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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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4answers
536 views

Can a free radical be created by chemical reaction of non-radical species?

Here's my thinking: Atomic oxygen in its ground state is a free radical because there are two unpaired electrons in p-orbitals. When species react new orbitals are formed, and perhaps a situation ...
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1answer
2k views

Why are free radicals so reactive?

Why are free radicals are so reactive? They can break almost any bond, including $\ce{C-H}$ bonds, which are fairly stable. Don’t they have an activation energy or something? Do they not also ...
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0answers
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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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1answer
4k views

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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2answers
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Is it possible to react chlorine with hydrogen under a UV lamp during the electrolysis of salty water?

I have set up an experiment where I am generating chlorine by electrolysing water saturated in NaCl. I know chlorine gas is actually being generated because I hang wet litmus paper in the gas which ...
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1answer
125 views

Explaining differences in rate of propagation based on monomer structure

The values given below have been taken from my lecture hand out, and they weren't cited so I don't know where my instructor got them from The $k_\mathrm{p}$ (rate constant for propagation in radical ...
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2answers
976 views

Thermodynamic vs kinetic reaction control with radical substitution

Doing a revision for a chemistry class test tomorrow, I stumbled upon thermodynamic and kinetic reaction control in the context of radical substitution. Here, my chemistry teacher said, that ...
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1answer
5k views

Why is it possible to form bromoalkanes but not iodoalkanes from free radical substitution?

For a free radical substitution (FRS) reaction between iodine $\ce{I2}$ with ethane and bromine $\ce{Br2}$ with ethane $\ce{CH3CH3}$: $E_\mathrm d(\ce{H-I})=299\ \mathrm{kJ\ mol^{-1}}$ $E_\mathrm d(\...
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1answer
1k views

Reaction between free radicals and water

Free-radical substitution does not occur in aqueous solution as free radicals react with water (from school textbook). What does the reaction between free radicals, say Br, and water produce?
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510 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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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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1answer
5k views

Reaction between RCH2=CH2 and CCl4 — Why does it form RCHClCH2CH(R)CH2CCl3 along with RCHClCH2CCl3?

I am reading Organic Chemistry from Morrison & Boyd and there is this problem in it: Problem 6.8 From the addition of $\ce{CCl4}$ to alkenes (in presence of peroxides), $\ce{RCH2=CH2}$, there ...
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3answers
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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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1answer
152 views

Why Use Lewis Structures to Determine Radicals

As far as I know, Lewis Structures are convenient for representing molecules, but give no insight on the actual electron orbitals. For example: The Lewis Structure of $\ce{O_2}$ does not reflect ...
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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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3answers
684 views

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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1answer
248 views

Radicals' formation

If carbon atom is tetravalent while oxygen atom is divalent so when they combine together the result should be $\ce{C2O4}$ then how are there compounds of formulas with $\ce{CO2}$, $\ce{CO3}$ and ...
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1answer
331 views

Ullmann's Reaction (similar to Wurtz) - aryl chloride with deactivating groups - stability of free radical

Ullmann's Reaction: Mechanism: Question: My textbook says with $\ce{X} = \ce{Cl}$, the reaction gives less yield compared to using $\ce{X} = \ce{I}$ since $\ce{Cu}$ is not as reactive as $\ce{Na}$ (...
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1answer
77 views

Peroxide in acidic conditions being reacted with iron sulphate mechanism

For the proposed mechanism, I would like to think the $\ce{O-O}$ bond would be cleaved first, thus creating two radicals (an $\ce{OH}$ radical and the radical situated on the other Oxygen), then ...
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1answer
220 views

Photolysis of N-bromo compound in acidic conditions (radical cyclisation)

For the proposed mechanism, I believe that the N-Br bond is firstly broken by the absorbed light hv, then the radical formed on the N will perform an intra-molecular attack on the end of the carbon ...
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0answers
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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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 ...
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1answer
677 views

Radical Bromination of a 1-isopropyl-4-methylcyclohexane

I'm considering a problem whereby 1-isopropyl-4-methylcyclohexane with the indicated stereochemistry shown undergoes radical bromination at the indicated position. I understand there are other ...
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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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Do free radicals re-arrange? [duplicate]

For example reaction of but-1-ene in the presence of $\ce{Br2}$ and light should give 1-bromobut-2-ene which is thermodynamically more stable than 3-bromobut-1-ene on the basis of number of alpha ...
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2answers
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Why won't ethene and ethyne react with halogens?

With alkanes, a free-radical halogenation (substitution) is observed. I was told that there will be no reaction in a similar situation with ethene and ethyne — and I am having trouble understanding ...
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1answer
292 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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1answer
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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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2answers
596 views

What is the state of the oxygen free radical in the following reaction?

$$\ce{O2(g) ->[h\nu][\nu\,<\,240~nm]2O^{.}(?)}$$ Oxygen is split by UV light below 240 nm to form oxygen radicals, which then go on to react with oxygen molecules to form ozone. Firstly, is ...
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1answer
244 views

Geometries of methyl and silyl radicals

The $\ce{.CH3}$ radical is planar but the $\ce{.SiH3}$ radical is a trigonal pyramid. Why are they different? After all, $\ce{C}$ and $\ce{Si}$ are in the same group.
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1answer
454 views

Radical Computational Calculations [closed]

I am trying to calculate the total energies for a particular organic molecule that undergoes radical decomposition. I was able to calculate the neutral molecule with the exact results of a paper I ...
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1answer
961 views

Formation of radicals from C-H and C-C bonds

Why do radical mechanisms favor the homolytic dissociation of a $\ce{C-H}$ bond over a $\ce{C-C}$ bond? The $\ce{C-H}$ bond is stronger in magnitude (and it's also slightly polarized), so why would ...
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1answer
150 views

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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1answer
8k views

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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1answer
4k views

Why is the methyl radical planar?

Why is the methyl radical planar? The VSEPR theory would predict an angle between 120 and 109.5 degrees, while it is actually 120 degrees.
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2answers
10k views

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 ...
9
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1answer
986 views

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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1answer
1k views

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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1answer
140 views

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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1answer
3k views

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?