Questions tagged [nucleophilic-substitution]
For questions having their focus on SN1, SN2, SNi, SN1', SN2', or SN2th (nucleophilic acyl substitution).
330
questions
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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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0answers
26 views
Does the character of a leaving group affect SN1/SN2 and E1/E2 differently?
This is coming from a fairly unusual question on an old test. If we consider this reaction:
Will the ratio of (2+3):1 be greater if I is the leaving group?
As far as I knew, the an increase in the ...
0
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1answer
50 views
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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0answers
26 views
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 ...
1
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0answers
29 views
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 > ...
2
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0answers
44 views
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?
1
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1answer
26 views
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?
0
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1answer
38 views
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 ...
4
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1answer
74 views
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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0answers
76 views
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 ...
0
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1answer
38 views
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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1answer
89 views
Should we consider reactant as the product of a no reaction?
If a reaction doesn't take place, should we call the reactant as the product? What is the convention? Let me illustrate the question with an example from JEE Advanced 2021, paper 1:
The reaction of Q ...
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0answers
30 views
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 ...
-4
votes
1answer
59 views
CH3I + NaCl in acetone gives [closed]
How will methyl iodide react with $\ce{NaCl}$ in acetone?
According to me $S_N2$ reaction will take place where iodine will be replaced by chlorine and we will get $\ce{CH3Cl}$. Can anyone suggest why ...
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1answer
65 views
SN1 mechanism on 3,5-dimethylbenzyl bromide [closed]
I wanted to see how to make the product on the right so my thought was to have an SN1 reaction to remove water and have the bromine ion attack making the product on the right hand side.
Is this ...
4
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1answer
79 views
nBuLi and tBuLi can take part in halogen metal exchange OR deprotonate. Is there any way to predict which it favours?
I have included a synarchive pathway: https://synarchive.com/syn/144 where BuLi favours deprotonation over halogen metal exchange
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75 views
What is the mechanism when 1-chloro-4-nitrobenzene reacts with NaOH?
The reaction mechanism in my textbook when 1-chloro-4-nitrobenzene reacts with NaOH is given as follows,
When chlorobenzene reacts with NaOH the product formed is phenol with benzyne as the reaction ...
0
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1answer
47 views
How to convert benzyl alcohol to 2-phenylethanoic acid?
How can we convert benzyl alcohol to 2-phenylethanoic acid?
This is what I have tried.
Can someone tell me whether this is correct because I am not sure about the second reaction.
In my textbook it ...
8
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1answer
264 views
Can NaH open the epoxide ring to form alcohol? If so, how?
I was looking at the organic chemistry 8th Ed textbook by Paula Yurknais Brucie. On page 509, I found this:
I think about it for a while and I am doubting that it is wrong. I believe the hydride ion ...
7
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1answer
158 views
Why doesn't NGP happen in the bromination of fumaric acid?
In this question from JEE $2015$, a surprising neighbouring group participation occurs, and the product turns out to be $(3)$. A link for the mechanism can be found here.
However, why doesn't the same ...
4
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1answer
102 views
Acid catalyzed bromine substitution in an alcoholic ester. What is the major product and why?
This was in a paper I gave. I want to know the mechanism by which both of these products will be formed and why is the 1st one the major product.
My thinking is that the -OH group will be converted ...
6
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1answer
432 views
Reaction of phenol with phosphorus tribromide
I know that aliphatic alcohols react with reagents like $\ce{PBr3},$ $\ce{PBr5},$ $\ce{SOCl2}$ etc. to give alkyl halides as a product. But what will happen if we put aromatic alcohols like phenols ...
0
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2answers
56 views
If rate of SN1 is more does that automatically mean rate of SN2 is less, and vice versa?
If I have a list of compounds and I compare their SN1 reactivity, for SN2 reactivity, is it correct to use the same list but order inverted? Are there any exceptions?
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90 views
Reaction mechanism of formation of salicylic acid with Phenol and carbon tetrachloride in basic medium?
With classic Reimer-Tiemann reaction a variation is also given in my lecture notes which use carbon tetrachloride instead of chloroform. But to me, it seems like it would be just a substitution ...
1
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1answer
96 views
Double bond or carbanion for nucleophillic attack [closed]
I came across this question:
According to me the Hydride ion should take hydrogen from left (unsubstituted carbon) because carbanion will be more stable there and this carbanion will then act as a ...
3
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0answers
62 views
Advantages of p-toluenesulfonic acid over sulfuric acid in the formation of acetals
I am currently working on an undergraduate experiment to form a cyclic acetal.
We were asked to use p-toluenesulfonic acid as a catalyst rather than sulfuric acid.
This seems to be common practice ...
3
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0answers
73 views
Does amide ion prefers to act as a base than a nucleophile?
In this question, I think that amide ion, being a good nucleophile should attack on the terminal carbon through $\mathrm{S_N2}$ mechanism to form compound (c), but the answer given is (b), and the ...
5
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0answers
92 views
Which is better leaving group out of iodide and water?
In hydrolysis reaction of an tertiary alkyl halide , $\ce{H_2O}$ will replace the $\ce{I-}$ through $\ce{S_N1}$ mechanism and then $\ce{H+}$ will be removed from $\ce{H_2O}$ in order to form an ...
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1answer
53 views
When does bimolecular nucleophilic substitution reaction take place in phenyl group containing compounds?
We were studying SN Mechanism, and our professor gave us a question to identify the SN, mechanisms which would happen in the given compound.
They were $\ce{CH3Cl}$, $\ce{PhCH2Cl}$, $\ce{Ph2CHCl}$, $\...
4
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0answers
69 views
Mechanism of Wiliamson Synthesis
I was studying about Williamson's Synthesis, and my textbook had the following statement:
Williamson's Synthesis is a nucleophilic substitution reaction and proceeds via $\ce{S_N2}$ mechanism.
Then ...
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0answers
49 views
In benzyne intermiediate of anisole why -I effect of OCH3 is considered not +M effect of it?
Here they considered -I effect of $\ce{OCH3}$ so carboanion is stable at orthroposition;
But $\ce{OCH3}$ also shows $\text{+M}$ effect if $\text{+M}$ is shown carboanion will be stable at meta ...
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0answers
21 views
Confusion regarding nucleophilicity [duplicate]
My teacher told me that to compare nucleophilicity, check the size of the attacking atom. Bigger the attacking atom more the nucleophilicity. But while reading Solomon, I found out that the order of ...
4
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1answer
371 views
Is the SN1 reactions stereospecific or stereoselective? [duplicate]
In the SN1 reaction, the product show retention and inversion. Since one of them is major unless it forms a racemic mixture, does it mean that the SN1 reaction is stereospecific?
6
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1answer
159 views
Why is nitrate anion substituted but bromide anion is not in Von Richter reaction?
In Von Richter reaction which is a nucleophilic aromatic substitution. As according to this source, there is only a 37% yield of the product.I want to know what are the competing side reactions which ...
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0answers
55 views
Does ammonolysis of primary and secondary alkyl halides proceed through SN2 mechanism?
We know that the first the ammonia acting as nucleophile attack the alkyl halide forming the substituted ammonium salt, but my question is why cannot it proceed through a typical $S_\text N2$ type, ...
9
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1answer
149 views
Why does this ring contraction take place in the following nucleophilic substitution? [closed]
While attempting this problem I thought that P1 would simply be Bromine getting substituted by OH through nucleophilic substitution.
P2 would give a product formed through ring expansion as a 4 ...
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0answers
28 views
Determining the leaving group for substituted benzene in Aromatic nucleophilic substitution
I could figure out that After the substitution of one of the halogens, with the $\ce{-OCH3}$ group(Electron donating group), the ring would be deactivated towards nucleophilic substitution hence the ...
4
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0answers
107 views
Why is chlorosulfite a good leaving group?
I came across the following website article[1]:
I understand the mechanism and also get the fact that this is nothing but an experimental result but why does the $\ce{ClSOO-}$ group departs ...
6
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1answer
89 views
Analysing reaction with chair conformation of substituted cyclohexane
Why doesn't Iodine liberate in the following reaction?
(A) Inadequate ring size
(B) Two Bromines are in equatorial positions
(C) Steric hindrance of t-butyl group towards attacking $\ce{I-}$
...
5
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1answer
85 views
What is role of copper powder, calcium chloride and cuprous chloride in the SN1 reaction of hydrochloric acid with propargylic alcohol?
For the synthesis of a 2H-cromene from a phenol I need to prepare 3-chloro-2-methyl-but-1-yne from the corresponding alcohol 2-methylbut-3-yn-2-ol. This reaction could be seen as a simple $S_\text N1$ ...
3
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1answer
428 views
bromobenzene and NaOH reaction at high temperature and pressure
Find the product of the following reaction
Note that the carbon marked as a star is a special labelled carbon which may be considered as a $\ce{C-14}$ isotope
The given answer is (c)
Why would the ...
5
votes
1answer
84 views
When does reaction of alcohol with alumina give an ether and when an alkene?
What is the main product when an excess of ethyl alcohol vapour is passed over heated alumina at 250 °C?
I read that this reaction gives an ether (here, diethyl ether) at relatively lower temperature ...
4
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1answer
172 views
What is the correct reaction mechanism?
I came across this question:
I propose two things to happen:
It can undergo Aldol condensation
or
it can undergo SN by replacing $\ce{-Cl}$ with $\ce{-OH}$.
But apparently, both these mechanism ...
7
votes
3answers
253 views
Comparing the rates of hydrolysis of different haloalkanes
The title may not completely explain my exact doubt so I'll explain it here:
My teacher gave me the following problem during a lecture about SN1 reactions and I had to determine the order of the rate ...
2
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1answer
175 views
Reaction of acyl chloride with excess Grignard reagent
I have a reaction to which I must find the majority organic product.
I think I found the correct product but the fact that the reaction takes two moles of propylmagnesiumbromide confuses me a bit. I ...
5
votes
3answers
239 views
Possible carbocation rearrangement in substitution reaction to give two different products
In the following substitution reaction, is compound I formed by $\mathrm{S_N}$2 and compound II formed by $\mathrm{S_N}$1 and carbocation rearrangement?
Or is there some rearrangement I'm not aware ...
1
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1answer
72 views
Carbocation stability + determining position of attack on a carbocation in SN1 reaction
It's implied that the right structure is the more stable carbocation because it undergoes the second half of an SN1 reaction, but I'm not entirely sure why:
I'm also not sure why the $\ce{MeOH}$ ...
6
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1answer
405 views
The reaction of Alkyl Halides with sodium nitrite in DMF
How does the reaction of Alkyl Halides with sodium nitrite in DMF proceed?
I was aware of the reaction of alkyl halides with aqueous sodium nitrite which results in the formation of an alkyl nitrite ...
7
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2answers
283 views
Proton removal during benzyne formation in substituted haloarenes
I encountered the following question in an organic chemistry paper -
The reaction follows benzyne mechanism. My answer was B.
However, the answer given in the test solutions was D. The mechanism ...
1
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1answer
196 views
Rate of aromatic nucleophilic substitution reaction on ortho and para fluoronitrobenzene
Why rate of aromatic nucleophilic substitution of Ortho-fluoronitrobenzene is greater than para-fluoronitrobenzene?
Kindly note question is about why rate of ortho is greater than para position. Not ...
