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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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7
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1answer
621 views

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 ...
6
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1answer
307 views

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 ...
6
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3answers
3k views

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? ...
5
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2answers
3k views

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 ...
5
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2answers
5k views

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 ...
5
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0answers
713 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 ...
4
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2answers
20k views

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 ...
3
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1answer
3k views

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 ...
3
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1answer
2k views

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 ...
3
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1answer
20k views

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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2answers
255 views

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{...
2
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1answer
279 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, ...
1
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1answer
396 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
1k views

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 ...
19
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1answer
243 views

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: ...
15
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1answer
894 views

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 ...
12
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1answer
393 views

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 ...
12
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1answer
11k views

Mechanism for chloromethylation of benzene with formaldehyde and HCl

What is the mechanism of the above reaction? I have thought of one possibility: Would this work? How exactly is the chlorine installed on the alkyl chain?
10
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2answers
2k views

Ring expansion from a given cyclic carbocation

How will the cyclobutane ring behave in the case of cyclobutylmethylium (cyclobutylmethyl cation)? I initially thought there would be ring expansion to a five membered ring so that there may be less ...
10
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2answers
9k views

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 ...
9
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1answer
4k views

Reaction mechanism for oxidation of primary alcohol to carboxylic acid

Can someone help me identify the steps for the following reaction? I'd like to keep track of everything that happens. I can't figure out what happens with oxidation in this context, and thus can't get ...
9
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3answers
45k views

CH4 + O2 => CO2 + 2H2, what's wrong with it?

It says in my textbook that: $$\ce{CH4 + 2 O2 -> CO2 + 2 H2O}$$ which seems like a displacement reaction to me. Shouldn't the reaction be: $$\ce{CH4 + O2 -> CO2 + 2 H2}$$ since $\ce{4H}$ ...
9
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1answer
5k views

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 ...
9
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1answer
4k views

Decarboxylation of Salicylic acid

I would like to know how and under what conditions can decarboxylation of salicylic acid (o-hydroxybenzoic acid) occur. I couldn't find any sources for it online. Here are some reasons I think it ...
8
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2answers
2k views

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 ...
8
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5answers
9k views

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 ...
8
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2answers
1k views

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 ...
8
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2answers
872 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 ...
7
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1answer
532 views

E1 and E2 elimination reactions of isotopically labeled bromocyclohexanes

Question a) What would the product of the reaction be for an E2 mechanism b) What would the products be for an E1 mechanism The Br coming out of the page is the 79 isotope while the ...
7
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3answers
7k views

Why is it necessary to avoid even traces of moisture from a Grignard reagent?

This fact was written in my text book. I wonder why that should be so.
7
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1answer
2k views

Why does a mixture of nitrous acid with concentrated nitric acid cause nitration of benzene instead of nitrosation?

A question came up in our worksheet to predict the reaction product of nitrous acid and concentrated nitric acid with benzene. I quickly recognized it to be similar to the nitration reaction. ...
6
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1answer
3k views

What are some ways to predict that a double replacement reaction will occur? [duplicate]

For instance, say: $\ce{2KOH + Pb(NO3)2 -> 2KNO3 + Pb(OH)2}$ How would I even go about beginning to predict this?
6
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1answer
265 views

Clarification on the $\mathrm{S_N2}$ mechanism

The question is about the specifics of the $\mathrm{S_N2}$ mechanism (nucleophilic bi-molecular substitution). (Source: Wikipedia) As we know that in this reaction the nucelophile ($\ce{Nu-}$) ...
6
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1answer
2k views

Stability of a carbocation, in part of camphor synthesis

Can someone explain to me why there is a rearrangement reaction of carbocation 1 to carbocation 2? To me the second carbocation appears to be less stable than the first because it is less substituted. ...
6
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1answer
204 views

Hydroboration oxidation reaction on trans,trans,trans-1,5,9-cyclododecatriene with carbon monoxide

The given solution: I got this question in an entrance exam coaching test paper in India. Product P is easily covered by the mechanism of simple hydroboration-oxidation reaction, and I've understood ...
5
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2answers
11k views

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 ...
5
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1answer
2k views

How can I choose the correct mechanism for nucleophilic substitution of aryl halides?

I was reading about nucleophilic substitutions of aryl halides, and there are three different mechanisms discussed, namely the SN1, SNAr (addition-elimination), and benzyne (elimination-addition) ...
5
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0answers
7k views

Reaction of phenol and zinc dust

There is a reduction reaction of phenol with zinc dust which is found in many books. $\ce{Ph-OH + Zn -> Benzene + ZnO}$ However, a simple google search fails to explain anything about the ...
5
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1answer
1k views

Least likely product of a hydrocarbon cracking reaction?

The hydrocarbon $\ce{C17H36}$ can be cracked. Which compound is the least likely to be produced in this reaction? A: $\ce{C3H8}$ B: $\ce{C4H8}$ C: $\ce{C8H16}$ D: $\ce{C16H34}$ Is it D because ...
5
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2answers
588 views

How this tricky Wagner-Meerwein rearrangement occurs?

In 1979, Karel Frantisek Wiesner performed a tremondous total synthesis in $59$ steps of the 13-desoxydelphonine. In one of those steps there is a very tricky Wagner-Meervien rearrangement. I tried to ...
4
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2answers
9k views

Endo rule and stereoselectivity in the Diels-Alder reaction

Do you agree with the stereocenter with the $\ce{-CF3}$ and $\ce{-CN}$ substituents in the product? source I thought that since $\ce{-CF3}$ is a better electron withdrawing group than $\ce{-CN}$, it ...
4
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3answers
86 views

Equilibrium for very small amounts of reactants

Is there any difference in the concept of equilibrium when it comes down to dealing with extremely small amounts of reactants? Say we have $$\ce{A + B <=> C + D}$$ and $K_c$ is $100,000$. If ...
4
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1answer
4k views

Benzotriazole to o-phenylenediamine

So I was reading benzotriazole's synthesis is o-phenylenediamine with acetic acid and sodium nitrite. Is this a reversible process? Not even specifically to o-phenylenediamine but any derivative. ...
4
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1answer
5k views

Why are 1,3-diols protected with aldehydes but 1,2-diols are protected with ketones?

1,3 diols are usually reacted with benzaldehyde when protection of the OH groups is desirable, but acetone is used when the relation between the hydroxyl groups is 1,2. Why is it so?
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2answers
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In Reimer-Tiemann reaction why does phenol attack the carbene from ortho position?

From the Wikipedia article on Reimer-Tiemann reation: In step 5, why doesn't the oxygen attack the carbene. The way I see it: upon attacking the carbene from ortho position, the mechanism ...
4
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1answer
439 views

Hydrolysis of 4-chloro-3,3-dimethylbut-1-ene forms which products much faster than primary alkyl halides?

Question My Attempt First a primary carbocation is formed and then methyl shift occurs to form a more stable secondary carbocation hence making (C) the major product, consequently I also ...
4
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2answers
483 views

Finding all Chemical Reactions Given Products and Reactants

Suppose only a set of chemical formulas is given. How can you find all mathematically possible chemical equations whose educts and products are only from this set? Take e.g. the set $\{ \ce{C, H2, O2,...
3
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2answers
881 views

Rate of catalytic hydrogenation of alkenes

What does the rate of catalytic hydrogenation of alkenes depend upon? What'd be the increasing order of rate towards catalytic hydrogenation of the following alkenes, A (2-methylpropene), B (cis-but-2-...
3
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2answers
3k views

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 $\ce{H2O}$?
3
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0answers
529 views

Comparison of the rate of SN1 and SN2 reaction

It is known that $\mathrm{S_N1}$ (Substitution Nucleophilic Unimolecular) follows the order of rate of reaction: Tertiary ($3^\circ$) > Secondary ($2^\circ$) > Primary ($1^\circ$) For $\mathrm{...