Questions tagged [c-c-addition]
For questions about addition to C–C π bonds (i.e. C=C or C≡C).
62
questions
7
votes
1answer
147 views
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 ...
3
votes
1answer
69 views
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{...
6
votes
3answers
233 views
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 ...
0
votes
0answers
27 views
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 ...
3
votes
0answers
60 views
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 ...
-1
votes
1answer
31 views
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 ...
1
vote
1answer
91 views
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 ...
4
votes
2answers
146 views
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 ...
0
votes
1answer
155 views
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'...
3
votes
0answers
41 views
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 ...
2
votes
0answers
45 views
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 ...
0
votes
1answer
69 views
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 ...
4
votes
1answer
135 views
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 ...
0
votes
0answers
47 views
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 ...
2
votes
1answer
93 views
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 ...
1
vote
0answers
58 views
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 ...
9
votes
1answer
1k views
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 ...
2
votes
2answers
200 views
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 ...
2
votes
1answer
64 views
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?
4
votes
0answers
792 views
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 ...
3
votes
1answer
123 views
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 ...
4
votes
1answer
594 views
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 ...
2
votes
0answers
117 views
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 ...
2
votes
0answers
220 views
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 ...
3
votes
0answers
3k views
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 ...
0
votes
0answers
35 views
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 ...
5
votes
0answers
352 views
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 ...
0
votes
2answers
398 views
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?
1
vote
0answers
2k views
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 ...
5
votes
1answer
587 views
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 ...
3
votes
0answers
156 views
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 ...
0
votes
1answer
71 views
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, ...
3
votes
1answer
165 views
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 ...
2
votes
1answer
369 views
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?
4
votes
0answers
360 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 ...
2
votes
1answer
1k views
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 ...
5
votes
1answer
1k views
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 ...
7
votes
1answer
279 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 ...
0
votes
1answer
262 views
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) ...
3
votes
1answer
843 views
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 ...
8
votes
2answers
2k views
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 ...
2
votes
1answer
261 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 ...
6
votes
1answer
453 views
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-...
5
votes
1answer
221 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, ...
0
votes
1answer
978 views
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?
...
11
votes
1answer
1k views
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?
0
votes
2answers
6k views
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{...
3
votes
2answers
652 views
Product of the addition of 1 eq. bromine to 1-methylcyclohexa-1,4-diene
When we add one equivalent of $\ce{Br2}$ then which double bond will get brominated?
The double bond in the molecule with methyl group will be more stable as it will have more hyper conjugating ...
16
votes
3answers
5k views
Why does bromine add to a double bond instead of a triple bond if both are present?
According to my textbook, the addition of bromine to pent-1-en-4-yne at low temperature yields 4,5-dibromopent-1-yne:
Why does bromination of the double bond occur selectively?
2
votes
1answer
3k views
What is the stereochemistry resulting from hydroboration of 1-methylcyclopentene?
What is the major product of the following reaction sequence?
I'm supposed to work out the structures of both 2 and 3, but I already know 2 to be 1-methylcyclopentene (as the most substituted ...
