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How do I know what the IUPAC name is of arenes? Watch

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    in an exam if I am asked to name an arene

    it could be:
    ethyl benzene or phenyl ethane.
    Both are correct but examiners may be picky and demand one and not the other.
    I think the safest option is to use IUPAC.
    BUT when do I use phenyl- and when do I use -benzene (e.g: phenyl amine or chlorobenzene)??

    thanks
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    Use phenyl when it can be treated as a side-chain, use benzene when it can be treated as a functional group.

    If you can't decide which, use benzene as it's often easier to integrate.
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    (Original post by dmccririck)
    Use phenyl when it can be treated as a side-chain, use benzene when it can be treated as a functional group.

    If you can't decide which, use benzene as it's often easier to integrate.
    what do you mean use phneyl when it can be reated as a side-chain
    surely in phenyl amine the AMINE group is a side chain NOT phenyl??
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    (Original post by ilovemath)
    what do you mean use phneyl when it can be reated as a side-chain
    surely in phenyl amine the AMINE group is a side chain NOT phenyl??
    The amine will be the functional group, as it's the most reactive bit... the benzene ring won't take part in the reaction so is treated as a side-chain.
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    (Original post by dmccririck)
    The amine will be the functional group, as it's the most reactive bit... the benzene ring won't take part in the reaction so is treated as a side-chain.
    but in benzoic acid, the acid takes part so it should be pheyl methanoic acid? but it is not
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    (Original post by ilovemath)
    but in benzoic acid, the acid takes part so it should be pheyl methanoic acid? but it is not
    Hmmm okay, let me change my answer:

    Use phenyl when the benzene is a substituent to another carbon chain.

    Use benzene if other substituents like -F, -Cl, -CH3, -OH are bonded to the benzene ring.
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    (Original post by dmccririck)
    Hmmm okay, let me change my answer:

    Use phenyl when the benzene is a substituent to another carbon chain.

    Use benzene if other substituents like -F, -Cl, -CH3, -OH are bonded to the benzene ring.
    see this is why it is confusing
    -NH2 is a substituent but it is phenyl amine???
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    (Original post by ilovemath)
    see this is why it is confusing
    -NH2 is a substituent but it is phenyl amine???
    It's all to do with priority. Groups with priority get the suffix.

    Amines have a greater priority, so they get the suffix. Out of amines and benzene rings, benzene rings have less priority, so they get the prefix, phenyl-.

    Hence, it's phenylamine.

    According to IUPAC, calling it aminobenzene is wrong.

    However, halogens have less priority than benzene rings, so they get the prefix, and benzene rings get the suffix, -benzene.

    Hence, C6H5Cl = chlorobenzene.
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    (Original post by thegodofgod)
    It's all to do with priority. Groups with priority get the suffix.

    Amines have a greater priority, so they get the suffix. Out of amines and benzene rings, benzene rings have less priority, so they get the prefix, phenyl-.

    Hence, it's phenylamine.

    According to IUPAC, calling it aminobenzene is wrong.

    However, halogens have less priority than benzene rings, so they get the prefix, and benzene rings get the suffix, -benzene.

    Hence, C6H5Cl = chlorobenzene.
    do you have a priority table / list?
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    https://en.wikipedia.org/wiki/IUPAC_...ence_of_groups
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    Welcome to the minefield that is nomenclature :awesome:

    There is a difference between IUPAC accepted names and systematic names (which A-level exam boards tend to favour, as it's methodical).
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    (Original post by EierVonSatan)
    Welcome to the minefield that is nomenclature :awesome:

    There is a difference between IUPAC accepted names and systematic names (which A-level exam boards tend to favour, as it's methodical).
    ok well if exam boards favour systematic they are likely to accept more than one alternative
    e.g: aminobenzene and phenyl amine, right?
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    (Original post by ilovemath)
    ok well if exam boards favour systematic they are likely to accept more than one alternative
    e.g: aminobenzene and phenyl amine, right?
    I'd have thought so but you should check. Just don't call it aniline
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    (Original post by ilovemath)
    ok well if exam boards favour systematic they are likely to accept more than one alternative
    e.g: aminobenzene and phenyl amine, right?
    I would guess so, don't take my word for it though :p:

    There is enough complexity in nomenclature to baffle most examiners, so they'd make it so that it's not too strict

    To see some of this complexity, see this 'simple' chart to naming TNT.

    Spoiler:
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