Previous Page 142

Purification of Organic Chemicals

N-Chlorocarbonyl isocyanate {27738-96-11 M 105.5, m -6S0, b 63.6O/atm, d i 0 1.310. Fractionally distd at atmospheric pressure using a 40cm column. TOXIC vupour use a good fume hood. Store dry, v 2260 (NCO), 1818 (CO) and 1420 (NCO sym) cm-l. [B 106 1752 19751. 4-Chlorocinnamic acid [1615-02-71 M 182.6, m 243O, 248-250°, 249-251O. Recrystd from EtOH or aq EtOH (charcoal). [Org Synth Coll Vol IV 731 1963, Walling and Wolfstin JACS 69 852 1947. Chlorocresol see chloromethylphenol. Chlorocyclohexane [542-18-71 M 118.6, b 142S0, d 1.00, n25 1.46265. Washed several times with dilute NaHCO3, then repeatedly with distilled water. Dried with CaC12 and fractionally distd.

4-Chloro-2,6-diaminopyrimidine (2,4-diamino-6-chloropyrimidine) [156-83-21 M 144.6, m 198O, 199-202O. Purified by recrystn from boiling H20 (charcoal) as needles; also crystallises from Me2CO. Its pKa25 in H20 is 3.57. [Buttner B 36 2232 1903; Roth JACS 72 1914 1950; W: JCS 3172 19621. 2-Chloro-1,4-dihydroxybenzene see chloroquinol. 4-Chloro-3,5-dimethylphenol [88-04-01 M 156.6, m 115.5O. Crystd from benzene or toluene.

l-Chloro-2,4-dinitrobenzene [97-00-71 M 202.6, m 48-50°, 51°, 52-54O, 54O, b 31S0/atm, d:* 1.697. Usually crystd from EtOH or MeOH. Has also been crystd from Et20, C6H6, CgH6-pet ether or isopropyl alcohol. A preliminary purification step has been to pass its soln in benzene through an alumina column. Also purified by zone refining. It exists in three forms: one stable and two unstable. The stable form crysts as yellow needles from Et20, m 51°, b 315O/atm with some dec, and is sol in EtOH. The labile forms also crystallises from Et20, m 43O, and is more soluble in organic solvents. The second labile form has m 27O. [Hoffman and Dame, JACS 41 1015 1919, Welsh JACS 63 3276 1941; JCS 2476 1957).

4-Chloro-3,5-dinitrobenzoicacid [I 1 8-97-81 M 246.6, m 159-161O. Crystd from EtOH/water, EtOH or benzene. 2-Chloro-3,5-dinitropyridine [ 2 5 7 8 - 4 5 - 2 1 M 203.5, m 62-6S0, 63-65O, 6 4 O . Dissolve in CHC13, shake with saturated NaHCO3, dry (MgS04), evaporate and apply to an A1203 column, elute with pet ether (b 60-80°), evaporate and recryst from C6H6 or pet ether. [Chem Pharm Bull Japan 8 28 1960;Rec Trav Chim Pays Bas 72 573 19531.

Chloroethane see ethyl chloride. 2-Chloroethanol [107-07-31 M 80.5, b 51.0°/31mm, 128.6°/760mm, d 1.201, Dried with, then distd from, CaS04 in the presence of a little Na2C03 to remove traces of acid.

d51.44380.

2-Chloroethyl bromide [107-04-01 M 143.4, b 106-108°. Washed with conc H2SO4, water, 10% Na2C03 soln, and again with water, then dried with CaC12 and fractionally distd before use. 2-Chlorethyl chloroformate [627-11-21 M 143.0, b 52-54O/12mm, 50°/15mm, 153°/760mm, d18 1.3760, nko 1.4460. Purified by fractional distn, preferably in a vacuum and stored in dry atmosphere. [JCS 2735 19571. 1-(2-Chloroethyl)pyrrolidine hydrochloride [ 7250-67-11 M 170.1, m 167-170°, 173.5-174O. Purified by recrystn from isopropanol-di-idopropylether (charcoal) and recrystallised twice more. Thefree base, b 55-56O/1 lmm, 60-63O/23mm and 90°/56mm, is relatively unstable and should be converted to the hydrochloride immediately, by dissolving in iso-propanol and bubbling dry HCl through the s o h at Oo, and filtering off the hydrochloride and recrystallising it. The picrate has m 107.3-107.8° (from EtOH), [Cason JOC 24 247 1959; JACS 70 3098 19481.

Purification of Organic Chemicals

143

2-Chloroethyl vinyl ether [IIO-75-81M 106.6, b 109°/760mm, d 1.048, n 1.437. Washed repeatedly with equal volumes of water made slightly alkaline with KOH, dried with sodium, and distd under vacuum. TOXIC. Chloroform [67-66-31M 119.4, b 61.2O, d15 1.49845, d10 1.47060, n15 1.44858. Reacts slowly with oxygen or oxidising agents, when exposed to air and light, giving, mainly, phosgene, C12 and HCl. Commercial CHC13 is usually stabilized by addn of up to 1% EtOH or of dimethylaminoazobenzene. Simplest purifications involve washing with water to remove the EtOH, drying with K2CO3 or CaC12, refluxing with P2O5, CaC12, CaS04 or Na2S04, and distilling. It must not be dried with sodium. The distd CHC13 should be stored in the dark to avoid photochemical formation of phosgene. As an alternative purification, CHC13 can be shaken with several small portions of conc H2SO4, washed thoroughly with water, and dried with CaC12 or K2CO3 before filtering and distilling. EtOH can be removed from CHC13 by passage through a column of activated alumina, or through a column of silica gel 4-ft long by 1.75-in diameter at a flow rate of 3ml/min. (The column, which can hold about 8% of its weight of EtOH, is regenerated by air drying and then heating at 6Oo0 for 6h. It is pre-purified by washing with CHC13, then EtOH, leaving in conc H2SO4 for about 8hr, washing with water until the washings are neutral, then air drying, followed by activation at 600° for 6h. Just before use it is reheated for 2h to 154O.) [McLaughlin, Kaniecki and Gray AC 30 1517 19581. Carbonyl-containing impurities can be removed from CHC13 by percolation through a Celite column impregnated with 2,4-dinitrophenylhydrazine,phosphoric acid and water. (Prepared by dissolving 0.5g DNPH in 6ml of 85% H3P04 by grinding together, then mixing with 4ml of distilled water and log of Celite.) [Schwartz and Parks AC 33 1396 19611. Chloroform can be dried by distn from powdered type 4A Linde molecular sieves. For use as a solvent in IR spectroscopy, chloroform is washed with water (to remove EtOH), then dried for several hours over anhydrous CaC12 and fractionally distd. This treatment removes material absorbing near 1600 cm-l. (Percolation through activated alumina increases this absorbing impurity). [Goodspeed and Millson Chemistry & Industry (London) 1594 19671. Chlorogenic acid [327-97-91 M 354.3, m 208O. [a&,’ -36O (c 1, HzO). Crystd from water. Dried at 1 loo.

5-Chloro-8-hydroxy-7-iodoquinoline [I 30-26-71 M 305.5, m 178-179O. Crystd from abs EtOH. 5-Chloroindole [I 7422-32-11 M 151.6, m 67-68O, 69-71°, 71.5-72S0, 72-73O, b 120130°/0.4mm. It is distd at high vacuum and recrystallises from pet ether (b 4G-6Oo) or (b 80-looo) as glistening plates. The picrate has m 147O ( 146.5-147S0)(from C&). [JCS 3493 1955;JOC 44 578 19791. 4-Chloroiodobenzene [637-87-61M 238.5, m 53-54O. Crystd from EtOH. 2,3-Chloromaleic anhydride [1122-17-41 M 166.9, m 112-115O. Purified by sublimation in vacuum [Katakis et al. JCSDT 1491 19861.

4-(Chloromercuri)benzenesulphonic acid monosodium salt [I4110-97-51 M 415.2. The free acid is obtained by acidifying an aq soln, filtering off the acid, washing it with H20 and recrystallising from hot H20 to give a colourless solid which is dried in a vacuum over P2O5 and should give negative C1- ions. The Na salt is made by dissolving in one equivalent of aqueous NaOH and evaporate to dryness. [ B 67 130 1934; J A CS 76 433 1 19541. 5-Chloro-2-methoxyaniline (2-amino-4-chloroanisole) [95-03-41M 157.6, m 81-83O, 82&lo, &lo. Purified by steam distn and recrystn from H20 or 40% aqueous EtOH. The N-acetare forms needles from hot H20 m 104O; the N-benzoyl derivative forms needles from aq EtOH m 77-78O; the picrare has m 1 9 4 O dec. [JACS 48 2657 19261. 9-Chloromethyl anthracene [24463-19-21M 226.7, m 141-142O dec, 141-142.5O. If it is free from OH in the IR then recryst from hexane-CgH,j or C6H6 as needles. If OH is present then some solvolysis has occurred. In this case treat 8.5g with SOC12 (4.8g) in dioxane (6Oml) and reflux for 5h, then evaporate to

144

Purification of Organic Chemicals

dryness and wash the residue with cold C6H6 and recrystallise. With KI/Me2CO it forms the iodomethyl derivative. [Martin et al. HCA 38 2009 1955; J O C 21 1512 19561.

2-Chloro-3-methylindole (2-chloroskatole) [51206-73-61 M 165.6, m 114.5-115S0. Purified by chromatography on silica gel in CH2C121pet ether (1:2), followed by recrystn from aqueous EtOH or aqueous acetic acid. [Phillips and Cohen JACS 108 2023 19861. 4-Chloro-2-methylphenol [1570-64-51 M 142.6, m 49O. Purified by zone melting. 4-Chloro-3-methylphenol [59-50- 761 M 142.6, m 66O. Crystd from pet ether. 4-Chloro-2-methylphenoxyaceytic acid MCPA [94-74-61 M 200.6, m 113-117O, 120°, 122123O. It is insoluble in H20 (sol 0.55gL at ZOO), and recrystallises from C6H6 or chlorobenzene as plates. The pKaZ0in H20 is 3.62 (3.05) [Acta Chem Scand 6 993 19521. The S-benzylthiouronium salt has m 164165O, and the Cu2+ salt has m 247-249Odec [Armarego et al. Nature 183 1176 1959; UV: Duvaux and Grabe Acta Chem Scand 4 806 1950; IR: Joberg Acta Chem Scand 4 798 19501. Chloromethyl phenyl sulphide { 7205-91 -61 M 158.7, b 63"/0.lmm, 9S0/12rnm, 11311S0/20mm. Dissolve in CH2C12 or CCI4 and dry over CaCI2, or pass through a tube of CaC12 and fractionally distil using a fractionating column. Harmful vapours. It gives the sulphone (b 1300/lmm and m 53O from EtOH) on oxidation with permonophthalic acid. [ A 563 54 64 19491. N-(Chloromethy1)phthalimide [ I 7564-64-61 M 195.6, m 131-13S0, 134-13S0, 136.5O. Purified by recrystn from EtOAc or CCl4 [JACS 70 2822 1948; Bohme et al. B 92 1258 19591.

1-Chloro-2-methylpropane see isobutyl chloride. 2-Chloro-2-methylpropane see rerr-butyl chloride.

4-(Chloromethy1)pyridine hydrochloride [1822-51-11 M 164.0, m 160-163O, 170-175O, 172173O. Purified by recrystn from EtOH or EtOH-dry Et20. It melts between 171O and 175O and the clear melt resolidifies on further heating at 190° and turns red to black at 280° but does not melt again. The picrutehydrochloride (prepared in EtOH) has m 146-147O. The free base is an oil, [Mosher and Tessieri JACS 73 4925 19511. 2-Chloro-1-methylpyridinium iodide [14338-32-01 M 255.5, m 203-20S0, 205-206O(dec), 207O. Purified by dissolving in EtOH and adding dry Et20. The solid is washed with Me2CO and dried at 20°/0.35mm. Store in the dark. Attempted recrystn from Me2CO-EtOH-pet ether (b 40-60°) caused some exchange of the C1 substituent by I. The picrate has m 106-107O, and the perchlorate has m 212-213O. [W and solvolysis: Barlin and Benbow JCS Perk Trans 2 790 19741. Chloromycetin see chloramphenicol. Chloromycetin palmitate see chloramphenicol palmitate. 1-Chloronaphthalene [90-13-11 M 162.6, f.p. -2.3O, b 136-136S0/20mm, 259.3°/760mm, d 1.194, n 1.6326. Washed with dilute NaHC03, then dried with Na2S04 and fractionally distd under reduced pressure. Alternatively, before distn, it was passed through a column of activated alumina, or dried with CaC12, then distd from sodium. It can be further purified by fractional crystn by partial freezing or by crystn of its picrate to constant melting point (132-133O) from EtOH, and recovering from the picrate. 2-Chloronaphthalene [91-58-71 M 162.6, m 61°, b 264-266O. Crystd from 25% EtOWwater and dried under vacuum. 1-Chloro-2 naphthol [633-99-81 M 178.6, m 70°. Cryst from pet ether. Acetate has m 42-43O.

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Purification of Organic Chemicals

2-Chloro-l-naphthol [606-40-61 M 178.6, m 64-65O. Crystd from pet ether 4-Chloro-l-naphthol chlorofonn.

[604-44-41 M 178.6, m 116-117O, 120-121O.

Crystd from EtOH or

6-Chloronicotinic acid [5326-23-81 M 157.6, m 190-193O, 198-199O(dec). Purified by recrystn from hot H20 and is sublimed in a vacuum. [Pechmann and Welsch B 17 2384 1884; Herz and Murty JOC 26 122 19611. 4-Chloro-2-nitroaniline [89-63-41 M 172.6, m 116-116.5O. Crystd from hot water or EtOHIwater and dried for 1Oh at 600 under vacuum. 2-Chloro-4-nitrobenzamide [3011-89-0] M 200.6, m 172O. Crystd from EtOH.

2-Chloro-l-nitrobenzene [88-73-31 M 157.6, m 32.8-33.2O. Crystd from EtOH, MeOH or pentane (charcoal). 3-Chloro-l-nitrobenzene [121-73-31 M 157.6, m 45.3-45.8O. Crystd from MeOH or 95% EtOH (charcoal), then pentane. 4-Chloro-l-nitrobenzene [100-00-5] M 157.6, m 80-83O, 83.5-84O, b 113°/8mm, 242O/atm, d :00-5 1.2914. Crystd from 95% EtOH (charcoal) and sublimes in a vacuum. [Emmons JACS 76 3470 1954; Newman and Forres JACS 69 1221 19471. 4-Chloro-7-nitrobenzofurazane (7-chloro-4-nitrobenzoxadiazole) [I 0 1 99-89-01 M 199.6, m 96.5-97O, 97O, 99-looo. Wash the solid with H20 and recrystallise from aqueous EtOH (1:l) as pale yellow needles. It sublimes in a vacuum [W,NMR: Bolton, Gosh and Katritzky JCS 1004 19661. l-Chloronitroethane [625-47-81 M 109.5, b 37-3S0/20mm, n 1.4224, n25 1.4235. Dissolved in alkali, extracted with ether (discarded), then the aqueous phase was acidified with hydroxylamine hydrochloride, and the nitro compound fractionally distd under reduced pressure. [Pearson and Dillon JACS 75 2439 19531. 2-Chloro-3-nitropyridine [5470-18-81 M 158.5, m 100-103°, 101-102°, 103-104O (sublimes). Forms needles from H20. Purified by continuous sublimation over a period of 2 weeks at 506O0/0.lmm. It has a pKa20 in H20 of -2.6 [Barlin JCS 2150 19641. The N-oxide has m 99-100°(from CH2C12-Et20). [Taylor and Driscoll JOC 25 1716 1960; Ochiai and Kaneko Chem Pharm Bull Japan 8 28 19601. 2-Chloro-5-nitropyridine [4548-45-21 M 158.5, m logo. Crystd from benzene or benzenelpet ether.

a-Chloro-3-nitrotoluene see 3-nitrobenzyl chloride. l-Chloropentane see n-amyl chloride. 3-Chloroperbenzoic acid [937-14-41 M 172.6, m 92-94O(dec). Recrystd from CH2C12 [Traylor and Mikztal JACS 109 2770 19871. Peracid of 99+% purity can be obtained by washing commercial 85% material with phosphate buffer pH 7.5 and drying the residue under reduced pressure. Alternatively the peracid can be freed from m-chlorobenzoic acid by dissolving 5 0 a of benzene and washing with an aq soln buffered at pH 7.4 (NaH2POflaOH) (5 x 100ml). The organic layer was dried over MgS04 and carefully evaporated under vacuum. Necessary care should be taken in case of EXPLOSION. The solid was recrystd twice from C H 2 C l ~ E t 2 0and stored at Oo in a plastic container as glass catalyses the decomposition of the peracid. The acid is assayed iodometrically. [JOC 29 1976 1964; Bortolini et al. JOC 52 5093 19871. 2-Chlorophenol [95-57-81 M 128.6, m 8.8O, b 61-62°/10mm, 176O/atm. Passed at least twice through a gas chromatograph column. Also purified by fractional distn. It has pKa 8.34 at 2 5 O in water.

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Purification of Organic Chemicals

3-Chlorophenol [108-43-01 M 128.6, m 33O, b 44.2O/lmm, 214OIatm. Could not be obtained solid by crystn from pet ether. Punfied by distn under reduced pressure. It has pKa 9.06 at 15O in water. 4-Chlorophenol [106-48-91 M 128.6, m 43O, 100-lO1°/lOmm. Distd, then crystd from pet ether (b 40-60°) or hexane, and dried under vacuum over P2O5 at room temp. It has pKa 9.38 at 20° in water. [Bernasconi and Paschalis JACS 108 2969 19861. Chlorophenol Red [4430-20-01 M 423.3, hm,,573nm. Crystd from glacial acetic acid. 4-Chlorophenoxyacetic acid [122-88-31 M 186.6, m 157O, a-4-Chlorophenoxypropionic acid [3307-39-91 M 200.6, m 116O, B-4-Chlorophenoxypropionic acid [3284- 79-51 M 200.6, m 138O. Crystd from EtOH. 3-Chlorophenylacetic acid [1878-65-51 M 170.6, m 74O, 4-Chlorophenylacetic acid [1878-66-61 M 170.6, m 102-105O, 105O, 106O. Crystd from EtOWwater, or as needles from C6H6 or H20 (charcoal). The pKa is 4.12. The acid chloride (prepared by boiling with SOC12) has b 127-129O/15mm. [Dippy and Williams JCS 161 1934; Misra and Shukla JlCS 28 480 19511. 4-Chloro-1-phenylbutan-1-one1939-52-61 M 182.7, m 19-20°, b 134-137°/5mm, d:' 1.149, nho 1.55413. Fractionate several times using a short column. It can be recrystd from anhydrous pet ether at -2OO as glistening white rosettes and filtered at Oo and dried in a vacuum desiccator over H2SO4. The semicarbazone has m 136-137O. [JACS 46 1882 1924,51 1174 1929, Hart and Curtis JACS 79 931 1957.

1-(2-Chlorophenyl)-1-(4-chlorophenyl)-2,2-dichloroethane(Mitotane, op'-DDD) [53-19-01 M 320.1, m 75.8-76.8O, 76-78O. Purified by recrystallisation from pentane and from MeOH or EtOH. It is sol in isooctane and CC14. [Hailer et a]. JACS 67 1600 19451. 3-(4-Chlorophenyl)-l,l-dimethylurea [150-68-51 M 198.7, m 171O. Crystd from MeOH. 2-Chlorophenyl diphenyl phosphate see Chapter 4.

4-Chloro-l,2-phenylenediamine[95-83-01 M 142.6, m 69-70O. Recrystd from pet. ether. 4-Chlorophenyl isocyanate [104-12-21 M 153.6, m 28-31°, 31-32O, 32O, 32S0, b 80.680.9°/9.5mm, 115-117°/45mm. Purified by recrystn from pet ether (b 30-40°) or better by fractional distn. TOXIC irritant. 4-Chlorophenyl isothiocyanate [2131-55-71 M 169.6, m 44O, 43-45O, 45O, 46O, 47O, b 110115°/4mm, 135-136°/24mm. Check the IR first. Slur with pet ether (b 30-60°) and decant the solvent. Repeat 5 times. The combined extracts are evap under reduced press to give almost pure compound as a readily crystallisable oil with a pleasant anise odour. It can be recrystd from the minimum vol of EtOH at 50° (do not boil too long in case it reacts). It can be purified by vac distn. Irritant [Org Synrh Coll Voi V 223 19731. 4-Chlorophenyl 2-nitrobenzyl ether, M 263.7, m 69O, 4-Chlorophenyl4-nitrobenzyl ether [5442-44-41 M 263.7, m 102O. Crystd from EtOH. 9-Chloro-9-phenylxanthene [42506-03-61 M 292.8, m 105-106O. Possible impurity is 9-hydroxy-9phenylxanthene. If material contains a lot of the hydroxy product then boil log in CHCI, (5Oml) with redistd acetyl chloride (lml) until liberation of HCI is complete. Evapn leaves the chlorophenylxanthene as the hydrochloride which on heating with benzene loses HCl; and on adding pet ether prisms of chlorophenylxanthene separate and contain 0.5mol of benzene. The benzene-free compound is obtained on drying and melts to a colourless liquid. [A 370 142 19091. The 9-phenylxanthyl group is called pixyl. [JCSCC 639 19781.

Purification of Organic Chemicals

147

Chlorophyll a [ 4 7 9 - 6 1 - 8 1 M 983.5, m 117-120°, 150-153O, 178-180O (sinters at -150°), [a]? -262O (Me2CO). Forms green crystals from MezCO, Et20 + H20, Et20 + hexane + H20 or Et2O + pentane + H20. It is sparingly soluble in MeOH and insol in pet ether. In alkaline s o h it gives a blue-green colour with deep red fluorescence. A very crude chlorophyll mixture has been purified by chromatography on low melting polyethylene (MI 0.044; 'Dow' melting index MI 13 in H20. [McOmie et al. JCS 3478 1955; West and Barrett JACS 76 3146 19541. 4 - C h 1o r o - 3,5 - x y 1e no1 see 4 - C h 1o r o - 3,5 -dimet h y 1p he n 01. Cholamine chloride hydrochloride.

hydrochloride see (2-aminoethy1)trimethylammonium

5-P-Cholanic acid [546-18-91 M 360.6, m 164-165O, [a]:

chloride

+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°, ether/EtOH.

+29S0 (c 2, CHC13).

Crystd from ethyl

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 ethedacetone. [Berzbrester and Chandran JACS 109 174 1987.

+64O.

Recrystd from MeOH or ethyl

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 109 4501 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 [303-43-51 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&. Chromazurol S [1667-99-81 M 539.3, A,,, 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. 4-Chromanone [ 4 9 1 - 3 7 - 2 1 M 148.2, m 35-37O, 38S0, 39O, 41°, b 92-93O/3mm, 130132°/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 s o h 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 s o h 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 , N dimethylformamideand 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 1011 19641. It can be sublimed in a vacuum. Chrysoidine G (4-phenylazo-1,3-benzenediaminemonohydrochloride) [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 SOCJapan 31 864 1958; B 10 213 18771. -127.5O (c 0.5, EtOH).

Cinchonidine [485-71-21 M 294.4, m 210S0, aqueous EtOH. Cinchonine [118-10-5] M 294.4, m 265O, ether.

Crystd from

+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 ocresol or resorcinol addition compounds. Stored with sodium until required.

151

Purification of Organic Chemicals

[14271-10-91 M 132.2, m -4O, -7S0, -9O, b 8 0 ° / 0 . 4 m m , trans-Cinnamaldehyde 85.8O/l. lmm, 125-128O/l lmm, 152.2°/40mm, 163.7°/60mm, 199.3°/200mm, 246O/7 60 m m 1.0510, n i o 1.623. Purified by steam distn (sol 1 in 700 parts H20) followed by distn in vacuo. dec, The cis-isomer has b 67-69°/40mm and 'd: 1.0436 and 1.5937. The trans-semicarbazone has m 210° dec from CHC13-MeOH (cis-semicarbazone has m 196O); the trans-phenylsemicarbazone has m 177O from CHC13MeOH (the cis-phenylsernicarbazone has m 146O); the trans-2,4-dinitrophenylhydra~one has m 250° dec from MeOH as the cis-isomer [Gamboni et al. H C A 38 255 1955;Peine B 17 21 17 1884; J O C 26 4814 1961; J A C S 86 198 19641.

di0

4'

trans-Cinnamic acid [140-10-31M 148.2, m 134.5-135O. Crystd from benzene, CCl4, hot water, water/EtOH (3: l), or 20% aqueous EtOH. Dried at 600 under vacuum. Cinnamic anhydride [538-56-71M 278.4, m 136O. Crystd from benzene or toluene/pet ether (b 6080O). N-Cinnamoyl-N-phenylhydroxylamine [7369-44-01 M 239.3, m 158-163O. Recrystd from EtOH. Cinnamyl alcohol [104-54-1J M 134.2, m 3 3 O , b 143S0/14mm, ,A cm-l). Crystd from ethyl ethedpentane.

251nm (E 18,180M-I

Cinnoline [253-66-71M 130.2, m 3 8 O . Crystd from pet ether. Kept under N2 in sealed tubes in the dark at Oo. Citraconic acid [498-23-71M 130.1, m 91O. Steam distd and crystd from EtOWligroin. Citraconic anhydride [616-02-41M 112.1, m 8-9O, b 47°/0.03mm, 213°/760mm, d i 0 1.245, nio 1.472. Possible contamination is from the acid formed by hydrolysis. If the IR has OH bands then reflux with Ac2O for 30 min, evaporate then distil the residue in a vacuum; otherwise distil in a vacuum. Store in a dry atmosphere. [BJ 191 269 19801. C i t r a n a x a n t h i n [3604-90-81M 456.7, m 155-156O, &llTm410 (349nm), 275 (466nm) in hexane. Purified by chromatography on a column of 1:1 magnesia-HyfloSuperceI. Crystd from pet ether. Stored in the dark, under inert atmosphere, at Oo. Citrazinic acid (2,6-dihydroxyisonicotinic acid) [99-11-61M 155.1, m >300°. Yellow powder with a greenish shade, but is white when ultra pure and turns blue on long standing. It is insoluble in H20 but slightly soluble in hot HCI and soluble in alkali or carbonate solutions. Purified by precipitation from alkaline solutions with dilute HCI, and dry in a vacuum over P2O5. Its pKa values in H20 are 3.00 and 4.76. The ethyl ester has m 232O (evacuated tube) and a pKa of 4.8 1 in MeOCH2CH20H [IR: Pitha Coll Czech Chem Comm 28 1408 19631. Citric acid ( H 2 0 ) [5949-29-11M 210.1, m 156-157O. 1 5 3 O (anhyd). Crystd from water. Citronella1 (3,7-dimethyloctan-6-al) [(+): 2385-77-51[(-): 5949-05-31 M 154.3, b 67°/4mm, 89°/14mm, 104-105°/21mm, 207°/760mm, f20°, [a]V+16So (neat). Fractionally distd. Alternatively extracted with NaHS03 solution, washed with Et20 then acidified to decompose the bisulphite adduct and extracted with Et20, dried (Na2S04), evaporated and distd. Check for purity by hydroxylamine titration. The RD in MeOH (c 0.167) is: [a],,, +9O, [a1589 +1l0, [ a 1 2 7 5 +12O and [a1260 12O. The semicarbazone has m 8 5 O , and the 2,4-dinitrophenylhydrazonehas m 79-80°. [IR: J C S 3457 1950;ORD: Djerassi and Krakower JACS 81 237 19591. P-Citronellene (2,6-dimethylocta-2,7-diene) [S-(+): 2436-90-01 [R-(-):10281-56-81M 138.3, b 153-154°/730mm, 15S0/atm, di20.7566, n ',?, 1.43070, [a];!6 + 1 3 O , [a];!6 * l o o ( n e a t ) . Purified by distillation over Na three times and fractionation. [(-) Arigoni and Jeager H C A 37 881 12954;(+) Eschenmoser and Schinz HCA 33 171 19501. Next Page