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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Why don't electrons pair up in an oxygen radical?

In an oxygen radical (produced by the break down of O3 for instance), there are 2 unpaired electrons in the outermost subshell which make the molecule unstable. Why don't these electrons pair up which ...
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Is a carbon-fluorine bond stronger than a carbon-chlorine bond?

In hydrolysis/nucleophilic substitution of haloalkanes, the bond enthalpy indicates the rate of hydrolysis (e.g. the $\ce {C-I}$ bond is weaker than the $\ce {C-Cl}$ bond so in hydrolysis the alkane ...
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How to check if azobisisobutyronitrile (AIBN) is still active?

I will have some samples of azobisisobutyronitrile and I want to perform Barton-McCombie reaction. The problem is that the reagent is quite old and I need to know whether it has not decomposed. Do ...
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Reactions in water radiolysis - producing hydroxyl radicals

There’s an excellent question on Stack Exchange regarding the radiolysis of water here but I have one simple outstanding question that perhaps someone might now; in radiobiology, a common DNA damaging ...
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Why don't unstable odd electron species dimerize so that they become stable?

Why doesn't unstable odd electron compound $\ce{NO}$ dimerize to $\ce{N2O2}$? Why doesn't this structure of ozonide dimerize? But why then does $\ce{BH3}$ dimerizes to $\ce{B2H6}$, and $\ce{AlCl3}$ to ...
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Why is the methyl radical planar?

Why is the methyl radical planar? The VSEPR theory would predict an angle between 120° and 109.5°, while it is actually 120°.
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Formation of azobenzene from nitrosobenzene and N-hydroxyaniline

I'm trying to create a reasonable reaction mechanism for the reaction of nitrosobenzene and N-hydroxyaniline, which happens as part of the reduction of nitrobenzene to azobenzene using magnesium as ...
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What has stronger antioxidant potential: BHT or BHA?

Butyl Hydroxy Toluene (BHT) has two tert-butyl groups that can stabilize a free radical. Butyl Hydroxy Anisol (BHA) doesn't, though it has the 4-substituted methoxy group (I'm not sure what that does)....
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Exceptions to motif: nucleophile attacks electrophile

I hear this motif - nucleophile attacks electrophile - all the time with regard to organic chemistry. Are there any exceptions? I think this statement is always true in general because it's a ...
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What does a radical mean here?

I'm really confused as none of the definitions of radical on the internet compare to this. This is from my college textbook of Applied Chemistry- Radicals Every inorganic compound is made up ...
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Why is O2 a biradical?

$\ce{O2}$ has a double bond in its normal form. That is $\ce{O=O}$. There are no unpaired electrons in this case are there since there are 2 lone pairs on each oxygen. However 1 resonance structure ...
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What exactly does it mean for the reaction of superoxide with non-radicals to be spin-forbidden?

From Wikipedia: The reaction of superoxide with non-radicals is spin forbidden. In biological systems, this means its main reactions are with itself (dismutation) or with another biological ...
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What is the functional difference between a radical anion and a nucleophile?

Radical Anions are hundreds if not thousands of times more reactive than nucleophiles (right?). A radical anion is just a molecule with an unpaired electron. Where as a normal radical is missing an ...
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Redox properties of methyl radical

The methyl radical, $\ce{.CH3}$, is a strong oxidant and a strong reductant according to Wikipedia. Why is this so? Any additional reasons to the ones below? I know that an oxidant itself is ...
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How does neutralization of free radicals by $\beta$-carotene work?

In my understanding, by bonding to the free radical species, say by one of the double bonds, a new free radical on the $\beta$-carotene develops.
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Free Radical Reaction of Methane and Chlorine

The problem statement: Lets say you have $1 L$ of $2 M$ methane and the same amount of chlorine. Lets also say that both are liquids since those are most likely to react. Now the only way they can ...
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What are radicals and how do they act in radical chain reactions?

What really is a radical? For example, when $\ce{Cl2}$ receives enough energy to dissociate the bond and turn into $\ce{ 2Cl.}$, the two chlorine atoms each carry one of the electrons that form the ...
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Why are radicals unstable?

Why are unpaired electrons especially reactive? Does pairing electrons decrease the reactivity of the electrons? But then doesn't forcing two electrons into the same orbital cost energy?
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What are the possible products in allylic bromination of 3-methylcyclopentene?

Bromination of an alkene by N-bromosuccinimide (NBS) in the presence of light or peroxide is a radical reaction and produces an allylic bromide. For the following bromination of 3-methylcyclopentene, ...
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306 views

Anti-Markovnikov Effect

We have seen that $\ce{HBr}$ shows an anti-Markovnikov effect when it reacts with alkenes in the presence of peroxides. Why does only $\ce{HBr}$ shows this effect? How about the other hydrogen halides ...
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Regioselectivity in Kharasch addition of bromotrichloromethane

When hex-1-ene is treated with bromotrichloromethane in the presence of a peroxide initiator (e.g. dibenzoyl peroxide), what is the regioselectivity of the addition? I know that the radical addition ...
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Which C-C bond would break first, the one in ethane, or 2,2-dimethylpropane?

I have drawn the figures and determined intuitively that the larger molecule's $\ce{C-C}$ would break first. I made this assumption that ethane has the stronger $\ce{C-C}$ bond and I am correct, ...
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What makes a radical 'free'?

The qualifier 'free' seems to be ubiquitously attached to discussion of radicals as highly reactive species with unpaired spins. What, precisely (or imprecisely, as the case may be) does 'free' really ...

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