pls explain me this first of all i read arihant organic chemistry there i found something which i need to clarify

pls explain me stability order of carbocation

benzylic~3'>allylic~2'>1'>ch3+

i thought that non resonating are less stable than resonating

ques 2

singlet carbene is more stable than triplet carbene? how

there are more question i will edit it so please keep looking them !

thanks

benzyllic > allylic > 3 > 2 > 1

ofcourse      singlet carbene is more stable dan triplet carbene

as   triplet carbene has 2 unpaired electrons  & is thus more reactive & more unstable

ofcourse      singlet carbene is more stable dan triplet carbene

as   triplet carbene has 2 unpaired electrons  & is thus more reactive & more unstable

@TC

there are many mistakes in arihant, this is one of em.

@vaibhavbright



Triplet carbene is much more stable than singlet carbene.

i'm damn sure bout it, if ya have any probs, go 4 any good book.



the reason is that singlet carbene has unshared electrons in the same orbital, therefore, more repulsions will be there, and henceforth less stabitliy.



and one more reason triplet carbene will have more electron transfers (internal) to enhance itz stabitliy.

singlet dichlorocarbene is more stable than triplet dichlorocarbene

but

singlet methylene carbene is less stable than triplet methylene carbene

(konsa  pooch rai hai)??????)

there r 2 diff types of carbene which depends upon whether the two unpaired electrons are  placed in one orbital (singlet) or in two orbitals(triplet)

the stability is decided by interlectronic repulsion..

in a triplet carbene electrons are in diff orbitals so repulsion is min. but in singlt energy is required to over power the repulsion so  singlet is less stable

but this happens only in case of methylene carbene

now taking dichloro carbene dueto intereectronic repulsion betwen chlorine lp electrons

the 2 elec . of carbne .........the two ele  r easily paired up in one obital 

now singlet carbene is more stable(hav less energy) than triplet

About the carbocation stability,

3 degree will be more stable because alkyl groups have a +I effect which implies that they release electrons to the adjoining atom if it is deficient.Since more electrons will be provided by 3 alkyl groups than by two and so on,therefore 3 degree carbocation is more stable than 2 degree and so on.

wat? silverdo pls give an explaination for it i too agree with svj29 abt the mistake thing !

and studen9t_iit i wanna ask u dat how come a structure getting stabilised by resonance be less stable than non resonanting strucutre

pls solve my querie and thanks for the reply yet thnks

in benzylic carbocation due to resonance the positive charge will gel delocalized so its over all stability will increase

WelL this is the most precise answer,

(i'm damn sure about mah answer)

3degree > benzylic > allylic > 2degree >1degree

Explanation:

though the stability of benzylic carbocation and 3degree

carbocation are almost same, but for single choice questions the

answer preferred would be 3 degree.

Reason for this unusual happening...

if we see the deficiency in carbocation is much more a free radical,

so due to more deficiency hyperconjugation effect will happen at a

very fast rate, hence increasing the stability given by

hyperconjugation. Hyperconjugation is much more prominent and

dominating in case of carbocations in comparison to free radicals.

Though its not that dominating as much as resonance is...

but now if we compare benzylic and 3degree, we find that there

are 9 hyperconjugating structures in 3deg and 3 resonating

structures in benzylic. Comparing the ratio of canonical forms, we

clearly see that the stability given by 9 hyperconjugating structures

is some what equivalent to the stability given by the 3 canonical