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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6
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1answer
2k views

Rate and order confusion

I just learned about rate and order... I just want to confirm if these three ideas are correct: If the first elementary step is the slow step, will the stoichiometric coefficients of the reactants in ...
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Oxidation of naphthalene with KMnO4

What is the product when naphthalene is oxidized by alkaline (or acidic) solutions of $\ce{KMnO4}$? Some possible reactions show up in a google search, but they have no references: Naphthalene to ...
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Why is the addition of a singlet carbene to an alkene stereospecific?

Why is the addition of a singlet carbene to an alkene stereospecific, but not when a triplet carbene is added?
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Crossed Cannizzaro reaction

What is the major product of the following reaction: I think methanol will be formed. Although formaldehyde is more reactive to nucleophilic addition, the rate determining step of the Cannizzaro ...
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How does sodium in ethanol reduce carbonyl compounds?

According to my teacher, Na in ethanol reduces carbonyl compounds (e.g. aldehydes and ketones) to alcohols. However, I can't see where the hydrogen needed for reduction comes from. How does the ...
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780 views

α,β-unsaturated carbonyl compounds and alkyl addition

In my book it is suggested that in order to add alkyl groups in α,β-unsaturated carbonyl compounds we use organometallic reagents such as organolithium reagents. In the previous chapters it was ...
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Birch Reduction Of Anthracene

Which ring of anthracene is reduced during Birch Reduction? What will the final product look like? Why? My teacher said that the more electron deficient ring should undergo the reduction but I ...
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Why do SN2 reactions of alkyl halides proceed differently with KCN and AgCN?

Alkyl halides react with $\ce{KCN}$ to form alkyl cyanides as the main product, whereas the use of $\ce{AgCN}$ leads to isocyanides as the chief product. Why does this happen?
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Why does depurination happen at a higher pH (or under less harsh conditions) than depyrimidation?

I've always wondered why the N-glycosidic bond, which connects the adenine or guanine purine bases to their sugars, was the easiest to cleave via acid hydrolysis, or why purines have the lowest ...
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Fehling's test arrow pushing mechanism

I am currently attempting to generate an arrow pushing mechanism for the oxidation of glucose to gluconic acid using Fehling's solution. My original thought was to go the route of alcohol oxidation ...
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How does sulfuric acid dehydrate sugars?

I know sugars have $\ce{-OH}$ groups, and that sulfuric acid is a strong acid. What I'm failing to see is how exactly sulfuric acid dehydrates sugars. Does it protonate the hydroxyl groups, making ...
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What is the chemistry behind this “petrol from air” technology?

A recent news report in the UK claimed a breakthrough in making a petrol equivalent from carbon dioxide and water: A small British company has produced the first "petrol from air" using a ...
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Mechanism for basic hydrolysis of α-chloronitrile to ketone?

In Corey's 1969 prostaglandin synthesis,1 compound 2 is formed from compound 1 by: [...] treatment with 2.5 equiv of potassium hydroxide (added as a hot saturated aqueous solution) in dimethyl ...
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In the elementary steps of a reaction, why do we assume that the coefficients of a reactant correspond to its order?

Recently, I was taught that the coefficients of the reactants in an elementary step of a reaction indicates that reactant's order. Why is this the case? I thought that the order of a reactant was not ...
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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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What is the oxidation mechanism of gunpowder?

I've been recently looking into fireworks and the chemistry of explosives, and I found out that, amongst others, one of the most important reactions in gunpowder ignition is the oxidation of charcoal ...
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1answer
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Why does trihaloacetaldehyde formed during the haloform reaction not undergo a Cannizzaro reaction?

We know trihaloacetaldehyde is formed during the haloform reaction of acetaldehyde with a halogen in strong base. Since it has no alpha hydrogens, I expected that it might undergo a Cannizzaro ...
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808 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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Ring contraction in pinacol rearrangement of cyclohexane-1,2-diol

I came across this question in three different textbooks. The question was: What is the major product obtained on dehydration (treatment with concentrated $\ce{H2SO4}$) of cyclohexane-1,2-diol. I ...
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1answer
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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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Exothermic or Endothermic reactions

Can we determine whether a reaction is endothermic or exothermic? For example if we are given the following reactions: $$\ce{2SO2 + O2 -> 2SO3}$$ $$\ce{H2 + I2 ->2HI}$$ $$\ce{N2 + 3H2 -> ...
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1answer
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What is the reaction mechanism of nitrogen leaving from diazo compounds?

When a diazo compound is formed, and then a nucleophile is added to the mixture. Will nitrogen gas leave first or will the nucleophile have to "do" a substitution reaction? What I mean is will the ...
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1answer
847 views

What is the chemical basis for superglues?

There are a variety of different types of glues, some derived from animal or natural materials and some designed by chemists. Some glues need to be activated before they harden and stick (many epoxies,...
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Bromination of acetanilide

Why does acetanilide gives exclusively para isomer. I know that -I of nitrogen must decrease the yield of ortho product, but still it should be made in accountable amounts. Where am I going wrong. I ...
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Periodically oscillating chemical reactions?

I've seen before chemistry demonstrations where solutions are mixed with one another and subsequently where the resulting product goes through periodic color changes: for example blue to orange and ...
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How are alkalide ions synthesized?

How are alkalide molecules synthesized, for example, I have read in a paper that the reaction $$\ce{2Na -> Na+ + Na-}$$ is exothermic with a $\Delta H = \pu{-438 kJ/mol}$. I have also read that in ...
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1answer
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Reduction of nitrobenzene with LiAlH4 and NaBH4

After searching a lot on the internet I've found that nitrobenzene is reduced by LiAlH4 to the following compound whose naming I couldn't do. I couldn't find the mechanism for this reaction anywhere. ...
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E2 Elimination; Anti-periplanar beta hydrogen

I'm confused by this picture I found on masterorganicchemistry.com—a very popular organic chemistry website: I agree that the product is a product. However, can't there be another product? ...
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269 views

Base-promoted rearrangement of β-ketoester

Propose a reasonable mechanism for the following transformation: I guess an enolate probably forms first, but then what does it attack to give something like the product in the question?
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Isonitrile to nitrile conversion

If we are given $\ce{CH3NC}$ and told to convert it into $\ce{CH3CN}$ by doing some chemical reactions. My attempt According to my textbook there are no chemical reaction of isocyanide conpounds. I ...
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954 views

Why PI3 is not used in HVZ reaction?

With the help of HVZ reaction, we can get alpha-chloro or alpha-bromo carboxylic acid. But can we make alpha-iodocarboxylic acid with the help of HVZ reaction? I could not find any reference of HVZ ...
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Why does neighbouring group participation happen?

Can someone please explain why neighbouring group participation happens? Does it stabilise the carbocation? If so then is NGP dominant over an intermolecular SN2 reaction (especially in aprotic ...
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Mechanism of Friedel-Crafts acylation with succinic anhydride

Here is my proposed mechanism, something tells me that the intramolecular deprotonation happens after, and that this is not concerted. Is my mechanism correct?
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Carbonyl oxygen as nucleophile

Aldehydes and ketones have electrophilic centres at their carbonyl C, since the carbonyl O polarises the bond and attracts electron density towards itself on account of its high electronegativity. But ...
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Reaction between sulfur and sodium hydroxide

Sulfur reacts with sodium hydroxide in the following way: $\ce{3S + 6NaOH->2Na_2S + Na_2SO_3 + 3H_2O}$ It is a disproportionation reaction: sulfur's oxidation changes from zero to -2 in sodium ...
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2answers
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Why doesn't nitric oxide react with water?

Why doesn't $\ce{NO}$ (nitric oxide) react with water? I know it is a neutral oxide, but I'm really curious as to why that is. Why will $\ce{NO}$ not react with $\ce{H2O}$?
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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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1answer
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Relationship between rate equation and equilibrium constant

I have read mannaia's answer on the question of 'rate order and confusion', as well as Nicolau Saker Neto's answer to a related question. They have both been very helpful. As I understand, the ...
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1answer
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Gattermann-Koch reaction - Role of cuprous chloride

I am unable to figure out what the role of $\ce{CuCl}$ in Gatterman-Koch reaction is. Does it provide $\ce{Cl-}$ ions by dissociating into $\ce{CuCl2}$ and $\ce{2Cl-}$, but that can also be achieved ...
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How do these cascade reactions work?

A. $\ce{Cr2O7^2-}$ B. $\ce{H+}$ C. $\ce{OH-}$ D. $\ce{Cr^3+}$ E. $\ce{Ba^2+}$ Which of the above is the appropriate ion for each blank in the following series of reactions? $$\begin{...
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1answer
394 views

Does the reaction of 1-bromobutane with cyanide ion follow an SN1 or SN2 mechanism?

In my textbook it's mentioned that the reaction undergoes $\mathrm{S_N2}$ mechanism. I understand that the carbon attached to the bromine is primary, but both solvents here are polar protic solvents, ...
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1answer
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How can aqueous KOH give alcohol by SN2 of alkyl halide?

I ask this because SN2 requires a strong nucleophile, and I have read $\ce{OH-}$ isn't a strong nucleophile in a polar protic solvent like water. So, how can $\ce{OH-}$ replace, say $\ce{I-}$ from $\...
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What is the mechanism of trialkylborane oxidation with hydroperoxide?

This is the mechanism of trialkylborane. In this mechanism I can't understand why should the -OH group leave and the -R group enter in its place to form borate ester. Can someone please explain me ...
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1answer
591 views

How to be able to tell if a molecule will react via SN1 or SN2?

I've been having a lot of issues with a question. 2 compounds, (1-chloro-2,2-dimethylpropyl)benzene and (1-chloro-2-methylpropyl)benzene react with EtOH in water. It asks to classify the reaction ...
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1answer
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What did actually happen when Staudinger tried to synthesise diamond?

It is a famous reaction that used to be a teaching lab experiment, but is now banned in Germany, because it is too dangerous. To quote-translate quite liberally from the German www.seilnacht.com: ...
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Neighbouring group participation with and without retention of configuration in nucleophilic substitution of 2,6-dichloro-9-thiabicyclo[3.3.1]nonane

Treatment of the dichloride A under the conditions indicated gives B with retention of configuration, while treatment of dichloride C gives D with inversion of configuration. I am having difficulty ...
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1answer
559 views

Can reactions produce microwave or radio wave radiation?

I know that many reactions produce visible light, heat and sound, but is there a reaction (preferably one example for an inorganic and organic one) that could produce electromagnetic waves in the ...
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What's the reaction type of the Hydrogen shift?

Rearrangement of cycloheptatrienyl carbene yields heptafulvene via a hydrogen shift. I see that the reaction is favorable because there is a conjugative effect with the $\pi$ system of the ring in ...
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1answer
633 views

What are the key chemical characteristics that determine the octane rating of fuel?

The octane rating of petrol (gasoline) is a measure of the how much compression a fuel air mixture can have before detonating (which in petrol engines is a bad thing as you want the mix to combust ...
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Mercury assisted deprotection of dithiane

1,3 dithianes are used in umpolung reactions and can be deprotected by mercury containing compounds - but could anyone help explain what the exact mechanism is? Many texts seem to skim over this by ...

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