[NovaSoccer]

In lab, I crystallized and melted an unknown compound in which the melting range was between 76 and 80 degrees Celsius. Ethanol was used as a solvent. My compound didn't smell like anything until after it was crystallized and stored in my lab locker. It smelled a bit like acid. The problem is, I don't know what compound it is out of glycolic acid, phenylacetic acid, and naphathalene. I know that ethanol is a solvent for phenylacetic acid, but what about glycolic acid? I don't think my compound is naphathalene since it didn't smell much like mothballs. What is the solvent for glycolic acid? Can anyone help me with this? Thank you.

[Borek]

It would be surprising if glycolic acid were not soluble in ethanol.

http://www.nicnas.gov.au/__data/assets/pdf_file/0017/4373/PEC_12_Glycolic-Acid_Full_Report_PDF.pdf

[Arkcon]

OK.  This is a typical undergraduate Organic chemistry lab.  You haven't organized your question very carefully 'tho.  So lets work together on that ...

In lab, I crystallized and melted an unknown compound in which the melting range was between 76 and 80 degrees Celsius.

OK.  That a slightly wider range than I'd like to see.  But fine.  The CRC lists compounds by melting point.  But we rarely work by starting here.

Ethanol was used as a solvent.

OK, we can use this information to narrow down possibilities, using reference sources.   But we're not here yet.

My compound didn't smell like anything

Odorless solid.  Good info for narrowing down.  Not time to be narrowing down, yet.

until after it was crystallized

OK, acquired odor after purification.  That's weird.  Unless it decomposed at that point.  Yet more info we really can't use.

and stored in my lab locker.

You're sure it didn't pick up odors from the storage locker.  Right?

It smelled a bit like acid.

I'm sorry.  I don't recognize 'acid' as an odor.  This makes it hard for me to take any of this seriously.  But with better starting information, we can use the info for later.

The problem is, I don't know what compound it is out of glycolic acid, phenylacetic acid, and naphathalene.

OK, this is where you should have started the question.  Also, how did you react them?  What is the topic of this particular organic chem laboratory session?

I know that ethanol is a solvent for phenylacetic acid, but what about glycolic acid? I don't think my compound is naphathalene since it didn't smell much like mothballs. What is the solvent for glycolic acid? Can anyone help me with this? Thank you.

Like Borek: said, you have to review references to get information for yourself that isn't confusing.

[NovaSoccer]

The topic is entitled "Identifying an Unknown Organic Compound." In the lab report I'm writing, I am only allowed to use the melting point to identify my compound. This is why it's confusing to me. It makes sense that the odor of the compound picked up a scent from the lab locker. The compound crystallized almost immediately after I placed it into an ice bath after purifying it, and it also melted very fast. I noticed that at 80 degrees Celsius, the crystals melted. According to my lab manual, naphthalene melts at 80 and glycolic acid melts at 79 degrees. Does this help at all?

[Altered State]

Wait a minute, are you expected to identify a compound just using the melting point out of two compounds that melt at 80 and 79 ºC? That definetly doesn't make sense.

[NovaSoccer]

Yep - so I wanted to know the solvents of each. It doesn't make sense at all.

[NovaSoccer]

Sorry for responding twice, but I don't think it's naphathalene. I think I would have identified the odor. That melts at 80. The only compound that makes sense that is close to the melting point is glycolic acid.

[Altered State]

Maybe boiling point?
Naphtalene boils at ~200ºC, but glycolic acid decomposes before boiling.
http://www.chemspider.com/906
http://www.chemspider.com/737

And about solubility, just looking each compound structure, you can tell that glycolic acid is going to be very soluble in water and naphtalene at a veeeery low rate.

There are plenty of properties you can use to difference between them two compouds (If you are sure it's one of them), but melting point is not definetly the one.

[NovaSoccer]

Okay, I tried water as a solvent, and the solid didn't dissolve, even when heated. I could have mixed water and ethanol together to use as a solvent, but I didn't have to since ethanol dissolved the solid first. We didn't have to find the boiling point in the lab, so I don't have that number written. Can crystal structure help identify this compound? After using the Buchner filter, crystals formed immediately and took the appearance of snow.

[Altered State]

If it's not soluble in water nor in ethanol, I don't see the way it can be Glycolic acid... Just look at the structure, it can form many hydrogen bonds with water or short chain alcohols.

[NovaSoccer]

It's soluble in ethanol!

[Altered State]

Still doesn't seem to be Glycolic acid if it's not soluble in water..
Are you sure those are your only choices?

[NovaSoccer]

What do you think about phenylacetic acid?

[Altered State]

What do you think about phenylacetic acid?

More likely to be your product than the other 2... And with similar melting point. It will be more soluble in water than naphtalene, but way less than glycolic acid. But I don't know any of these values, check CRC or somewhere

[NovaSoccer]

Thanks so much for your help. I really appreciate it.