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    When naming compounds when do you add the prefix oxo for ketones and hydroxy for alcohols
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    hydroxy is used when there is also a carboxyl group, e.g. 2-hydroxypropanoic acid.

    for ketones you hardly ever use the oxo prefix, in fact in A level chem im pretty sure its never used.
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    (Original post by The Diplomat.)
    hydroxy is used when there is also a carboxyl group, e.g. 2-hydroxypropanoic acid.

    for ketones you hardly ever use the oxo prefix, in fact in A level chem im pretty sure its never used.
    Right, thanks. What if if you had, butane for example and you had ethyl on the 2nd carbon and methyl on 3rd carbon. Would you label ethyl with the lowest number or methyl?
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    (Original post by kiiten)
    Right, thanks. What if if you had, butane for example and you had ethyl on the 2nd carbon and methyl on 3rd carbon. Would you label ethyl with the lowest number or methyl?
    the longest carbon chain in that compound is 5, so it would be 2,3-dimethylpentane
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    (Original post by The Diplomat.)
    the longest carbon chain in that compound is 5, so it would be 2,3-dimethylpentane
    Ohhh, ok maybe that was a bad example. What about something like nonane or decane with the 2 branches in the middle e.g. If you label from either end one will have a lower no. then the other
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    (Original post by kiiten)
    Ohhh, ok maybe that was a bad example. What about something like nonane or decane with the 2 branches in the middle e.g. If you label from either end one will have a lower no. then the other
    I think you would do the ethyl with the smallest number because isn't it alphabetical order for the prefixes? I may be wrong thoigh


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    (Original post by kiiten)
    Ohhh, ok maybe that was a bad example. What about something like nonane or decane with the 2 branches in the middle e.g. If you label from either end one will have a lower no. then the other
    You put the smaller number with ethyl because aplhabetical order
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    (Original post by isabellacappio)
    I think you would do the ethyl with the smallest number because isn't it alphabetical order for the prefixes? I may be wrong thoigh


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    Wait - that does apply when naming the compound. But i mean which one would be attached to the lowest carbon
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    Whichever gives you the lowest number at the start.

    e.g. 4-ethyl-2-methylhexane rather than 3-ethyl-5-methylhexane.
 
 
 
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