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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In dehydrogenation reaction, if Na radical were introduced into the system, would they react with C radical over H?
I was confused about the relative strengths and priorities of radical-radical reactions as we usually only ever see one pair in a chemical reaction. Would sodium radical react with more preference ...
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What is the free radical mechanism of Ruff's degradation?
There are very few resources on the mechanism of Ruff's degradation of carbohydrates, which adds $\ce{Br2}$ to oxidize aldehydic group of reducing sugars like glucose to carboxylic acid and then adds ...
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Free-radical addition of bromine to alkene
If light and radical initiators are present, radical addition of $\ce{HBr}$ to alkenes takes place and outcompetes electrophilic addition of $\ce{HBr}$ to alkenes. Why isn't a similar thing same ...
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Why is the phrase "abstraction" used in radical reactions? [closed]
Often, I see the phrase "abstraction" used to describe certain radical reactions. Why is this specific term "abstraction" used in the case of radicals? This may be more of a ...
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+M or -I for chlorine? Major product in free radical chlorination and bromination of 2-chloropropane?
Is the +M or -I effect more dominant in when an alkyl (mono)halide is subject to free radical chlorination/bromination?
For example what will be the major product in case of free radical (mono)...
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How does tetraethyl lead prevent knocking?
My understanding of knocking is that in a spark ignition engine as the fuel is being compressed it heats up. The heat causes some of the oxygen to break up into oxygen radicals the $\ce{O^.}$ ...
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Radicals, reaction intermediate, activated complex [closed]
I'm really confused about those three concepts: radicals, reaction intermediate, activated complex.
First of all, in my course we have seen radicals in the context of chain radical reactions. But ...
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Radical chain reactions
I have some questions about radical chain reactions. Let's take an example:
And here are my questions:
How can we define in the above case at which level the reaction 2) is located (initiation or ...
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Why are free radicals not considered as positive or negative even though they usually have 1 excess electron? [closed]
Same as the question, I looked up radicals etc, and could see that methyl radical or phenyl radical had 1 extra electron that would have been a bonding electron normally. However it is not considered ...
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How does Hammond's Postulate explain the greater selectivity of Bromination over Chlorination?
I know that Hammond's Postulate states that related species are closer in energy are also closer in structure. Thus, bromination's transition state resembles its products, while chlorination's ...
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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 -...
user124377
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PVP-iodine and octenidine can stain skin purple, does the reaction create iodine radicals?
In this paper it is mentioned that
... octenidine can release iodine radicals from the
PVP complex, resulting in a tissue irritation as well as
strong brown to violet discolouration in the border ...
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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 ...
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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 ...
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The major product of radical halogenation: Why is it a halogen attached to a primary carbon and not a tertiary carbon in the given example?
There's this problem that I saw in my Organic Chemistry book:
The reaction between $\ce{(CH3)3CH}$ and $\ce{Cl2}$ forms two products: $\ce{(CH3)2CHCH2Cl}$ (63%) and $\ce{(CH3)3CCl}$ (37%). Why is the ...
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Why are radicals considered electron deficient?
I have often read that radicals are electron-deficient and are therefore stabilized by things like electron-donating groups (EDGs) and hyperconjugation. However, today I learned that electron-...
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How are antioxidants different from other compounds that contain hydroxyl group?
From my book:
An antioxidant is a substance that prevents oxidation by reacting with an oxidizing agent
If that's the case, why do we distinguish between antioxidants? Are all compounds containing ...
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How does Hyperconjugation stabilize a Carbon Free Radical? [closed]
I tried drawing the resonance structures but just cannot see how donating two electrons to a carbon that only needs one electron make it more stable?
I stumbled upon this question asked years ago ...
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Kharasch Peroxide effect with heating
From what i have learnt, kharasch Peroxide effect is only applicable for HBr. The reason for this is for the other halogens, HCl and HI the propagation steps in the radical mechanism are endothermic. ...
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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}
\...
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Can uv light cause heterolytic cleavage?
All sources I've read stated that UV-light can only cause homolytic cleavage (homolytic fission), producing radicals while not mentioning whether it was possible for it to cause heterolytic cleavage ...
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How to name radical
The name of biradical —CO—CH2–O—CH2–CO— is Oxybis (1-oxo-2,1-ethanediyl). Why is it wrong to write 1,2-ethanediyl instead of 2,1?
Thanks in advance!
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Why do radical inhibitors inhibit a reaction by creating a "more stable" radical, but for monohalogenation, we WANT to form the most stable radical?
According to my notes, radical inhibitors tend to turn a more reactive radical into a less reactive radical by making it more stable. For instance, the hydroquinone reacts with a radical species, ...
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Why is carbon tetrachloride more stable than methane?
When a mixture of methane and chlorine is exposed to ultraviolet light – typically sunlight – a substitution reaction occurs and the organic product is chloromethane. However, the reaction doesn't ...
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Reaction Mechanism for a radical ring opening
I have a radical reaction which I got from an organic chemistry lecture and was drawing the possible mechanism for it.
Fig 2. shows my thought process. The I is removed making a radical and ISnBu$_3$. ...
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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 ...
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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 ...
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g-tensor and hyperfine tensor for nitroxide spin label with 15N
Does anyone know where I can find numerical data for the $g$ tensor and hyperfine tensor for a nitroxide spin label where the nitrogen-14 atom has been replaced by a nitrogen-15 atom?
I'm really ...
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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....
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How would this reaction occur through free radical substitution?
So, I was trying to solve this through free radical substitution:
(Side note, the (ac) means (aq))
The best product I managed to do/think was the following:
However, according to what I've seen, it'...
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Bromochlorofluoromethane as a reagent in Riemer-Tiemann reaction
The reagent usually used in Riemer-Tiemann reaction is $\ce{CHCl_3 }$ however one of the variations I read used $\ce{CHFClBr}$ as a reagent. Now $\ce{CHCl_3}$ produces the $\ce{:CCl_2}$ radical using ...
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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 ...
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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 ...
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Is “double dot” (“··”) notation used for a double radical?
I wondered if this was a typo in the notes given to me. I haven’t come across notation like this before:
Branching — steps in which number of radicals increases (can lead
to explosion)
$$\ce{H^. + O2 ...
user85551
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Flavonoid Xanthine Oxydase Inhibitors vs Hydroxychloroquine
Regarding COVID-19 and hydroxychloroquine (HCQ), HCQ is known to increase pH in lysosomes by 1-2 orders of magnitude, and also results in lethal intracellular heme overload in parasites responsible ...
user108546
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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 ...
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TEMPO Radical Analogue
After investigating what makes the persistent radical TEMPO stable, I was wondering if another compound which is more feasible for my needs would be comparable to it.
Would oxidizing 2,2’-dimethyl-...
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Photodissociated iodine laser and population inversion
Iodine molecules ($\ce{I2}$) can absorb in the visible region and dissociate into $\ce{2 I^.}$ radicals. One of the I atoms is in ground electronic state $\mathrm{^2P_{3/2}}$ and the other I atom is ...
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Why doesn't fluorine harm the ozone layer the way chlorine and bromine do? [closed]
I don't understand the chemistry here: fluorine is a halogen too.
I read that fluorine in the atmosphere readily forms HF, which is (somewhat) stable and doesn't catalytically break down ozone.
But, ...
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What is the geometry of a tri-substituted methyl free radical?
My teacher explained that free radicals could have a geometry that is planar or pyramidal(tending to tetrahedral) based on whether or not it is substituted by lone-pair containing atoms.
For example,
$...
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Why is gasoline consisting of heavily branched alkanes better fuel than gasoline consisting of more linear alkanes? [duplicate]
As far as I know, the reason isooctane is better than octane in gasoline engines is because the octane is more prone to ignition by pressure. This makes it ignite when it is not supposed to, which ...
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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 ...
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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 ...
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Reaction of 1,3-dibromobutane with zinc dust upon heating
I've studied that when 1,3-dibromopropane (or in general any halogen, not just bromine) is heated with Zn dust, the electrons produced cause the halogens to break away homolytically and two free ...
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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-...
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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 ...
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Chemical reaction of radicals with different multiplicity
I am studying the chemical reaction of radicals by computational chemistry software.
I just want to know what is the rules for multiplicity.
I have two radicals for which, the ground state of one is a ...
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Electrophilic addition on cyclopropane using sunlight
I encountered a weird question in an exam. The statement says that instead of radical substitution, cyclopropane undergoes electrophilic addition reaction in sunlight.
I know that all saturated ...
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Stability of radicals
I recently came across a question about the stability of radicals and this option was given as correct.
$\ce {F2C^.H}>\ce {C^.H3} $
And the solution was given that $\ce{FC^.H2}$ and $\ce{F2CH^.}$...
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sp2 hybridisation of alkyl radicals causing formation of racemic mixture
What I know about $\ce{^{.}CR3}$ radical is that it has both $\ce{sp^2}$ and $\ce{sp^3}$ character but the $\ce{sp^2}$ character dominates and so the radical is $\ce{sp^2}$ in nature.
So, suppose we ...
user92687