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150 Purification of Organic Chemicals
Cholic acid [81-25-41 M 408.6, m 198-200°, [a1546 +41° (c 0.6, EtOH).
Dried under vacuum at 94O.
Crystd from EtOH.
Choline chloride [67-48-11 M 139.6. Extremely deliquescent. Purity checked by AgN03 titration or by
titration of free base after passage through an anion-exchange column. Crystd from absolute EtOH, or EtOHethyl
ether, dried under vacuum and stored in a vacuum desiccator over P2O5 or Mg(ClO&.
540nm, E 7.80 x lo4 (10M HCI). Crude material
(40g) is dissolved in water (25Oml) and filtered. Then added conc HCI (50ml) to filtrate, with stirring. Ppte is
filtered off, washed with HCl (2M) and dried. Redissolved in water (25Oml) and pptn repeated twice more in
water bath at 70°. Then dned under vacuum over solid KOH (first) then P2O5 [Martynov et al. Zh Analit Khim
32 519 19771.
Chromazurol S [1667-99-81 M 539.3, A ,
4-Chromanone [491-37-21 M 148.2, m 35-37O, 38S0, 39O, 41°, b 92-93O/3mm, 130-
132°/15mm, 160°/50mm. It has been recryst from pet ether, or purified by dissolving in C6H6 washing
with H20, drying (MgSOd), evaporate and dist in a vacuum, then recryst the residue. The liquid has a pleasant
lemon-like odour. The semicarbutone has m 227O. [Loudon and Razdan JCS 4299 19541. The oxime is
prepared from 3g of chromanone, 3g NH20H.HCI in EtOH (5Oml), 6g K2C03 and refluxed on a water bath for
6h. The soh is poured into HzO, the solid is filtered off, dried and dissolved in hot C6H6 which on addition of
pet ether yields the oxime as glisteneing needles m 140O. Decomposition of this gives very pure chromanone.
The benzal derivative is prepared from 3g of chromanone, 4g PhCHO in 50ml EtOH, heated to boiling, lOml
of conc HCI are added dropwise and set aside for several days. The derivative separates and is recrystd from EtOH
to give yellow needles, m 112O [JACS 45 2711 19231. Reaction with Pb(OAc)4 yields the 3-acetoxy
derivative m 74O (from pet ether + trace of EtOAc, [Cavil] et al. JCS 4573 19541.
Chromotropic acid [148-25-41 M 120.3. Crystd from water by addition of EtOH.
Chrysene [218-01-91 M 228.3, m 255-256O. Purified by chromatography on alumina from pet ether in
a darkened room. Its soh in C6H6 was passed through a column of decolorizing charcoal, then crystd by
concentration of the eluate. Also purified by crystn from C6H6 or CgH6-pet ether , and by zone refining.
[Gorman et a]. JACS 107 4404 19851. It was freed from 5H-benzo[b]carbazole by dissolving in N,Ndimethylformamide
and successively adding small portions of alkali and iodomethane until the fluorescent colour
of the carbazole anion no longer appeared when alkali was added. The chrysene (and alkylated 5Hbenzo[b]carbazole)
separated on addition of water. Final purification was by crystn from ethylcyclohexane and
from 2-methoxyethanol [Bender, Sawicki and Wilson AC 36 101 1 19641. It can be sublimed in a vacuum.
Chrysoidine G (4-phenylazo-1,3-benzenediamine monohydrochloride) [532-82-11 M 248.7, m
118-118.5O. Red-brown powder which is recrystd from H20. It gives a yellow soln in conc H2SO4 which
turns orange on dilution. Its solubility at 15O is 5.5% (H20), 4.75% (EtOH), 6.0% (cellosolve), 9.5%
(ethylene glycol), 0.005% (xylene) and insol in C6H6. The hydroiodide has m 184O (from EtOH) and the
picrate forms red needles m 196O. It has pKa values of 3.32 and 5.21 in H20. [Bull Chem SOC Japan 31 864
1958; B 10 213 18771.
Cinchonidine [485-71-21 M 294.4, m 210S0, -127.5O (c 0.5, EtOH). Crystd from
aqueous EtOH.
Cinchonine [118-10-5] M 294.4, m 265O,
ether.
+268O (c 0.5, EtOH). Crystd from EtOH or ethyl
Cincophen see 2-phenyl-4-quinolinecarboxylic acid.
1,8-Cineole [478-82-61 M 154.2, f.p. 1.3O, b 176.0°, d 0.9251. Purified by dilution with an equal
volume of pet ether, then saturation with dry HBr. The ppte was filtered off, washed with small portions of pet
ether, and then cineole was regenerated by stimng the crystals with water. It can also be purified through its o-
cresol or resorcinol addition compounds. Stored with sodium until required.