Questions tagged [nucleophilic-substitution]
For questions having their focus on SN1, SN2, SNi, SN1', SN2', or SN2th (nucleophilic acyl substitution).
367
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Can Acyl halides react with PCl5, if not, why?
I was searching for reaction of $\ce{PCl5}$ with carboxylic acids and found this mechanism:
Here a corresponding acyl chloride is formed from a carboxylic acid.
Now I doubt if this is the final ...
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0
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What mechanism do reaction of PCl5 follows, SNi or SN2?
I was taught that $\ce{PCl5}$ reacts with alcohols by $S_Ni$ mechanism as shown below:
Here it can be seen that $\ce{PCl5}$ exists as $\ce{[PCl4]+[PCl6]-}$ and so lone pair of the alcohol is donated ...
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What is the major product on mono chlorination of 2-methypentane?
I understand that mono chlorination of 2-methylpentane are :
My Question is : How can you determine the major product from those results ?
The probability of monochlorination of :
Amount of 1-chloro-...
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3
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1
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32
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Speed of substitution reactions
What is the order of speed of SN1 and SN2 for the following molecules?
My idea:
For SN1 I think it is C>A>B>D
C - the carbocation has resonance
A - I believe the double bond acts as an ...
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3
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Pyrazole iodination
I'm now working on synthesizing 4-Iodo-1,3-dimethyl-1H-pyrazole starting from 1,3-Dimethylpyrazole, iodine, and hydrogen peroxide. I think the mechanism is just a simple aromatic nucleophilic ...
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1
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131
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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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1
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149
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Why is more than one product formed in Swarts Reaction?
I have got a very clear idea about Swarts reaction for monohalo compound. But I found the following reaction in Chrome
Now, my question is why are 2 products formed? Secondly why is there no ...
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1
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What nucleophilic reaction takes place in case of bad leaving group as well as 1* alpha carbon?
If we add HI to a substrate Ph-C-C-OH what will be the major product and what reaction mechn. will be followed?
My attempt: as -OH is bad Leaving Group, we cannot just simply proceed with Sn2 and ...
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2
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1
answer
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Effect of Solvent - Nucleophilicity of RS- and RO-
While reading on order of nucleophilicity of $\ce{RS-}$ and $\ce{RO-}$, I came across this:
Source: Page 355, Organic Chemistry by Jonathan Clayden, Nick Greeves, and Stuart Warren
However, my teacher ...
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2
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Iodide ion is good leaving group and a good nucleophile. How can both be correct?
Leaving Group Tendency of Iodide
$\ce{I-}$ size is big.
$\ce{I-}$ has stable negative charge.
$\implies$ $\ce{I-}$ is good leaving group.
Nucleophilicity of Iodide
$\ce{I-}$ size is big.
$\ce{I-}$...
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1
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Neighbouring Group Participation of Aldehyde group
Does the aldehyde group -CHO give neighbouring group participation? For example in the following compound:
Why or why not will the formyl group show neighboring group participation? Although I have ...
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1
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1
answer
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Do Benzyl Halides undergo SN1 or SN2 with Ammonia?
Does this reaction show SN1 or SN2 mechanism? Our teacher told that it shows SN2. But wouldn't the stability of benzylic carbocation mean an inclination towards SN1?
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Does resonance stablization of carbocation increase ease of $\ce{S_N1}$ reaction or decrease it due to delocalization?
(A)
(B)
In both of the cases when a nucleophile approaches for $\ce{S_N1}$ reaction a carbocation is formed in place of $\ce{Cl}$ atom. I know that the rate of $\ce{S_N1}$ increases with increase in ...
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Possibility of carbocation rearrangements in SNi reactions
According to several sources, the $S_{N}i$ reactions follow a mechanism allowing carbocation formation while others disagree. Precisely, for example, according to A Guidebook to Mechanism in Organic ...
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What is the energy of activation of uncatalyzed ATP hydrolysis reaction?
If we ignore all the biological significans for a while, ATP hydrolysis, the reaction:
ATP + H2O -> ADP + Pi
is still a chemical reaction that must go through transition state to yield product. ...
2
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Feasibility of aromatic nucleophilic substitution of NO group by SH- nucleophile
(My approach)
In the first step, NO+ electrophile is generated which is substituted at the p position of the alkylated phenol. In the second step, HS- acts as a nucleophile and substitutes at p ...
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Transesterfication: Which is a suitable acid that does not contaminate the polar product?
In my PhD Project I am doing a transesterfication of a phosphonic ester with methanol. If you use HCl 37 % you introduce water necessarly which slows the reaction. Sulfuric acid is more or less dry, ...
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Haloalkanes gives acid base reactions or SN2
Consider the following reaction:
I am confused whether $SN_2$ reaction will take place or acid - base reaction.
According to me:
This should be an acid - base reaction since the carbonanion(On carbon ...
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1
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306
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reaction of PCl5 with alcohol [closed]
I am able to think of two possible mechanisms for alcohol+PCl5 here, SN1 and SN2. In SN1, Inversion won't occur whereas, in SN2 inversion will occur. Which of the two is correct?
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2
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Protonation in acid-catalyzed nucleophilic attack of alcohol on carbonyl
When studying acid-catalyzed nucleophilic attack of alcohol on carbonyl, I got puzzled by the first protonation step. In textbooks, they often show that the first step is to protonate the carbonyl ...
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Feasibility comparison of symmetric ether synthesis and HCl + alcohol SN2 reactions
According to Solomons & Fryhle 10$^{th}$ edition Ch 11.8,
Because the chloride ion is a weaker nucleophile than bromide or iodide ions, hydrogen chloride doesn't react with primary/secondary ...
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What are the highest and lowest (un)occupied molecular orbitals in this nucleophilic reaction?
I need to find the highest occupied molecular orbital and lowest unoccupied molecular orbital for this reaction. I'm not really sure where to start. I think it might be an SN2 reaction but I don't ...
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3-Step Transformation to Humulone
I have some ideas on how this transformation may occur. We're currently studying Ch. 3 (Polar Rxn's under Acidic Conditions) from Grossman's book.
I've found some data online that shows we can perform ...
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2
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2
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266
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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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What is the reaction priority when methyl 2-(chloromethyl)benzoate reacts with potassium cyanide?
I was going through some PYQ'S of JEE Advanced where I encountered this question.
I was not able to decide whether I should go for an SN2 reaction to substitute $\ce{-Cl}$ or a nucleophilic attack on ...
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0
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53
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Why bromoacetone is more reactive towards SN2 than alkyl bromides? [duplicate]
Compare the rates towards SN2 reaction:
I got the point that 2-bromobutane d is a secondary halide, so the steric hinderance is highest making it least reactive among the four. Both b and c are ...
2
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0
answers
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Can alkyl halides react with guanidine/guanidino groups?
I wonder how the π delocalization of guanidino groups affects the reactivity of the terminal nitrogens with respect to alkyl halides compared to, say, primary amines?
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Does aqueous KOH favor SN2 or SN1 with secondary halides?
I have read that aq. KOH is equally reactive towards SN1 and SN2 with secondary halides. I'm aware that aq. KOH will participate in SN2 as well because of the lack of steric hindrance in secondary ...
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0
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Effect of beta branching and carbocation rearrangement on SN1 reaction rates
My book (NCERT class 12 Chemistry) asks
Predict the order of reactivity of the four isomeric bromobutanes in SN1 and SN2 reactions.
The answer given for SN1 is
1-bromobutane < 1-bromo-2-...
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2
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1
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152
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Regioselectivity of SN2 reaction on adenine
I found the following question in my examination:
I was able to make out from the options that the usage of a base is to remove the supposedly acidic hydrogen from either the Nitrogen $A$ or $B$. ...
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Why doesn't an acid-base reaction occur in basic amide hydrolysis instead of nucleophilic acyl substitution?
In the reaction of Grignard reagent with a primary and secondary amide, nucleophilic acyl substiution doesn't happen. The reason given is that R- is a strong base as well as strong nucleophile, an ...
user121185
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1
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What determines whether a mechanism is nucleo/electrophillic addition/substitution?
So I recognise what an electrophile and a nucleophile is, but not all mechanisms (that I know of at least) have one species substituting or adding. For example, propanone added to NaBH$_4$ has an ...
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3
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Comparing reactivity of 3-bromocyclohexa-1,4-diene and 5-bromocyclohexa-1,3-diene towards SN1 reaction
Compare reactivity of 3-bromocyclohexa-1,4-diene (P) and 5-bromocyclohexa-1,3-diene (Q) towards $\mathrm{S_N1}$ reaction.
My teacher claims that the reactivity of P is more than that of Q. He ...
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0
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Why don't secondary alcohols react with HBr/HI via SN2?
In polar protic solvents, $\ce{Br-}$ and $\ce{I-}$ are considered to be very good nucleophiles. Now, here the solvent is alcohol which is polar protic. So, why don't secondary alcohols react with $\ce{...
user121185
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How do I determine if a nucleophile attacks the electrophilic atom directly or indirectly?
How do I determine if a nucleophile attacks the electrophilic atom directly or indirectly? For instance a nucleophile could attack the carbon in a molecule with a carbonyl directly, but in another ...
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0
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Rearrangement vs. Ring Strain in Cyclobutanecarboxaldehyde Nucleophilic Reaction
Predict the major product of the following reaction:
Note: Product A is incorrectly marked as secondary halide, it should have been primary halide
This question appeared in an national level ...
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0
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How to explain mesylate structural homologues (e.g., "esylate") being weaker leaving groups than mesylate itself?
I came across a piece of scientific literature (https://patents.google.com/patent/US20080045602A1/en) that would seem to imply leaving groups formed by reacting hydroxy groups with, e.g., ...
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2
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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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How do mechanisms of acidic cleavage of ethers differ for anhydrous, concentrated, and aqueous HI?
I have seen the usage of anhydrous, concentrated, and aqueous HI for the acidic cleavage of ethers. What is the difference in the mechanisms and which will follow either of SN1/SN2 mechanism?
Once the ...
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0
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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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1
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Why doesn't tetrachloromethane react with aqueous sodium hydroxide under reflux?
$\ce{CCl4}$ does not react with hydroxide nucleophile whereas $\ce{CH3Cl}$ does.
I had initially thought that it was due to symmetrical geometry of $\ce{CCl4}$ and so the dipoles cancel out and the ...
0
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1
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75
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Racemization on nucleophilic substitution by OH- ion [closed]
Here's the question I'm stumped by -
According to the answer key, i) is the answer but why can't it be iv)? There is a chiral carbon in compound c) CH3(C2H5)CHCH2Br , so why won't the product (2-...
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2
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1
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On what basis is the rate of Sn1 reaction dependent
Does the rate of reaction depend on the stability of the 1st carbocation formed just after the leaving group leaves or the rearranged carbocation's stability? for eg
Here if i compare the stability ...
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0
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How can we say that one reaction is faster than another if two conflicting factors are at play in both of them
While learning about the preparation of alkyl halides from alcohols by reacting them with hydrohalic acids, it was mentioned that the order of reactivity of different alcohols is Tertiary > ...
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0
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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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1
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Would TFA be a strong enough acid to perform an SN1 reaction on alcohols?
The pKa of sulfuric acid, which is usually used to do this reaction is -3, but would TFA be sufficient even though it has a pKa of 0.5?
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Reaction of primary amine with mixed acid anhydride
Is this reaction $\ce{S_N2}$ (because attack of nucleophile and removal of leaving group are not taking place in a single step)?
Which part of anhydride should form the substituted amide? If it is an ...
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1
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Regioselectivity in the opening of 3-membered heterocycles
(a) Consider the following reactions :
For these two reactions, the nucleophile attacks the less substituted carbon as it is less sterically hindered.
(b) Now consider the following reactions :
For ...
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0
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147
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Formation of α,β-unsaturated ketone from tertiary propargyl halide
My attempt: I went ahead with an $\mathrm{S_N1}$ type reaction followed by the attack of $\ce{OH-}$ on the 3 degree carbocation formed.
This does not match with the answer given (see image below), in ...
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1
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242
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Finding the order of decreasing rate of solvolysis of the following molecules with aqueous ethanol [closed]
In this question, I need to find the order of decreasing rate of solvolysis of the above molecules with aqueous ethanol.
I think this can be done by finding the species that can form the most stable ...
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