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4 added chemdraw, rephrased, retagged, retitled. If anybody has issues with the way I drew the nucleophilic substitution at sulfur, please ping me in chat. I still have the ChemDraw files and can change them accordingly but I am too lazy to do so now. (comment edited Mar 3 '17 at 15:28)
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Why do the tosylation and mesylation of an alcohol proceed via different mechanisms?

More specifically,

  1. In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.

  2. Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$? It's clear that this mechanism cannot happen with TsCl which has no alpha protons, but I fail to see why it should happen with MsCl.

Tosylation with pyridine:

Mechanism of tosylation with pyridine

Mesylation with triethylamine:

Mechanism of mesylation with triethylamine

Why do the tosylation and mesylation of an alcohol proceed via different mechanisms?

More specifically,

  1. In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.

  2. Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$?

Why do the tosylation and mesylation of an alcohol proceed via different mechanisms?

More specifically,

  1. In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.

  2. Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$? It's clear that this mechanism cannot happen with TsCl which has no alpha protons, but I fail to see why it should happen with MsCl.

Tosylation with pyridine:

Mechanism of tosylation with pyridine

Mesylation with triethylamine:

Mechanism of mesylation with triethylamine

3 retagged
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mechanism in formation of mesylates Why do tosylation and tosylatesmesylation of alcohols follow different mechanisms?

enter image description here enter image description here

in these reaction(Ts and Ms), why Why do theythe tosylation and mesylation of an alcohol proceed invia different mechanism/mechanisms?

moreMore specifically,

1.(Ts) e- pair from O attacks S, (Ms)but not in latter reaction. why?

it makes no sense. because TsCl is more sterically hindered by benzene ring.

2.in Ms, e- from hydroxyl group attack H attached to methyl group instead. I'm not famillar with H that was attached to C taken by other things. strong base can do this?

help me~

  1. In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.

  2. Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$?

mechanism in formation of mesylates and tosylates

enter image description here enter image description here

in these reaction(Ts and Ms), why do they proceed in different mechanism/?

more specifically,

1.(Ts) e- pair from O attacks S, (Ms)but not in latter reaction. why?

it makes no sense. because TsCl is more sterically hindered by benzene ring.

2.in Ms, e- from hydroxyl group attack H attached to methyl group instead. I'm not famillar with H that was attached to C taken by other things. strong base can do this?

help me~

Why do tosylation and mesylation of alcohols follow different mechanisms?

Why do the tosylation and mesylation of an alcohol proceed via different mechanisms?

More specifically,

  1. In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.

  2. Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$?

2 changed pictures with other pictures with fully drawn mechanism, and rewrote the question
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enter image description here

enter image description hereenter image description here enter image description here

in these reaction(Ts and Ms), why do they proceed in different mechanism/?

more specifically,

1.(Ts) e- pair from O attacks S, (Ms)but not in latter reaction. why?

it makes no sense. because TsCl is more sterically hindered by benzene ring.

2.in Ms, e- from hydroxyl group attack H attached to methyl group instead. I'm not famillar with H that was attached to C taken by other things. strong base can do this?

help me~

enter image description here

enter image description here

in these reaction(Ts and Ms), why do they proceed in different mechanism/?

more specifically,

(Ts) e- pair from O attacks S, (Ms)but not in latter reaction. why?

it makes no sense. because TsCl is more sterically hindered by benzene ring.

help me~

enter image description here enter image description here

in these reaction(Ts and Ms), why do they proceed in different mechanism/?

more specifically,

1.(Ts) e- pair from O attacks S, (Ms)but not in latter reaction. why?

it makes no sense. because TsCl is more sterically hindered by benzene ring.

2.in Ms, e- from hydroxyl group attack H attached to methyl group instead. I'm not famillar with H that was attached to C taken by other things. strong base can do this?

help me~

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