Questions tagged [radicals]

Radicals are highly reactive species, that have one or more unpaired electrons. Whether a species has unpaired electron(s) can be experimentally determined through electron pair resonance spectroscopy. Radicals are paramagnetic. This tag should be applied to questions that involve free radicals as a species or radicals in reactions and their mechanisms.

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Which singlet dihalocarbene has the strongest carbon-halogen bond?

There are three singlet carbenes - difluorocarbene, dichlorocarbene and dibromocarbene. Which has the strongest carbon halogen bond? Obviously backbonding is a point to be considered, as carbene is ...
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82 views

What, if any, are the differences between radical scavenging and radical quenching?

Hindered amine light stabilizers (HALS), introduced in the 1970s, function mainly as free radical scavengers, although they also may act as quenchers or peroxide decomposers. (Polypropylene: The ...
4
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1answer
96 views

Does presence of alkyl groups on alpha carbon increase yield of alkane in Kolbe's Decarboxylation?

We know that, during the synthesis of alkanes by Kolbe's Decarboxylation reaction, the reaction proceeds via a free radical $\ce{R.}$ at the anode. So, an alkyl group, say methyl, when substituted at ...
4
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1answer
81 views

Terminology for “proton stripping”?

This is going to probably be an easy question for an organic chemist, but I am looking for the proper terminology to describe the following reaction mechanism. In particular, what is a more precise ...
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16 views

What is the largest one step radical cyclization ever achieved?

When I was an undergrad, roughly around 2005, I took a grad level class that covered various topics in advanced organic synthesis. I don't remember much clearly from the class, but one thing that I ...
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82 views

Why are “diene” structures in the C-ring of anthocyanins singled out for their singlet-oxygen quenching ability?

Anthocyanins are a class of water-soluble vacuolar pigments. They are sensitive to pH, and can undergo a series of structural changes according to a pH-dependent equilibrium as illustrated in Figure 1....
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181 views

Mechanism for the addition of chlorine to benzene to form hexachlorocyclohexane

I am familiar with electrophilic substitutions of benzene, with chlorine using a halogen carrier catalyst such as $\ce{AlCl3}$, to produce chlorobenzene, and I am aware of the mechanism. But, ...
3
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1answer
2k views

What is the rate-determining step in free radical halogenation?

Recently, we were learning about free radical halogenation in school. A set of notes given to us wrote that the rate-determining step is the propagation step. This seems to go against my understanding ...
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109 views

Mechanism of photochemical hydroamination with LDA

I've recently come across a couple examples of intramolecular alkene hydroamination accomplished by treatment with LDA followed by visible light irradiation (tungsten light bulb):[1,2] I'd assume ...
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59 views

How long can solid DPPH powder last for in terms of shelf-life before its free-radical status is quenched by the atmosphere?

I am writing in my research on the free-radical scavenging activity of various flavylium compounds. I may need to have DPPH shipped as a result of a lack of supply; I am just wondering what sort of ...
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408 views

Different behavior of bromine radical with alkenes

Let's assume we have propene and it's undergoing two different reactions: a Kharasch reaction and allylic substitution reaction. In both reaction bromine radicals are formed, and the attacking ...
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53 views

Can someone explain the differences in decomposition rates for when two molecules which have 2 different substituents?

Just having trouble on why these two have such different decomposition rates, I would like to think its because NO2 is electron withdrawing but I cannot see why this would change the rate...some ...
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139 views

Could any constituent of normal human urine produce a false positive in a Kastle-Meyer test for presence of blood?

From my understanding, one forensic test for the presence of traces of blood at a crime scene is (or was) the Kastle-Meyer test. Doing some research, I understand that in the test, hemoglobin reacts ...
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30 views

What is the name of the glyoxal radical after removing two hydrogen atoms?

What is the name of the radical that results from removing two hydrogen atoms from glyoxal ($\ce{CHO-CHO}$)? It has a roughly this structure: $$\ce{O=C^.-C^.=O}$$ It is an important intermediate in ...
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95 views

Is it possible to arrest the post-actinic effects of photodegradation in ABS polymers?

Polymers like acrylonitrile butadiene styrene (ABS) are adversely effected by UV exposure, both visually (by yellowing) and with regard to other material properties [1]. What's worse is that the ...
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35 views

Benzophenone Ketyl color origin

I was recently preparing the benzophenone ketyl radical by reacting it with sodium in toluene. Although this compound is really well known and it seems somewhat obvious and accepted in literature that ...
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97 views

Which natural orbitals are better for CASSCF calculations for organic diradicals?

I am trying to perform CASSCF calculations for a series of diradicals. As input orbitals I have used two types of natural orbitals. One is unrestricted natural orbitals and the other MP2-based natural ...
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31 views

It is possible to make radical Chlorination on the α-position of ketones?

I need examples of radical α-Chlorination of ketones. It is possible to make radical chlorination happen in the alpha position?
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452 views

Reactivity and selectivity in free radical halogenation of alkanes

I read about the free radical halogenation of alkanes with $\ce{X2}$ and I have the following questions: Given that the first step is the homolytic breaking of the $\ce{X-X}$ bond, and the homolytic ...
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250 views

How many different alkyl chlorides result from C4H10 and chlorine?

Let's say there's a reaction $\ce{C4H10 + Cl2}$ taking place under UV light. How many different alkyl chlorides do we obtain? I'm not sure if the resulting molecule would be monochlorinated or ...
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269 views

Differences in specific free radical reactions enthalpies

Iodination of alkanes using iodine $(\ce{I2})$ is usually an unfavorable reaction. Tetraiodomethane $(\ce{CI4})$ can be used as the iodine source for iodination, in the presence of a free-radical ...
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29 views

How to analysis the amount of reactive oxygen atom in specific molecules

From a Phd dissertation here, I read about the material follows: "Odd oxygen is a measure of oxidative capacity of the atmosphere. It contains species with an oxygen atom avaliable to serve as ...
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20 views

UV-Vis absorbtion spectra of a radical cation/anion. Is it different compared to its even counterpart?

I am studying gas-phase Uv-Vis spectra of radical molecules. If one electron is removed/captured from the neutral even electron molecule, what can I expect from the absorption spectra? Will new peaks ...
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132 views

How does conversion of a free radical to a carbonyl compound take place? Unsure about mechanism

Came across a question that talked about fragmentation of peroxyesters, about the peroxide linkage of course. After the fragmentation of the peroxyester was done, it gave out three products (2 being ...
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56 views

How is occupation number of lowest unoccupied natural orbital defined?

I have run some calculations to analyse the occupation of natural orbitals. Since it is needed to run in triplet state, I get two orbitals with occupation number 1. Now, which orbital occupation ...
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100 views

Electrophilic nature of bromine free radical

My chemistry teacher told me that Bromine radical is a weak electrophile, and that it is more likely to join the more electron rich part of a molecule. However I could not verify his statement from ...
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45 views

Bromine radical reaction with an alkene - What factors determine whether radical addition occurs as oppose to radical abstraction?

From what I can tell, radical addition occurs when using HBr + Organic peroxides as reagents, and radical abstraction occurs when using trace amounts of bromine radicals (generated by NBS, trace HBr ...
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153 views

Why is cyclopropylmethyl radical opening so fast?

Ring opening of the cyclopropylmethyl radical is reliable and fast, and so has been used as a radical trap and a radical clock. Could someone please explain what exactly makes this reaction so fast, ...
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329 views

Confusing stability order of free radical structures

I have question regarding the solution that has been given. Question: In the given compound the order of case with which hydrogen atom can be abstracted from carbons I to VI is The solution that ...
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394 views

Why aren't free radicals considered resonance forms?

In C, the answer states that electrons must come in pairs. And so C does not show resonance forms. But here I read that if there is an unpaired electron, it is a free radical. Why can't free radicals ...
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76 views

Can equivalent mass be more than the molecular mass? Can it be applied to radical reactions?

Consider a reaction involving radicals: $$\ce{CH3^. + Cl^. -> CH3Cl}$$ Is the definition of equivalent mass applicable here? If yes, how? Are there reactions where equivalent mass of a reagent ...
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288 views

Regarding allylic free radicals and anti-Markovnikov product

I was searching a question "What is the primary product when cyclohexene reacts with bromine in the presence of UV light?" and in a website they said: 3-Bromocyclohexene will be the product ...
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614 views

Properties of a free radical scavenger

Antioxidants are free radical scavengers and are able to reduce free radicals to make them stable. What I am interested in is why some molecules make for superb free radical scavengers and why others ...
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508 views

Free-Radical chlorination: Find all unique mono-chlorinated products

I'm having trouble with this problem. I suspect that there is a typo, as the methylcyclohexene described in the wording does not match the methylcyclopentene shown in the image(someone please confirm ...
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1k views

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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20 views

what is the material used to detect the presence of free radicals in the reaction?

To detect the presence of free radicals in the reaction usually, acrylonitrile used but this material is not available in my university. Is there another material used to detect the presence of free ...
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39 views

Can a Hydrogen Radical form in a chemical reaction?

Original question: During kolbe electrolysis of Formic acid, H2 is released at which electrode? What I thought: H2 will form at cathode due to reduction of water. But will the Formic acid decompose ...
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230 views

Is OH + CO → CO2 + H an elementary reaction?

Is $$\rm OH + CO \longrightarrow CO_2 + H$$ an elementary reaction? How could I tell? I could break the reaction into $$\rm OH\ (+ M) \longrightarrow O + H\ (+ M)$$ $$\rm CO + O \longrightarrow ...
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92 views

Bromine Homolysis Using Handheld UV Lamp

I'm trying to investigate the homolysis of bromine for an IB Chemistry (high school) Internal Assessment. To do so, I need a UV lamp capable of splitting diatomic bromine into bromine radicals. Would ...