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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2answers
490 views

Mechanism of hydrolysis of polycyclic oxetan

The reaction is this: The only idea I have thus far is if we have a chloride acid that can form an ester, then we might be able to find a suitable mechanism. This would require a chloride reagent.
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631 views

How does an oscillating reaction work?

I watched a video showing an orange solution that goes to clear and then back to orange (and so forth.) The reaction goes through a number of cycles before it will no longer oscillate. This tells me ...
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1answer
757 views

Reaction mechanism for the synthesis of 9,10-phenanthrenequinone

In my lab course I had to synthesize 9,10-phenanthrenequinone (phenanthrene-9,10-dione) from phenanthrene and chromium(VI) oxide. The synthesis was made as explained in Organic Syntheses, Coll. Vol. 4,...
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519 views

Is rearrangement possible in cyclic bromonium ion?

I wonder what the product of the above reaction is, that is, bromination of the given alkene in non polar solvent carbon tetrachloride (proceeds through cyclic bromonium ion intermediate). Once the ...
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1answer
811 views

Why don't hydride shifts occur with hydrohalogenation of 4-methyl-cyclohexene?

My book (see bottom) implies that hydrohalogenation of 4-methyl-cyclohexene follows this mechanism: Why not undergo consecutive hydride shifts to furnish a tertiary carbocation? I would guess that ...
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1answer
631 views

Grignard reagent reaction mechanism: Which bond breaks during the decomposition of the adduct?

We just finished our Organic Chem. chapter Aldehydes, Ketones and Carboxylic acids at school, but I still have one lingering doubt. Considering the reaction between an alkyl magnesium halide and an ...
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1answer
543 views

Primary carbocation in addition of HBr to ethylene?

All mechanisms of the addition of a halogen acid to ethylene (ethene) I can find involves a primary carbocation as the intermediate ion. However, primary carbocations are generally unstable and ...
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1k views

Mechanism for reaction of aryl diazonium with potassium iodide

I’m working on a synthesis problem that requires me to draw the arrow mechanism for the second half of the Sandmeyer reaction. Basically it’s the halogenation of an aryl diazonium compound. Typically ...
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1answer
96 views

Why is the initial carbocation not formed adjacent to the phenyl moiety?

I know that after rearrangement the carbocation is more stable, but we should protonate the compound first where the carbocation it is more stable, i.e. adjacent to the phenyl group. Why do they ...
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Synthesis of Anthracene: Mechanism

Recently, I happened to find a problem that involved the synthesis of anthracene from bromobenzene in the presence of tert-butyl lithium, using THF as the solvent, and at room temperature. I am ...
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158 views

Does a cationic 1,3-triphosphinane react with a methyl cation?

The question is: Reaction of $\ce{Et2P(CH2)3PEt2}\text{ with }\ce{PCl3}$ ($1:1$) in the presence of $\ce{SnCl2}$ gives a ring system A, which exhibits two phosporus NMR resonances, a doublet and a ...
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Can I make Ferrofluid without evaporating Ammonium?

I want to make ferrofluid, which is ferromagnetic particles suspended in a carrier fluid. Three methods I have seen involve using magnetic ink (for MICR codes), cassette tapes, or ferric chloride as ...
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Why does chlorination of toluene stop at two chlorine atoms?

My instructor mentioned a reaction for preparation of benzaldehyde by chlorination of toluene in presence of sunlight to form benzal dichloride, which on hydrolysis gives benzaldehyde. However, I'm ...
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Claisen condensation

Aren't two last steps superfluous? I just do not see how the fourth and last forms differ.
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Aromatic ether to phenol reagents

I have been asked to identify suitable reagents for the following transformation: (Apologies it's back to front - the question is a map of reactions and I took a snapshot). I really have no idea ...
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Best ways to start a thermite reaction?

I'm trying to do a thermite reaction with rust and aluminum and am trying to figure out the optimal way to get the reaction started. My understanding is that I need a temperature of around 3200F to ...
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460 views

Is the carbanion formed in benzyne mechanism non-planar?

I was told by my chemistry teacher that the carbanion formed in the picture above is non-planar. I don't understand why. It looks like benzene with an extra electron pair at one of the carbons so ...
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8k views

When is a reaction reversible?

When speaking in thermodynamic terms, when is a reaction reversible? My attempt: A reaction is reversible when $\Delta\text{S} < 0$, because according to the second law of thermodynamics, "in ...
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820 views

Migratory preference in a rearrangement involving carbocations

I just read about the Pinacol rearrangement and the following reaction was presented just after it. The book (Clayden) shows path 1 being taken. My question is why is the second path not taken? I ...
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Why does the Wurtz reaction form such an unstable compound with torsional strain?

What would be the product formed when 1-bromo-3-chlorocyclobutane with two equivalents of metallic sodium in ether? I know that there would be a free radical formation and then it will form a ...
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238 views

How to explain this acid-catalysed acetal rearrangement mechanistically?

I have spotted a protecting acetal group and thought this would undergo hydrolysis … My working is such: But I cannot get to the desired isomer. Could someone please help? (Diagrams would be very ...
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1answer
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Reaction mechanism for reduction of nitrobenzene to aniline in catalytic and acidic media

Can anyone explain the reaction mechanism of the two reactions given below? They are the conversion of nitrobenzene to aniline in catalytic ($\ce{H2/Pd}$ in ethanol) and acidic ($\ce{Sn/HCl}$ or $\ce{...
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1answer
364 views

Mechanism of substitution reaction with no change in stereochemistry

When (2​S,3​R)-3-iodobutan-2-ol undergoes a substitution reaction with sodium azide the only organic product from the reaction is (2​S,3​R)-3-azidobutan-2-ol. Give a mechanism for the reaction. My ...
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4answers
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What is the reaction between Magnesium chloride and Sodium bicarbonate?

For some reason it has been very difficult to find the right answer for this question as there's so much conflicting information to be found online. Some mention a reaction where carbonic acid is made,...
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81 views

Two reactions which speed each other up [closed]

Recently I have started looking for two reactions that would speed each other up. That means that the products of the first reaction accelerate the second one, and in turn, the products formed in the ...
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1answer
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Why are beta-ketoacids better at decarboxylation than gamma or delta?

My book claims that beta-ketoacids and beta-dicarboxylic acids are better at decarboxylating than their gamma and delta counterparts. Why is that? I would assume that since gamma and delta keto-acids ...
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1answer
256 views

What happens in the attempted diazotisation of 1,2-diaminobenzene?

Usually, $\ce{NaNO2}$ and $\ce{HCl}$ are the reagents used to generate an aryldiazonium chloride from an aniline. However, in this compound there are two amine groups adjacent to each other, so it ...
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1answer
4k views

Mozingo reduction mechanism

I have been searching for the mechanism of the Mozingo reduction on Google but I haven't found anything relevant. Is the mechanism known? If so, what is it; if not, what hypothetical mechanisms can ...
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2answers
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What is the actual mechanism of Fenton reaction?

Fenton reaction was supposedly discovered by Fenton as Tartaric Acid oxidation by hydrogen peroxide in presence of ferrous cation in 1894. Research Paper link. I have worked on this reaction for ...
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1answer
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What are SN1' and SN2' reactions?

I went through the problems on the pictures: The answer of the problem 119 is $\mathrm{S_N1'}$, and that of 120 is $\mathrm{S_N2'}$. I actually can't figure out what $\mathrm{S_N1'}$ ($\mathrm{S_N1}$...
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725 views

Reaction of potassium cyanide with 2-(chloromethyl)furan

What would the mechanism for the reaction between 2-(chloromethyl)furan and potassium cyanide be, as detailed below? I know that for 6-membered rings like pyridine, a $\mathrm{S_NAr}$ reaction can ...
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Mechanism for ring contraction from 2-methylenecyclobutanol to 1-methylcyclopropanecarbaldehyde

I am stuck between two paths. I was going to protonate the alcohol to give a better leaving group, leaving a 2 degree carbocation and then go on with a hydride shift. But, I'm not sure what that may ...
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Ring closure via intramolecular nucleophilic substitution or intermolecular dimerization: which is favoured?

What reaction does the following enolate undergo? Both are nucleophilic substitution reactions. Ordinarily, the intramolecular product should be favoured, but I know that the transition state has a ...
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1answer
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In cracking, why does C form double bonds?

I've been reading about cracking and I've found various images and animations that show a process like this: But I haven't been able to find out the sequence of events to get to this, and why this ...
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Reaction Pathways: What to do when IRC geometries are relaxed (optimized) and the energy changes significantly

The Story: Reaction pathways can be difficult things to deal with using electronic structure methods. Intrinsic reaction coordinates (IRCs) can be determined a number of ways (a discussion of these ...
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Is there a general way to predict products of a chemical reaction [duplicate]

Is there a general way to predict products of a chemical reaction, given only the atomic masses of masses of all elements involved? for example: $\ce{CuFeS2 + O2->}$ $\ce{K2CrO4 + H2SO4->}$ $\...
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1answer
3k views

Diazo transfer to 1,3-dicarbonyl with tosyl azide

What is the mechanism for the above reaction?
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1answer
5k views

Why is the less substituted alkene favoured in Hofmann elimination?

In the reaction, $\ce{OH-}$ group attacks a hydrogen ion in an E2 reaction, forming a transition state in which simultaneously $\ce{NCH3}$ is removed. In this reaction, the $\ce{OH-}$ should attack, ...
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1answer
7k views

Reduction of acids with borane

What is the mechanism of the reduction of organic acids with borane? Borane reductions don't work well with electron deficient carbonyl groups. Why is that so, and how isn't the carboxyl group an ...
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1answer
864 views

If Alkynes can be reduced to Alkenes using Sodium in liquid ammonia, why can't Alkenes be reduced to Alkanes?

Firstly, I would like to ask why the alkyne reacts at all with the solvated electron? Surely the alkyne group is extremely nucleophilic (more so than the alkene). This, to me, seems to suggest that an ...
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1answer
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Bridgehead carbocation: Violation of Bredt's Rule

This is the solution of a university's problem set (nucleophilic substitutions) It says that the given compound undergoes SN1 type substitution. What confuses me is that even though iodide is a good ...
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1answer
247 views

What is the mechanism behind the formation of phosgene from tetrachloroethylene

Tetrachloroethylene used to be a popular automobile brake cleaner. Unfortunately, when applied to hot brake rotors, it can turn into phosgene. This has resulted in many injuries and even fatalities. ...
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1answer
2k views

Why doesn't this β-hydroxycarboxylic acid undergo dehydration upon heating?

This is a β-hydroxyacid, but why doesn't it get dehydrated to give an α,β-unsaturated acid on heating? The mechanism which I think should occur is:
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297 views

Competitive 'Wittig' vs 'Peterson' C=C bond formation

If one considers the intermediate above, there are immediately two possibilities for subsequent reaction: 1. A Wittig-type olefination which would lead to a vinyl silane: This reaction happens to be ...
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1answer
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Naproxene syntheses: electrophilic aromatic substitution on activated naphthalene

I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand. The first one is a Friedel-Crafts acylation: the products are ...
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1answer
3k views

Reaction mechanism of imine reduction to amine using an aluminium amalgam

I can not find any good resources on the Internet except for some shady drug syntheses. I was hoping that someone could provide me with some more educational information. I'm interested in imine-...
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1answer
782 views

Intrinsic Reaction Coordinate - What does 'Connectivity' really mean?

I am currently in the process of connecting transition state (TS) structures to other minima in order to determine a reaction pathway. Now I understand the basic concepts of this method. You start ...
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1answer
963 views

Racemization of ketones in presence of catalytic acid

Question: Which of the following ketones racemise in aqueous solution containing acidic or basic impurities? My answer: A and B should racemise in aqueous solution, for the carbonyl groups in A and B ...
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1answer
182 views

Does the mechanism of the Schmidt reaction involve a nitrene as an intermediate?

Per the mechanism described here the reaction does not involve nitrene as an intermediate.(EDIT-1---I initially thought the written mechanism described so, but as Zhe points out,I was wrong in my ...
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1answer
590 views

Search for the last step of an altered Raschig process reaction mechanism

The Raschig process (according to the german wikipedia) is divided in the following steps: $\ce{2NaOH + Cl2 -> NaOCl + NaCl + H2O}$ $\ce{NaOCl + H2O -> HOCl + NaOH}$ $\ce{HClO + NH3 -> NH2Cl ...