Science Buddies: "Ask an Expert"

Hi,

I am looking for the correct structure of aspirin and I have surfed many sites. However I came up with different answers so I am very confused now. I don't know which website to trust. Pls help me! Thanks

1. acetic anhydride +salicylic acid = acetyl salicylic acid +acetic acid
(is this elimination, addition or substitution?)

2. acetic acid + salicylic acid = aspirin + water
(is this elimination, addition or substitution?)

3. there's another that has CH3COOH as a by-product

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This page has a flat model structure of aspirin:
http://www.chemheritage.org/Educational ... p/draw.htm

1. The alcohol from the salicylic acid reacts with an acid from the acetic anhydride (this would be substitution). This website has a good diagram to illustrate this reaction: http://www.chemheritage.org/educational ... /asp31.htm