Why doesn't MS allow a secondary carbocation to be drawn?

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tsr3129
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#1
Report Thread starter 7 years ago
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Hi everyone,

I've attached a question and mark scheme from the June 2011 paper which I'm having trouble with.

I don't understand why the mark scheme wants the tertiary carbocation to be drawn out. For instance, why don't they allow the secondary carbocation to be drawn out? After all they give the same product.

Thanks!
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trasitszy
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#2
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The secondary carbocation would have only 2 Alkyl groups attatched (+1 hydrogen)
The tertiary carbocation is formed because the reactive carbon has 3 alkyl groups attached so it must be what forms.

Sorry if I am missing something obvious or anything! I am brain dead from revising chem all day
Good luck tomorrow
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trasitszy
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(Original post by tsr3129)
Hi everyone,

I've attached a question and mark scheme from the June 2011 paper which I'm having trouble with.

I don't understand why the mark scheme wants the tertiary carbocation to be drawn out. For instance, why don't they allow the secondary carbocation to be drawn out? After all they give the same product.

Thanks!
Also, even if a secondary carbocation could be formed the tertiary one would be the major product as it is more stable.
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Necrosyrtes
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(Original post by tsr3129)
Hi everyone,

I've attached a question and mark scheme from the June 2011 paper which I'm having trouble with.

I don't understand why the mark scheme wants the tertiary carbocation to be drawn out. For instance, why don't they allow the secondary carbocation to be drawn out? After all they give the same product.

Thanks!

(Original post by trasitszy)
Also, even if a secondary carbocation could be formed the tertiary one would be the major product as it is more stable.
A primary carbocation could be formed, but since tertiary carbocations are more stable, they are formed instead (at least mostly).
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tsr3129
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#5
Report Thread starter 7 years ago
#5
Thanks everyone!
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