[friedpork]

For my lab experiment I had to identify an unknown compound. After the results, I have two that I narrowed it down to. N-methylacetanilide and phenathrene. When doing my lab experiment I found that the melting point of the compound was between 100.9-104.1 degrees Celsius. The neutral compound was white and developed plate like crystals after using alcohol for recrystallization.

According to my lab manual N-methylacetanilide has a melting point of between 102-104 degrees Celsius but it supposes to develop prisms in alcohol after recrystallization. Phenathrene only has a melting point of 100 degrees Celsius but it develops plates in alcohol after recrystallization.

Which compound should I say it is or should I mention both in my lab report to play it safe?

[discodermolide]

Well from your observations it looks like phenanthrene. Get an original sample and do a mixed MPt.

[curiouscat]

Wikipedia says:

"Phenanthrene appears as a white powder having blue fluorescence."

Does that help narrow it down? (No idea if N-methylacetanilide  flurosces too....)

Another option:
"Phenanthrene: Solubility in water   1.6 mg/L"
A casual search reveals that  N-methylacetanilide has an order of magnitude higher solubility in H2O; though the online source was not very trustworthy to quote. But I'd follow up on that..

[curiouscat]

Also, couldn't you do a qualitative test for Nitrogen?

e.g. http://en.wikipedia.org/wiki/Sodium_fusion_test

No idea how much sample you need for the test etc.