Did I Successfully Obtain Crystals in My Organic Lab Experiment?

In summary, in organic lab this week, the conversation revolved around mixing ephedrine and mandelic acid to get crystals. The student accidentally added methylene chloride during the cooling process and was unable to get crystals at room temperature. They then boiled off the solvent and added more ethanol, finally getting crystals after cooling the solution on ice. They are unsure if the crystals are of the resulting compound, but plan to take melting point data and carefully cool the sample to avoid shocking it with ice.
  • #1
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In organic lab this week we were mixing (1-R, 2-S) ephedrine with mandelic acid to get crystals. I dissolved both compounds in 6 mL 95% EtOH and then poured them together. After cooling + glass prodding I should have had no trouble getting crystals. HOWEVER, during the cooling I accidently added about 10 mL of methylene chloride to the mixture, and was unable to get crystals at room temp. I knew DCM has a low boiling point so I just boiled off all of the solvent and added 12 mL of EtOH 95%. I then re-heated the soln and let it cool. I prodded the sides with a glass rod and still nothing. Then I decided to put the soln (it was in a 100 ml erlenmeyer) on ice. Before you know it I had crystals. Can I be confident that these are the crystals of the resulting compound when ephedrine and mandelic acid are reacted?

Once I got crystals I stored them in my drawer for next week at room temp. It seems nobody else needed ice, so I'm worried that everything will be redissolved when I get back.

Thanks.
 
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  • #2
A lot of things can happen with boiling , I would take some melting point data of the sample.
 
  • #3
You want to carefully cool the sample... not shock it with ice. If you are unsure about your procedure, just remove a few crystals of what you have and reheat the whole thing. Once it has slowly come to room temperature, add the crystals and pray to whatever deity you worship.

Good luck.
 

1. What could cause my crystals to disappear?

There are several possible reasons for your crystals disappearing, including misplacement, theft, or natural erosion. It is also possible that they were never actually there in the first place and you may have been mistaken.

2. Can crystals really disappear without any explanation?

Yes, there are many instances where crystals have seemingly disappeared without any logical explanation. This phenomenon is often referred to as "crystal vanishing" and is still not fully understood by scientists.

3. Is it possible for my crystals to reappear on their own?

While it is highly unlikely, there have been rare cases where crystals have inexplicably reappeared in their original location after disappearing. However, this is not a common occurrence and should not be relied upon.

4. Could someone have stolen my crystals?

It is possible that someone could have stolen your crystals, especially if they were valuable or easily accessible. If you suspect this to be the case, it is best to report it to the proper authorities.

5. How can I prevent my crystals from disappearing in the future?

To ensure the safety of your crystals, it is important to keep them in a secure location and to regularly check on them. Avoid leaving them in places where they could easily be stolen or damaged. Additionally, consider investing in a security system to protect your valuable crystals.

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