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    In naming this organic compound, should we say it propanone or 2-propanone?

    CH3COCH3

    Thanks.
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    Propanone. It is the shortest possible ketone. Think about a ketone beginning with eth-, surely it is an aldehyde! You can only have the O on the second C.
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    (Original post by JK471993)
    Propanone. It is the shortest possible ketone. Think about a ketone beginning with eth-, surely it is an aldehyde! You can only have the O on the second C.
    Thanks for your reply. Can you explain that further? For example CH3COCH2CH2CH3 is considered 2-pentanone. Why didn't we include 2 in propanone?
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    Because the carbonyl can only be on the 2nd carbon. If it's on the 1st carbon then it wouldn't fit the general formula of R-CO-R.
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    (Original post by ThisIsOurDecision)
    Because the carbonyl can only be on the 2nd carbon. If it's on the 1st carbon then it wouldn't fit the general formula of R-CO-R.
    Thanks for your reply.

    I still really can't get the idea. Can you just explain how you name the two ketones here? Maybe it will make it more clear.

    Thanks.
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    (Original post by SWEngineer)
    Thanks for your reply.

    I still really can't get the idea. Can you just explain how you name the two ketones here? Maybe it will make it more clear.

    Thanks.
    The reason you don't include the 2 in propanone is because if it was on either carbon 1 or carbon 3 then it wouldnt be propanone at all, it'd be propanal.

    So it goes without saying.

    Its like why you dont include numbers on carboxylic acids, the acid group must go at the end of the carbon chain, it can't go anywhere else so no need for numbers.
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    (Original post by Ollie901)
    The reason you don't include the 2 in propanone is because if it was on either carbon 1 or carbon 3 then it wouldnt be propanone at all, it'd be propanal.

    So it goes without saying.

    Its like why you dont include numbers on carboxylic acids, the acid group must go at the end of the carbon chain, it can't go anywhere else so no need for numbers.
    Thanks for your reply.

    So, is it OK to say 2-propanone?
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    (Original post by SWEngineer)
    Thanks for your reply.

    I still really can't get the idea. Can you just explain how you name the two ketones here? Maybe it will make it more clear.

    Thanks.
    Try and draw out propan-1-one on some scrap paper, maybe you'll see where you're going wrong.
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    (Original post by SWEngineer)
    Thanks for your reply.

    So, is it OK to say 2-propanone?
    I doubt you'd ever lose a mark in exam for including the numbers. So yeah, it's fine.
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    (Original post by ThisIsOurDecision)
    Try and draw out propan-1-one on some scrap paper, maybe you'll see where you're going wrong.
    When I do this, I get:

    CHOCH2CH3

    Which is I think now will be called propanal?

    So, how could I draw 1-propanone? Or, it doesn't exist?

    Thanks.
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    (Original post by SWEngineer)
    When I do this, I get:

    CHOCH2CH3

    Which is I think now will be called propanal?

    So, how could I draw 1-propanone? Or, it doesn't exist?

    Thanks.
    It doesn't exist and that is why you don't need to specify the '2' in propanone.

    It's called redundancy - I've already explained this principle to you...
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    (Original post by SWEngineer)
    When I do this, I get:

    CHOCH2CH3

    Which is I think now will be called propanal?

    So, how could I draw 1-propanone? Or, it doesn't exist?

    Thanks.
    Exactly, if the oxygen is on the end it becomes an aldehyde, which is why you don't have to include the position of the carbonyl when naming propanone or butanone.
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    (Original post by ThisIsOurDecision)
    Exactly, if the oxygen is on the end it becomes an aldehyde, which is why you don't have to include the position of the carbonyl when naming propanone or butanone.
    Got what you mean.

    Thanks.
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    Thanks for your replies.
 
 
 

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