Questions tagged [nucleophilic-substitution]
For questions having their focus on SN1, SN2, SNi, SN1', SN2', or SN2th (nucleophilic acyl substitution).
391 questions
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Why can't the aldehydes tautomerize in the reaction of Aldehydes with PCl5 to form alkyl chlorides?
My teacher gave us this question where CH3CH=O (ethan-1-al) reacts with PCl5 to form geminal dichloride CH3CHCl2 (1,1-Dichloroethane).
CH3-CH=O + PCl5 → CH3-CHCl2 + POCl3 + HCl
He explained the ...
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Formaldehyde in SEAr with deactivated ring, and reactivity of bromoacetic acid in substitution reaction?
About this paper:
https://doi.org/10.1021/la0000623
They reacted PET with 18.5 % formaldehyde and 1M acetic acid in a nucelophilic substitution to produce a primary alcohol on the aromatic ring, which ...
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Why does CH3ONa with CH3OH leads to E2 reaction with 2°alkyl halide? Why not Sn2?
2° alkyl halide with strong base/ nucleophile can undergo Sn2 or E2 reaction depending on the other factors involved like temperature, solvent etc. So how does the presence of CH3OH ( which is a poor ...
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How dangerous really is iodomethane?
I'm a school student and I'm planning to use iodomethane (AKA methyl iodide, MeI) as a methylating agent in a SN2 reaction. I've seen conflicting information regarding its hazardous nature across the ...
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Amide group nucleophilic attack pi or lone pair electrons?
I am confused about the drawing of a mechanism in the solutions to the textbook problems to chapter 10 from the Clayden Organic Chemistry textbook:
Why is the electron arrow in the second step ...
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Selecting between SN2 and E2 primary alkyl halide
This might be a meaningless question, but I just want the ideas and opinions of my fellow stackexchangeiers.
The question is that, does a primary alkyl halide undergo SN2 or E2 with a strong $...
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Weak nucleophile with primary alkyl hailde
Why do weak nucleophile react with primary alkyl halide at all? This question was asked earlier, but did not receive much attention:
Why can SN2 reactions occur when the reagents are a primary ...
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Iodine monochloride (I-Cl) bond cleavage issue
During an electrophilic addition of iodine monochloride $(\ce{ICl})$ with alkene, the $\ce{I-Cl}$ bond cleaves as $\ce{I+}$ and $\ce{Cl-}$. Then $\ce{I+}$ attacks the double bond, and later $\ce{Cl-}$ ...
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Nucleophile attack and stability of carbocation
I have studied that in SN1 REACTION nucleophile prefers teritiary carbocation over primary and secondary , because tertiary carbocation is more Stable becuase of delocalisation of positive charge due ...
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How come strong nucleophiles can also be weak bases?
I'm currently taking an introductory organic chemistry course, and have come across the idea that strong nucleophiles can simultaneously also be weak bases numerous times. Also that this can then help ...
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Do alkoxides work as bases in the aryne mechanism?
I'm teaching a course, and when it came to nucleophilic aromatic substitution, some professors at my department started teaching undergrads that when you have a non-activated halobenzene, it undergoes ...
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Nucleophilic attack on Double bond carbon vs Carbonyl group in conjugated Aldehyde
I came across a question in which aldol condenstation is to be performed first and than a nucleophilic addition with CN- , I thought it will attack the carbonyl carbon as it is more electrophilic , ...
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Are halides or gem-dihalides more susceptible to nucleophillic substitution?
Is 1-bromo-1-iodocyclohexane ($\ce{C6H10BrI}$) really more susceptible to $\mathrm{S_N1}$ than 2-chloropropane ($\ce{CH3-CHCl-CH3}$)? I can't exactly understand why.
According to my understanding, $\...
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How do I identify a nucleophile against a base to determine if a reaction proceeds via substitution or elimination? [duplicate]
So our professor taught us, in an attempt to somehow generalize and easily memorize concepts, that substitution reactions involve a nucleophile reagent which attacks the alpha carbon in alkyl halides, ...
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how can I remove salt from water chemically(a direct reaction) ,or convert it to other compound in order to irrigate the soil or any substitutions?
we've a salty water that is approximately 20% wt./wt. conc.(a soaking solution) in a food product company we consumes daily a huge amount of water about 3000L of water , we are seeking about a way ...
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Major product of reaction between 1,1-dibromo-2-(pent-4-en-1-yl)cyclopropane and methyllithium
What is the major product of the reaction between 1,1-dibromo-2-(pent-4-en-1-yl)cyclopropane and methyllithium in diethyl ether?
I suppose the nucleophilic double bond will react with the ...
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Substitution reaction with alcoholic KOH
Whenever, there is the reagent "alcoholic KOH", we prefer E2 Elimination reaction. However in case of 3 degree alkyl halides, like tert-butyl chloride, why do we not consider SN1 pathway? ...
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Relation between formation of carbocation and availability of nucleophile
Many sources suggest that in SN1 reactions the leaving group first exits the molecule, and the resulting carbocation is subsequently attacked by the nucleophile, suggesting that there is no relation ...
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Explaination of order of leaving groups
In Solomons' Organic Chemistry, in a section discussing leaving groups, it is stated that$-$
Among the halogens, an iodide ion is the best leaving group and a fluoride ion is
the poorest:
$$I− > ...
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Which is more nucleophilic: acetamide or aniline?
Which compound will be more nucleophilic, knowing that the electron pair will be more delocalized in the ring for aniline? On the contrary, for the acetamide the electron pair will only be delocalized ...
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Why is the Markovnikov product favoured in electrophilic addition of alkenes in non-polar solvents?
I understand the reason for why Markovnikov product is favoured in the addition of acidic reagents (HX) where the electrophilic addition reaction is brought out by the attack of a proton on the double ...
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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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522
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Using Thionyl Chloride with tertiary alcohol
I have a question regarding using $\ce{SOCl2}$ to convert an alcohol into a alkyl halide.
The Klein book mentions that $\ce{SOCl2}$ is only used for primary and secondary alcohol; however, in the ...
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Will benzyl halides undergo SN1 or SN2 mechanism in a polar aprotic solvent?
If benzyl bromide reacts with KF in the presence of a polar aprotic solvent like DMF, will it undergo SN1 mechanism or SN2 mechanism ?
I understand that polar aprotic solvents favour SN2 mechanism but ...
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what would be the mechanism for these reactions?
I believe the first one would have an intramolecular attack by the sulfur inverting the stereochem followed by an attack by OH- but I can’t get the second one.
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When does negative charge represent a pair of electrons?
Probably a stupid question but it has been bugging me for quite some time.
I was reading Clayden (organic chemistry textbook) and in it, the author gives an example of $\ce{OH-}$ and $\ce{BH4-}$ to ...
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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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What mechanism does the reaction of PCl5 with alcohols follow, 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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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 ...
