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What do the dots mean in HN.CO.CH3 connected to the second carbon of N- Acetylglucosamine? And what do the N and acetyl indicate?

  • 1
    $\begingroup$ What is glucosamine? What is an acetyl? The acetyl is connected to the amine at the nitrogen atom, hence N-acetyl. These "dots" (they look more like blobs to me) are just a simple covalent bond. Why they look like blobs I have no idea. $\endgroup$
    – Karl
    Jan 5, 2019 at 12:46
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    $\begingroup$ These don't look like dots to me, more like en-dashes used for denoting chemical bonds (e.g. $\ce{HN-CO-CH3}$). Probably they were chosen short by the typography in order to fit an entire structure on the page. N- indicate the substituent on the nitrogen, and the task of finding what is acetyl is I leave to you:) $\endgroup$
    – andselisk
    Jan 5, 2019 at 12:47
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    $\begingroup$ They look more like dashs to me, a dash is a common symbol for a single bond $\endgroup$ Jan 5, 2019 at 13:14

1 Answer 1


These are not dots. They actually are single bonds though I do not know why they are printed that way. As such, they should be represented by a half-long dash (called EN DASH in Unicode).

In the name N-acetylglucosamine, acetyl means that a hydrogen atom has been replaced an acetyl group (i.e. –CO–CH3) and that the replacement occurred on the nitrogen (aka "N") atom.

Overall, it means something like: "consider glucosamine but replace one hydrogen on the nitrogen atom by an acetyl group". This is the standard "substitutive naming" defined by the IUPAC.


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