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Purification of Organic Chemicals 149 2-Chlorotriethylamine hydrochloride [869-24-91 M 172.1, m 208-210°. MeOH (to remove highly coloured impurities). Crystd from absolute Chlorotrifluoroethylene [79-38-91 M 116.5, b -26 to -24O. Scrubbed with 10% KOH soln, then 10% H2SO4 soln to remove inhibitors, and dried. Passed through silica gel. Chlorotrifluoromethane [75-72-91 M 104.5, m -MOO, b -81.5O. Main impurities were C02, 02, and N2. The C02 was removed by passage through saturated aqueous KOH, followed by conc H2SO4. The 0 2 was removed using a tower packed with activated copper on kieselguhr at 2W0, and the gas dried over P205. Chlorotriphenylrnethane [76-83-51 M 278.8, m 112-113O. Crystd from benzene soln (100ml) containing a little acetyl chloride, by addition of 200ml of pet ether and cooling. Alternatively, a soln in ethyl ether was saturated with dry HCl (by dripping conc HCl into conc H2SO4 and passing the gas through P205 towers) at Oo, then cooled in a Dry-ice/acetone bath. The crystals so obtained were recrystd from pet ether (b 30- 60°) using Dry-ice/acetone baths [Thomas and Rochow JACS 79 1843 1957. 5-Chlorouracil (5-chloro-2,4(6)-dihydroxypyrimidine) [1820-81 -11 M 146.5, m 314-418O dec, 324-325O dec. Recrystallised from hot H20 (4g/500ml) using charcoal. It has pKa25 7.95 (7.90) and >13 in H20. [McOmie et al. JCS 3478 1955; West and Barrett JACS 76 3146 19541. 4 - C h 1 o ro - 3,5 - x y 1 e no1 see 4 - C h 1 or o - 3,5 -dime t h y 1 p he n 01. Cholamine chloride hydrochloride see (2-aminoethy1)trimethylammonium hydrochloride. chloride 5-P-Cholanic acid [546-18-91 M 360.6, m 164-165O, [a]: +21.7O (CHC13). Crystd from EtOH. Cholanthrene 1479-23-21 M 254.3, m 173O. Crystd from benzene/ethyl ether. Cholestane [481-21-01 M 372.7, m 80°, +29S0 (c 2, CHC13). Crystd from ethyl ether/EtOH. 5a-Cholestan-30-01 [80-97-71 M 388.7, m 142-143°(monohydrate), +28O (c 1, CHCl3), [a]~ +27.4O (in CHC13). Crystd from EtOH or slightly aqueous EtOH. [Mizutani and Whitten JACS 107 3621 19851. 2-Cholestene [102850-21-5] M 370.6, m 75-76O, [01]2D4 +64O. Recrystd from MeOH or ethyl ethedacetone. [Berzbrester and Chandran JACS 109 174 1987. Cholesterol (57-88-51 M 386.7, m 148.9-149.4O, [ a ]-35O ~ ~ (hexane). ~ Crystd from ethyl acetate, EtOH or isopropyl ether/MeOH. [Hiromitsu and Kevan JACS 1094501 1987. For extensive details of purification through the dibromide, see Fieser [JACS 75 5421 19531 and Schwenk and Werthessen [Arch Biochem Biophys 40 334 19521, and by repeated crystn from acetic acid, see Fieser [JACS 75 4395 19531. Cholesteryl acetate [604-35-31 M 428.7, m 112-115O, [a]?$6 n-pentanol. -51O (c 5, CHC13). Crystd from Cholesteryl myristate [1989-52-21 M 597.0. Crystd from n-pentanol. Purified by column chromatography with MeOH and evaporated to dryness. Dissolved in water and ppted with HCl (spot 1) or passed through a cation-exchange column (spot 2). Finally, dried in vacuum over P205. [Malanik and Malat Anal Chim Acta 76 464 19751. Cholesteryl oleate [303-43-5 1 M 651.1, m 48.8-49.4O. Purified by chromatography on silica gel.
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.
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