Questions tagged [c-c-addition]

For questions about addition to C–C π bonds (i.e. C=C or C≡C).

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What is the meaning of a “halide component” for Friedel–Crafts reaction? [closed]

Among the given halides, which one can be used as halide component for Friedel–Crafts reaction? (a) Isopropyl chloride (b) Bromobenzene (c) Chlorobenzene (d) Chloroethene I don't understand what a &...
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Stereochemical outcomes for hydrohalogenation when there is a carbocation rearrangement

The following reaction is given: I want to be able to tell which of the following stereochemical outcomes are possible. I am aware that there are other possible products than the ones shown here ...
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3 votes
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What are the major products when naphthalene reacts with ethyl chloride in the presence of AlCl₃?

From Arihant Test Drive, JEE Advanced 2020; Ramchaya builiding, Daryanganj, New Delhi, India; January 2019, p. 342: Napthalene gives 1-ethylnapthalene on reaction with ethyl choride in the presence ...
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7 votes
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Electrophillic susbtitution of bromine on styrene and cinnamic acid in the presence of FeBr3, a Lewis acid

Bromine gas, in the presence of $\ce{CCl4}$, undergoes on addition reaction at the double bond in both styrene and cinnamic acid, illustrated below. Styrene: Cinnamic acid: Bromination of benzene in ...
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3 votes
1 answer
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The dependency on electron density in the reactivity order of electrophilic and nucleophilic additions

It is well-known that for electrophilic addition across an alkene, the reactivity increases when intermediate carbocation is more stable (eg. addition of $\ce{HBr}$ or acid-catalyzed addition of $\ce{...
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6 votes
3 answers
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Does rearrangement take place in the reaction between ethenylcyclohexane and iodine chloride?

I am stuck at the point if a non classical carbocation should be formed on the 2nd Carbon of the side chain. One of my friend gave me the following suggestion: I guess $\ce{ICl}$ will break in the ...
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Addition of 1 equivalent bromine to 1,3 pentadiene at temperature below 0 degree Celsius gives which compound?

As far as I know reactivity of alkenes towards addition with halogens is directly proportional to their nucleophilicity, so bromine in this particular case should attack the double bond at Carbon-3 ...
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Stereochemistry of the product of crotonic acid with bromine

Is there a a simple rule for determining the stereochemistry for the product of a reaction between an unsymmetrical alkene like (2E)-but-2-enoic acid and bromine (anti reaction)? If it's an anti ...
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-1 votes
1 answer
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Addition reaction of alkenes [closed]

During an addition reaction of an alkene, how does a double bond break to form two bonds with the two atoms of the reactant plus a bond between the carbon atoms? Not sure if this is a silly question ...
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1 answer
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Regioselectivity of electrophilic addition of Halogen and Water (Halohydrin) on Alkenes?

I am currently studying for an organic chemistry exam and I just couldn't come up with a solution to the following question: Consider the reaction of 1-Propene + Br2 with water as solvent. Why will ...
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4 votes
2 answers
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Stereoselectivity of ring closure in intramolecular iodolactonisation

What is the product of the reaction above? I am mainly confused between the following two options: How do we decide the resulting stereochemistry of the $\ce{CH_2I}$ group? The answer given is the ...
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What are the products of alkene oxymercuration with diols?

I was wondering what would be the product of the reaction of alkene with a diol (such as glycol) in alkoxymerucuration/demercuration, i.e. $\ce{(CF3CO2)2Hg/NaBH4}$? I tried to look online but I couldn'...
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3 votes
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In what case would water attack the least substituted carbon in an oxymercuration–demercuration reaction? [closed]

I understand that oxymercuration–demercuration is textbook Markovnikov. However, in a case like this, where the $\ce{OH}$ is formed on the least substituted carbon (secondary) rather than the most ...
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How is elimination reaction (E1) possible without base and in presence of acid?

When learning about E1 we were taught that three things are important factors to judge if the reaction is E1 or E2 Substrate ( 3,2,1 favours E2 but only 3 favours E1 ) Base ( Stronger Base favours E2 ...
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Ozonolysis of alkene

(from Wikipedia) I am having trouble in the last step where the alkene ozonide is reduced to ketones / aldehydes specifically in the presence of water. My teacher is telling me that water will be ...
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1 answer
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Method for regioselective hydroalkylation of terminal alkyne

I'm trying to figure out a method to add a linear alkyl chain R and a hydrogen atom H across the triple bond of a terminal alkyne. The alkyl chain should end up on the internal carbon (C-2): My ...
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Is it possible to produce an epoxide from 2-bromoacetyl bromide using methyl magnesium bromide

This is also one of the questions from practice papers for the JEE , asks for 2 step reaction for epoxidation of ketene For product A , π complex is generated on c-c bond since carbon labelled 1 is ...
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2 votes
1 answer
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Why alkyl shift happens during hydroboration oxidation?

In this oxidation step, where alkyl shift happens for 3 times to kick out the OH- to obtain the boron-ester. But why does this happen? Won't the boron atom become less stable as the empty p orbital is ...
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Can Diels-Alder reaction occur using reagents of Robinson annulation?

Robinson annulation seemed somewhat like the Diels-Alder reaction to me, if all ketonic groups were to be represented as enol then cyclohexanone would be like diene and the Michael acceptor as a ...
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9 votes
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Reaction of vinylacetylene (but-1-en-3-yne) with HCl

Vinylacetylene contains both a double bond and a triple bond. We know that alkenes are more reactive to electrophillic addition reactions, so I thought that the $\ce{H+}$ from $\ce{HCl}$ would get ...
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2 votes
2 answers
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Anti-Markovnikov addition of HCl

The following reaction has been troubling me for a while now. Since peroxides won't give the anti-Markovnikov product when used with HCl, I cannot think of any reagents that would result in the ...
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2 votes
1 answer
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Addition to equally substituted carbons

I was wondering whether there is a trick in the following problem: Since both carbons are equally substituted, shouldn't the products be the same with or without the use of peroxides?
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4 votes
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Reaction of alkenes with AlCl3/HCl

I stumbled upon an interesting organic chemistry problem: Previously I thought $\ce{AlCl3}$ would only be used with benzene in acylation and alkylation, but apparently it can also be used in ...
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3 votes
1 answer
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How can a β,γ-unsaturated ketone be converted to 1-pyrroline?

I am working towards a natural product. Presented are three intermediate compounds. After oxidation of the hydroxyl to a carbonyl, I want to introduce an imino-nitrogen atom into the structure. This ...
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Can someone explain my professor's answers for these alkene additions? [closed]

(a) Why would cyclohexane expand into cycloheptane? Cyclohexane is stable. (b) Why would cyclopentane not ring expand into cyclohexane? In the process a tertiary carbocation would be formed just like ...
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Varying sizes in LUMO of acrolein

I want to ask a question about the varying sizes in the LUMO of acrolein during a 1,2- or 1,4-addition. Today in our introductory lesson to Organic Synthesis with 1,2- and 1,4-addition we were ...
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2 votes
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If alkyl-substituted alkenes are more stable, how does one explain their increased addition reactivity?

My understanding is that in alkyl-substituted alkenes there is hyperconjugation between $𝜎(\ce{C−X})$ and $𝜋^∗(\ce{C=C})$. I also have read that more alkyl-substituted alkenes are many folds more ...
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What is the major product of the reaction of 2-methylbuta-1,3-diene with HBr? [duplicate]

What is the product of the reaction of 2-methylbuta-1,3-diene (isoprene) with HBr? What I understand is that carbon (2) will get a positive charge after protonation. But after this, which should be ...
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Addition v/s elimination with double bond and OH together

If a compound has both an hydroxyl group and a double bond and we add $\ce{HBr}$ to it, (a) substitution reaction to the hydroxyl group can take place, or (b) an addition reaction of a double bond can ...
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Shouldn't the 5-membered ring expand to a six membered one in this nucleophilic addition reaction?

I am dealing with a problem involving addition of $\ce{HCl}$ to a ring: According to what I think, the ring should expand to a six-membered following carbocation formation at the tertiary site, as a ...
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0 votes
2 answers
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Markovnikov Rule of Alkenes

$$\ce{CH3CH(CH3)CHCHCH2CH3 + HBr ->}$$ According to Markovnikov Rule, "the rich get richer". But, as we can see the 2 carbons have the same amount of $\ce{H}$. So, what's probably the answer?
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1 vote
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Electrophilic addition of IBr to alkene

I would assume options A and B are possible products due to the $\ce{I+}$ electrophile attacking the alkene, and hence are ruled out. However, I am torn between options C and D. Both products are ...
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5 votes
1 answer
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Regioselectivity of bromination of alkenes

Recently, in my chemistry lesson, we were discussing the mechanism of the bromination of alkenes. The teacher brought up the involvement of the cyclic bromonium intermediate. She also mentioned that ...
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3 votes
0 answers
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Mechanism of photochemical hydroamination with LDA

I've recently come across a couple examples of intramolecular alkene hydroamination accomplished by treatment with LDA followed by visible light irradiation (tungsten light bulb):[1,2] I'd assume ...
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1 answer
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How far-reaching is the effect of conjugation?

Due to conjugation, it is possible for 1,4-addition, or conjugate addition, to occur. I was thinking, since conjugation and resonance effects do no diminish with distance, unlike inductive effects, ...
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3 votes
1 answer
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Conjugate addition vs Electrophilic addition

I was just doing an organic chemistry problem from an online source recently, on the topic of conjugate additions (or 1,4-additions). Below is an image illustrating the problem. I chose the upper ...
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2 votes
1 answer
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On the addition of HCl to a conjugated diene [closed]

Is this allylic chloride formed by an ionic or radical mechanism? Is it the more stable isomer?
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4 votes
0 answers
380 views

Sigma bond behaving as stronger nucleophile despite presence of pi bond?

In my book, the following reaction is given The solution states that the sigma bond between hydrogen and carbon (3 degree) in isobutane attacks $\ce{H+}$ from $\ce{HF}$ to generate tert-butyl ...
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2 votes
1 answer
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Why do more substituted alkenes undergo epoxidation, but the less substituted alkenes undergo hydrogenation?

We know that, in case of a choice, catalytic hydrogenation will hydrogenate the less substituted alkene, because the less substituted alkene is less stable. But, we also know that, in case of a ...
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5 votes
1 answer
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Why doesn't the bromide anion attack during electrophilic addition of bromine in methanol solvent?

It is known that addition of bromine (in methanol) to ethene will yield 1-bromo-2-methoxyethane. The reaction proceeds with the formation of a bromonium intermediate in the first step. In the second ...
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7 votes
1 answer
301 views

How to decide what pathway a reaction will follow, elimination, addition to a carbonyl or nucleophilic substitution?

There is a substrate such as this, and it is treated with alcoholic KOH. I know that a hydrogen in $\alpha$-position to the carbonyl group will be abstracted, leaving a carbanion. My query lies in ...
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0 votes
1 answer
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In halogenation of ethene using bromine for example, why does the lone pair of bromine attack the C atom?

In the presence of the electron rich (pi bond) of ethene, the bromine molecule becomes a temporary induced dipole, one end being electron deficient and acting as the electrophile. (The pi bond in) ...
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3 votes
1 answer
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In the presence of an electron-rich species, why is Br2 the stronger electrophile than water? [closed]

In the electrophilic addition of aqueous bromine to ethene, the first slow step involves the electron rich (pi bond) of ethene attacking the bromine molecule to form a carbocation and Br-: And, then ...
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9 votes
2 answers
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Bromonium ion or Mesomeric effect ( intermediate during addition to alkenes)

It's mentioned in Peter Sykes , A Guidebook To Mechanism In Organic Chemistry , 6th edition, 13th impression by Pearson, Pg. No. 185 , that on addition of $\ce{HBr}$ to bromoethene the only product ...
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2 votes
1 answer
285 views

Electrophilic addition to alkenes

Consider the addition of HBr (in absence of any radical initiators or environment that promotes radical mechanistic pathway), to 3-bromocyclopentene. The first step is the attack of $\ce{H^+}$ On the ...
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6 votes
1 answer
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Why must polymers have a repeating unit?

In organic chemistry, we learned that small molecules can form a polymer via a process called polymerization. For example, $\ce{CH2=CH-Br}$ molecules can form the polymer \begin{align} \ce{nCH2=CH-Br-...
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5 votes
1 answer
235 views

Intramolecular lactonisation in an unsaturated carboxylic acid

I am having some trouble figuring out how this reaction proceeds: Attempt 1: The most obvious thing to do is deprotonate the acid group. I tried using the carboxylate group to attack the alkene, ...
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0 votes
1 answer
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Regioselectivity in addition of hydrogen iodide to vinyl chloride

I encountered a question which was stated as: The reaction of vinyl chloride with hydrogen iodide to give 1-chloro-1-iodoethane is an example of anti-Markovnikov addition. Is this true or false? ...
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11 votes
1 answer
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Why does boron add to the less substituted carbon in the hydroboration of an alkene?

In the hydroboration of a typical alkene, the boron fragment ends up attached to the less substituted carbon: What are the electronic or steric factors that lead to this regioselectivity?
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0 votes
2 answers
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Reactivity order in hydrogenation reaction of but-2-yne and butene isomers

Question 1: The reactivity order towards hydrogenation of the following compounds is: but-2-yne ($\ce{CH3-C\bond{3}C-CH3}$) cis-but-2-ene ($\ce{CH3-CH=CH-CH3}$) trans-but-2-ene ($\ce{...
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