Sciencemadness Discussion Board

Best organic compounds for crystallization

crystal grower - 19-4-2018 at 11:47

Hello,
I'm looking for organic compounds that would be worthwhile making crystals of.
I'll appreciate any suggestions of compounds that you think have interresting crystal structure, colour, et cetora.
Also I'd prefer chemicals that aren't very expensive and are/can be synthesised from relatively OTC stuff.



[Edited on 19-4-2018 by crystal grower]

Sulaiman - 19-4-2018 at 13:02

@MrHomeScientist https://en.wikipedia.org/wiki/Cocrystal >

I like salicylic acid as it forms hollow crystals.

(I deleted my own post :( hence the odd comment above)

Tsjerk - 19-4-2018 at 14:41

I was happily surprised with my home made sample of hydroxylamine hydrochloride crystalized directly from the reaction mixture (hydrochloric/nitromethane), square flat crystals.

crystal grower - 19-4-2018 at 23:36

Thanks for the ideas. Salicylic acid seems to be a great one.
Once I've seen a beautiful crystal of water on a partially frozen lake, shame I haven't taken any photos.
Regarding the crystallization of mixtures like blood, I dont think that's worth spending time on it. You'd have to add some anticoagulant so it doesn't make just a big blob of coagulated blood. And if that's done pretty much only thing that will really crystallize is the NaCl and maybe urea or keatinine, you get the idea.

CobaltChloride - 20-4-2018 at 07:14

Naphthalene recrystallized from ethanol makes quite nice, white, shiny crystals. The only problem it has is that it may not always crystallize and has a tendency to sometimes remain dissolved in the ethanol even if the solution is supersaturated.

Tsjerk - 20-4-2018 at 10:03

Dinitrophenol crystallized from ethanol is also nice, I left a solution in a plastic tube with screw cap on its side. After some days the tube was full with centimeter long crystals which stayed there when I poured of the remaining solution. I kept the tube for display.

Mononitro and trinitrophenol apperently stay in solution if they are not too abundant.

crystal grower - 20-4-2018 at 10:28

Quote: Originally posted by Tsjerk  
Dinitrophenol crystallized from ethanol is also nice, I left a solution in a plastic tube with screw cap on its side. After some days the tube was full with centimeter long crystals which stayed there when I poured of the remaining solution. I kept the tube for display.

Mononitro and trinitrophenol apperently stay in solution if they are not too abundant.

Do you still have it?
If yes, could please take a photo?
I'm very curious.

Tsjerk - 20-4-2018 at 11:39

Too bad, I "lost" a lot of things while moving from Germany back too the Netherlands, this tube being one of them. Maybe it is still on a shelf in the lab, probably someone threw it.

Edit: it looked a bit like these crystals, but they were longer. I believe I dissolved the crystals at 65 degrees Celsius, and crystallized somewhere during summer when it was around 30 degrees.

[Edited on 20-4-2018 by Tsjerk]

download.jpg - 9kB

Fulmen - 20-4-2018 at 15:17

The simplest organic to crystallize would probably be urea. It produces incredible long needles with very little effort.

chemplayer... - 20-4-2018 at 20:04

Favourites:

1. Piperine (beautiful pale yellow long needle-like crystals).
2. Cyanogen iodide (incredible fine needles but fair enough if you don't want to do this as it's evil stuff).
3. Iodine trichloride (see: https://www.youtube.com/watch?v=YCEaL4y0fM8)
4. Phenylacetic acid (not very otc but really pretty).

Boffis - 21-4-2018 at 06:59

How about xylitol, it is available cheap and crystallises into large crystals with care. UTSE for xylitol I am pretty sure there are photos on this site of this compound that someone has grown. None toxic too.

crystal grower - 21-4-2018 at 08:02

@Fulmen Hmm urea could be fun for a timelapse video I guess.

@chemplayer I've already tried piperine, neat stuff.
Thanks for the ideas

@Boffis xylitol is really nice, I believe it was Dmishin that has grown beautiful crystals of it.
I'll have to buy some now that you pointed that one out :D.

[Edited on 21-4-2018 by crystal grower]

crystal grower - 21-4-2018 at 08:03

Quote: Originally posted by Tsjerk  
Too bad, I "lost" a lot of things while moving from Germany back too the Netherlands, this tube being one of them. Maybe it is still on a shelf in the lab, probably someone threw it.

Edit: it looked a bit like these crystals, but they were longer. I believe I dissolved the crystals at 65 degrees Celsius, and crystallized somewhere during summer when it was around 30 degrees.

[Edited on 20-4-2018 by Tsjerk]

Thanks!

Hegi - 22-4-2018 at 00:05

Quote: Originally posted by chemplayer...  
Favourites:

1. Piperine (beautiful pale yellow long needle-like crystals).
2. Cyanogen iodide (incredible fine needles but fair enough if you don't want to do this as it's evil stuff).
3. Iodine trichloride (see: https://www.youtube.com/watch?v=YCEaL4y0fM8)
4. Phenylacetic acid (not very otc but really pretty).


I agree with you that piperine forms beautiful crystals, but it is problem to obtain such crystals when the compound its not pure enough from IPA (I did not try ethanol/water mixture though)

Iodine trichloride is the stuff we do not want to deal with.

I suppose once I get phenol, picric acid could be the way.

LearnedAmateur - 22-4-2018 at 02:09

Quote: Originally posted by Hegi  

I agree with you that piperine forms beautiful crystals, but it is problem to obtain such crystals when the compound its not pure enough from IPA (I did not try ethanol/water mixture though)


To obtain relatively pure piperine, all you need to do is dump in ice cold water to the IPA extract and collect the cloudy precipitate after a few hours, then redissolve in a minimum amount of hot IPA again. I’ve done this and you get stunning small crystals - catching them in the right light can cause nice refraction, giving you little sparkling bits of colour, when disturbed to get a ‘snowglobe’ effect.