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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 ...
ksr's user avatar
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6 votes
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Geometry of a free radical at the bridgehead carbon

With reference to J. Am. Chem. Soc. 1968, 90 (19), 5266–5267, they state: The most favorable geometry of aliphatic free radicals remains an unsolved problem, since existing data are consistent with a ...
Safdar Faisal's user avatar
6 votes
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Mulliken Spin Density

I would like to know if a Mulliken population analysis to calculate spin densities is in general a valid choice. I see that it is made use of, for example here1. So up to-date researches apparently ...
Martin 's user avatar
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5 votes
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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, ...
GabrielAlx's user avatar
4 votes
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136 views

After neutralizing a free radical, why don't anti-oxidants become free radicals themselves?

This is my understanding: A free radical is a molecule with a single unpaired electron. This molecule is highly reactive because it wants to steal an electron from another molecule (oxidation). Anti-...
gardenhead's user avatar
4 votes
1 answer
245 views

Why does the heat of formation of organic radicals and positive ions decrease with their size and degree of branching at the radical or ionic site?

I am currently studying the textbook Mass Spectrometry, third edition, by Jürgen H. Gross. Chapter 2.4.3 Bond Dissociation Energies and Heats of Formation says the following: The heat of formation ...
The Pointer's user avatar
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4 votes
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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 ...
user47181's user avatar
4 votes
1 answer
375 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 ...
user138523's user avatar
4 votes
1 answer
121 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 ...
Coherent's user avatar
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Calculate frequency dose from different light intensities

The quantum yield for homolytic O-O cleavage of (CH$_3$)$_3$COOC(CH$_3$)$_3$ at $266$ nm is $0.21$. In one experiment, a pulsed laser of this wavelength was used to induce the formation of t-butoxyl ...
katara 's user avatar
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Preferred radical attack on a polyester

My question concerns the relative stability of a radical next to an ester oxygen compared to a radical next to an ester carbonyl carbon. The stabilizing effect of the electron pairs of ether oxygen ...
Lothar Maier's user avatar
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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 ...
Nate's user avatar
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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 ...
Edwin Steiner's user avatar
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508 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....
user47181's user avatar
3 votes
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551 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, ...
Davidmb65's user avatar
3 votes
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197 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 ...
orthocresol's user avatar
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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 ...
GuestyMcGuestFace's user avatar
3 votes
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1k 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 ...
wolphram's user avatar
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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 ...
Michael Nguyen's user avatar
3 votes
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164 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 ...
PJ_Mag's user avatar
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3 votes
1 answer
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Ozone depletion with the OH radical

$\ce{OH*}$ radicals are known to deplete the ozone layer. Fill out the gaps below to complete the propagation stage: \begin{align} \ce{? + O3 &-> ? + O2}\\ \ce{? + O3 &-> ? + O2} \...
FShrike's user avatar
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2 votes
0 answers
36 views

What is the reaction steps taken when producing auroral forcing?

As described in here: https://www.nasa.gov/feature/goddard/2018/sounding-rocket-mission-will-trace-auroral-winds A mixture of Trimethylaluminium, Barium and Strontium reacts and ionize in the upper ...
C-Consciousness's user avatar
2 votes
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Plotting second order reaction with different reactants

In a laser flash photolysis experiment, $\ce{C6H5NH2}$ $(C_0 = \pu{60 \mu M})$ is oxidize to its corresponding radical cations. There are three possible reaction pathways for the formation of the ...
katara 's user avatar
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2 votes
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28 views

Measured g-factor of a free-radical changing as a function of something. But I cant work out what?

I'm looking at EPR of a paramagnetic organic molecule in solution that has a very stable free-radical signature with gfactor ~2.0035. All good. Except when watching one particular experiment I saw ...
Tunneller's user avatar
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2 votes
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307 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 ...
juno's user avatar
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2 votes
0 answers
39 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?
user65404's user avatar
2 votes
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1k 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 ...
Anurag Baundwal's user avatar
2 votes
0 answers
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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 ...
Glycerius's user avatar
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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 ...
Quaddro's user avatar
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2 votes
0 answers
34 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 ...
Han Zhengzu's user avatar
1 vote
0 answers
27 views

Confusion in Free Radical Reactions with alkenes

I was reading the free radical reactions, therein I saw two almost same(atleast that's what i think) but forming different products. First, we have cyclohexene reacting with Br2 in presence of ...
PinkAura's user avatar
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1 vote
0 answers
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Can I Detect Hydroxyl Radicals Using Methylene Blue Spectrophotometry?

I am going to be pulsing radiation into a chamber containing a solution of water and both ferric and ferrous iron. The irradiation event should cause a Fenton reaction to ensue and I'd like to trap ...
Bon's user avatar
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1 vote
0 answers
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Order of radical dimerization ability

In a question I came across recently, it was asked to arrange the following radicals in the ascending order of dimerization ability. I have read about the triphenylmethyl radical undergoing Gomberg ...
Cyclopropanol's user avatar
1 vote
0 answers
295 views

Monochlorination of (R)-2-chlorohexane: Number of possible chiral dichloro products

How many possible chiral dichloro products can be formed when (R)-2-chlorohexane reacted with one equivelent of $\ce{Cl2}$ in the presence of UV radiation (monochlorination only)? $$\ce{C6H11Cl + Cl2 -...
user avatar
1 vote
0 answers
62 views

Photobromination of cyclohexene

During bromination of cyclohexene in the presence of hv via free radical mechanism, there are two allylic carbons. Why does the major product have only one Br an not a Br on either side of double bond....
Niescte's user avatar
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1 vote
0 answers
55 views

How to graph a second order reaction with two different reactants

In a laser flash photolysis experiment, $\ce{C6H5NH2}$ $(C_0 = \pu{60 \mu M})$ is oxidized to the corresponding radical cation. The disappearance of radical cation is monitored spectrophotometrically ...
katara 's user avatar
  • 1,095
1 vote
0 answers
155 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 ...
juno's user avatar
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1 vote
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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 ...
Aumkaar Pranav's user avatar
1 vote
0 answers
65 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 ...
kytosine's user avatar
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1 vote
0 answers
317 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, ...
GingerBadger's user avatar
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1 vote
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692 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 ...
K-Feldspar's user avatar
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1 vote
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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 ...
Yashas's user avatar
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1 vote
0 answers
353 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 ...
cumulonimbus's user avatar
1 vote
0 answers
684 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 ...
John Doe's user avatar
  • 139
1 vote
0 answers
700 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 ...
Garner Deng's user avatar
1 vote
0 answers
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 ...
KeatonB's user avatar
  • 630
0 votes
0 answers
27 views

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 ...
Nightwing's user avatar
  • 418
0 votes
0 answers
29 views

Two wavelength photo-initiators?

Not a chemist so I hope you'll forgive any amateur mistakes. I found an overview of 3D printing resin photo-initiators here: https://pubs.acs.org/doi/10.1021/acsapm.8b00165#tbl1 All these activate ...
Stefan's user avatar
  • 101
0 votes
0 answers
582 views

Stabillity of ethyl, iso propyl and vinyl free radicals

Well this might seem like a dumb question but I was just wondering if any other factor would apply here as well? By simply looking at the number of hyperconjugative structures, I could easily tell ...
Prajwal Tiwari's user avatar
0 votes
0 answers
59 views

What are some convenient examples of so-called dissolved organic matter (DOM) for lab work?

Background, I have come across a chemical reaction system, occurring in nature, that apparently involves the presence of dissolved organic matter (in a catalytic role). My research returns, for ...
AJKOER's user avatar
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