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Questions tagged [nucleophilic-substitution]

For questions having their focus on SN1, SN2, SNi, SN1', SN2', or SN2th (nucleophilic acyl substitution).

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24 views

What would this reaction produce? [on hold]

What would this reaction produce? Would it even produce anything? Since NH2CH3HCL would have to many hydrogens?
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31 views

How many moles of methyl iodide will be consumed by one mole of crixivan?

My take on this question : a total of 5 moles of $\ce{CH3I}$ should be consumed. The oxygen atoms in the $\ce{2 OH}$ groups each have a lone pair of electrons. They should displace $\ce{I-}$ from ...
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17 views

Oxirane and ring opening

I have a problem given as :- I thought of a sn1 type mechanism in acidic medium and a sn2 pathway in basic medium . Am I correct or not . Please also check the mechanism according to which I formed ...
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1answer
66 views

Bromination of but-3-en-1-ol in basic medium and Baldwin's rules

After formation of the bromocarbocation the alkoxide anion attacks the bromocarbocation which leads to ring formation and can proceed through two pathways 5 endo tet cyclization is disfavored but 4 ...
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36 views

Nucleophilic addition - Propanal vs Benzaldehyde

According to my school textbook, carbon atom of the carbonyl group benzaldehyde is less electrophilic than that of propanal because polarity of the carbonyl group is reduced in benzaldehyde due to ...
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1answer
38 views

SN2 reactions with primary alcohols [closed]

A problem I was recently working on poses the following scenario: A student realizes that protonation of an alcohol makes the -OH into a better leaving group. Therefore, he suggested the following ...
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1answer
47 views

Order of reactivity of hydrogen halides

Solomon and Fryhle $11^{th}$ edition says : Order of reactivity of HX in the acid catalyzed conversion of alcohols to alkyl halides follows the order : HI>HBr>HCl We can account for this by saying ...
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1answer
46 views

Reaction of cyclobutylmethanol with HX

I am interested in the reaction of cyclobutylmethanol with HX where these are the only reagents. My question is whether the reaction proceeds via SN1 or SN2. My reference text insists that primary ...
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1answer
46 views

What is the expected number of rings obtained in the following ring formation process?

Refluxing, say, one mole of 1,5-dibromo-pentane with excess ammonia in ethanol can result in the formation of rings. (e.g. $1\lambda^2$-piperidine) However, it is also possible for the 1,5-dibromo-...
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1answer
28 views

Reagents in Krapcho's decarboxylation

Krapcho's decarboxylation is a reaction involving esters with a electron-withdrawing group $\beta$ to the carbonyl group and halide ions. It is typically conducted with $\ce {LiCl}$ and $\ce {DMSO}$ ...
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1answer
87 views

Nucleophillic addition vs SN2

The following question came in Paper 2 of JEE Advanced 2014- Here we have $\ce{CH3-}$ as the nucleophile. There are 2 possible attacks: SN2 type attack on the chlorine group. Nucleophilic addition ...
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2answers
83 views

Reactivity of primary and tertiary alkyl halides

From USNCO 2004, Q58: The reaction between which pair of reactants occurs the fastest for $[\ce{OH-}] = \pu{0.010 M}$? (A) $\ce{CH3CH2CH2CH2Cl + OH-}$ (B) $\ce{(CH3)3CCl + OH-}$ (C) $...
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1answer
86 views

Alcohol or Carbonyl - Which is more reactive towards PCl5?

We're aware that ketones and alcohols both react with phosphorus pentachloride, to produce geminal dichlorides and alkyl chlorides respectively. What happens in the compound shown below, when ...
2
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1answer
166 views

Order of reactivity of nucleophilic addition at carbonyl group with Grignard reagent

I thought the order would be $1 > 3 > 2$ as 1 is aldehyde and 2, 3 are ketones. As generally aldehydes are more reactive, I placed it first. I chose 3 over 2 as two alkyl groups would make ...
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1answer
51 views

Why can't you form an anhydride from an ester via nucleophilic attack?

The reaction referred to is the nucleophilic acyl substitution reaction, where the nucleophile is a carboxylate ion and the electrophile is the ester. I am having a difficult time visualizing why this ...
2
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0answers
34 views

Charge distributions in the transition state of the SN2 reaction

I understand that a similar question has been posed here. However, the scope of my question is framed differently. I will present analysis of two different sources of information and I would like to ...
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0answers
68 views

Effect of solvent polarity on SN1 reactions of different charge types

On the topic of the ionisation mechanism (i.e. $\mathrm{S_N1}$), Carey & Sundberg (2007) discuss the effect of polarity of solvent on the rate of $\mathrm{S_N1}$ reactions of different charge ...
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1answer
66 views

Dependence of rates of neighbouring group participation on length of alkyl chain

On the topic on neigbouring group participation, it is mentioned in Carey & Sundberg (2007)[1] that the effectiveness of the participation is dependent on on the ease with which the molecular ...
4
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2answers
74 views

Regioselectivity in iodolactonisation of γ,δ-unsaturated carboxylic acid

In the last step of the iodolactonisation of 3,3-dimethylpent-4-enoic acid,[1,2] why does the carboxylate attack the iodonium to form a 5-membered ring, when a more stable 6-membered ring is possible? ...
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3answers
109 views

Why does using NaI as a nucleophile and acetone as solvent lead to an SN2 reaction mechanism instead of SN1? Is I- not considered a weak nucleophile?

In a reaction with a secondary leaving group, why does using $\ce{NaI}$ with acetone as a solvent lead to an $\mathrm{S_N2}$ reaction mechanism instead of $\mathrm{S_N1}$? I thought that halogens were ...
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2answers
39 views

Addition reaction(Haloalkane) [closed]

In these reactions if two reagent is given how to decide who is going to react with the compound.HBr is a strong acid CH3OH is a weak base.So HBr dissociate easily but CH3OH is reacting with the given ...
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1answer
62 views

Displacement of leaving groups in organic reactions

When I initially learned about substitution reactions, there would be times where a poor leaving group had to be changed into a better one in order to proceed with a substitution reaction. For ...
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1answer
50 views

Do bulky bases participate in substitution reactions?

I see how bulky bases influence the regioselectivity of E2 and E1 reactions. I do not see very much content on the involvement of bulky bases in substitution reactions. I know that bulky bases like t-...
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1answer
91 views

Electronic effects of substituents in the benzyne mechanism

On the topic of nucleophilic aromatic substitution (S$_N$Ar) reactions, the benzyne mechanism is discussed. When considering the position of substitution, electronic and steric factors are mentioned. ...
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1answer
108 views

Converting a thioester to an amide

What reagents can I use for the following transformation? I think this has something to do with formation of an iminium salt and reductive amination, but I'm not so sure.
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3answers
509 views

How does ring size affect SN2 reactions?

Suppose we have to compare the $\mathrm{S_N2}$ reactivity order for cyclopropyl and cyclopentyl chloride. How can we do that? I think that cyclopentyl should be more reactive towards $\mathrm{S_N2}$ ...
2
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1answer
69 views

Why do *tert*-butyl ethers in diluted sulfuric acid undergo elimation instead of solvolysis?

My organic textbook states the pathway for propyl tert-butyl ether in dilute sulfuric acid will follow E1 with a tertiary carbocation intermediate. It mentions that Sn1 will only occur with good ...
12
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1answer
249 views

Rearrangement with sodium iodide (ring opening)

I'm not able to figure out the mechanism for this reaction. I don't see how sodium iodide in acetone could lead to rearrangement, and surprisingly ring opening! What is this reaction called, if it ...
2
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0answers
369 views

What are the partial charges in an SN2 transition state?

What are the partial charges of on the atoms in a SN2 reaction? The nucleophile is normally negatively charged and has a lone pair of electrons. This would make you think the transition state would ...
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1answer
187 views

Organic reaction with Na2S2O4 [closed]

Question: In the first step due to cooperating Inductive and resonance effect C6H5N2 + will be attached at the ortho position of methyl group for which para position is occupied by Amine group ...
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0answers
71 views

Why ammonium salts can not undergo substitution

Why is ammonium salt, such as RNH3+, can not react with nucleophiles like HI to give RI and NH4+? The reaction is pretty much like the substitution of alcohol in acid condition. In my opinion, NH3 (...
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0answers
124 views

Multiple leaving groups and SN2/E2

In the first stage of the reaction i am confused in which place will the SN2 happen (we have aprotic polar solvent and 4 leaving groups). In my opinion SN2 will happen either to the carbon with F- ...
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1answer
52 views

Formation of acid chlorides

In Sn2 nucleophilic substitution reactions,the attacking nucleophile or leaving group is eliminated. The weaker base is eliminated. Then how do acid chlorides form as OH- is a stronger base than Cl–.
3
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1answer
84 views

What hinders SN2 more: geminal alkyl group or alkyl group on the aromatic ring?

Which among these two (1-chloro-1-phenyl-ethane and 2-(chloromethyl)-1,3-dimethylbenzene) is more reactive towards SN2? I strongly believe that it should be Y because of lesser hindrance on ...
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0answers
102 views

What is the product formed when 4-chlorobut-1-ene is treated with acetic acid?

My teacher did like this forming a really unstable cyclopropyl group but this is the correct answer instead. My question is why the product will be even formed? In the mechanism that my teacher had ...
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41 views

Reactivity of carbonyl adjacent to cyclopropyl group

We know that cyclopropyl, because of $\ce{sp^{\sim 5}}$, hybrid orbitals behaves much like a double bond. It even takes part in conjugation to stabilise positive charge on carbons adjacent to it. I ...
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1answer
973 views

Does neopentyl halide undergo SN1?

Carbocation formed from neopentyl halide is primary in nature. So it is not stable. Although it undergoes rearrangement reaction to form tertiary one, now it can undergo SN1 easily. So if we say it ...
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0answers
166 views

Competition of H2O and NH3 leaving groups in nucleophilic acyl substitutions

I've learned in several textbooks, that in the nucleophilic acyl substitution $\ce{H2O}$ is a better leaving group than $\ce{NH3}$. This can be explained by the "thumb rule" of the $\mathrm{p}K_\...
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2answers
400 views

Which will give faster Sn2 reaction

In $\ce{H2C=CH-Br}$ and $\ce{H3C-CH2-Br}$, which will react faster towards a SN2 reaction? According to me, as double bond exhibit -I effect, hence the 1st should do a faster reaction. Am I right or ...
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1answer
94 views

Can someone confirm and/or correct my logic regarding this mechanism?

In the picture, Ethyl 2-oxocyclopentanecarboxylate (I) reacts with ethyl 2-(4-chloromethylphenyl)propionate (II) in the presence of KOH in hot DMF to afford ethyl 2-[4-(1-ethoxycarbonyl-2-...
2
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1answer
280 views

Are SN2 reactions in equilibrium?

I'm learning about SN2-reactions, and my text book gives the following examples of these reactions: $$\ce{HO^- +CH_3Br -> CH_3OH + Br^-}\tag{1}$$ $$\ce{I^- +CH_3Br -> CH_3I + Br^-}\tag{2}$$ ...
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1answer
92 views

What is the product of the reaction of diol with tosyl chloride followed by lithium aluminum hydride?

This question is about the structure of products X and Y. According to me, the answer should be only A (as OTs will substitute on benzylic carbon). But in the answer key, they have given B and D. ...
4
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2answers
158 views

Can the alkyl-oxygen bond in lactones be cleaved in an SN2 reaction?

I understand that nucleophiles typically attack the electrophilic carbonyl carbon of the lactone and open the ring through a nucleophilic acyl substitution. Has there ever been the case where the ...
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2answers
885 views

Reactivity of meta- and para-bromo-nitrobenzene towards nucleophilic substitution

Among 1-bromo-3-nitrobenzene and 1-bromo-4-nitrobenzene, which would be more reactive towards nucleophilic substitution? From what I can infer, the answer should have been 1-bromo-3-nitrobenzene. ...
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42 views

Substitution reaction rate for tertiary halide substrate with adjacent carbonyl

In the book "Organic Chemistry" by Clayden et al. p 343 it is stated that this substrate reacts very slowly through both the SN1 and SN2 pathways. It is shown side by side with neopentyl chloride as ...
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2answers
280 views

Reaction of NaOD/D2O with semicarbazone

I managed to solve the question till D but I'm stuck at the last reaction. I tried to find its solution and the source suggest it as
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76 views

The effect of the groups at para position on SN2 reactivity

Compare the SN2 reactivity order for: The benzyl group stabilises the transition state of SN2 reaction using the π system of the benzene ring for conjugation with the p- orbital of the ...
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0answers
154 views

Attack of ethoxide on epichlorohydrin

I eliminated the possibility of the first two options since they included an alcohol and the solvent has not been specified so we do not know whether it is polar protic or polar aprotic. As for the ...
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2answers
771 views

Mechanism for reaction of aryl diazonium with potassium iodide

I’m working on a synthesis problem that requires me to draw the arrow mechanism for the second half of the Sandmeyer reaction. Basically it’s the halogenation of an aryl diazonium compound. Typically ...
12
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1answer
415 views

Why does a six-membered ring contract in this SN1 reaction?

I was watching this video on Khan Academy (YouTube link) regarding SN1 mechanisms and carbocation rearrangements and came across this mechanism. At around timestamp 4:20 in the video, why does step 2 ...