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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Why does formic acid give positive Fehling's test?

$$\ce{HCOOH ->[\text{Fehling's solution}] CO2 + H2O}$$ The points discussed in a previous question do not account for the fact that formic acid also gives positive Fehling's test since it is not ...
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Elimination from Vinylic Halides

Vinylic halides do not show nucleophilic substitution at all, because of their stability due to resonance. But elimination to form alkynes is possible. No nucleophile at all can displace the halide ...
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Cleavage of Ethers

Very confused by this video I stumbled across describing the cleavage of ethers with strong acids: From what I can gather, the cleavage of ethers is run in aqueous strong acids such as HI or HBr. ...
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Preparation of picric acid

My textbook says "Nowadays picric acid is prepared by treating phenol first with concentrated sulfuric acid which converts it to phenol-2,4-disulfuric acid and then with concentrated nitric acid to ...
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Facial selectivity of iodonium formation in an iodolactonisation

I am trying to understand the stereochemistry of iodolactonisation of this cyclohexene. I can't work out if the iodonium ion would form on top or the bottom. There is $\ce{CH2COO-}$ and $\ce{Me}$ ...
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Selectivity in aldol condensation between pivaldehyde and acetone

In a crossed aldol condensation (condensation between aldehyde and a ketone), the primary products are such, that the carbonyl group of the ketone remains intact, and the $\alpha$-hydrogen of ketone ...
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A few questions about the conditions of the Diels Alder Reactions

I'm attempting to extract the diels alder reaction into a generic reaction and am trying to gain a better understanding of it. Can a conjugated diene react with another conjugated diene via the diels ...
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Allylic Radicals Bromination Mechanism

For (a) (iii), how do you get the second product listed in the answers manual? I just can't visualize it. What about (c) (i), why are there three resonance structures? If a hydrogen is taken away ...
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Is the compound CH2(OH)(ONa) possible?

I was just pondering about the reaction mechanism of Cannizzaro reaction. $\ce{H2C^{+}-O- + OH- -> H2C(OH)O-}$ $\ce{HCHO + H2C(OH)O- -> H3CO- + HCOOH}$ $\ce{H3CO- + HCOOH -> HCOO- + H3COH}$...
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Are all esterification reactions reversible? What is their general mechanism?

For example the reaction of ethanoic acid with ethanol is reversible, however is this true for all esters? I'm not quite whether it is as easy for a reversible reaction to occur both ways. Is there a ...
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What are the roles of pyridine and DCM in the acylation of an alcohol?

What role does pyridine and $\ce{CH2Cl2}$ play in this reaction? (Prior to this step, the corresponding carboxylic acid was converted to the acyl chloride using DMF, oxalyl chloride, and DCM.) This ...
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Which of these reduction reagents would me most appropriate to yield this product?

I am very confused, I think using reduction would be a good start, but LiAl would go straight to an OH.
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Can grignard reagent contain secondary amino group?

Is there any reason why this grignard reagent wouldn't work? My best guess is that perhaps the nitrogen could act as a second nucleophilic "head", thereby not giving a good yield on the intended ...
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Why does the Birch reaction not yield fully saturated products?

Why isn't benzene reduced all the way down to cyclohexane when performing a Birch reaction? (Why is it not reduced further?) Similarly for the reaction with sodium dissolved in liquid ammonia, why ...
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Why does carbocation stability increase in the order 1°, 2°, 3°?

I'm reading about $\:\mathrm{S_N1}$ and $\:\mathrm{S_N2}$ reaction mechanisms. 1° carbocations are unstable to the point of not having been observed in solution, ever. 2° are more stable, and 3° ...
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Oxidation of alkyl side chain using KMnO4 [duplicate]

I was reading about side chain oxidation of alkyl side chains of benzene using alkaline $\ce{KMnO4}$ and heat. My book (Solomon's and Frhyle) says that this is only for compounds having a benzylic ...
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Is there a relation between the ionization energy and the electron affinity?

I am aware of the definition and equation of IE and EA. I was wondering if there is a direct relation between this two quantities with the energy of the neutral specie.
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Mechanism for the reaction between trisilylamine and hydrogen chloride

In Concise Inorganic Chemistry by J. D. Lee (adapted by Sudarsan Guha), in the chapter "Chemical Bonding", under the topic "Back Bonding with Nitrogen as a donor atom" the following reaction is given: ...
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Reactions in the presence of sunlight

Some reactions in my textbook specify the need for the presence of sunlight, eg-photolytic decomposition of silver bromide and substitution reaction of methane with chlorine. What is going on in ...
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Does Wurtz-Fittig-reaction involves Sn1 or Sn2?

Following mechanism is commonly proposed for the Wurtz-Fittig-Reaction: Picture from Wikipedia The red marked reaction steps is a nucleophilic substitution (SN). I suppose that this is a SN1 ...
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Why do some nucleophiles attack at the carbonyl group while others at an alpha-carbon in ketones?

I was reading about the iodoform reaction and it stated that $\ce{OH^-}$ attacks at the $\alpha$-carbon and makes a substitution reaction possible. But there is also the possibility of attacking the ...
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What is trans-addition?

A question from JEE-Advanced(2017) : Bromination of both Z-but-2ene and E-but-2-ene involve syn and anti addition. So, there would be 4 products as suggested in the question. But, I don't ...
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Are there natural conditions that could enable the formation of noble gas compounds?

Noble gases were considered to be inert until compounds that include them, such as xenon trioxide (as an example) were found. My question is, what natural conditions allow the formation of noble gas ...
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Dehydrobromination of 3-bromo-3-cyclopentylhexane and number of possible alkene products

I faced a question like this: The total number of alkene products possible from the dehydrobromination of 3-bromo-3-cyclopentylhexane is: The answer is given 5. But I only found 3. 3-...
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Does the addition of chlorine to carbon-carbon double bonds proceed through a halonium ion?

I need some serious help with the mechanism of ionic addition, both my textbook and my teacher are at odds with internet videos (khan academy) which both seem to be at odds with quote, "recent ...
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Why does the rate-determining step determine the overall rate of reaction?

I can appreciate that the rate determining step affects the rate of reaction. What I take issue with however is the exact wording given in the definition of the RDS. From here: The rate ...
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Diazo Coupling reaction with para-substituted phenol?

Usually Diazo coupling occurs at para-position unless the para-position is occupied, in which case coupling occurs at ortho-position. While solving questions I found in both the cases as shown, the ...
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Niobium (V) Fluoride becoming sticky

Today I was making a pastille of Niobium Pentafluoride powder. The procedure includes a 6 ton squeezer, precision wipes, silica gel, filter papers and acetone. The first suspicious part was that on ...
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Mechanism of Halogenation of Alkene

In the above reaction, we use a non-polar compound (such as CCl$_4$) as a solvent. Then, why does the Br$_2$ polarise on attack by the alkene, even though a non-polar solvent does not encourage ...
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Why is sodium acetate a good nucleophile?

As $\ce{CH3COONa}$ is bulky, I thought that $\ce{CH3COONa}$ is a weak nucleophile. But I found out that it's a nucleophile good enough to perform $\mathrm{S_N2}$ reaction on a secondary carbon. Why ...
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Pinacol pinacolone rearrangement

I was reading the topic alcohol in that I saw a reaction Pinacol pinacolone rearrangement . But I am not able to find the sterochemistry of the reaction . Can anyone please tell me the ...
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Please explain the mechanism of Cannizzaro's reaction

I did not completely understand the mechanism of Cannizzaro's reaction, especially the rate determining step i.e. the hydride transfer step, and the effect of electron withdrawing substituents on this ...
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To model early earth chemical reactions which types of reactions should be included?

I'm currently working on building a simulator for the early earth to examine the spontaneous occurrence of food generated autocatalytic sets. No one in my group is a chemist, so the bottle neck for ...
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Confusion about the SN1 and SN2 Mechanism

My book says, and I understand, that the $\mathrm{S_N1}$ mechanism is much faster for tertiary alkyl halides than primary. And the opposite for $\mathrm{S_N2}.$ This all makes sense. What I don't get ...
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t-butylbenzene in highly acidic medium

Why would the following mechanism be valid for the conversion of t-butylbenzene to benzene in highly acidic medium followed by an aqueous workup? The main problem I have with this mechanism is the ...
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What is the chemical reaction in a home-made high-bouncer ball?

I took the kids to the Science Museum in Canberra (Questacon) and one of the toys we brought back was a Home-Made High Bouncing Ball. Now I did it with the kids and it was amazing. You pour the ...
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Halogenation of alcohols in the presence of ZnCl2

I know that $\ce{OH-}$ is usually a bad leaving group, but why does the following reaction occur via SN1 in presence of anhydrous $\ce{ZnCl2}$?
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Carbocation Rearrangements in SN1 reactions

Would one get 1-(1-chloroethyl)-1-methylcyclobutane? I am not sure if the driving force identification is correct? Is my going from a 2° to a 3° carbocation correct? Does anyone have any tips for ...
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Calculating rate constant and order of a multi-step reaction

If I’m given a multi-step reaction, say: $$\ce{2 NO + O2 -> 2 NO2} \label{rxn:R1}\tag{R1}$$ with the following mechanism: $$ \begin{align} \ce{NO + O2 &<=>[$K$] NO3} &\quad &\...
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Mechanism for Hydrogen Peroxide decomposition?

Someone asked this question earlier and made no attempt at understanding it on their own so the question was flagged. However, it prompted me to attempt to figure it out. This is what I have come up ...
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Acids generating nascent gas atoms

When sulfuric acid reacts with copper, then $\ce{H2SO4}$ gives nascent oxygen $\ce{[O]}$. The reaction is: $$\ce{H2SO4 -> H2O + SO2 + [O]}$$ This nascent oxygen reacts with copper to create $\ce{...
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Which mechanism do ethers follow when cleaved by hydrogen halides?

Ethers can be cleaved under acidic conditions by treatment with hydrogen halides (HX, where X = Cl/Br/I). Some of these reactions proceed by SN1 mechanisms and some by SN2 mechanisms. How can I tell ...
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nucleophilic attack in Acid chloride formation

First mechanism is the one taught in lecture, and I wondered why the electrons from carbonyl Oxygen wouldn't react with thionyl chloride. So I tried to draw a second mechanism as much as I could but ...
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Why do Grignard reagents form? [closed]

Why does magnesium insert itself between a carbon atom and halogen atom? Can anyone give any vague idea about why this occurs? Also does a Grignard reagent only form when there is carbon atom and ...
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mechanism in Birch reduction

at first I wondered why 2 H are added to opposite side of benzene like reaction below. because I could imagine 2 H added right next to each other or 1 C away from each other. so, looking for ...
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Is this reaction with H+ and OH− a possible reaction?

I am wondering about the reaction $\ce{H+ + O^2- -> OH-}$. Is it possible? I think this is not a possible reaction, because here a strong acid plus another particle reacts to a strong base. If it ...
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287 views

Deuteration of enone - mechanism?

What happens when the above compound is mixed with D2O (deuterated water)? As a result of tautomerism, I'd expect the 4H atoms, one alpha to carbonyl carbon, and three at gamma position; to be ...
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567 views

How to determine if a reaction proceeds via SN1, SN2, E1 or E2 mechanism?

Give the main product and reaction type: SN1, SN2, E1 , E2. As the 1-bromohexane is primary and the nucleophile a strong unhindered base, the reaction should be a SN2 reaction. However, the solvent $...
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Hydrolysis of 3,4-dihydropyran

In the 3,4-dihydropyran shown below will the oxygen or the pi electrons of the double bond attack the hydrogen cation during hydrolysis and why? This is my attempt towards a solution: The oxygen ...
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Why are more electronegative atoms better leaving groups?

My book says, "halide anions are electronegative and can easily stabilise negative charge, hence are good leaving groups." 1) what exactly does "stabilising negative charge" mean? I have read: " ...

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