Sciencemadness Discussion Board - Hollow salycylic acid crystals !?

Hollow salycylic acid crystals !?

Sulaiman - 15-8-2016 at 04:53

While I was researching the solubility of salicylic acid in various solvents I came across this article
https://www.researchgate.net/publication/231536452_Solubilit...
In this article they wrote that salicylic acid recrystalised from organic solvents gave needle-like crystals but water gave hollow square needles.

anyone noticed these hollow crystals ?
or any other compound that forms hollow crystals
(other than hard-to-synthesize CdS,ZnS BaTiO₃ etc.)

[Edited on 15-8-2016 by Sulaiman]

The Volatile Chemist - 15-8-2016 at 14:24

Hmm. Isn't one of the phases of ice (not vanilla ice) supposed to form hollow crystals? Sorry, probably should have a source...

Sulaiman - 15-8-2016 at 16:04

I have 35g salicylic acid on order so I may give this one a try if I can improvise something for microphotography.

Mabus - 16-8-2016 at 06:55

All my large urea crystals are also hollow square needles. I too used water for recrystallization.
I think that's how most organic compounds recrystallize from water, cause all inorganic salts that I've recrystallized from water are compact. Could be wrong though.

Sulaiman - 16-8-2016 at 07:48

what a wonderful world chemistry can be

35g of salycylic acid arrived this morning, and I'm hoping to be mobile soon,
and I want some re-crystalised salicylic acid to compare m.p. with a sample that DJF90 kindly sent me
and a lens in front of my webcam seems to work, so this may be my first experiment in weeks.
(I am also keen to test my new 24/28 500ml distillation kit ... methyl salicylate)

The Volatile Chemist - 17-9-2016 at 08:07

Quote: Originally posted by Mabus

All my large urea crystals are also hollow square needles. I too used water for recrystallization.
I think that's how most organic compounds recrystallize from water, cause all inorganic salts that I've recrystallized from water are compact. Could be wrong though.

Yes, I suppose so. Though solid needles and flat orthorhombic crystals are common for organic salts.

Sulaiman - 20-9-2016 at 13:16

My first bit of chemistry for months,
salicylic acid recrystalised from dH₂O

With a magnifying glass I can see that some are like the photo in OP
long hollow square cross-section needles
unfortunately a lousy photo