Previous Page 244

Ibogaine

Purification of Organic Chemicals

[83-74-91 M 300.3, m 152-153O. Crystd from aqueous EtoH.

Imidazole [288-32-41 M 68.1, m 89.5-91°, b 256O. Crystd from benzene, CC14, CH2C12, EtOH, pet ether, acetone/pet ether and distd deionized water. Dried at 40° under vacuum over P2O5. Distd at low pressure. Also purified by sublimation or by zone melting. [Caswell and Spiro JACS 108 6470 19863. '5N-imidazole was crystd from benzene [Scholes et al. JACS 108 1660 19861. 2-Imidazolidinethione 2-Imidazolidone

see ethylene thiourea.

see ethylene urea.

4-(Imidazol-l-yl)acetophenone [I0041-06-21 M 186.2, m 104-107O. Twice recrystd from CH2C12/hexane [Collman et al. JACS 108 2588 19861.

4,4'-(imidocarbonyl)bis(N,N'-dimethylaniline)

monohydrochloride see Auramine 0.

Iminodiacetic acid [142-73-41 M 133.1, m 225O(dec). Crystd from water. 2,2'-Iminodiethanol

see diethanolamine.

1,3-Indandione [606-23-51 M 146.2, m 129-132O. Recrystd from EtOH [Bernasconi and Paschalis JACS 108 2969 19861. Indane [496-11-71 M 118.1, b 177O, d 0.960, n 1.538. Shaken with conc H2SO4, then water, dried and fractionally distd. Indanthrone [81-77-61 M 442.4, m 470-500°. Crystd repeatedly from 1,2,4-trichlorobenzene. Indazole [271-44-31 M 118.1, m 147O. Crystd from water, sublimed under a vacuum, then pet ether (b 60-80O). Indene [95-13-61 M 116.2, f.p. -lSO,b 114.5°/100mm, d 0.994, n 1.5763. Shaken with 6M HCI for 24h (to remove basic nitrogenous material), then refluxed with 40% NaOH for 2h (to remove benzonitrile). Fractionally distd, then fractionally crystd by partial freezing. The higher-melting portion was converted to its sodium salt by adding a quarter of its weight of sodamide under nitrogen and stimng for 3h at 1200. Unreacted organic material was distd off at 120°/lmm. The sodium salts were hydrolysed with water, and the organic fraction was separated by steam distn, followed by fractional distn. Before use, the distillate was passed, under nitrogen, through a column of activated silica gel. [Russell JACS 78 1041 19561. Indigo [482-89-31 M 262.3, and halogen-substituted indigo dyes. Reduced in alkaline s o h with sodium hydrosulphite, and filtered. The filtrate was then oxidised by air, and the resulting ppte was filtered off, dried at 65-700, ground to a fine powder, and extracted with CHC13 in a Soxhlet extractor. Evapn of the CHC13 gave the purified dye. [Brode, Pearson and Wyman JACS 76 1034 1954; spectral characteristics are listed]. Indigocarmine (2[1,3-dihydro-3-oxo-5-sulpho-2H-indol-2-ylidene]-2,3-dihydro-3-oxo-lHindole-5-sulpfonic acid disodium salt) [860-22-01 M 466.4. Its solubility in H20 is lg/lOOml at 25O. Could be purified by dissolving in H20, filtering and adding EtOH to cause the salt to separate. Wash the solid with EtOH, Et20 and dry in vacuo. It has pKa values of 2.8 and 12.3 in H20. [Vorlander and Schubert B 34 1860 1901; UV: Smit et al. A C 27 1159 1955; Preisler et al. JACS 81 1991 19591. Indole [120-72-91 M 117.2, m 52O, 124O/5mm, b 253-254°/760mm. Crystd from benzene, hexane, water or EtOWwater (1 :10). Further purified by sublimation in a vacuum or zone melting. Indole-3-acetic acid [87-51-41 M 175.2, m 167-169O. Recrystd from EtOH/water [James and Ware JPC 89 5450 19851.

Purification of Organic Chemicals

245

3 - I n d o l e a c e t o n i t r i l e [ 7 7 1 - 5 1 - 7 ] M 156.2, m 33-36O, 36-3S0, b 157°/0.2mm, 158160°/0.1mm, viscous oil nko 1.6097. Distil in very high vacuum and the viscous distillate crystallises on standing after a few days; the picrate has m 127-128O (from EtOH) [Coker et al. JOC 27 850 1962; Thesing and Schulde B 85 324 19521, The N-acetate has m 118O (from MeOH) and has RF = 0.8, on Silica Gel F254 in CHC12-MeOH 19:l [Buzas et al. S 129 1978. Indole-3-butanoic acid [133-32-41 M 203.2, m 124-125O, Indole-3-propionic acid [830-96-61 M 189.2, m 134-135O. Recrystd from EtOH/water [James and Ware JPC 89 5450 19851. (-)-Inosine 80% EtOH.

[58-63-91 M 268.2, m 215O,

[~1]?&

-76O (c 1, 0.1M NaOH). Crystd from aqueous

i-Inositol [87-88-81 M 180.2, m 228O. Crystd from water or aqueous 50% EtOH. Dried under vacuum. meso-Inositol [87-89-81 M 180.2, m 223-225O. Crystd from aqueous EtOH. Inositol monophosphate [15421-51-9/ M 260.1, m 195-197O(dec). Crystd from water and EtOH. Inulin [9005-80-5] M (162.14)". Crystd from water. Iodoacetamide [144-48-91 M 185.0, m ca 143O(dec). Crystd from water or CCl4. Iodoacetic acid [64-69-71 M 160.6, m 78O. Crystd from pet ether (b 60-80°) or CHC13/CCl 1-Iodoadamantane see 1-adamantyl iodide. 2-Iodoaniline [615-43-01 M 219.0, m 60-61O. Distd with steam and crystd from benzene/pet ether. 4-Iodoaniline [540-37-41 M 219.0, m 62-63O. Crystd from pet ether (b 60-80°) by refluxing, then cooling in an ice-salt bath freezing mixture. Dried in air. Also crystd from EtOH and dried in a vacuum for 6h at 40° [Edidin et al. JACS 109 3945 1 9 8 8 . 4-Iodoanisole aqueous EtOH.

[696-62-81 M 234.0, m 51-52O, b 139O/35mm, 237O/726mm.

Crystd from

Iodobenzene [591-50-4] M 204.0, b 63-65O/lOrnm, 18S0/atm, d 1.829, n25 1.6169. W a s h e d with dilute aqueous Na2S203, then water. Dried with CaC12 or CaS04. Decolorised with charcoal. Distd under reduced pressure and stored with mercury or silver powder to stabilise it. o-Iodobenzoic acid [88-67-51 M 248.4, m 162O, m-Iodobenzoic acid [618-51-91 M 248.4, m 186.6-186.8O, p-Iodobenzoic acid [619-58-91 M 248.4, m 271-272O. Crystd repeatedly from water and EtOH. Sublimed under vacuum at 1W. 4-Iodobiphenyl [1591-31-71 M 280.1,m 113.7-114.3O. Crystd from EtOH/benzene and dried under vacuum over P2O5. 1-Iodobutane

see n-butyl iodide.

2-Iodobutane [513-48-41 M 184.0, b 120.0, d 1.50, n25 1.4973. Purified by shaking with conc H2SO4, then washing with water, aq Na2S03 and again with water. Dried with MgS04 and distd. Alternatively, passed through a column of activated alumina before distn, or treated with elemental bromine, followed by extraction of the free halogen with aqueous Na2S203, thorough washing with water, drying and distilling. It is stored over silver powder and distd before use.

246

Purification of Organic Chemicals

l-Iodo-2,4-dinitrobenzene [709-49-91 M 294.0, m 8 8 O . Crystd from ethyl acetate. Iodoethane

see ethyl iodide.

Iodoform [75-47-81 M 393.7, m 119O. Crystd from MeOH, EtOH or EtOH/ethyl acetate. 1-Iodo-2-methylpropane

see isobutyl iodide.

1-Iodo-4-nitrobenzene [636-98-61 M 249.0, m 171-172O. Ppted from acetone by addition of water, then recrystd from EtOH. o-Iodophenol [533-58-41 M 280.1, m 42O. Crystd from CHC13 or ethyl ether. p-Iodophenol [540-38-51 M 280.1, m 94O. Crystd from pet ether (b 80-looo). 1-Iodopropane see n-propyl iodide. 2-Iodopropane see isopropyl iodide 3-Iodopropene

see allyl iodide.

5-Iodosalicylic acid [119-30-21 M 264.0, m 197O. Crystd from water. o-Iodosobenzoic acid [304-91-61 M 264.0, m >200°. Crystd from EtOH. N-Iodosuccinimide p-Iodotoluene

[512-12-11 M 225.0, m 200-201°. Crystd from dioxane/CC14.

[624-31-71 M 218.0, m 35O, b 211-212O. Crystd from EtOH.

3-Iodo-L-tyrosine [70-78-01 M 307.1, m 205-208°(dec), [a]L5 -4.4O (1M HCI). L i k e l y impurities are tyrosine, diiodotyrosine and iodide. Crystd by soln in dilute ammonia, at room temperature, followed by addition of dilute acetic acid to pH 6. Stored in the cold. a-Ionone [127-41-31 M 192.3, b 131°/13mm, d 0.931, n 1.520, on a spinning band fractionating column.

[a]y +347O (neat).

Purified

p-Ionone [79-77-61 M 192.3, b 150-151°/24mm, d 0.945, n 1.5211, &296nm 10,700. Converted to the semicarbazone (m 149O) by adding 50g of semicarbazide hydrochloride and 44g of potassium acetate in 150ml of water to a soln of 85g of 6-ionone in EtOH. (More EtOH was added to redissolve any Bionone that ppted.) The semicarbazone crystallised on cooling in an ice-bath and was recrystallised from EtOH or 75% MeOH to constant m (148-149O). The semicarbazone (5g) was shaken at room temperature for several days with 20ml of pet ether and 48ml of M H2SO4, then the ether layer was washed with water and dilute aqueous NaHC03, dried and the solvent was evaporated. The B-ionone was distilled under vacuum. (The customary steam distillation of B-ionone semicarbazone did not increase the purity.) [Young et al. JACS 66 855 19441. Iproniazid phosphate [305-33-91 M 277.2, m 178-179O. Crystd from water and acetone. (+)-Irone (6-methyl-ionone, f-trans-(a)-4t-[2,5,6,6-tetramethyl-cyclohex-2-yl]but-3t-en2-one) [79-69-61 M 206.3, b 85-86°/0.05mm, 109°/0.7mm, d:' 0.9340, n i o 1.4998. If large amounts are available then fractionate through a Podbielniak column or an efficient spinning band column, but small amounts are distilled using a Kugelrohr apparatus. The 4-phenyl-semicarbazone has m 174-175O(165165.5O). [IR: Seidel and Ruzocka HCA 35 1826 1952; Naves HCA 31 1280 J948; Lecomte and Naves J Chimique Physique 53 462 19561.

Purification of Organic Chemicals

247

Isatin [91-56-51 M 147.1, m 200O. Crystd from amyl alcohol. Isatoic anhydride (3,1-benzoxazin-2,4[l-H]-dione)[ I 18-48-91 M 1633.1, m 235-240°, 240243O, 243O, 243-245O. Recryst from EtOH or 95% EtOH (30ml/g) or dioxane (lOml/g) and dried in a vacuum. [Wagner and Fegley Org Synth Coll Vol 111 488 1955; Ben-Ishai and Katchalski JACS 74 3688 1952; UV: Zentmyer and Wagner JOC 14 967 19491. Isoamyl acetate [123-92-21 M 130.2, b 142.0°, d 0.871, n 1.40535. Dried with finely divided K2CO3 and fractionally distd. Isoamyl alcohol [123-51-31 M 88.2, b 132°/760mm, d 0.809, n 1.408. Dried with K2CO3 or CaS04, then fractionally distd. If more nearly anhydrous alcohol is required, the distillate can be refluxed with the appropriate alkyl phthalate or succinate as described for ethanol. Isoamyl bromide [107-82-41 M 151.1, f.p. -112O, b 119.2°/737mm, d 1.208, n 1.444. Shaken with conc H2SO4, washed with water, dried with K2CO3 and fractionally distd. Isoamyl chloride [513-36-01 M 106.6, b 99O/734mm, d 0.8704, n 1.4084. Shaken vigorously with 95% H2SO4 until the acid layer no longer became coloured during 12h, then washcd with water, saturated aq Na2C03, and more water. Dried with MgS04, filtered and fractionally distd. Alternatively, a stream of oxygen containing 5% of ozone was passed through the chloride for a time, three times longer than was necessary to cause the first coloration of starch iodide paper by the exit gas. Subsequent washing of the liquid with aqueous NaHC03 hydrolysed the ozonides and removed organic acids. After drying and filtering, the isoamyl chloride was distd. [Chien and Willard JACS 75 6160 19531. Isoamyl ether [544-01-41 M 158.3, b 173.4O, d 0.778, n 1.40850. This is a mixture of 2- and 3methylbutyl ether. It is purified by refluxing with sodium for 5h, then distilled under reduced pro,ssure, to remove alcohols. Isoamyl ether can also be dried with CaC12 and fractionally distd from P2O5. Isoascorbic acid dioxane.

[89-65-61 M 176.1, m 174O(dec), [a]: -16.8O (c 2, H 2 0 ) . Crystd from H20 or

dl-Isoborneol [124-76-51 M 154.3, m 212O (sealed tube). Crystd from EtOH or pet ether (b 6080°). Sublimes in a vacuum. Isobutane [75-28-51 M 58.1, b -10.2O, d 0.557. Olefines and moisture can be removed by passage at 65O through a bed of silica-alumina catalyst which has previously been evacuated at about 4 0 0 O . Alternatively, water and C02 can be taken out by passage through P2O5 then asbestos impregnated with NaOH. Treatment with anhydrous AlBr3 at Oo then removes traces of olefines. Inert gases can be separated by freezing the isobutane at -195O and evacuating out the system. Isobutene [115-11-7] M 56.1, b -6.6°/760mm. Dried by passage through anhydrous C a s 0 4 at Oo. Purified by freeze-pump-thaw cycles and trap-to-trap distn. Isobutyl alcohol [78-83-11 M 74.1, b 108°/760mm, d 0.801, n 1.396. Dried with K2CO3, Cas04 or CaC12, filtered and fractionally distd. For further drying, the redistd alcohol can be refluxed with the appropriate alkyl phthalate or succinate as described under ethanol. Isobutyl bromide [78-77-31 M 137.0, b 91.2O, d 1.260, n 1.437. Partially hydrolysed to remove any tertiary alkyl halide, then fractionally distd, washed with conc H2SO4, water and aqueous K2CO3, then redistd from dry K2CO3. [Dunbar and Hammett JACS 72 109 19501. Isobutyl chloride 1513-36-01 M 92.3, b 68.8°/760mm, d 0.877, n 1.398. described under isoamyl chloride.

Same methods as

248

Purification of Organic Chemicals

Isobutylene see Isobutene. Isobutyl formate [543-27-11 M 102.1, b 98.4O, d 0.885, q 1.38546. Washed with saturated aqueous NaHC03 in the presence of saturatedd NaCl, until no further reaction occurred, then with saturated aqueous NaCl, dried (MgS04) and fractionally distd. Isobutyl iodide [513-38-21 M 184.0, b 83°/250mm, 120°/760mm, d 1.60, n 1.495. S h a k e n with conc H2SO4, and washed with water, aqueous Na2S03, and water, dried with MgS04 and distd. Alternatively, passed through a column of activated alumina before distn. Stored under nitrogen with mercury in a brown bottle or in the dark. Isobutyl mercaptan

see 2-methylpropane-1-thiol.

Isobutyl vinyl ether [109-53-51 M 100.2, b 108-llOo, d 0.768, n 1.398. Washed three times with equal volumes of aqueous 1% NaOH, dried with CaH2, refluxed with sodium for several hours, then fractionally distd from sodium. Isobutyraldehyde [78-84-21 M 72.1, b 62.0°, d 0.789, n 1.377. Dried with C a s 0 4 and used immediately after distn under nitrogen because of the great difficulty in preventing oxidation. Can be purified through its acid bisulphite derivative. Isobutyramide [563-83-71 M 87.1, m 128-129O, b 217-221O. Crystd from acetone, benzene, CHC13 or water, then dried under vacuum over P2O5 or 99% H2SO4. Sublimed under vacuum. Isobutyric acid [79-31-21 M 88.1. b 154-154S0, d 0.949, n 1.393. Distd from KMn04, then redistd from P2O5. Isobutyronitrile [78-82-01 M 69.1, b 103.6O, d25 0.7650, n 1.378. Shaken with conc HCl (to remove isonitriles), then with water and aq NaHCO3. After a preliminary drying with silica gel or Linde type 4A molecular sieves, it is shaken or stirred with CaH2 until hydrogen evolution ceases, then decanted and distd from P2O5 (not more than 5 g L , to minimize gel formation). Finally it is refluxed with, and slowly distd from CaH2 (5gL), taking precautions to exclude moisture. (-)-y-Isocaryophyllene (8-methylene-4,11,11-trimethylbicyclo[7,2,O]undec-4-ene) [118-65O] M 204.4, b 122-124°/12mm, 131-133°/16mm, 130-131°/24mm, 271-273O/atm, d;' 0.8959, n v 1.496, -31°, [ a ] v-27O (neat). Purified by vac dist or GLC using a nitrile-silicone column [Corey et al. JACS 86 485 1964; Ramage and Simonsen JCS 741 1936; Kumar et al. S 461 19761.

Isodurene see 1,2,3,5-tetramethylbenzene. L-Isoleucine [73-32-51 M 131.2, m 285-286O(dec), [a];' +40.6O (6M HCI). Crystd from water by addition of 4 volumes of EtOH. (-)-P-Isolongifolene (1-R02,2,7,7-tetramethyltricyclo[6.2.1.01~6]undec-5-ene) [ I 135-66-61 M 204.4, b82-83°/0.4mm, 144-146°/30mm, 255-256O/atm, d;' 0.930, n i ' 1.4992, [ a -166O, [a]:' -138O (c 1, EtOH). Refluxed over and distd from Na. [Zeiss and Arakawa JACS 76 1653 1954; IR: Reinaecker and Graafe Angew Chemie, Engl Edn. 97 348 1985; UV and NMR: Ranganathan et al. TET 26 621 19701. Isolysergic acid water.

[478-95-51 M 268.3, m 218O(dec), [a];'

+281° (c 1, pyridine). Crystd from

Isonicotinamide [1453-82-31 M 122.1, m 155.5-156O. Recrystd from hot water. Isonicotinic acid [55-22-1]M 123.1, m 320O. Crystd repeatedly from water. Dried under vac at 1loo.

Purification of Organic Chemicals

Isonicotinic acid hydrazide

249

[54-87-31 M 137.1, m 172O. Crystd from 95% EtOH.

1-Isonicotinic acid 2-isopropylhydrazide benzene/pet ether.

[54-92-21 M 179.2, m 112.5-113.5°. Crystd from

1-Isonicotinyl-2-salicylidenehydrazide [495-84-11 M 241.2, m 232-233O. Crystd from EtOH. Isonitrosoacetone [31915-82-91 M 87.1, m 69O. Crystd from ether/pet ether or CCl4. Isonitrosoacetophenone

[532-54-71 M 149.2, m 126-128O. Crystd from water.

5-Isonitrosobarbituric acid (violuric acid) or EtOH.

[87-39-81 M 175.1, m 245-250°. Crystd from water

Isononane [34464-40-91 M 128.3, b 142O/760mm. Passed through columns of activated silica gel and basic alumina (activity 1). Distd under high vacuum from Na/K alloy. Isooctane Isopentane

see 2,2,4-trimethylpentane. see 2-methylbutane.

Isopentenyl pyrophosphate Isopentyl-

see Chapter 5

see isoamyl-.

Isopentyl formate [ I 10-45-21 M 116.2, b 121-123O/atm, 123-123.6O/atm, 123-l24O/atm7 d:' 0.8713, n;' 1.391. Colourless liquid which is soluble in 300 volumes of H2O and is soluble in common organic solvents. It is purified by repeated distn using an efficient column at atmospheric pressure. Isophorone [78-59-11 M 138.2, b 94°/16mm, d 0.921, n l S 1.4778. Washed with aqueous 5% Na2C03 and then distd under reduced pressure, immediately before use. Alternatively, can be purified via the semicarbazone. [Erskine and Waight JCS 3425 19601. Isophthalic acid [121-91-51 M 166.1, m 345-348O. Crystd from aqueous EtOH. (+)-(1S92S,3S,5R)[27779-29-91 and (-)-(lR,2R,3R,SS) (25465-65-01 I s o p i n o c a m p h e o l (pinan-3-01, 2,6,6-trimethylbicyclo[3.l.l]heptan-3-ol) M 154.25, m 52-5S0, 55-56O, 5557O, b 103°/11mm, n y 1.4832, [ a ] & f43O, [a]ko+36O (c 20, EtOH). Dissolve in Et20, dry MgS04, filter, evaporate, then recryst from pet ether. Also recryst from aqueous EtOH and has been distd in a vacuum. [Kergomard and Geneix Bull SOC Chim France 394 1958; Zweifel and Brown JACS 86 393 19641. The 3,4-dinitrobenzoyl deriv has m 100- 101O, the phenylcarbamoyl derivative has m 137-138O and the acid -phrhallate has m 125-126O. Isoprene [78-79-51 M 68.1, b 34.5-35°/762mm, d 0.681, n25 1.4225. Refluxed with sodium. Distd from sodium or NaBH4 under nitrogen, then passed through a column containing KOH, Cas04 and silica gel. tert-Butylcatechol (0.02% w/w) was added, and the isoprene was stored in this way until redistd before use. The inhibitor (tert-butylcatechol) in isoprene can be removed by several washings with dil NaOH and water. The isoprene is then dried over CaH2, distd under nitrogen at atmospheric pressure, and the fraction distilling at 32O is collected. Stored under nitrogen at -15O. Isopropanol [67-63-01 M 60.1, b 82S0, d 0.783, n25-8 1.3739. Isopropyl alcohol is prepared commercially by dissolution of propene i n H2SO4, followed by hydrolysis of the sulphate ester. Major impurities are water, lower alcohols and oxidation products such as aldehydes and ketones. Purification of isopropanol follows substantially the same procedure as for n-propyl alcohol.

250

Purification of Organic Chemicals

Isopropanol forms a constant-boiling mixture, b 80.3O, with water. Most of the water can be removed from this 91% isopropanol by refluxing with CaO (200gk) for several hours, then distilling. The distillate can be dried further with CaH2, magnesium ribbon, BaO, CaS04, calcium, anhydrous CuSO4 or Linde type 5A molecular sieves. Distn from sulphanilic acid removes ammonia and other basic impurities. Peroxides [indicated by liberation of iodine from weakly acid (HCl) solns of 2% KI] can be removed by refluxing with solid stannous chloride or with NaBH4 then fractionally distilling. To obtain isopropanol containing only 0.002M of water, sodium (8&) has been dissolved in material dried by distn from CaS04, 35ml of isopropyl benzoate has been added and, after refluxing for 3h, the alcohol has been distd through a 50-cm Vigreux column. [Hine and Tanabe JACS 80 3002 19581. Other purification steps for isopropanol include refluxing with solid aluminium isopropoxide, refluxing with NaBH4 for 24h, and the removal of acetone by treatment with, and distn from 2,4-dinitrophenylhydrazine. Peroxides re-form in isopropanol if it is stood for several days.

Isopropenylcyclobutane [3019-22-51 M 98.1. Purified by preparative chromatography (silicon oil column). Dried with molecular sieves. Isopropyl acetate [108-22-51 M 102.1, b 88.4O, d 0.873, n 1.3773. Washed with 50% aq K2CO3 (to remove acid), then with saturated aq CaC12 (to remove any alcohol). Dried with CaC12 and fractionally distd. Isopropyl alcohol

see isopropanol.

Isopropyl benzene see cumene. Isopropyl bromide [75-26-31 M 123.0, b 0°/69.2mm, 59.4°/760mm, d 1.31, n15 1.42847, n 1.4251. Washed with 95% H2SO4 (conc acid partially oxidised it) until a fresh portion of acid did not become coloured after several hours, then with water, aq NaHS03, aq 10%Na2C03 and again with water. (The H2SO4 can be replaced by conc HCl.) Prior to this treatment, isopropyl bromide has been purified by bubbling a stream of oxygen containing 5% ozone through it for lh, followed by shaking with 3% hydrogen peroxide s o h , neutralising with aq Na2C03, washing with distilled water and drying. Alternatively, it has been treated with elemental bromine and stored for 4 weeks, then extracted with aq NaHS03 and dried with MgS04. After the acid treatment, isopropyl bromide can be dried with Na2S04, MgS04 or CaH2, and fractionally distd. N-Isopropylcarbazole [1484-09-91 M 209.3. Crystd from isopropanol. Sublimed under vacuum. Zone refined. Isopropyl chloride [75-29-61 M 78.5, b 34.S0, d 0.864, n 1.3779, n25 1.3754. Purified with 95% H2SO4 as described for isopropyl bromide, then dried with MgS04, P2O5 or CaH2, and fractionally distd from Na2C03 or CaH2. Alternatively, a stream of oxygen containing cu 5% ozone has been passed through the chloride for about three times as long as was necessary to obtain the first coloration of starch iodide paper by the exit gas, and the liquid was then washed with NaHC03 soln to hydrolyse ozonides and remove organic acids before drying and distilling.

Isopropyl ether [108-20-31 M 102.2, b 68.3O, d 0.719, n 1.3688, nZ5 1.36618. C o m m o n impurities are water and peroxides [detected by the liberation of iodine from weakly acid (HCl) solns of 2% KI]. Peroxides can be removed by shaking with aqueous Na2S03 or with acidified ferrous sulphate (0.6g FeSO4 and 6ml conc H2SO4 in 1 lOml of water, using 5-log of soln per L of ether), or aqueous NaBH4 soln. The ether is then washed with water, dried with CaC12 and distd. Alternatively, refluxing with LiAlH4 or CaH2, or drying with CaS04, then passage through an activated alumina column, can be used to remove water and peroxides. Other dehydrating agents used with isopropyl ether include P2O5, sodium amalgam and sodium wire. (The ether is often stored in brown bottles, or in the dark, with sodium wire.) Bonner and Goishi (JACS 83 85 1961) treated isopropyl ether with dil sodium dichromate/sulphuric acid soln, followed by repeated shaking with a 1 :1 mixture of 6M NaOH and saturated KMnO4. The ether was washed several times with water, dilute aqueous HCl, and water, with a final washing with, and storage over, ferrous ammonium sulphate acidified with H2SO4. Blaustein and Gryder (JACS 79 540 19.53, after washing with alkaline KMnO4, then water, treated the ether with ceric nitrate in nitric acid, and again washed with water. Hydroquinone was added before drying with CaC12 and MgS04, and refluxing with sodium amalgam (108g Hg/100g Na) for 2h under nitrogen. The distillate

Purification of Organic Chemicals

251

(nitrogen atmosphere) was made 2 x 10-5M in hydroquinone to inhibit peroxide formation (which was negligible if the ether was stored in the dark). Pyrocatechol and resorcinol are alternative inhibitors.

4,4'-Isopropylidenediphenol [80-05-7] M 228.3, m 158O. Crystd from acetic acid/water (1 :1). Isopropyl iodide [75-30-91 M 170.0, b 88.9O, d 1.70, n 1.4987. Treated with elemental bromine, followed by extraction of free halogen with aqueous Na2S203 or NaHSO3, washing with water, drying (MgS04 or CaC12) and distn. (The treatment with bromine is optional.) Other purification methods include passage through activated alumina, or shaking with copper powder or mercury to remove iodine, drying with P2O5 and distn. Washing with conc H2SO4, water, aqueous Na2S03, water and aqueous Na2C03 has also been used. Treatment with silica gel causes some liberation of iodine. Distillations should be carried out at slightly reduced pressure. Purified isopropyl iodide is stored in the dark in the presence of a little mercury. Isopropyl mercaptan

see

propane-2-thiol.

Isopropyl methyl ether [598-53-81 M 74.1, b 32S0/777mm, d15 0.724, n 1.3576. Purified by drying with CaSO4, passage through a column of alumina (to remove peroxides) and fractional distn. Isopropyl p-nitrobenzoate [13756-40-61 M 209.2, m 105-106O. Dissolved in ethyl ether, washed with aqueous alkali, then water and dried. Evapn of the ether and recrystn from EtOH gave pure material. p-Isopropyl toluene [99-87-61 M 134.2, b 176.9O/744mm, d 0.856, n 1.4902. CaH2 and fractionally distd. Stored with CaH2.

Dried with

Isoquinoline [119-65-31 M 129.2, m 2 4 O , b 120°/18mm, d 1.0986, n 1.6148. Dried with Linde type 5A molecular sieves or Na2S04 and fractionally distd at reduced pressure. Alternatively, it was refluxed with, and distd from, BaO. Also purified by fractional crystn from the melt and distd from zinc dust. Converted to its phosphate (m 135O) or picrate (m 223O), which were purified by crystn and the free base recovered and distd. [Packer, Vaughn and Wong JACS 80 905 19581. The procedure for purifying via the picrate comprises the addition of quinoline to picric acid dissolved in the minimum volume of 95% EtOH to yield yellow crystals which are washed with EtOH and air dried before recrystn from acetonitrile. The crystals are dissolved in dimethyl sulphoxide (previously dried over 4A molecular sieves) and passed through a basic alumina column, on which picric acid is adsorbed. The free base in the effluent is extracted with n-pentane and distd under vacuum. Traces of solvent are removed by vapour phase chromatography. [Mooman and Anton JPC 80 2243 19761. Isovaleric acid [502-74-21 M 102.1, b 176S0/762mm, d 0.927, n15 1.4064, n 1.40331. Dried with Na2S04, then fractionally distd. L-Isovaline [595-40-41 M 117.2, m c a 300° (sublimes in vac), [ 0 r ] ' , ~ + 9 ~(2M HCI). C r y s t d from aqueous acetone. Isovanillin (3-hydroxy-4-methoxybenzaldehyde)[621-59-01 175O/14mm. Cryst from H20 or C&. The oxime has m 147O.

M 152.2, m 117O, b

Isoviolanthrone [128-64-3] M 456.5, m 510-511°(uncorrected). Dissolved in 98% H2SO4 and ppted by adding water to reduce the acid concentration to about 90%. Sublimes in vacuo. [Parkyns and Ubblehode JCS 4188 19601. Itaconic acid [97-65-41 M 130.1, m 165-166O. Crystd from EtOH, EtOWwater or EtOHbenzene. Itaconic anhydride (2-propen-1,2-dicarboxylicanhydride) [2170-03-81 M 112.1, m 66-68O, 67-68O, 68O, b 139-140°/30mm. Crystd from CHC13/pet ether. Can be distd under reduced press. Distn at atm press, or prolonged distn causes rearrangement to citraconic anhydride (2-methylmaleic anhydride). If the material (as seen in the IR spectrum) contains much free acid then heat with acetyl chloride or SOC12, evaporate

Next Page