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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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Why do fluoride ions "win" over thiocyanate ions in a solution with iron ions?

When you mix aqueous iron(III) nitrate and potassium thiocyanate together you get a red solution. Then if you add sodium fluoride, the red colour disappears. This is basically because the $\ce{Fe(...
1 vote
1 answer
36 views

Mechanism of Zn + NaOH?

I was reading block chemistry in class, and I was taught by my chemistry professor this method of preparation of hydrogen: $\ce{Zn + NaOH -> Na2ZnO2 + H2}$ In this reaction, zinc reacts with ...
-1 votes
2 answers
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Is dissolution of NH4Cl in water a physical change or chemical change?

A chemical change involves a reorientation of atoms of the substance, resulting in the formation of new substances. A physical change causes changes in physical properties of the substance, like its ...
-4 votes
0 answers
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Why are heavy metals toxic? Lead and Carbon are in the same group. One is toxic, the other is not [closed]

I have read the different answers on the toxicity of heavy metals but I am still confused about the topic. Why does the mass of the nuclei matter when chemical reactions only involve valence electrons....
1 vote
0 answers
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Finding the relative position of the molecule in the adsorbate and adsorbent by minimizing the Hamiltonian

I am trying to model an adsorbing process (or more precisely, Heterogeneous catalysis process between solid catalyst and gas reactants). One of the step is to minimize the Hamiltonian by optimizing ...
0 votes
0 answers
20 views

Bicarbonate concentration in the RO permeate

I am facing a challenge since long ago, but have not been able to find a suitable solution for it. Please share your thoughts if you have the knowledge or experience in this area. I am running an RO ...
0 votes
0 answers
53 views

Conflict: Sandmeyer reaction and Gattermann reaction

So it is known that benzene diazonium chloride when reaction with cuprous(I) chloride would produce a chlorobenzene which is called Sandmeyer reaction. Now for the same salt, if we react it with ...
4 votes
1 answer
78 views

Compatibility of DCM/CCl3 with sodium hydride

In our undergraduate studies we were told that chlorinated solvents should not get in contact with alkaline elements like sodium, potassium etc., due to the violent reaction that will form the ...
-2 votes
0 answers
48 views

When is the activity of a solid equal to 1

The activity of a solid is often equal to 1. Is it always the case? Or only in liquids and gases? In particular, if we consider the following reaction : $Sn(\alpha)_{(s)} = Sn(\beta)_{(s)}$, where $\...
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0 answers
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Why does allylic bromination occur with N-bromosuccinimide?

For the purpose of allylic bromination on an alkene, say propan-1-ene, N-bromosuccinimide (NBS) is added to HBr in carbon tetrachloride which leads to the formation of bromine. The bromine, in the ...
1 vote
1 answer
79 views

Dehydration of isoborneol with carbocation rearrangement

What rearrangement happens when isoborneol (structure below) is heated with acid? Since acid is used and the hydroxyl group is present, the reaction mechanism is dehydration. My attempt: In the ...
3 votes
0 answers
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Is the "heat or UV" necessary for PVC10 + Cl => CPVC10 catalytic or endothermic and if endothermic how much energy?

Production of Chlorinated PolyVinyl Chloride (CPVC) from PVC and chlorine requires incorporating about one part chlorine in 10 PCV to achieve around 63% chlorine mass CPVC. This reaction is "...
8 votes
2 answers
863 views

Why does the Wurtz-Fittig reaction occur?

In the Wurtz-Fittig reaction, an aryl halide and an alkyl halide react with sodium in the presence of dry ether to give R-Ar as the major product. Why is the coupling of R and Ar favoured? In other ...
4 votes
2 answers
9k views

Reaction mechanism for 7-hydroxy-4-methylcoumarin synthesis with an iodine catalyst

7-Hydroxy-4-methylcoumarin can be synthesized from ethyl acetoacetate and resorcinol with iodine as a catalyst. What is the mechanism for this? From what I understand it follows the Pechmann reaction ...
6 votes
2 answers
3k views

Étard Reaction of Ethylbenzene

What is the major product when the following compound undergoes Étard reaction? Is it acetophenone or a terminal aldehyde. The mechanism discussed in Mechanism for an Étard reaction (chromium complex)...
3 votes
2 answers
77 views

What does phosphorodibromidous acid do in solution?

When tribromophosphine is used to activate an OH to enable its substitution, the leaving group is listed by PubChem as "phosphorodibromidous acid" and doesn't seem to really exist from a ...
3 votes
1 answer
680 views

Reaction of 1,3-butadiene with HBr in the presence of peroxides

I have learnt that the reaction of 1,3-butadiene with HBr depends on the temperature as the temperature determines whether the reaction is under kinetic or thermodynamic control. I believe that this ...
0 votes
1 answer
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What is the major product formed when you react 1,3-butadiene with HBr in the presence of both ROOR and heat? [duplicate]

I just had an exam where we were given 1,3-butadiene as our reactant and our major product as 1-bromo-2-butene, where we had to state what the reagent was for that particular reaction. I stated that ...
-2 votes
1 answer
78 views

Why is the phenyl shift happening?

In the mechanism here, why is the phenyl shift happening instead of O from OH attacking the +ve carbon? also both the carbons are 3 degree...so what is the need of shift ?
-1 votes
0 answers
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Why is Hoffmann product preferred over Zaitsev in this reaction?

[] Why is Hoffman product formed here in the elimination step in place of Zaitsev product? My guess is that adjacent double bonds are unstable for some reason In the next step $\ce{H^+}$ does not ...
10 votes
2 answers
21k 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 ...
3 votes
1 answer
164 views

Efficient absorption techniques for oxygen gas

This question is somewhat vague, but I am interested in biogas treatment and a major component in biogas treatment is oxygen filtration. I know there are various methods for oxygen filtration such as ...
-2 votes
2 answers
124 views

What is the mechanism of cleavage reaction of ethers using hydrochloric acid? [closed]

I have referred to the mechanism shown in the text which is: But I am not able to figure out how this took place: Source: Solomon's Practice problem 11.18
-2 votes
1 answer
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Mechanism of Jones oxidation

We were required to find the number of moles of $CrO_3$ required to oxidize 6 moles of heptan-2-ol. I tried balancing the equation but I am not aware of the final chromium containing product. Knowing ...
-1 votes
1 answer
102 views

Mechanism of cyclic ether formation from alcohol [closed]

first thought was protonating alkene to give carbocation which does EAS on the phenyl group followed by attack of oxygen on the 3 deg carbon to break the newly formed 4 membered ring. problem with ...
0 votes
0 answers
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How to predict whether a redox or an acid-base reaction will occur? [duplicate]

I've been thinking a lot about this question, but even after intense research, I didn't find any satisfying answer, even here. So here's my question, illustrated with an example: We have a negatively ...
0 votes
1 answer
44 views

Leaving group ability vs Stability of Transition state for determining rate of E2 elimination reaction [closed]

Source: Teacher's Assignment. (not a homework doubt, but a big conceptual doubt about the question) In this question we have to compare rate of E2 reactions and the answer is C2H4I2 > C2H4Br2 > ...
0 votes
0 answers
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Substitution reaction with alcoholic KOH

Whenever, there is the reagent "alcoholic KOH", we prefer E2 Elimination reaction. However in case of 3 degree alkyl halides, like tert-butyl chloride, why do we not consider SN1 pathway? ...
0 votes
1 answer
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Questions on protonation / substituent effects on the energies of HOMO and LUMO

I am trying to understand mechanisms through HOMO/LUMO and am struggling to understand 3 points from a lecture slide I found on the internet: Focusing on sigma*(C-F), sigma*(C-O) and sigma*(C-C), I ...
2 votes
0 answers
34 views

Aluminum foil & Iron (III) chloride hexahydrate

When I put an aluminum foil strip into 25mL of 0.4M FeCl3.6H2O I was expecting a single replacement reaction with aluminum chloride forming and iron forming a ppt, instead nothing happened. A reaction ...
2 votes
1 answer
78 views

3,3'-methylimino-di-propionic acid diethyl ester, to 1-Methyl-4-piperidone, via an Intermediate

They ask us to give the structure of the intermediate "A" and the mechanisms of both steps My attempt: I found the name of the started and end molecules on reaxys.com NaOEt could ...
2 votes
0 answers
32 views

Relation between formation of carbocation and availability of nucleophile

Many sources suggest that in SN1 reactions the leaving group first exits the molecule, and the resulting carbocation is subsequently attacked by the nucleophile, suggesting that there is no relation ...
4 votes
0 answers
794 views

Why does the OAc group leave in the first step of Oxymercuration?

The above picture shows the first step of Oxymercuration. The electrons attack the Mercury atom but the OAc group leaves. Why is this? Hg is a transition metal with a number of available oxidation ...
4 votes
0 answers
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Does catechol give Tollens’ test?

Do hydroquinones like catechol or p-hydroxyphenol give Tollens’ test? I know that β-diketones can reduce Tollens’ reagent to give a “silver mirror”, so I would guess that due to tautomerization ...
0 votes
0 answers
44 views

Dehalogenation of geminal dihalide

I found a reaction of a geminal dihalide with zinc in the book Organic chemistry by Clayden. The reaction in question is : I cannot find any reference online to the second reaction of Zn which seems ...
2 votes
1 answer
53 views

Frequency to induce nitrogen inversion

I would like to know how to compute the frequency at which nitrogen inversion happens in ammonia gas at STP. The activation energy for such process is 24.2 kJ/mol, therefore I thought that it is ...
0 votes
0 answers
44 views

Explaination of order of leaving groups

In Solomons' Organic Chemistry, in a section discussing leaving groups, it is stated that$-$ Among the halogens, an iodide ion is the best leaving group and a fluoride ion is the poorest: $$I− > ...
0 votes
0 answers
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Why do carbenes react differently with different alkenes in Reimer-Tiemann reaction?

Carbenes in the usual form of reimer-tiemann reaction react by forming one bond and getting negatively charged like this but in abnormal reactions of cyclopentadiene(and I suspect all 5 member rings) ...
0 votes
0 answers
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Why nitration of aniline carried out after acetylation give ortho and para major products?

I was reading about the meta directing nature of anilinium cations and the answer mentioned that these reactions are usually carried out with 90-98% sulphuric acid. At these concentrations I would ...
-1 votes
1 answer
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A curly arrow can only have its tail starting from a double bond or lone pair?

According to this video, a curly arrow representing a reaction mechanism can only have its tail starting from a double bond or a lone pair. I am wondering if the tail of a curly arrow could also start ...
0 votes
1 answer
2k views

How many products are generated when an alkene is subjected to bromination using NBS/CCl4?

Suppose we have an alkene(e.g. 2-butene). We try to subject it to allylic bromination using NBS/$\ce{CCl4}$ and then the mixture is separated using fractional distillation. According to my ...
11 votes
2 answers
2k views

How does an oscillating reaction work?

I watched a Belousov--Zhabotinsky reaction 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 ...
5 votes
0 answers
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Mechanism of Cu Catalyzed reaction between Benzoic acid with DMF

I'm looking for the mechanism of this reaction that I have stumbled upon. It is believed to be a radical reaction and I can kinda see that but I'm not convinced that I can understand all of the steps, ...
0 votes
0 answers
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Reaction SMARTS for Secondary Amine and Carboxylic Acid

I'm working on replicating methods from Klarich et al. [1] and the authors do not provide the reaction SMARTS used for synthesizing secondary amine + carboxylic acid building blocks. Does anyone have ...
3 votes
1 answer
93 views

Calculation of Reaction Extent as a Function of Pressure and Temperature: Issue with Activity-Based Approach

I'm working on modeling reactions involving combinations of hydrogen (H), nitrogen (N), and strontium (Sr) elements. I've obtained the temperature-dependent Gibbs free energy of formation, enthalpy, ...
8 votes
1 answer
2k views

Do all α-hydroxy ketones give Tollens’ test?

It is well known that terminal α-hydroxy ketones give Tollens’ test, via tautomerisation. Also, α-hydroxy ketones flanked by aromatic groups give Tollens’ test, such as benzoin. But do all α-hydroxy ...
1 vote
1 answer
112 views

1-Bromo-4-tert-butylbenzene reaction with NaNH2 [closed]

I'm struggling to grasp how the reaction would turn out. Could you help? My idea was that the bromide atom will get replaced by the amino group of $\ce{NaNH2}$, but when I google, I read that $\ce{...
0 votes
3 answers
110 views

Why are we permitted to add things to balance redox equations?

Consider balancing redox half equations. As a general rule, we can add electrons, water, hydrogen ions or hydroxide ions to balance the redox half equation. However, it is not entirely clear why we ...
0 votes
1 answer
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What is the full mechanism for the controlled reduction of an alkyne using LiAlH₄?

Was going through my notes and realised I didn't completely fill them in. The first few steps I think are quite self-explanatory but I'm really confused about the last step where I go from the five-...
7 votes
1 answer
380 views

Does the acetic acid in vinegar oxidize significantly?

I apologize in advance for this question. I did very well in O Chem, but that was 50 years ago and I had to study very hard. I don't remember much of it now except what's common in basic biological ...

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