Questions tagged [elimination]
Questions whose main focus is on E1, E2, E1cb, or any other type of elimination reaction.
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How are major products defined- Thermodynamically or Kinetically?
In many organic chemistry questions, we use mechanisms that favours thermodynamically stable product (like aromatic rings), compromising the rate by some factor. For example, if there were two ...
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Leaving group ability vs Stability of Transition state for determining rate of E2 elimination reaction [closed]
Source: Teacher's Assignment. (not a homework doubt, but a big conceptual doubt about the question)
In this question we have to compare rate of E2 reactions and the answer is C2H4I2 > C2H4Br2 > ...
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Substitution reaction with alcoholic KOH
Whenever, there is the reagent "alcoholic KOH", we prefer E2 Elimination reaction. However in case of 3 degree alkyl halides, like tert-butyl chloride, why do we not consider SN1 pathway? ...
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If bromomethyl cyclopentane reacts with Alcoholic KOH with Heat. Can this produce some very minor products through E1 mechanism also?
I know that alcoholic KOH with heat will majorly give E2 mechanism products but I want to know if it is possible to get minor products through E1 mechanism here also.
The carbocation generated here ...
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Secondary alkyl halides and strong base: Sn2 vs E2
I got this question from the PYQs of a college entrance exam. According to the answer key, 4-chloro-3-methylpent-1-ene reacts with NaOH in water to give 4-hydroxy-3-methylpent-1-ene via the SN2 ...
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Difference in reactivity of sodium ethoxide and NaOH in ethanol
What is the difference in the reaction that proceeds when we use the reagent $\ce{C2H5O- Na+}$ and $\ce{NaOH}$ in $\ce{C2H5OH}$ in with, say ethyl chloride. Is the latter considered to be "...
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Product of 4-chlorobutan-1-ol treated with KOH in alcohol
I am looking at this problem:
I thought the KOH in alcohol would support a nucleophilic attack of hydroxide on the haloalkane, so the product I would get is B (elimination of HCl). However, this ...
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Mechanism for elimination in 3-Chloro-1,4-cyclohexadiene
So, I came across this reaction as an example of E2 elimination.
Our teacher told us that this is what we call E2' reaction, as in, the $\ce{OH^-}$ takes the terminal $\ce{H^+}$, followed by ...
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What is the enthalpy change for elimination reactions of alkyl halide - exothermic or endothermic?
There are a few questions in thermodynamics (with unverified data) that the addition reaction of ethene to give ethyl chloride has a +ve enthalpy change, thereby elimination to give alkene must be ...
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Substitution or elimination when a chloroalkene reacts with NaOH in ethanol?
NaOH + EtOH will eliminate the Cl atom forming a double bond. At least, that's what I think. 3 could also be a viable answer since the OH can also attack the said double bond (this is probably not ...
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Why does alpha-carbon substituents increase the rate of E2 reactions?
The reason for more reactivity of more substituted alkyl halides for E2 Reaction is said to be due to the more stability of its more substituted alkene character having transition state but here (...
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Why can't ethoxide ion act as nucleophile?
Consider the reaction of chlorocyclohexane with ethoxide in a suitable inert solvent. The major product according to my textbook is cyclohexene, which implies E2 reaction pathway. Why not SN2?
$\ce{...
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how does enolate affect an elimination reaction?
From my class:
But why wouldn't the reaction proceed through this way, which makes more sense? Since the reaction above generates an enolate bearing a negative charge first, making the molecule less ...
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Which substrates will undergo an E2 reaction to give a (Z) alkene?
What I do know: E2 reactions are concerted and have an anti-coplanar transition state, where the leaving group and the hydrogen being abstracted have a dihedral angle of 180 degrees.
What I don't ...
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NaOt-Bu + chloroethane
What is the major product formed by reaction of sodium tert-butoxide and chloroethane?
I thought NaOt-Bu is a bulky base and the major product will be ethene due to E2. But the answer says t-butyl ...
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Which 1,2-methylene shift is more favourable in ring expansions where ring has substituents
In the above reaction, first the -OH group is protonated after which it leaves creating a carbocation intermediate as shown
Now, ring expansion is a more favourable rearrangement, however there is a ...
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Why will a lone pair from H2O not attack a C+ atom in elimination reaction?
In step three of reaction between H2SO4 and alcohol, why will the H2O attack the H atom instead of the C+ atom? they both have positive charge and in nucleophilic substitution reactions the c+ atom is ...
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What would be the product(s) when 2-iodobutane is heated with tertiary butoxide?
The following question from Black Book Organic Chemistry IIT JEE Advanced Level Papers [1]:
Choose the correct option(s) among the following about [P]:
A) Two C−H bonds in [P] are involved in ...
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Does E1 mechanism always imply first order reaction?
Oxford University Press, Okuyama & Maskill: Organic Chemistry — Chapter 13: Multiple Choice Questions, Question 1:
Which of the following statements regarding the E1 mechanism is wrong?
a) ...
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Does E1cB take place over here?
I formed this product (reason: alkene has 6 alpha hydrogens)
---->
However, it turns out, this is the answer:
The reason why I suspect this is e1cb is because NO2 could stabilize the carboanion (...
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What kind of rearrangement happens between 2,2,5-trimethylcyclopentanol and concentrated sulfuric acid?
Question:
My attempt:
After getting the carbocation after protonation, in order to form a more stable alkene, it rearranged the methyl group on the adjacent carbon so as to get the alkene in the ...
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Reactivity of 1-bromo-4-tert-butylcyclohexane isomers with methanol
(1s,4s)-1-bromo-4-tert-butylcyclohexane (1) and (1r,4r)-1-bromo-4-tert-butylcyclohexane (2) are heated (E2) with $\ce{NaOCH3}/\ce{CH3OH}.$ Which isomer will react faster?
What will change when $\ce{...
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Difference between SN' and elimination reactions
My professor has recently taught us about SN' reaction example in which 3-bromo-3-methyl-but-1-ene was reacted with with KCN to yield 4-methyl-pent-3-ene-nitrile as the major product.When I asked him ...
user120451
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Why is the major product of an elimination reaction an alkyne and not the diene?
1,2-Dibromopropane and KOH react together to form propyne. But I wondered if 1,2-propadiene was also being produced since the there is also a proton on the $\ce{CH3}$ group to be used in the ...
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Mechanism of this addition-elimination process
In Part 1 of the synthesis of Maoecrystal V (found on synarchive), the last step subjects a $\ce {\alpha, \beta}$-unsaturated ketone to $\ce {I2}$ and pyridine, as shown below:
I am wondering what is ...
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Conversion of cyclohepta-1,3-diene to cyclohepta-1,3,5-triene
In the landmark synthesis of tropinone by Willstatter in 1901, an interesting step involves the use of $\ce {Br_2}$, quinoline to convert cyclohexa-1,3-diene to cyclohexa-1,3,5-triene. In the scheme ...
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Why do active methylene compounds give Sn2 reactions?
I dont understand why they are strong nucleophiles when the negative charge is resonance stabilised. Also it is bulky, is there any chance of elimination?
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Reaction of aqueous KOH and alcoholic KOH with alkyl halide [duplicate]
CONTEXT:
Here's reaction of alkyl halide with aqueous $\ce{KOH}$
and here's the reaction for dehydrohalogenation by alcoholic $\ce{KOH}$
Question
Initially $\ce{KOH}$ is aqueous. On reacting with ...
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Can methoxide ion be used as a base in an E1 elimination reaction?
This one problem given in my textbook is confusing because all I know is we can use a weak base for an E1 Reaction. But the reagent given is a methoxide ion. I thought the answer would B but it is C. ...
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Mechanism of acid-catalyzed ring opening of a cyclopropane ring
I have a question regarding following synthesis which apparently only needs a sour medium to occur:
What exactly happens as a mechanism? What I thought was: The alcohol group gets protonated and ...
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