyl groups to benzene using Fridel-Crafts alkylation: I know that it is very common to use $\ce{AlCl3/AlBr3}$ as Lewis acid catalyst in this reaction. But I am just wondering ...
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2answers
69 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 ...
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1answer
214 views

Yield of possible products from acid catalysed hydration of an alkene with a phenyl group

Here, (d) may be the major product due to high temperature. My questions are: Will a kinetically favoured (minor) product (c) form? What shall be the order of yield of products?
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How does ammonium nitrate explode on its own?

I thought ammonium nitrate was an oxidizer that needed to be mixed with fuel to form a high explosive (e.g., ANFO). But apparently there have been accidental explosions involving just the "...
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1answer
168 views

Can I use potassium acetate instead of potassium carbonate?

In the synthesis of N-ethoxycarbonyl L-proline methyl ester from L-proline and ethyl chloroformate, I use $\ce{K2CO3}$ to neutralize $\ce{HCl}$. Can I use $\ce{CH3CO2K}$ instead of $\ce{K2CO3}$? I ...
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1answer
163 views

Pyridine synthesis by tin(II) chloride reduction of 5-nitronorbornene

What is the reaction mechanism here? I guess the $\ce{SnCl2}$ reduces $\ce{NO2}$ to $\ce{NH2}$ but then what happens?
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Acid dehydration to ether

Can anyone please help me come up for a curved arrow mechanism for the reaction pictured? I'm familiar with the mechanism for the general acid catalyzed dehydration of butanol, where the arrow comes ...
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2answers
206 views

What is the mechanism for this intramolecular SN1 reaction?

What is the mechanism for the following intramolecular $\mathrm{S_N1}$ reaction? For this question, my professor hinted at an intramolecular reaction, and he asked us to recall the bromonium ion as ...
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1answer
401 views

Why do electron-rich aryl groups have greater migratory aptitudes?

In the following reaction there are three possible aryl groups that can migrate: an unsubstituted phenyl group, a p-methoxyphenyl group, and a p-nitrophenyl group: Why does the electron-rich p-...
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1answer
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Reaction of carboxylic acid with phosphorus trichloride

The reaction of carboxylic acid $\ce{RCOOH}$ with $\ce{PCl5}$/ $\ce{SOCl2}$ / $\ce{PCl3}$ yields an acyl chloride $\ce{RCOCl}$. With $\ce{PCl5}$ and $\ce{SOCl2}$ the reaction is quite simple utilizing ...
2
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1answer
138 views

Regioselectivity in coupling reactions of α-naphthol

I have seen in the following reaction of azo coupling where coupling takes place at position 4 of $\alpha$-naphthol. Now the electron density accumulation is similar at both position $4$ as well as $...
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57 views

Mechanism of addition of H-X to alkynes

Vinylic carbocation is unstable as the carbocation is bonded to a $\mathrm{sp^2}$ carbon that has high electron density, and pulls the electrons from the carbocation, which is already electron-...
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Synthesis question: Using reductive amination to form pyrrolidine

What molecule results from treating 4-oxopentanal with $\ce{NH4Cl}$ and $\ce{NaCNBH3}$? Why? Is this a good, high yield reaction? I believe that pyrrolidine is formed because amination will convert ...
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2answers
323 views

Formation of toluene from (cyclobutane-1,2,3-triyl)trimethanol using conc. sulphuric acid

In my book this reaction is given without any mechanism: I thought that simple dehydration reaction is going to take place with rearrangement of the carbocation but I have no idea as to how toluene ...
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0answers
72 views

Alternate pathway of Gabriel synthesis to prepare secondary amine

Can modifying the Gabriel synthesis, which is generally restricted to synthesis of primary amines, be used to synthesise secondary amines? I have attached my idea regarding the synthesis (the final ...
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102 views

What drives the 'internal return' in SNi?

I just learnt that alcohols can undergo $\mathrm{S_N}i$ with $\ce{SOCl2}$ (without pyridine) to achieve retention: However, what I really do not understand is the 'internal return' step (forming '...
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Acidity of cyclopentadiene [duplicate]

Why is cyclopentadiene more acidic than dibenzocyclopentadiene although in the latter, the negative charge will be more distributed and consumed in resonance stabilization.?
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2answers
353 views

Mechansim of reaction between 1‐bromo‐2‐fluorobenzene and furan in the presence of Li/Hg

Problem From FITJEE AITS test series: What is the mechanism of the following reaction? Solution My approach It looks like Birch reduction with $\ce{Li}$ converting to $\ce{Li+}.$ But I can't make ...
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4answers
451 views

Most favorable position of attack of an electrophile on 4-trifluoromethyl-1,2-diphenylbenzene

Problem This problem is from a FIITJEE AITS paper Which position is most favorable for the attack of an electrophile? Answer My attempt The more favorable position for attack should be the on the ...
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42 views

Mechanism of R-OH to R-X using SOCl2 [duplicate]

https://youtu.be/ANlXQdpv6cc?t=1006 In this lecture, I am learning on the reaction of alcohol to alkyl halide using SOCl2 and pyridine. However, there are 2 different approaches on the first step. ...
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1answer
589 views

Reaction of acyl chlorides with diazomethane and silver(I) oxide

$$\ce{R-COOH ->[SOCl2,CH2N2][Ag2O/CH3OH] X}$$ While solving Carboxylic derivatives recently, I came across this. so following the reagents one by one- $\ce{SOCl2}$ will form acid chloride. $\ce{...
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1answer
201 views

How can I synthesize phenylpiracetam from styrene or benzaldehyde?

I am trying to design a proper synthesis route for phenylpiracetam. I am thinking a good starting material would be styrene or benzaldehyde. Here is my proposed route. Is there a better method? ...

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