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    Hi guys,

    Having a bit of trouble...but how can you tell which mechanism the question wants when it gives you just the reactants and solvent? Also how do you what is going to react with what to get the right product?

    Does any one have tips/ steps on how tackle such questions?

    E.g these two questions Name:  IMAG0856.jpg
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    (Original post by Princess Kawaii)
    Hi guys,

    Having a bit of trouble...but how can you tell which mechanism the question wants when it gives you just the reactants and solvent? Also how do you what is going to react with what to get the right product?

    Does any one have tips/ steps on how tackle such questions?

    E.g these two questions Name:  IMAG0856.jpg
Views: 130
Size:  520.7 KB
    I think that you just have to learn the conditions.

    The first one is the iodoform reaction. It's a fairly standard test for the CH3CO- group.

    The second one looks like the conditions for sulphonation, substitution of an HSO3 group to the ring.
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    (Original post by charco)
    I think that you just have to learn the conditions.

    The first one is the iodoform reaction. It's a fairly standard test for the CH3CO- group.

    The second one looks like the conditions for sulphonation, substitution of an HSO3 group to the ring.

    (Original post by Princess Kawaii)
    Hi guys,

    Having a bit of trouble...but how can you tell which mechanism the question wants when it gives you just the reactants and solvent? Also how do you what is going to react with what to get the right product?

    Does any one have tips/ steps on how tackle such questions?

    E.g these two questions Name:  IMAG0856.jpg
Views: 130
Size:  520.7 KB
    Yeah second that. You need to think about sterics for the position of sulphonation.
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    (Original post by Princess Kawaii)
    Hi guys,

    Having a bit of trouble...but how can you tell which mechanism the question wants when it gives you just the reactants and solvent? Also how do you what is going to react with what to get the right product?

    Does any one have tips/ steps on how tackle such questions?

    E.g these two questions Name:  IMAG0856.jpg
Views: 130
Size:  520.7 KB
    The first reaction is the iodoform reaction. This reaction occurs with methyl ketones or alcohols which when oxidised give methyl ketones. In this reaction, the methyl ketone group on the ring will be converted into that of methanoic acid.

    The second reaction is sulfonation. You have to rationalise where the pi electrons will attack the S03H+ ion. OMe is o/p directing and NO2 is meta directing, so where both those positions coincide is the para position, hence directly opposite to the OMe substituent.
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    (Original post by LeonVII)
    The first reaction is the iodoform reaction. This reaction occurs with methyl ketones or alcohols which when oxidised give methyl ketones. In this reaction, the methyl ketone group on the ring will be converted into that of methanoic acid.

    The second reaction is sulfonation. You have to rationalise where the pi electrons will attack the S03H+ ion. OMe is o/p directing and NO2 is meta directing, so where both those positions coincide is the para position, hence directly opposite to the OMe substituent.
    Well there are 2 positions if you justify it on those grounds... That explanation is true but as I said you need to account for steric effects which leads to the selectivity over the position para to the oxygen.

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    (Original post by JMaydom)
    Well there are 2 positions if you justify it on those grounds... That explanation is true but as I said you need to account for steric effects which leads to the selectivity over the position para to the oxygen.

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    Of course, but the steric interactions would make it extremely unfavourable, I thought maybe that was too obvious to post. Maybe i should be a bit more thorough
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    (Original post by LeonVII)
    Of course, but the steric interactions would make it extremely unfavourable, I thought maybe that was too obvious to post. Maybe i should be a bit more thorough
    Unfavourable yes, but I think you would still get a mixture.
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    (Original post by illusionz)
    You would still get a mixture, despite the sterics.
    Indeed, but the percentage of the 1,2 product would be dwarfed by the other, no?
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    (Original post by LeonVII)
    Indeed, but the percentage of the 1,2 product would be dwarfed by the other, no?
    Minor product indeed but any exam answer should, in my opinion, state that both are formed as it gives a more detailed description of the reaction and shows you understand what is going on.
 
 
 
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