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Yr 13 SN1/SN2 chemistry question

guys, I understand that SN2 is faster as its whole 1 step, unlike sn1 which has steric hindrance
but why is the hydrolysis of halogealkanes fastest with tertiary molecules?
tertiary has steric hindrance so it shouldnt it be the slowest?
This definitely isn't a level content but anyway:
SN1 is a two step process, where the leaving group (the halogen) goes, leaving a positively charged carbon (carbocation). Tertiary alkanes have more methyl groups surrounding the positive carbon, which allows for this thing called the 'positive inductive' effect to happen, where basically the carbons and hydrogens can donate electron density from their p orbitals into the empty p orbital of the positively charged carbon. This stabilises the positively charged carbon - primary carbocations are insanely unstable, nobody's ever made CH3 + exist (to the best of my knowledge)

And also SN2 does have steric hinderance, as the nucleophile has to attack as the leaving group goes, forming a highly hindered 5 member transition state, which is why it's more stable with primary and secondary haloalkanes
Original post by Ensorcell
This definitely isn't a level content but anyway:
SN1 is a two step process, where the leaving group (the halogen) goes, leaving a positively charged carbon (carbocation). Tertiary alkanes have more methyl groups surrounding the positive carbon, which allows for this thing called the 'positive inductive' effect to happen, where basically the carbons and hydrogens can donate electron density from their p orbitals into the empty p orbital of the positively charged carbon. This stabilises the positively charged carbon - primary carbocations are insanely unstable, nobody's ever made CH3 + exist (to the best of my knowledge)

And also SN2 does have steric hinderance, as the nucleophile has to attack as the leaving group goes, forming a highly hindered 5 member transition state, which is why it's more stable with primary and secondary haloalkanes

so which is fastest?
Original post by shooby
so which is fastest?

SN2 is fastest with primary, slowest with teritiary

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