[tashian]

Hello,

I thought I should have written all three as one topic- sorry I didn't (the topics seemed too big)

The third spectrum is attached, for C5H8O2.
With this one I have the biggest problem. I know it's nor an alcohol, neither a carboxylic acid. I analyzed the fragments, which gave me several options, which I don't know how to eliminate:
1. dialdehyle, which would be glutaraldehyde
2. diketone- either 2,3-Pentanedione or Acetylacetone
3. An ester- Acetic acid, 2-propenyl ester or Propanoic acid, ethenyl ester.

Another thing is that I don't know how to approach the 57 and 58 fragments- what are they? what do they hint for?

Thank you very very much for willing to help