For questions having their focus on SN1, SN2, SNi, SN1', SN2', or SN2th (nucleophilic acyl substitution).
-2
votes
1answer
18 views
Which SN1 Reaction in Each Pair is Faster [on hold]
Anyone have any ideas why the top one is wrong? Thanks a bunch!
Tyler
1
vote
1answer
26 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-...
2
votes
0answers
23 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. ...
-1
votes
1answer
36 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.
8
votes
3answers
215 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 $\mathrm{S_N2}$ ...
0
votes
0answers
21 views
Neutral nucleophiles in aprotic solvent - basicity vs polarizability?
According to my textbook, PH3 is more nucleophilic than NH3, whether the polar solvent is protic or aprotic. Because neutral molecules interact weakly with solvent molecules, polarizability wins out.
...
2
votes
1answer
47 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 ...
11
votes
1answer
164 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
votes
0answers
188 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 ...
-2
votes
1answer
61 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 ...
1
vote
0answers
37 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 (...
2
votes
0answers
83 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- ...
1
vote
1answer
42 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
votes
1answer
63 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 ...
0
votes
0answers
44 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 ...
1
vote
1answer
382 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 ...
1
vote
0answers
68 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_\...
0
votes
2answers
95 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 ...
1
vote
1answer
87 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
votes
1answer
162 views
Are SN2 reactions in equilibrium?
I'm learning about SN2-reactions, and my text book gives the following examples of these reactions:
$$\ce{HO^- +CH_3Br -> CH_3OH + Br^-}\tag{1}$$
$$\ce{I^- +CH_3Br -> CH_3I + Br^-}\tag{2}$$
...
1
vote
1answer
85 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
votes
2answers
123 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 ...
1
vote
2answers
181 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. ...
3
votes
0answers
36 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 ...
3
votes
2answers
151 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
6
votes
0answers
71 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 ...
5
votes
0answers
98 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 ...
9
votes
1answer
400 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
votes
1answer
304 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 ...
0
votes
0answers
39 views
Why do halohydrins in base react to give epoxides rather than a substitution or elimination reaction?
The halohydrin reaction in base is well known for making epoxides. However I am confused as to why the base does not simply perform SN2 on the bromine atom, or an E1 on an adjacent carbon atom.
4
votes
0answers
45 views
Activation of alcohols by forming sulphonate ester
In activation of alcohol by tosyl chloride, why does the chloride ion not displace the poor leaving group?
I think that's because chlorine is a poorer base than that thing which will be formed. But ...
3
votes
1answer
39 views
Which attack occurs first: nucleophilic acyl substitution or nucleophilic substitution?
If there is a compound with a site for nucleophilic acyl substitution (i.e. an ester group or the like) as well as a nucleophilic substitution (i.e. a bromine group or the like), will a nucleophile ...
6
votes
0answers
248 views
SN1 reactivity order for chloromethyl methyl ether and trityl chloride
Compare the reactivity order towards SN1 reaction for:
(2-chloropropan-2-yl)cyclopropane
$\ce{CH3OCH2Cl}$
$\ce{Ph3CCl}$
Owing to the exceptional stability of cyclopropyl ethyl ...
1
vote
0answers
67 views
Mechanism for the formation of an alkyl halide from alcohol and phosphorus trihalide [duplicate]
I was reading about synthesis of alkyl halides from $\ce{PX3}$. I want to know the mechanism for this reaction. According to Solomons and Fryhle, no rearrangement takes place in case of $\ce{PBr3}$ , ...
10
votes
1answer
268 views
Order of halide nucleophilicity in DMF
The order of nucleophilicity for halide family in DMF is: $\ce{Cl- > Br- > I-}$. I understand the reason for this must be that DMF, being a polar aprotic solvent, is unable to solvate the ...
4
votes
0answers
243 views
What is the SNi mechanism of the reaction of moist silver oxide with a halide?
I was told by my teacher that the following reaction proceeds through SNi:
Moist $\ce{Ag2O}$ is basically $\ce{AgOH}$, what role does it play in this reaction's mechanism? I think this is what ...
6
votes
1answer
74 views
Mechanism for the conversion of an unsaturated alkyl halide to an alcohol
Question:
Predict the mechanism for the following reaction:
Attempt:
I thought it will proceed through SN1 mechanism as $\ce{H_2O}$ is involved (solvolysis). So I proceeded with the ...
5
votes
2answers
51 views
Do alkyl halides with an alpha nitrogen atom undergo SN1 reaction?
Today, in my organic chemistry class, I learnt about the nucleophilic substitution reaction. The notes have stated that:
Alkyl halides with $\alpha$ oxygen atom can also undergo SN1 reaction ...
5
votes
1answer
187 views
Elimination reaction with 1,2-dibromo-4-methylcyclohexane
I was doing a question from a practice exercise on the topic of elimination reactions and alkene synthesis. It is shown below:
I predicted that the product would be 1,2-diiodo-4-methylcyclohexane ...
-1
votes
1answer
68 views
Picric Acid from Salicylic Acid
When Salicylic Acid is nitrated, the end $\ce{COOH}$ group is getting knocked out. How should I reason the knocking. Is it right to say, since $\ce{HCOOH}$ is more acidic than $\ce{HOH}$, hence, $\ce{...
1
vote
0answers
15 views
How do you know if a nucleophile is strong enough to to break a bond?
For instance, iodine can displace bromine in $\ce{CH3Br}$ Is this due to iodine being lower in the periodic table, thus having more electrons in the outer shell and being a stronger nucleophile?
-1
votes
1answer
65 views
When iodine replaces bromine in 2-bromobutane, does this lead to an overall lower energy level (electrons closer to nucleus) as well?
It seems to me that iodine is a nucleophile that replaces bromine because it has greater attraction to the carbon nucleus due to its electron properties. However, I thought that bonds are formed for ...
1
vote
0answers
70 views
How to compare the reactivity of sec-butyl iodide and n-butyl bromide for SN2?
Steric crowding is greater for the secondary halide, and this is important as the neucleophile will attack the back lobe of carbon atom. But the relative ability to leave is more for iodide than ...
4
votes
0answers
161 views
Textbook suggests secondary alkyl halides do not undergo SN1 reaction
The 8th edition of Organic Chemistry by Paula Bruice suggests that secondary alkyl halides do not undergo SN2 reactions. However, many other sources state the opposite. So, what is the correct answer?
...
5
votes
2answers
805 views
How to tell/control whether sodium ethoxide will react by a substitution or elimination pathway?
Why is the behavior of sodium ethoxide inconsistent?
In a reaction with 1-bromobutane, the anionic part of sodium ethoxide substitutes for $\ce{Br}$:
$$ \ce{CH3CH2CH2CH2Br + C2H5ONa -> ...
4
votes
2answers
119 views
Determining the stereochemistry of the product(s) when an alkyl shift in a carbocation generates a chiral carbon
Consider this carbocation:
We know that this carbocation would immediately rearrange - by a methyl shift - to form the more stable carbocation.
Now, notice that the migration will produce a chiral ...
0
votes
1answer
62 views
What is the necessity of re-hybridisation of carbon in the transition state of SN2 reaction?
In March's Advanced Organic Chemistry (The SN2 Mecahnism, page 374), it's stated:
When the transition state is reached the central carbon atom has gone from its initial sp3 hybridisation to ...
5
votes
3answers
2k views
Why is pyrrole more reactive than pyridine and benzene for an electrophilic substitution reaction?
According to me, pyridine should be the most reactive as it has got an extra pair of electrons on the nitrogen atom which is further localised and readily available for electrophile.
3
votes
3answers
237 views
Why does the SnAr reaction proceed by the Meisenheimer complex?
I am studying SNAr mechanism from this webpage. I am confused as to why this convoluted mechanism occurs. It seems as though we simply create an anion when the hydroxide attacks in order to quench it ...
3
votes
2answers
600 views
Does isopropyl chloride undergo SN1 or SN2 with sodium acetate?
What's the reaction of isopropyl chloride with sodium acetate? (The solvent is acetic acid)
Is it SN1 or SN2?
My thoughts:
It's not that difficult to approach isopropyl chloride's carbon, for there ...
