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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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13
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1answer
183 views

Ring opening of aziridinylmethyl and oxiranylmethyl radicals

When a radical is alpha to a three-membered ring, it is common for the ring to open via β-scission (to relieve ring strain): When the ring contains a heteroatom there are a couple of different ...
8
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1answer
3k views

How to find if the unpaired electron is placed in hybrid orbital or pure orbital in odd electron species?

Odd electron species contain an unpaired electron which can either be placed in hybrid orbital or in pure orbital. Example: In the case of $\ce{.CF3}$ radical, the unpaired electron is placed in $\...
8
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2answers
752 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
521 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 $\...
4
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1answer
396 views

Is propanone responsible for photochemical smog?

Many volatile organic compounds (VOC) are responsible for photochemical smog. Propanone is a VOC. It's produced in a great amount for industrial purposes. So, propanone can be a potential contributor ...
0
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0answers
229 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
378 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 ...
11
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1answer
200 views

Mechanism of radical cyclisation to form hydroazulene core

Recent studies on radical-induced cyclisation reactions have led to a simple, one-step method for the preparation of hydroazulenes from appropriately substituted cyclopentanone precursors. Treatment ...
0
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1answer
414 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 ...
3
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1answer
350 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 ...
14
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1answer
708 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 ...
-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 $...
6
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3answers
122 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 ...
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0answers
76 views

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 ...
-1
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1answer
781 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? ...
0
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1answer
705 views

Conditions for free radical bromination using NBS and peroxides?

In the free radical bromination of 1-methylcyclohexene using NBS and peroxides a very important consideration to get the appropriate product is: A. The wavelength of light used for initiation B. ...
6
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1answer
3k views

Why can UV light initiate a reaction between hydrogen and chlorine gas?

Can someone explain me how does UV light help combine chloride gas and hydrogen to produce hydrochloric acid? $$\ce{Cl2(g) + H2(g) -> 2HCl(g)}$$
19
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1answer
11k views

Structure of Br3O8

What is the structure of $\ce{Br3O8}$? It has an odd number of electrons; does that make it a free radical? The structure given in my book shows Where did the 7th electron of the central atom go? ...
4
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1answer
384 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
185 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 ...
4
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1answer
2k views

Free radical vs radical cation

What is the difference between a free radical and a radical cation? Are they different thing or do they mean same?
-3
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1answer
5k views

Is hydroperoxyl radical(HO2) toxic to the human body, or even flammable?

I understand that radicals are damaging to cells, due to their high chemical reactivity. Though I do not know whether they are flammable in any level.
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"?
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2answers
5k views

What is the hybridisation of the carbons in the allyl radical?

The example I am talking about is $\ce{CH2CHCH2^.}$. To find the steric number and hence the hybridization, we use steric number = No. of lone pairs + number of sigma bonds. In this example, the ...
4
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2answers
782 views

What determines the high degree of selectivity in free radical brominations?

In my organic chemistry class, we were asked what determines the relatively high degree of selectivity in the reaction of a bromine radical with primary, secondary, and tertiary C–H bonds. I said it ...
2
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0answers
240 views

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 ...
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2answers
194 views

Nitroxyl anion electron structure

Is the $\ce{NO-}$ a radical species? If so, can someone please explain why because $\ce{NO}$ has an odd number of electrons (11), so adding an additional electron would give 12 valence electrons and ...
1
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2answers
1k views

What is the difference between radical initiator and radical inhibitor?

I am confused between these two concepts. My book gives $\ce{O2}$ as an example of a radical inhibitor and peroxide as an example of an initiator. But I don’t know why this is so? Both have $\ce{O-O}$ ...
2
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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 ...
4
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4answers
535 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 ...
1
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0answers
287 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 ...
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0answers
608 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 ...
5
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2answers
3k views

Stability of cyclic radicals

How do we arrange the following in increasing order of stability? The answer given is: $5<3<1<2<4$ (numbering according to their order in the image). My Approach: I can figure that in ...
5
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1answer
121 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 ...
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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2answers
957 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
votes
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(\...
3
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1answer
997 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
499 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 ...
1
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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 ...
2
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0answers
262 views

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 ...
3
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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 ...
3
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2answers
20k views

Why can toluene be chlorinated at either the benzylic position or the ring depending on the conditions?

My book mentions a reaction for the preparation of benzaldehyde with toluene in which side chain chlorination of toluene gives (dichloromethyl)benzene, which upon hydrolysis gives benzaldehyde: Why ...
0
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1answer
150 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
28 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 ...
6
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1answer
8k views

What is the hybridisation of CF3 free radical?

Having 3 sigma bonds in a similar manner to CH3 free radical it should also have hybridisation sp2. However, if we look at its shape, it is pyramidal and not planar unlike CH3 free radical(which is ...
0
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1answer
244 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
votes
1answer
309 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
76 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
217 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 ...