math - 25-8-2015 at 17:09
Hi,
got some supplement-grade caffeine powder, anhydrous.
Would like to know if dissolving it in dH2O is sufficient to make large crystals or if I need to salt it with HCl to get something crystallizable,
possibly not too hygroscopic.
Thank you 
TGT - 25-8-2015 at 20:07
I have extracted caffeine from wake up pills and the pure crystals tend to clump together and almost look like pieces of wet paper or tissue paper.
They were extremely fine. I think it would be difficult to make them large, although I could be wrong. I am sure someone here will be able to help
you better. Good luck and if you succeed some pictures would be nice.
TGT
j_sum1 - 25-8-2015 at 21:15
Here is a beautifully presented extraction of caffeine from coffee. It shows a sublimation method to purify resulting in frosty-looking crystals.
This is followed by recrystallisation using ethyl acetate. In the absence of better information i would start by mimicking a procedure that works.
innervision - 26-8-2015 at 18:07
In case you're interested in sublimation. This is from the Merck Index 14:
Properties: Hexagonal prisms by sublimation, mp 238°. Odorless with bitter taste. Sublimes 178°. Fast sublimation is obtained at 160-165° under
1 mm press. at 5 mm distance. d418 1.23. pH of 1% soln 6.9. Absorption spectrum: Hartley, J. Chem. Soc. 87, 1802 (1905). One gram dissolves in 46
ml water, 5.5 ml water at 80°, 1.5 ml boiling water, 66 ml alcohol, 22 ml alcohol at 60°, 50 ml acetone, 5.5 ml chloroform, 530 ml ether, 100 ml
benzene, 22 ml boiling benzene. Freely sol in pyrrole; in tetrahydrofuran contg about 4% water; also sol in ethyl acetate; slightly in petr ether.
Soly in water is increased by alkali benzoates, cinnamates, citrates or salicylates. LD50 orally in mice, hamsters, rats, rabbits (mg/kg): 127, 230,
355, 246 (males); 137, 249, 247, 224 (females) (Palm).
Melting point: mp 238°
Density: d418 1.23
Toxicity data: LD50 orally in mice, hamsters, rats, rabbits (mg/kg): 127, 230, 355, 246 (males); 137, 249, 247, 224 (females) (Palm)
Derivative Type: Monohydrate
Properties: Felted needles, contg 8.5% H2O. Efflorescent in air; complete dehydration takes place at 80°.
innervision - 26-8-2015 at 18:10
In case you're interested in sublimation. This is from the Merck Index 14:
Properties: Hexagonal prisms by sublimation, mp 238°. Odorless with bitter taste. Sublimes 178°. Fast sublimation is obtained at 160-165° under
1 mm press. at 5 mm distance. d418 1.23. pH of 1% soln 6.9. Absorption spectrum: Hartley, J. Chem. Soc. 87, 1802 (1905). One gram dissolves in 46
ml water, 5.5 ml water at 80°, 1.5 ml boiling water, 66 ml alcohol, 22 ml alcohol at 60°, 50 ml acetone, 5.5 ml chloroform, 530 ml ether, 100 ml
benzene, 22 ml boiling benzene. Freely sol in pyrrole; in tetrahydrofuran contg about 4% water; also sol in ethyl acetate; slightly in petr ether.
Soly in water is increased by alkali benzoates, cinnamates, citrates or salicylates. LD50 orally in mice, hamsters, rats, rabbits (mg/kg): 127, 230,
355, 246 (males); 137, 249, 247, 224 (females) (Palm).
Melting point: mp 238°
Density: d418 1.23
Toxicity data: LD50 orally in mice, hamsters, rats, rabbits (mg/kg): 127, 230, 355, 246 (males); 137, 249, 247, 224 (females) (Palm)
Derivative Type: Monohydrate
Properties: Felted needles, contg 8.5% H2O. Efflorescent in air; complete dehydration takes place at 80°.
chemrox - 27-8-2015 at 14:26
You copied and pasted this I presume? Where's the e-copy of Merck? Library?
I would make the citrate.
innervision - 28-8-2015 at 01:32
I don't remember where I got it. It's been installed on my computer for a long time. A google search should yield something.
I left the Merck part out about citrate. I suppose if you're going that route, here's that:
Derivative Type: Mixture with citric acid
CAS Registry Number: 69-22-7
Additional Names: Caffeine citrate; citrated caffeine
Trademarks: Cafcit (Roxane)
Literature References: Clinical trial in treatment of apnea in premature neonates: P. B. Larsen et al., Acta Paediatr. 84, 360 (1995).
Properties: White, crystalline powder; acid reaction. Sol in about 4 parts warm water.
innervision - 28-8-2015 at 01:35
I don't remember where I got it. It's been installed on my computer for a long time. A google search should yield something.
I left the Merck part out about citrate. I suppose if you're going that route, here's that:
Derivative Type: Mixture with citric acid
CAS Registry Number: 69-22-7
Additional Names: Caffeine citrate; citrated caffeine
Trademarks: Cafcit (Roxane)
Literature References: Clinical trial in treatment of apnea in premature neonates: P. B. Larsen et al., Acta Paediatr. 84, 360 (1995).
Properties: White, crystalline powder; acid reaction. Sol in about 4 parts warm water.