Questions tagged [c-c-addition]

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

Filter by
Sorted by
Tagged with
1
vote
1answer
41 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 ...
2
votes
2answers
91 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
118 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
29 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
25 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 ...
-1
votes
1answer
57 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
115 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
32 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
52 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
45 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 ...
8
votes
1answer
470 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
133 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
38 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?
3
votes
0answers
243 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
117 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
308 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
61 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 ...
1
vote
0answers
128 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 ...
0
votes
0answers
1k views

What is the major product of the reaction of 2-methyl-but-1,3-diene with HBr?

What is the product of the reaction of 2-methyl-but-1,3-diene with HBr? What I understand is that carbon (2) will get a positive charge after protonation. But after this, which should be the major ...
0
votes
0answers
33 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
232 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
227 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
1k 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
448 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
142 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
66 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
131 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
287 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
251 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 ...
1
vote
1answer
840 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
256 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
208 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
624 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
219 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
403 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
200 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
900 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? ...
8
votes
1answer
975 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
5k 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
514 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 ...
15
votes
3answers
4k 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
2k 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 ...
7
votes
1answer
1k views

Why does the chlorination of indene occur with syn selectivity in heptane?

In the chlorination of indene to form 1,2-dichloro-2,3-dihydro-1​H-indene in heptane as solvent, the syn dichloride is formed as the major product, as reported in J. Org. Chem. 1980, 45 (25), 5150–...
10
votes
2answers
1k views

Getting 3,4-dimethylhex-3-ene from but-2-ene

How can one get 3,4-dimethylhex-3-ene from but-2-ene ? $\hskip2in$ Using $\ce{Br_2}$ then two equivalents of $\ce{CH_3CH_2MgBr}$, I can get the corresponding alkane (3,4-dimethylhexane) but I don't ...
5
votes
1answer
719 views

Addition reaction of hydroiodic acid to 2-bromo-3-chloro-2-butene

How can the major product of the addition reaction of 2-bromo-3-chloro-2-butene with hydroiodic acid be predicted, since Markovnikov's rule fails to distinguish it? $$\ce{H3C-C(Cl)=C(Br)-CH3~+~HI~-&...
10
votes
2answers
7k views

What are the products of the reaction of 1-methoxycyclohexene with dilute hydrochloric acid?

When 1-methoxycyclohexene is treated with dilute aqueous hydrochloric acid, methanol is produced along with another organic product. Identify this product. Explain why methoxycyclohexane is inert ...
8
votes
1answer
4k views

What is the difference between “bromine” and “bromine water” in their reaction with an alkene?

In question 16 of the A-Level Chemistry 2013 exam, there is this reaction scheme: $$\ce{CH3CH=CH2 ->[?] CH3-CHBr-CH2Br}$$ The question asks for both the name of the reagent and the product. I ...
7
votes
2answers
2k views

Hydroboration/oxidation vs acid-catalyzed hydration of 1-phenylpropene

I am trying to predict the products of both the hydroboration/oxidation and acid-catalyzed hydration of 1-phenylpropene: Both C1 and C2 of the double bond are secondary carbons. However, I have the ...