JEE Chemistry Club

Avnish Kabaj

00:43

@Abcd I think so

@Abcd once the ngp product the other time sn2

Gaurang Tandon

01:16

@Abcd yep, probably a mistake

Abcd

02:47

Leave it.

Gaurang Tandon

03:12

dude, sorry, there was an electricity cut

let me refocus on where i was

i've seen that question before, and it's slightly tricky

Abcd

@GaurangTandon oh okay ..

Gaurang Tandon

in anti position, $\ce{-NMe2}$ can do NGP attack, but cannot in cis position. Agreed?

Abcd

@GaurangTandon ya

Gaurang Tandon

good. now the problem is whether the NGP attack in trans position was even necessary or not, right?

Abcd

@GaurangTandon NGP condition: Leaving group should be anti to NGP group

Gaurang Tandon

03:18

@Abcd that's right, so what's the problem?

Abcd

@GaurangTandon why is enantiomer formed is the problem

Gaurang Tandon

@Abcd ...because NGP occurred in that reaction? i guess that's the one NGP product and one without it?

Abcd

@GaurangTandon You mean: Take a conformer in which NMe2 is in equatorial position?

Gaurang Tandon

no, I'm not talking about conformers, what's the need to bring them in?

Abcd

@GaurangTandon Please tell me directly why the enantiomer is formeddd

@GaurangTandon Need to bring them: Leaving group should be anti to NGP group

Gaurang Tandon

03:22

@Abcd it's anti as it is shown in the diagram as well

@Abcd the way I had understood it was that there was one product with NGP, and one without it. these two products (draw and you'll see) are enantiomers of each other

Abcd

@GaurangTandon Nitrogen always gived NGP

@GaurangTandon They aren't enantiomers

Gaurang Tandon

@Abcd well that's awkward; then i probably understood something wrong :(

Abcd

@GaurangTandon Indeed

Gaurang Tandon

lemme check again..

sorry i've no clue now :(

Abcd

0

Q: Why is the enantiomer formed in this NGP reaction?

I would like to know why is the enantiomer formed in this reaction. The reaction proceeds by Neighbouring Group Mechanism ($\ce{S_N2}$ twice) leading to retention of configuration of the chiral centre. Is the enantiomer always formed in an NGP-type reaction? Why or why not?

organic-chemistry

Gaurang Tandon

03:27

@Abcd take my upvote

Abcd

Okay, ty.

Gaurang Tandon

Also, it appears you're using ChemSketch. If so, there's a Draw Mode - next to the Structure Mode - in the top left of the window. Screenshots obtained from the Draw Mode will be much more beautiful than the ones you've currently posted ;)

@Abcd hmm, i get much better pictures...

i

Abcd

@GaurangTandon edited

Gaurang Tandon

@Abcd good

you could also lengthen the arrow...

Abcd

04:00

Man @AvnishKabaj when you know the answer just answer in chat itself please...

There's no point in adding a new question.

Anyway thanks.

Avnish Kabaj

@Abcd I told you but you still asked it

Abcd

@AvnishKabaj You didn't

I mean you could have sent the mechanism here.

Anyway, never mind. Got it. cc: @GaurangTandon

Avnish Kabaj

@Abcd why no upvotes

in trash, 59 mins ago, by Avnish Kabaj

What happens is after the ring is formed

Abcd

Okay, I'll upvote

Today.

1

Q: Hydroboration oxidation reaction on trans,trans,trans-1,5,9-cyclododecatriene with carbon monoxide

The given solution: I got this question in an entrance exam coaching test paper in India. Product P is easily covered by the mechanism of simple hydroboration-oxidation reaction, and I've understood it well. However, product Q is what intrigues me. Looking at the product and the reactan...

organic-chemistry reaction-mechanism hydrocarbons organic-reduction

> I got this question in an entrance exam coaching test paper in India.

@GaurangTandon but this question was posted by someone else right ? And you are reposting coz you are curious?

Gaurang Tandon

04:18

@Abcd if you look at the other question, you'll know that the first comment by me below it says that I too had got it in one of my tests.

Abcd

@GaurangTandon Oh nice.

Abcd

09:25

yesterday, by Gaurang Tandon

okay, please wait till evening till I get back with a proper response

@GaurangTandon @AvnishKabaj Compare the nucleophilicity in DMF:
$\ce{OH- vs NH2-}$

Anonymous

13:30

'Molecules can still be nucleophilic without non bonding lone pairs' Means?

Anonymous

14:02

Got it. No need to read the above message of mine. Thanks.

Abcd

16:10

Okay @AvnishKabaj done

Jasmine

Can anyone help me understand sn1 and sn2 sn1 prime and sn2 prime reactions?

My teacher said that there is no difference in sn1 and sn1 prime its only like if sn1 is ramesh the sn1 prime is ramesh kumar. Please someone help me

Abcd

@AvnishKabaj I have deleted that question coz it was getting way too many downvotes.

In order to thank you I have upvoted your other answerrs right now

@GaurangTandon Please reply

Gaurang Tandon

16:28

@Abcd NH2- higher?

Abcd

@GaurangTandon No acc to MSc its OH-

Gaurang Tandon

@Abcd ahh. I recall that question, and it's probably incorrect

@Jasmine quora.com/…?

Abcd

@GaurangTandon Are you Damn sure?

coz its DMF

as solvent

Gaurang Tandon

In chemistry, I'm never sure cries

Jasmine

@GaurangTandon thank you!

I have a question as well.

Abcd

16:37

@Jasmine What are you not getting?

What is NH2- called @GaurangTandon

Like OH- is called hydroxide

Jasmine

@Abcd probably the difference between sn1 and sn1 prime but now i understood somewhat more than earlier

Abcd

@Jasmine But this question is about anionic stability

Gaurang Tandon

@Abcd amide

Abcd

@GaurangTandon no azadine ... (i googled after asking)

Gaurang Tandon

@Jasmine answer is Abcd? (pun intended)

@Abcd o.O I never heard that before

@Abcd hmm, I can't seem to find it. Link please?

Abcd

16:41

@GaurangTandon pubchem.ncbi.nlm.nih.gov/compound/azanide

Gaurang Tandon

@Abcd under "Chemical Names:", another name given is amide ion -_-

Jasmine

@Abcd yeah this is another question. Sorry @GaurangTandoni dont have the answer

Gaurang Tandon

@Jasmine which option are you confused in?

Jasmine

Number A

@GaurangTandon in case of F i effect dominates

Gaurang Tandon

@Jasmine logic: substituent with stronger negative mesomeric effect will stabilize the anion more

@Jasmine no need to check inductive effect at such large distance (third carbon!)

Abcd

16:46

@GaurangTandon Look what I found

2

Q: Nucleophilicity order

I know that Nucleophilicity order depends on what type of solvent we take, polar protic or polar aprotic and also on the basicity of nucleophile. I have to decide which among OH- and NH2- in DMF as solvent will be more nucleophilic. I think that since the solvent is polar aprotic, it doesn't have...

organic-chemistry

Please accept my edit

@GaurangTandon Think about a bounty

Jasmine

Oh yeah i effect is distance dependent. Dumb me!

Abcd

@Jasmine No. Sometimes we take I effect in cosideration in para position

4 mins ago, by Gaurang Tandon

@Jasmine logic: substituent with stronger negative mesomeric effect will stabilize the anion more

@GaurangTandon I effect indeed dominates over M effect

Jasmine

@Abcd probably mesomeric effect dominates

Abcd

And Cl has more -I effect

@Jasmine Look, I am sure.

5 mins ago, by Gaurang Tandon

@Jasmine logic: substituent with stronger negative mesomeric effect will stabilize the anion more

Gaurang Tandon

@Abcd I'll approve it tomorrow morn, coz I'm on mobile right now

Jasmine

16:50

Ok @Abcd

Abcd

Dude @GaurangTandon Halogens are +M things

Gaurang Tandon

@Abcd not really, I'm fairly confident the answer is wrong.

@Abcd hmm okay I see what you mean....

Abcd

@GaurangTandon Please tell Jasmine

Jasmine

Yeah yeah option A should be correct i got it i was taking wrong -i effect order

Gaurang Tandon

Good

Abcd

16:56

Something is fishy indeed ...

Jasmine

Try this

@Abcd are you in fiitjee?

Whats your answer @GaurangTandon @Abcd

Gaurang Tandon

I've to go, cya tomo!

Jasmine

Ok. Can someone else tell me the correct answer

Abcd

@Jasmine yes I am in FIITJEE

Jasmine

Oh which centre @Abcd ?

Abcd

17:05

@Jasmine I am In CRP batch (classroom program for school going students)

Jasmine

Then you must have already seen this question!

City ?

Abcd

@Jasmine Not really

Option B is correct for sure

checking others

Option C is correct of course

Option D is correct according to some people incorrect according to some other people

Jasmine

Yeah only B C i think. A is very confusing

Abcd

Look option B's first option is sure correct

But then comparing allylic and benzylic

Jasmine

D i feel is wrong

Abcd

17:08

I have evidence for both - allyl more stable

and benzyl more stable

I have to present my evidence before the scholars (read: ask a question on this on main)

@Jasmine you gotta present your evidence before the court

Jasmine

@Abcd ?

Abcd

Option A is correct too

Jasmine

Do you want me to ask this on main site?

Abcd

@Jasmine No

Jasmine

A why

Abcd

17:10

@Jasmine What's the answer given?

Tell me

Jasmine

I dont hav the key

Abcd

In all probabilty, the answer is Abcd

Look if anyone's planning to refute this ^ , I have evidence.

@Jasmine Steric inhibition of resonance

look phenyl is +M group right?

Jasmine

For D what evidence you have

Abcd

But when there are toooo bulky groups at ortho position

resonance is prevented

@Jasmine SN2 reactivity order given in Clayden

@Jasmine what is SN2 prime?

I know SN2 , SN1

but what is SN2 prime?

Jasmine

SN2 dash or Sn2 prime

Abcd

17:14

@Jasmine Phenyl is better at conjugation than allyl

2

I have read

@Jasmine I can't find it anywhere

What is it?

Jasmine

Reason ?

Ok sending my notes pic sorry for bad handwriting

Abcd

@Jasmine charge distribution on 3 carbons better than charge distribution at 1 carbon

But they will say "equivalent resonance structures"

And its controversial so I will ask it on main and notify you

Jasmine

Ok thanks @Abcd

However aromaticity more preferred than equivalent resonance

Abcd

@Jasmine ...

Jasmine

Ok

Abcd

17:18

3

Q: What are SN1' and SN2' reactions?

I went through the problems on the pictures: The answer of the problem 119 is $\mathrm{S_N1'}$, and that of 120 is $\mathrm{S_N2'}$. I actually can't figure out what $\mathrm{S_N1'}$ ($\mathrm{S_N1}$ prime) and $\mathrm{S_N2'}$ ($\mathrm{S_N2}$ prime) are. Also, how does the answer change b...

organic-chemistry reaction-mechanism notation

@Jasmine This might be helpful^

Jasmine

Abcd

@GaurangTandon Were you taught this?

Jasmine

@Abcd were you not taught this?

Abcd

@Jasmine Not really, I dont think its even in syllabus.

Maybe it is

@Jasmine I have found 2 links that can be helpful:

Allylic rearrangement

An allylic rearrangement or allylic shift is an organic reaction in which the double bond in an allyl chemical compound shifts to the next carbon atom. It is encountered in nucleophilic substitution. In reaction conditions that favor a SN1 reaction mechanism the intermediate is a carbocation for which several resonance structures are possible. This explains the product distribution (or product spread) after recombination with nucleophile Y. This type of process is called an SN1' substitution. Alternatively, it is possible for nucleophile to attack directly at the allylic position, displacing the...

4

Q: What are SN1' and SN2' reactions?

I went through the problems on the pictures: The answer of the problem 119 is $\mathrm{S_N1'}$, and that of 120 is $\mathrm{S_N2'}$. I actually can't figure out what $\mathrm{S_N1'}$ ($\mathrm{S_N1}$ prime) and $\mathrm{S_N2'}$ ($\mathrm{S_N2}$ prime) are. Also, how does the answer change b...

organic-chemistry reaction-mechanism notation

Jasmine

Ok. Thanks to my teacher

Its very similar to SN1 and SN2

Abcd

17:27

@Jasmine Okay Please post your questions regarding SN1' and SN2' here. I will answer them in morning (or someone else will )... What exactly are you confused about?

Jasmine

No no the stack exchange quedtion cleared my question abot thedouble bond in sn2 prime.Do you know the cyclic mechanism in grignard reagent.

Thanks a lot for the referenc

My teacher said that grignard reagents too have got a cyclic mechanism but he didnt elaborate on that in the previous class.

What is the meaning. Do you have any idea @Abcd

Ok i will wait for the answer tomorrow

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