1he he...[4]
In Arihant, it says that stability of carbocations is in the order:
benzylic>allylic>3°>2°>1°>-CH3
While in Morrison Boyd, Solomons and BT, it is given
3°>benzylic,allylic,2°>1°>-CH3
which one is correct?
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25 Answers
1As per Fiitjee package for SN1 mech:
Benzylic = Vinylic > 3° > 2° > 1° > CH3-
1i am not challenging the authirity of the aforementioned book ( rather i can't) but
PLEASE tell me how hyperconjugation dominates resonance stabilisation,as we always learn the contrary
1Tertiary carbocation (CH3)3-C+ is more stable than benzylic or allylic since it will have 9 hyperconjucative structure+ it is 3 degree( 1 particular case when hyperconugation dominates resonance stablization),but if i replace CH3 with CH2CH3 then it will have 6 hyperconjugative structure + 3 degree ...but this is less stable than benzylic or allylic(resonance stablised)...
got it from peter sykes(bible of organic chem) :)
that's y u r finding contradictions
I hope it is clear now
1use arihant for practice cbse for review ur teacher's notes for study and solomon or morrisson boyd for ref .....
1bhai log ncert ko follow karna..... kisi question me yeh logic lagtha hai
question number yaad nahi hai
and morrison doesn't know about iitjee indian authors ko iit ki zyada padi hai
11I have been using IL Finar and it gives the same order as Morrsion And Boyd... So I think ut would be apropriate to say arihant is wrong as usual .... One of the main draw back of arihant is that there are too many mistakes....
1hey ,why don/t you draw and count the equivalent no. of resonance structures and find out a solution
13no....arihant sucks dnt trust it at all
i researched over this bfr iit......askd abt 100 ppl
morrison boyd is absolutely correct/.......even out teahcer in narayan taught us that
24this was the first instant when i found morrison boyd wrong....it happened when i was in 11th.......
so guys dont fight over this question.....here Arihant is absolutely rite.
19 hyperconjugation is more than resonance of single benzene
see the values
BUT in NCERT it is given resonance is more than hyperconjugation
so benzylic> allylic
AND IIT FOLLOWS NCERT
so in jee go with ncert and in olympiad go with morrison
11don't beleive arihant
they SUCK
they make a lot of mistakes
use solomons and boyd as reference books oreven NCERT
but 4 chem please don't rely on Arihant[1]
1wat d heck prateek??
its about stability rite??
for that...d positive charge must be delocalised...........
and during resonance....the same thing happens at a lower level......but in hyperconjugation there are 9 H bonds for attacking d positive charge.......
1i dont think so shreyan...............
when i have champak wid me.....i wud rather read it rather than read a russian magazine hehehehehe
1yaar 3° main hyperconjugation woh 2° yah phir 1° ban jayega that will be less stable than 3°
1yup...morrison is correct...
dont ever think of even glancing at an indian book wen u hav foreign text wid u...
reason is exactly wat akand sed...
1tht too awesum hyperconjugation in tertiary............and is better than d resonanvce in benzyllic......
so morisson boyd is correct
1i dont think so prateek.,............in 3°...we have hyperconjugation....dont forget that.
1i think the ans in arihant is right.....tertiary,secondary,primary, -CH3 main inductive effect ki vajah se stability hai...
par allylic aur benzylic main resonance effect ki vajah se stability
since resonance is more strong as compared to inductive effect therefore the series of arihant is right...
11Morrison Boyd cant be wrong..Arihant theory is shit.. better to do only q. from there
1this is the same prob I once had..... discussed it here as well but arrived at no conclusion
11then i hope ur problem is solved
and ponder upon arihant chem much and use it as a tool to improve ur basics
ad now get back to ur work [3] and follow solomons and boyd