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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14
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1answer
792 views

Can we synthesize alcohols by the photolysis of hydrogen peroxide?

As I was going through my revision of organic chemistry, I came across free radical substitution of alkanes with halogens. In a similar process where we use hydrogen peroxide, instead of chlorine, so ...
8
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2answers
834 views

Can an organic molecule have a triplet ground state?

Can the ground state of an organic molecule be a triplet. This would imply something like a "HOMO" formed by 2 degenerate levels and less than 4 electrons to fill them. If yes, what are the conditions?...
5
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1answer
587 views

Why does chlorine replace a hydrogen in propene instead of adding to the double bond?

I read about the following reaction in my book: $$\ce{CH3-CH=CH2->[Cl2][\pu{773 K}] (Cl)CH2-CH=CH2}$$ It surprises me that the $\ce{Cl}$ doesn't attack the $\pi$ bond, rather it attacks the $\...
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0answers
242 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 ...
1
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0answers
466 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 ...
1
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1answer
517 views

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 ...
-1
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1answer
496 views

Explain mechanism for first step in synthesis of acetone and phenol

"The following reaction is the first step in the industrial synthesis of acetone and phenol. AIBN initiates radical reactions by breaking down upon heating to form two isobutyronitrile radicals and ...
6
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3answers
123 views

Determining the product which is not possible in the reaction

This is an objective type question I encountered in a objective test. NBS (N-bromosuccinimide) is used for the allylic substitution of $\ce{Br}$ in a reaction. In this reaction, since the allylic ...
3
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1answer
412 views

If a bond dissociation energy is listed, does it refer to homolytic or heterolytic fission?

I am perfectly sure than heterolytic fission of a bond needs more energy than homolytic ones, since it requires opposite charge separation. When the bond dissociation energy is listed, which one are ...
-1
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1answer
47 views

Are nitrogen oxides always radicals?

Some reactions between nitrogen oxides and ozone can be the following: $$NO\cdot(g) + O_3(g) \rightarrow NO_2\cdot(g)+O_2(g)$$ $$NO_2\cdot(g) + O\cdot(g) \rightarrow NO\cdot(g)+O_2(g)$$ Where the $...
-1
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1answer
898 views

Side chain chlorination of substituted toluene

I know that we can convert toluene to benzaldehyde using side chain chlorination in presence of light, followed by hydrolysis. Is it possible to use the same method to convert a substituted toluene? ...
4
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1answer
512 views

Major product of radical fluorination vs bromination

I understand what structure is formed by using $\ce{Br2}$ to brominate this alkane, and I know that $\ce{F2}$ will be less selective in its abstraction of hydrogen. However, how can I know where $\ce{...
7
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1answer
235 views

Why does the light catalyzed radical addition of tetrachloromethane to an alkene produce only a single regioisomer?

This reaction always occurs in the following, regiospecific way: $$\ce{CCl4 + R-CH=CH2 ->[$h\nu$] R-CHCl-CH2-CCl3}$$ The same should apparently also happen when there is a carbon that has two ...
0
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2answers
1k views

Why are radical intermediates are more stable on tertiary carbons?

Is this because there's more electron density? More carbons around means the tertiary carbon "has more electrons around it"?
28
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3answers
677 views

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 ...
4
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4answers
551 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 ...
3
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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 ...
1
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0answers
628 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 ...
3
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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 ...
0
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2answers
1k views

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 ...
5
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1answer
139 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 ...
5
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2answers
1k 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 ...
5
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1answer
6k 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(\...
3
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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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0answers
557 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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0answers
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 ...
3
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1answer
6k 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 ...
11
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3answers
2k views

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 ...
0
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1answer
165 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 ...
2
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0answers
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
906 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 ...
0
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1answer
270 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 ...
3
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1answer
410 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 $\ce{Na}$ (...
3
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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 ...
5
votes
1answer
224 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 ...
3
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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 ...
3
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0answers
141 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 ...
0
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0answers
103 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 ...
4
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1answer
823 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 ...
4
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1answer
88 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 ...
3
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0answers
52 views

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 ...
2
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2answers
1k views

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 ...
1
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1answer
302 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 ...
5
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1answer
1k views

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, ...
2
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2answers
639 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 ...
7
votes
1answer
271 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.
1
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1answer
476 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 ...
10
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1answer
1k 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 ...
1
vote
1answer
152 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 ...
5
votes
1answer
9k 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 ...