Previous Page Purification of Organic Chemicals

279

Morpholine [110-91-81 M 87.1, f.p. -4.9O, b 128.9O, d 1.0007, n 1.4540, n25 1.4533. D r i e d with KOH, fractionally distd, then refluxed with Na, and again fractionally distd. Dermer and Dermer [JACS 59 1148 19371 ppted as the oxalate by adding slowly to slightly more than 1 molar equivalent of oxalic acid in EtOH. The ppte was filtered and recrystd twice from 60% EtOH. Addition of the oxalate to conc aq NaOH regenerated the base, which was separated and dried with solid KOH, then sodium, before being fractionally distd.

2-(N-Morpholino)ethanesulphonic acid (MES) [4432-31-91 M 213.3, m >300°(dec). Crystd from hot EtOH containing a little water. It has a basic pKa of 6.95. Mucic acid see galactaric acid. Mucochloric acid [87-56-91 M 169.0, m 124-126O. Crystd twice from water (charcoal). trans,trans-Muconic acid [3588-17-81 M 142.1, m 300°, Muramic acid (H20) [1114-41-61 M 251.2, m 152-154O(dec), [a];' +155O to +llOo (in H2O). Crystd from water. 520nm (E 12,000). The sample may be grossly Murexide [3051-09-01 M 284.2, m >300°, ,,A contaminated with uramil, alloxanthine, etc. Difficult to purify. It is better to synthesise it from pure alloxanthine [Davidson JACS 58 1821 19361. Crystd from water. Myristic acid [544-63-81 M 228.4, m 5 8 O . Purified via the methyl ester (b 153-154°/10mm, n25 1.4350), as for capric acid. [Trachtman and Miller JACS 84 4828 19621. Also purified by zone melting. Crystd from pet ether.

Nap ht hacene

(benz[b]anthracene, 2,3-benzanthracene, rubene) [92-24-01 M 228.3,

m >300°, 341°(open capillary), 349O, 357O. Crystd from EtOH or benzene. Dissolved in sodiumdried benzene and passed through a column of alumina. The benzene was evaporated under vacuum, and the chromatography was repeated using fresh benzene. Finally, the naphthacene was sublimed under vacuum. [Martin and Ubblehode JCS 4948 19611. Also recrysts in orange needles from xylene and sublimes in vucuo at 186O. [UV: B 65 517 1932, 69 607 1936; IR: Spectrochim Actu 4 373 19511.

2-Naphthaldehyde [66-99-9] M 156.2, m 59O, b 260°/19mm. Distilled with steam and crystd from water or EtOH. Naphthalene [91-20-31 M 128.2, m 80.3O, b 87S0/10mm, 218.0°, d 1.0253, d1O0 0.9625, d 5 1.5590. Crystd one or more times from the following solvents: EtOH, MeOH, CC14, benzene, glacial acetic acid, acetone or ethyl ether, followed by drying at 60° in an Abderhalden drying apparatus. Also purified by vacuum sublimation and by fractional crystn from its melt. Other purification procedures include refluxing in EtOH over Raney Ni, and chromatography of a CC14 s o h on alumina with benzene as eluting solvent. Baly and Tuck [JCS 1902 19081 purified naphthalene for spectroscopy by heating with conc H2SO4 and MnO2, followed by steam distn (repeating the process), and formation of the picrate which, after recrystallisation, was decomposed and the naphthalene was steam distd. It was then crystd from dilute EtOH. It can be dried over P2O5 under vacuum. Also purified by sublimation and subsequent crystn from cyclohexane. Alternatively, it has been washed at 8 5 O with 10% NaOH to remove phenols, with 50% NaOH to remove nitriles, with 10% H2S04 to remove organic bases, and with 0.8g AIC13 to remove thianaphthalenes and various alkyl derivatives. Then it was treated with 20% H2SO4, 15% Na2C03 and finally distd. [Gorman et al. JACS 107 4404 19851.

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Purification of Organic Chemicals

Zone refining purified naphthalene from anthracene, 2,4-dinitrophenylhydrazine,methyl violet, benzoic acid, methyl red, chrysene, pentacene and indoline.

Naphthalene-2,5-disulphonicacid [92-41 -I] M 288.2. Crystd from conc HCI. Naphthalene Scarlet Red 4R [2611-82-71 M 623.5. Dissolved in the minimum quantity of boiling water, filtered and enough EtOH was added to ppte ca 80% of the dye. This process was repeated until a s o h of the dye in aqueous 20% pyridine had a constant extinction coefficient. Naphthalene-l-sulphonic acid (85-47-21 M 208.2, m (2H20) 90°, (anhydrous) 139-140°. Crystd from conc HCI and twice from water. Naphthalene-2-sulphonic acid [120-18-31 M 208.2, m 91O. Crystd from conc HCI. Naphthalene-l-sulphonyl chloride [85-46-11 M 226.7, m 64-67O, 6S0, b 147S0/0.9mm, 147S0/13mm. If the IR indicates the presence of OH then treat with an equal weight of PC15 and heat at ca looo for 3h, cool and pour into ice + H20, stir well and filter off the solid. Wash the solid with cold H20 and dry the solid in a vacuum desiccator over P2O5 + solid KOH. Extract the solid with pet ether (b 40-60°) filter off any insoluble solid and cool. Collect the crystalline sulphonyl chloride and recryst from pet ether or C6H6 pet ether. If large quantities are available then it can be distd under high vacuum. [Fierz-Davaid and Weissenbach H C A 3 2312 19201. The sulphonamide has m 150° (from EtOH or H20). Naphthalene-2-sulphonyl chloride [93-11-81 M 226.7, m 74-76O, 7S0, 79O, b 14S0/0.6mm, 201°/13mm. Crystd (twice) from benzene/pet ether (1: 1 v/v). Purified as the 2-sulphonyl chloride. [FierzDavaid and Weissenbach H C A 3 2312 19201. The sulphonamide has m 217O (from EtOH). Naphthalene-2-thiol

[91-60-11 M 160.2, m 81-82O. Crystd from EtOH.

1,s-Naphthalic anhydride [81-84-51 M 198.2, m 274O. Extracted with cold aqueous Na2C03 to remove free acid, then crystd from acetic anhydride. Naphthamide [2243-82-51 M 171.2, m 195O. Crystd from EtOH.

-

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) [475-38- 71 M 190.2, m 220-230°(dec), m 225-230°. Red-brown needles with a green reflex from EtOH. Also recrystd from hexane and purified by vacuum sublimation. [Huppert et al. JPC 89 581 1 19851. It is sparingly soluble in H20 but soluble in alkalis. It sublimes at 2-10mm. The diacerare forms golden yellow prisms from CHC13, m 192-193O and the 5,8-dimethoxy derivative has m 157O (155O) (from pet ether) [Bruce and Thompson JCS 1089 1955; IR: Schmand and Boldt J A C S 97 447 1975; NMR: Brockmann and Zeeck B 101 4221 19681. The monothiosemicarbazone has m 168O(dec) from EtOH [Gardner et al. JACS 74 2106 19521. Naphthionic acid (4-aminonaphthalene-l-sulphonicacid) [84-86-61 M 223.3, m > 300°(dec). It crystallises from H20 as needles of the 0.5 hydrate . Salt s o h fluoresce strongly blue. It has a pKa25of 2.68 in H20. a-Naphthoic acid [86-55-51 M 172.2, m 162.5-163.0°. Crystd from toluene (3ml/g) (charcoal), pet ether (b 80-100°), or aqueous 50% EtOH. P-Naphthoic acid [93-09-41 M 172.2, m 184-185O. Crystd from EtOH (4ml/g), or aqueous 50% EtOH. Dried at looo. or-Naphthol [90-15-31 M 144.2, m 95.5-96O. Sublimed, then crystd from aqueous MeOH (charcoal), aq 25% or 50% EtOH, benzene, cyclohexane, heptane, CC14 or boiling water. Dried over P205 under vacuum. [Shizuka et al. JACS 107 7816 19851.

Purification of Organic Chemicals

281

P-Naphthol [135-19-31 M 144.2, m 122.5-123.5O. Crystd from aqueous 25% EtOH (charcoal), water, benzene, toluene or CC14, e.g. by repeated extraction with small amounts of EtOH, followed by dissolution in a minimum amount of EtOH and pptn with distilled water, then drying over P2O5 under vacuum. Has also been dissolved in aqueous NaOH, and ppted by adding acid (repeated several times), then ppted from benzene by addition of heptane. Final purification can be by zone melting or sublimation in vacuo. [Bardez et al. JPC 89 5031 1985; Kikuchi et al. JPC 91 574 19871. Naphthol AS-D (3-hydroxy-2-naphthoic-o-toluide)[135-61-5] M 277.3, m 1196-198O. Purified by recrystn from xylene. Gives yellow-green fluorescent solutions at pH 8.2-9.5, [IR: Schnopper et al. AC 31 1542 19591. With AcCl naphthol AS-D acetute is obtained m 168-169O, and with chloroacetyl chloride naphthol AS-D-chloroacetate is obtained [Moloney et al. J Histochem Cytochem 8 200 1960; Burstone Arch Pathology 63 164 19571. a-Naphtholbenzein [6948-88-51 M 392.5, m 122-125O. Crystd from EtOH, aqueous EtOH or glacial acetic acid. 1-Naphthol-2-carboxylic acid [86-48-61 M 188.2, m 203-204O. Successively crystd from' EtOWwater, ethyl ether and acetonitrile, with filtration through a column of charcoal and Celite. [Tong and Glesmann JACS 79 583 19571. 2-Naphthol-3-carboxylic acid [92-70-61 M 188.2, m 222-223O. Crystd from water or acetic acid Naphthol Yellow S (citronin A, flavianic acid sodium salt, 8-hydroxy-5,7-dinitro-2naphthalene sulphonic acid disodium salt) [ 8 4 6 - 7 0 - 8 1 M 358.2, dec on heating. Greenish yellow powder soluble in H20. Thefree sulphonic acid can be recrystd from dil HCl (m 1 5 0 O ) or AcOHEtOAc (m 148-149.5O). The disodium salt is then obtained by dissolving the acid in two equivalents of aqueous NaOH and evaporating to dryness and drying the residue in a vacuum desiccator. The sodium salt can be recrystd from the minimum volume of H20 or from EtOH [Dermer and Dermer JACS 61 3302 19391. 1,2-Naphthoquinone [524-42-51 M 158.2, m 140-142O(dec). Crystd from ether (red needles) or benzene (orange leaflets). 1,4-Naphthoquinone [130-15-41 M 158.2, m 125-125.5O. Crystd from ethyl ether (charcoal). Steam distd. Crystd from benzene or aqueous EtOH. Sublimed in a vacuum.

1,2-Naphthoquinone-4-sulphonicacid sodium salt sulphonic acid sodium salt.

see 3,4-dihydro-3,4-dioxo-l-naphthlene

P-Naphthoxyacetic acid [120-23-01 M 202.2, m 156O. Crystd from hot water or benzene.

p-Naphthoyltrifluoroacetone

[893-33-41 M 254.1. Crystd from EtOH

Naphthvalene [34305-47-0]M 104.1. Purified by chromatography on alumina and eluting with pentane [Abelt et al. JACS 107 4148 19851. 1-Naphthyl acetate [830-81-91 M 186.2, m 45-46O. Chromatographed on silica gel. 2-Naphthyl acetate [1523-11-1] M 186.2, m 71O. Crystd from pet ether (b 60-80°) or dilute aq EtOH. 1-Naphthylacetic acid [86-87-31 M 186.2, m 132O. Crystd from EtOH or water. 2-Naphthylacetic acid [%I-96-41 M 186.2, m 143.1-143.4O. Crystd from water or benzene. a-Naphthylamine [134-32-71 M 143.2, m 50.8-51.2O, b 160O. Sublimed at 120° in a stream of nitrogen, then crystd from pet ether (b 60-80°), or abs EtOH then ethyl ether. Dried under vacuum in an

282

Purification of Organic Chemicals

Abderhalden pistol. Has also been purified by crystn of its hydrochloride from water, followed by liberation of the free base and distn; finally purified by zone melting. CARCINOGEN.

P-Naphthylamine [91-59-81 M 143.2, m 1 1 3 O . Sublimed at 180° in a stream of nitrogen. Crystd from hot water or benzene. Dried under vacuum in an Abderhalden pistol. CARCINOGEN. a-Naphthylamine hydrochloride L.552-46-51 M 179.7. Crystd from water (charcoal).

1-Naphthylamine-4-sulphonic acid [84-86-61 M 223.3, m >3W0(dec), 1-Naphthylamine-5-sulphonic acid [84-89-91 M 223.3, 2-Naphthylamine-1-sulphonicacid [81-16-31 M 223.3. Crystd under nitrogen from boiling water and dried in a steam oven. 2-Naphthylamine-6-sulphonicacid [93-00-51 M 223.3. Crystd from a large volume of hot water. R-(+)- [42177-25-31 and S-(-)-[15914-841 1-(1-Naphthyl) ethanol M, 172.2, m 46O, 4547.S0, 4S0, [a]::6 f94O, [ 0 r ] ~ ~ O +(c7 81,~MeOH). Purified by recrystn from Et20-pet ether, Et20, hexane [Balfe et al. JCS 797 1946; IR, NMR:Theisen and Heathcock JOC 53 2374 1988; see also Fredga et al. Acra Chem Scand 11 1609 19571. The RS-alcohol [57605-95-51 has m 63-65,O, 65-66O from hexane. R - ( + ) - [3886-70-21 and S-(-)- [10420-89-01 1-(1 - N a p h t h y l ) e t h y l a m i n e , M 171.2, b 153°/11mm, d i O1.067, n v 1.624, [a]::6 f6S0, [ a ] v + 5 5 ° (c 2, MeOH); [a]L'k82.So (neat). Purified by distn in a good vacuum. [Mori et al. TET 37 1343 1981; cf Wilson in Topics in Stereochemistry (Allinger and Eliel eds) vol 6 135 1 9 7 1 ; Fredga et al. Acta Chem Scand 11 1609 19571. The hydrochlorides crystallises from H20 [aC,83.9O (c 3, H20) and the sulphates recrystallises from H20 as tetrahydrates m 230-232O. The RS-amine has b 153O/1lmm, 156O/15mm, 183.5°/41mm [Blicke and Maxwell JACS 61 1780 19391.

2-Naphthylethylene [827-54-31 M 154.2, m 66O, b 95-96°/2.1mm, from aqueous EtOH.

N-(a-Naphthy1)ethylenediamine dihydrochloride from water.

135-137°/18mm. Crystd

[1465-25-41 M 291.2, m 188-190°. Crystd

1-Naphthyl isocyanate [30135-65-01 M 169.2, m 3-5", b 269-270°/atm., d i O1.18. Distd at atmospheric pressure or in a vacuum. Can be crystd from pet ether (b 60-700) at low temperature. It has a pungent odour, is TOXIC and is absorbed through the skin. 1-Naphthyl isothiocyanate [551-06-41 M 185.3, m 58-59O. Crystd from hexane ( l g in 9 ml). White needles soluble in most organic solvents but is insoluble in H20. It is absorbed through the skin and may cause dermatitis. [Org Synth Col.Vol. IV 700 19631. P-Naphthyl lactate [93-43-61 M 216.2. Crystd from EtOH. Naphthyl methyl ether see methoxynaphthalene. 2-(fi-Naphthyloxy)ethanol [93-20-91 M 188.2, m 76.7O. Crystd from benzene/pet ether. N - 1-Naphthylphthalamic acid

[132-66-11 M 291.3, m 203O. Crystd from EtOH.

P-Naphthyl salicyclate [613-78-51 M 264.3, m 95O, a-Naphthyl thiourea [86-88-41 M 202.2. Crystd from EtOH 1-Naphthyl urea [6950-84-11 M 186.2, m 215-220°, 2-Naphthyl urea [13114-62-0] M 186.2, m 219-220O. Crystd from EtOH.

283

Purification of Organic Chemicals

1,5-Naphthyridine

[254-79-51 M 130.1, m 75O, b 112°/15mm. Purified by repeated sublimation.

Narcein [131-28-21 M 445.4, m 176-177O (145O anhydrous). Crystd from water (as trihydrate). Narigenine [480-41-11 M 272.3, m 251O. Crystd from aqueous EtOH. Naringin [10236047-21 M 580.5, m 171O (2H20), [a]b9 -90° (c 1, EtOH), [a]:6 EtOH). Crystd from water. Dried at 110°(to give the dihydrate).

-107O (c 1,

Neopentane (2,2-dimethylpropane) [463-82-11 M 72.2, b 79.3O, d 0.6737, n 1.38273. Purified from isobutene by passage over conc H2SO4 or P2O5, and through silica gel. Neopentyl glycol

see 2,2-dime thyl- 1,3-propanol.

D(+)-Neopterin see entry in Chapter 5. Neostigmine bromide TOXIC).

[ I 14-80-71 M 303.2, m 176O(dec). Crystd from EtOH/ethyl ether. ( H i g h l y

Neostigmine methyl sulphate TOXIC].

[51-60-51 M

334.4, m 142-145O. Crystd from EtOH.

(Highly

Nerolidol [142-50-71 M 222.4, m of semicarbazide 134-135O. Purified by thin layer chromatography on plates of kieselguhr G [McSweeney JC 17 183 19651 or silica gel plates impregnated with AgN03, using 1,2-dichloromethane/CHC1~/ethyl acetate/propanol (10:10: 1: 1) as solvent system. Also by gadliquid chromatography on butanediol succinate (20%) on Chromosorb W. Stored in a cool place, in an inert atmosphere, in the dark. Neutral Red (Basic Red 5, CI 50040) [553-24-21 M 288.8, m 290°(dec). benzeneMeOH (1 : 1).

Crystd

from

New Methylene Blue N (CI 927) [6586-05-61 M 416.1. Crystd from benzene/MeOH (3:l). Nicotinaldehyde thiosemicarbazone Nicotinamide

[3608-75-11 M 180.2, m 222-223O. Crystd from water.

[98-92-01 M 122.1, m 128-131O. Crystd from benzene.

Nicotinic acid (niacin) [59-67-61 M 123.1, m 232-234O. Crystd from benzene. Nicotinic acid hydrazide [553-53-71 M 137.1, m 158-159O. Crystd from aqueous EtOH or benzene. Nile Blue A [3625-57-81 M 415.5, m 138O(dec). Crystd from pet ether. Ninhydrin [485-47-21 M 178.1, m 241-243O(dec). Crystd from hot water (charcoal). vacuum and stored in a sealed brown container.

Dried under

Nioxime see cyclohexanedione dioxime. Nitrioltriacetatic acid [139-13-91 M 191.1, m 247O(dec). Crystd from water. Dried at llOo. 2,2',2"-Nitrilotriethanol hydrochloride

see triethanolamine hydrochloride.

2-Nitroacetanilide [ 552-32-91 M 180.2, m 93-94O. Crystd from water.

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Purification of Organic Chemicals

4-Nitroacetanilide [104-04-11 M 180.2, m 217O. Ppted from 80% H2SO4 by adding ice, then washed with water, and crystd from EtOH. Dried in air. 3-Nitroacetophenone [ I 2 1 -89-11 M 165.2, m 81°, b 167°/18mm, 202O/760mm. steam and crystd from EtOH. 4-Nitroacetophenone aqueous EtOH.

Distilled in

[IOO-19-61 M 165.2, m 80-81°, b 145-152°/760mm. Crystd from EtOH or c

3-Nitroalizarin [568-93-41 M 285.2, m 244O(dec). Crystd from acetic acid. o-Nitroaniline [88-74-41 M 138.1, m 72.5-73.0°. Crystd from hot water (charcoal), then crystd from water, aqueous 50% EtOH, or EtOH, and dried in a vacuum desiccator. Has also been chromatographed on alumina, then recrystd from benzene. rn-Nitroaniline [99-09-21 M 138.1, m 114O. Purified as for o-nitroaniline. absorbed through the skin.

Warning: it is

p-Nitroaniline [IOO-01-61 M 138.1, m 148-148.5O. Purified as for o-nitroaniline. Also crystd from acetone. Freed from o- and rn-isomers by zone melting and sublimation. o-Nitroanisole [91-23-61 M 153.1, f.p. 9.4O, b 26S0/737mm, d 1.251, n 1.563. repeated vacuum distn in the absence of oxygen.

Purified by

p-Nitroanisole [IOO-17-41M 153.1, m 54O. Crystd from pet ether or hexane and dried in vacuo. 9-Nitroanthracene [602-60-81 M 223.2, m 142-143O. Purified by recrystn from EtOH or MeOH. Further purified by sublimation or TLC. 5-Nitrobarbituric acid [480-68-21 M 173.1, m 176O. Crystd from water o-Nitrobenzaldehyde [552-89-61 M 151.1, m 44-45O, b 120-144°/3-6mm. Crystd from toluene (2-2.5mVg) by addition of pet ether (b 40-60°)(7mVml of soln). Can also be distd at reduced pressures. rn-Nitrobenzaldehyde [99-61-61 M 151.1, m 5 8 O , p-Nitrobenzaldehyde 1555-16-81 M 151.1, m 1 0 6 O . Crystd from water or EtOWwater, then sublimed twice at 2mm pressure at a temperature slightly above its melting point. Nitrobenzene [98-95-31 M 123.1, f.p. 5 . 8 O , b 84-86S0/6.5-8mm, 210.8°/760mm, d 1.206, n15 1.55457, n 1.55257. Common impurities include nitrotoluene, dinitrothiophene, dinitrobenzene and aniline. Most impurities can be removed by steam distn in the presence of dilute H2SO4, followed by drying with CaC12, and shaking with, then distilling at low pressure from BaO, P2O5, AIC13 or activated alumina. It can also be purified by fractional crystn from absolute EtOH (by refrigeration). Another purification process includes extraction with aqueous 2M NaOH, then water, dilute HCl, and water, followed by drying (CaC12, MgS04 or CaS04) and fractional distn under reduced pressure. The pure material is stored in a brown bottle, in contact with silica gel or CaH2. It is very hygroscopic. 4-Nitrobenzene-azo-resorcinol (magneson 11) [74-39-51 M 259.2, m 199-200°. Crystd from EtOH.

4-Nitrobenzhydrazide

[606-26-81 M 181.1, m 213-214O. Crystd from EtOH.

4'-Nitrobenzo-15-crown-5[6083569-01 M 313.3, m 84-85O,93-95O. Recrystd from EtOH, MeOH or CgHg-hexane as for the 18-crown-6 compound below. It complexes with Na+, K+, NH4+, Ca2+, Mg2+ and Cd2+. NMR (CDC13) has 6 : 3.6-4.4 (m l6CH2), 6.8 (d 1H arom), 7.65 (d 1H arom), 7 3 0 (dd 1H arom Jab

Purification of Organic Chemicals

285

9Hz and Jbc 3Hz) ppm [Shmid et al. JACS 98 5198 1976; Kikukawa et al. Bull Chem Soc Japan 50 2207 1977; Toke et al. A 349 349, 761 1988; Lindner et al. Z Anal Chem 322 157 19851.

4'-Nitrobenzo-18-crown-6[53408-96-11 M 357.4, m 83-84O, 83-84O. If impure and discoloured then chromatograph on A1203 and eluting with C & j(1 :1) with 1% MeOH added. The fractions are followed by TLC on A1203 (using detection with Gragendorffs reagent RF 0.6 in the above solvent system). Recrystallise the residues from the fractions containing the product from CgHg-hexane to give yellowish leaflets. It complexes with Na or K ions with lOgKN, 3.95 and lOgKK 4.71. [Petranek and Ryba Coll Chem Czech Chem Commun 39 2033 19741.

2-Nitrobenzoic acid [552-16-91 M 167.1, m 146-148O. Crystd from benzene (twice), n-butyl ether (twice), then water (twice). Dried and stored in a vacuum desiccator. [Le Noble and Wheland JACS 80 5397 19581. Has also been crystd from EtOWwater. 3-Nitrobenzoic acid [121-92-61 M 167.1, m 143-143S0, 4-Nitrobenzoic acid [62-23-71 M 167.1, m 241-242O. Crystd from benzene, water, EtOH (charcoal), glacial acetic acid or MeOWwater. Dried and stored in a vacuum desiccator. 4-Nitrobenzoyl chloride [122-04-31 M 185.6, m 75O. b 15S0/20mm. Crystd from dry pet ether (b 60-80°) or CC14. Distilled under vacuum. Irritant. 4-Nitrobenzyl alcohol [619-73-81 M 153.1, m 93O. Crystd from EtOH and sublimed in a vacuum. Purity should be at least 99.5%. Sublimed samples should be stored in the dark over anhydrous CaS04 (Drierite). It the IR contains OH bands then the sample should be resublimed before use. (Mohammed and Kosower JACS 93 2709 19791. 4-Nitrobenzyl bromide [IOO-11-81 M 216.0, m 98.5-99.0°. Recrystd four times from abs EtOH, then twice from cyclohexanehexanehenzene (1: 1:l), followed by vac sublimation at 0.1mm and a final recrystn from the same solvent mixture. [Lichtin and Rao JACS83 2417 19611. Has also been crystd from pet ether (b 80-10O0, 10ml/g, charcoal). It slowly decomposes even when stored in a desiccator in the dark. Irritant. rn-Nitrobenzyl chloride [619-23-81 M 171.6, m 4 5 O . Crystd from pet ether (b 90-120O). Irritant. p-Nitrobenzyl chloride [IOO-14-11 M 171.6, m 72.5-73O. Crystd from CC14, dry ethyl ether, 95% EtOH or n-heptane, and dried under vacuum. Irritant. p-Nitrobenzyl cyanide [555-21-5] M 162.2, m 117O. Crystd from EtOH. TOXIC.

4-(4-Nitrobenzyl)pyridine [1083-48-31 M 214.2, m 70-71O. Crystd from cyclohexane. 2-Nitrobiphenyl [86-00-0] M 199.2, m 36.7O. Crystd from EtOH (seeding required). Sublimed under vacuum. 3-Nitrocinnamic acid [555-68-01 M 193.2, m 200-201°. Crystd from benzene or EtOH. 4-Nitrocinnamic acid

[619-89-61 M 193.2, m 143O (cis), 286O(truns). Crystd from water.

N-Nitrosodiethanolamine [ I 116-54-71 M 134.4. Purified by dissolving the amine (0.5g) in 1-propano1 (10ml) and 5g of anhydrous Na2S04 added with stirring. After standing for 1-2h, it was filtered and passed through a chromatographic column packed with AG 50W x 8 (H+form, a strongly acidic cation exchanger). The eluent and washings were combined and evapd to dryness at 3 5 O . [Fukuda et al. AC 53 2000 19811. Possible CARCINOGEN. 4-Nitrodiphenylamine

[836-30-61 M 214.2, m 133-134O. Crystd from EtOH.

286

Purification of Organic Chemicals

2-Nitrodiphenyl ether [2216-12-81 M 215.2, b 106-10SO/O.O1mm, 137-138°/0.5mm, 161162O/4mm, 188-189°/12mm, 195-200°/25mm, d i 0 1.241, n i 5 1.600. Purified by fractional distn. UV (EtOH): 255, 315mm (E 6200 and 2800); IR (CS2): 1350 (NO2) and 1245, 1265 (COC) cm-1 [W,IR: Dahlgard and Brewster JACS 80 5861 1958; Tomita and Takase J Pharm SOCJapan 75 1077 1955; Fox and Turner JCS 1115 1930, Henley JCS 1222 19301. Nitrodurene [38899-21-71 M 179.2, m 53-55O, b 143-144°/10mm. Crystd from EtOH, MeOH, acetic acid, pet ether or chloroform. Nitroethane [79-24-31 M 75.1, b 115O, d 1.049, n 1.3920, n25 1.39015. Purified as described for nitromethane. A spectroscopic impurity has been removed by shaking with activated alumina, decanting and rapidly distilling. 2-Nitrofluorene [607-57-81 M 211.2, m 156O. Crystd from aqueous acetic acid. Nitroguanine [556-88-71 M 104.1, m 232O(dec). Crystd from water (20ml/g). 5-Nitroindole [6146-52-71 M 162.1, m 141-142O. Decolorised (charcoal) and recrystd twice from aqueous EtOH. Nitromesitylene

[603-71-41 M 165.2, m

44O,

b 255O. Crystd from EtOH.

Nitromethane [75-52-51 M 61.0, f.p. -28S0, b 101.3O, d 1.13749, d30 1.12398, n 1.3819, n30 1.37730. Nitromethane is generally manufactured by gas-phase nitration of methane. The usual impurities include aldehydes, nitroethane, water and small amounts of alcohols. Most of these can be removed by drying with CaC12 or by distn to remove the watednitromethane azeotrope, followed by drying with CaS04. Phosphorus pentoxide is not suitable as a drying agent. [Wright et al. JCS 199 19361. The purified material should be stored by dark bottles, away from strong light, in a cool place. Purifications using extraction are commonly used. For example, Van Looy and Hammett [JACS 81 3872 19591 mixed about 15Oml of conc H2S04 with 1L of nitromethane and allowed it to stand for 1 or 2days. The solvent was washed with water, aqueous Na2C03, and again with water, then dried for several days with MgS04, filtered again with CaS04. It was fractionally distd before use. Smith, Fainberg and Winstein [JACS 83 618 19611 washed successively with aqueous NaHCO3, aqueous NaHS03, water, 5% H2SO4, water and dilute NaHC03. The solvent was dried with CaS04, then percolated through a column of Linde type 4A molecular sieves, followed by distn from some of this material (in powdered form). Buffagni and Dunn [JCS5105 19611 refluxed for 24h with activated charcoal while bubbling a stream of nitrogen through the liquid. The suspension was filtered, dried (Na2S04) and distd, then passed through an alumina column and redistd. It has also been refluxed over CaH2, distd and kept under argon over 4A molecular sieves. Can be purified by zone melting or by distn under vacuum at 00, subjecting the middle fraction to several freezepump-thaw cycles. An impure sample containing higher nitroalkanes and traces of cyanoalkanes was purified (on the basis of its NMR spectrum) by crystn from ethyl ether at -6OO (cooling in Dry-ice)[Pmett and Sun J Chem Educ 54 448 19771. Fractional crystn was more effective than fractional distn from Drierite i n purifying nitromethane for conductivity measurements. [Coetzee and Cunningham JACS 87 2529 19651. Specific conductivities around 5 x ohm-'cm-I were obtained. Nitron [487-88-71 M 312.4, m 189O(dec). Crystd from EtOH or chloroform. 1-Nitronaphthalene [86-57-71 M 173.2, m 57.3-58.3O, b 30-40°/0.01mm. Fractionally distd under reduced pressure, then crystd from EtOH, aqueous EtOH or heptane. Chromatographed on alumina from benzene/pet ether. Sublimes in vacuo. 2-Nitronaphthalene sublimed in a vacuum.

[58Z-89-5] M 173.2, m 79O, b 165O/15mrn. Crystd from aqueous EtOH and

Purification of Organic Chemicals

287

1-Nitro-2-naphthol [550-60-71 M 189.2, m 103O. Crystd (repeatedly) from benzene/pet ether (b 6080°)( 1:1). 2-Nitro-1-naphthol [607-24-91 M 189.2, m 127-128O. Crystd (repeatedly) from EtOH.

5-Nitro-1,lO-phenanthroline [4199-88-61 M 225.2, m 197-198O. Crystd from benzene/pet ether, until anhydrous. 2-Nitrophenol [88-75-51 M 139.1, m 44.5-45.5O. Crystd from EtOH/water, water, EtOH, benzene or MeOH/pet ether (b 70-90O). Can be steam distd. Petrucci and Weygandt [AC 33 275 19611 crystd from hot water (twice), then EtOH (twice), followed by fractional crystn from the melt (twice), drying over CaC12 in a vacuum desiccator and then in an Abderhalden drying pistol. 3-Nitrophenol [554-84-71 M 139.1, m 96O, b 160-165°/12mm. Crystd from water, CHC13, CS2, EtOH or pet ether (b 80-10O0), and dried under vacuum over P2O5 at room temperature. Can also be distd at low pressure. 4-Nitrophenol [IOO-02-71 M 139.1, m 113-114O. Crystd from water (which may be acidified, e.g. N H2SO4 or 0.5N HCI), EtOH, aqueous MeOH, CHC13, benzene or pet ether, then dried under vacuum over P2O5 at room temperature. Can be sublimed at 60°/10-4mm. 2-Nitrophenoxyacetic acid [1878-87-11 M 197.2, m 150-159O. Crystd from water. p-Nitrophenyl acetate 5520 19861.

[830-03-51 M 181.2. Recrystd from absolute EtOH [Moss et al. JACS 108

3-Nitrophenylacetic acid [3740-52-11 M 181.2, m 120O. Crystd from EtOH/water. 4-Nitrophenylacetic acid [104-03-O] M 181.2, m 80.5O. Crystd from EtOH/water ( l : l ) , then from sodium-dried ethyl ether and dried over P2O5 under vacuum. 4-Nitrophenylacetonitrile

1555-21-51 M 162.2, m 116-117O. Crystd from EtOH.

4-(4-Nitrophenylazo)resorcinol

see 4-nitrobenzene-azo-resorcinol.

4-Nitro-l,2-phenylenediamine [99-56-91 M 153.1, m 201O. Crystd from water.

R-(+)-[57233-86-01 and S-(-)- ( 132873-57-51 1-(4-Nitrophenyl)ethyIamine hydrochloride M 202.6. m 225O, 240-242O (dec), 243-245O (dec), 248-250°, [a]io+72O (c 1, 0.05 M NaOH), f 0.3O (H20). To ensure dryness the hydrochloride (ca 175 g) is extracted with EtOH (3 X 1OOml) and evaporated to dryness (any residual H 2 0 increases the solubility in EtOH and lowers the yield). The hydrochloride residue is triturated with absolute EtOH and dried in vucuo. The product is further purified by refluxing with absolute EtOH (200 ml for 83g) for lh, cool to loo to give 76.6g of hydrochloride m 243-245O (dec). Thefree base is prepd by dissolving in N NaOH, extract with CH2C12 (3 x 500ml), dry (Na2C03), filter, evaporate and distil, b 119-120°/0.5mm (105-107°/0.5mm, 157-159O/9mm, d p 1.1764, n 1.5688, [a]: f17.7O (neat)[Perry et al. S 492 1977; ORD: Nerdel and Liebig A 621 142 19591.

4-Nitrophenylhydrazine

[loo-16-31 M 153.1, m 158O(dec). Crystd from EtOH

3-Nitrophenyl isocyanate [3320-87-41 M 164.1, m 52-54O, 4-Nitrophenyl isocyanate [100-28-7] M 164.1, m 53O. Crystd from pet ether (b 28-38O). 4-Nitrophenyl trifluoroacetate [4195-17-91 M 223.2, m 93-95O. Recrystd from CHCl-Jhexane [Margolis et al. JBC 253 7891 10781.

288

Purification of Organic Chemicals

2-Nitrophenylpropiolic acid

[16619-65-11 M 191.1, m 157O(dec). Crystd from water.

4-Nitrophenyl urea [556-10-51 M 181.2, m 238O. Crystd from EtOH and hot water 3-Nitrophthalic acid [603-11-21 M 211.1, m 216-218O. Crystd from hot water (lSml/g). Air dried. 4-Nitrophthalic acid [610-27-51 M 211.1, m 165O. Crystd from ether or ethyl acetate. 3-Nitrophthalic anhydride [641-70-31 M 193.1, m 164O. Crystd from benzene, benzene/pet ether, acetic actic or acetone. Dried at looo. 1-Nitropropane 2-Nitropropane nitromethane.

[108-03-21 M 89.1, b 131.4O, d 1.004, n 1.40161, n25 1.39936, [79-46-91 M 89.1, b 120.3O, d 0.989, n 1.3949, n25 1.39206.

Purified as

5-Nitro-2-n-propoxyaniline [553-79-71 M 196.2, m 47.5-48.5O. Crystd from n-propyl alcohol/pet ether. 5-Nitroquinoline [607-34-11 M 174.2, m 70°. Crystd from pentane, then from benzene. 8-Nitroquinoline [706-35-21 M 174.2, m 88-89O. Crystd from hot water, MeOH, EtOH or EtOWethyl ether (3:1). 4-Nitroquinoline 1-oxide [56-57-5] M 190.2, m 157O. Recrystd from aqueous acetone [Seki et al. JPC 91 126 19871. 2-Nitroresorcinol [601-89-81 M 155.1, m 8 1 - 8 1 O . Crystd from aqueous EtOH. 4-Nitrosalicylic acid

[619-19-11 M 183.1, m 277-288O. Crystd from water.

5-Nitrosalicylic acid /96-97-91 M 183.1, m 233O. Crystd from acetone (charcoal), then twice more from acetone alone. N-Nitrosodiphenylamine 1-Nitroso-2-naphthol 7.5ml/g).

[156-10-51 M 198.2, m 144-145O(dec). Crystd from benzene. [131-91-91 M 173.2, m 110.4-110.8°. Crystd from pet ether (b 60-80°,

2-Nitroso-1-naphthol [132-53-61 M 173.2, m 15S0(dec). Purified by recrystn from pet ether (b 6080°) or by dissolving in hot EtOH, followed by successive addition of small volumes of water. 4-Nitroso-1-naphthol

[605-60-71 M 173.2, m 198O. Crystd from benzene.

2-Nitroso-1-naphthol-4-sulphonicacid (3H20) [3682-32-41 M 316.3, m 142-146O(dec). Crystd from dilute HCl soln. Crystals were dried over CaCl2 in a vacuum desiccator. Also purified by dissolution in aqueous alkali and pptn by addition of water.

4-Nitrosophenol

[104-91-61 M 123.1, m >lUO(dec). Crystd from xylene.

N-Nitroso-N-phenylbenzylamine [612-98-61 M 212.2, m 5 8 O . Crystd from absolute EtOH and dried in air. f3-Nitrostyrene [102-96-51 M 149.2, m 60°. Crystd from absolute EtOH, or three times from benzene/pet ether (b 60-80°) (1: 1).

Purification of Organic Chemicals

289

4-Nitrostyrene [IOO-13-01 M 149.2, m 20.5-21O. Crystd from CHC13/hexane. Purified by addition of MeOH to ppte the polymer, then crystd at -4OO from MeOH. Also crystd from EtOH. [Bernasconi et al. JACS 108 4541 19861. 2-Nitro-4-sulphobenzoic acid

[552-23-81 M 247.1, m 111O. Crystd from dilute HCl.

2-Nitrotoluene [88-72-21 M 137.1, m -9.55O (a-form), -3.85O (P-form), b 118°/16mm, d 1.163, 222.3°/760mm, n 1.545. Crystd (repeatedly) from absolute EtOH by cooling in a Dryice/alcohol mixture, Further purified by passage of an alcoholic soln through a column of alumina. 3-Nitrotoluene [99-08-11 M 137.1, m 16O, b 113-114°/15mm, 232.6O, d 1.156, n 1.544. Dried with P2O5 for 24h, then fractionally distd under reduced pressure. [Org. Synrh Vol I 416 19481. 4-Nitrotoluene [99-89-01 M 137.1, m 52O. Crystd from EtOH, MeOH/water, EtOH/water ( 1 :1 ) or MeOH. Air dried, then dried in a vac desiccator over H2SO4. [Wright and Grilliom JACS 108 2340 19861. 5-Nitrouracil (2,4-dihydroxy-5-nitropyrimidine)[611-08-5] M 157.1, m 280-285O, >300°. Recrystallises as prisms from boiling H20 as the monohydrate and loses H20 on drying in vucuo. It has pKa20 values of 0.03, 5.55 and 11.3 in H20 [W:Brown JCS 3647 1959; Brown J Appl Chem 2 239 1952; Johnson JACS 63 263 19411. Nitrourea [556-89-81 M 105.1, m 158.4-158.8°(dec). Crystd from EtOWpet ether. 5-Nitrovanillin (nitroveratric aldehyde) [ 6 6 3 5 - 2 0 - 71 M 197.2, m 172-175O, 176O, 178O. Forms yellow plates from AcOH, and needles from EtOH [Slotta and Szyszke B 68 184 19351. With diazomethane, 5-nitro-3,4-dimethoxyacetophenoneis formed [Brady and Manjunath JCS 125 I067 19241, The methyl ether crystallises from EtOAc or AcOH, m 88O, 90-91°, and the phenylhydrazone has m 1081 loo (from aqueous EtOH). [Finger and Schott J Prukt Chem [2] 115 288 19271. For oxime m 216O (from EtOH or AcOH) and the oxime -acetate has m 147O (from aq EtOH) [Vogel M 20 384 1899; Brady and Dunn JCS 107 1861 19151. Nonactin [6833-84-71 M 737.0, m 147-148O, [a];' 0 f2O (c 1.2, CHC13). Crystd from MeOH as colourless needles, and dries at 90°/20h/high vacuum. [HCA 38 1445 1955,55 1371 1972; TET L E U 3391 19751. n-Nonane [111-84-21 M 126.3, b 150.8O, d 0.719, n 1.40542, n25 1.40311. Fractionally distd, then stirred with successive volumes of conc H2SO4 for 12h each until no further colouration was observed in the acid layer. Then washed with water, dried with MgS04 and fractionally distd. Alternatively, it was purified by azeotropic distn with 2-ethoxyethanol, followed by washing out the alcohol with water, drying and distilling. [Forziati et al. J Res Nut Bur Stand 36 129 19461. Nonanoic acid see pelargonic acid. 2,5-Norbornadiene [121-46-01 M 92.1, b 89O, d 0.854, n 1.4707. Purified by distn from activated alumina [Landis and Halpern JACS 109 1746 1984.

cis-endo-5-Norbornene-2,3-dicarboxylic anhydride (carbic anhydride, 3 a a 7 4 , 7 , 7 , a a tetrahydro-4~~-7a-methanoisobenzofuran-l,3-dione) [ I 29-64-6J M 164.2, m 164.1°, 16416S0, 164-167O, d 1.417. Forms crystals from pet ether, hexane or cyclohexane. It is hydrolysed by H20 to form the acid [Diels and Alder A 460 98 1928; Maitte Bull Soc Chim France 499 19591. The exo-exoisomer has m 142-143O (from CgH6-pet ether) [Alder and Stein A 504 216 19.331. Norbornylene [498-66-81 M 94.2, m 44-46O, b 9 6 O . Refluxed over Na, and distd [Gilliom and Grubbs JACS 108 733 19861. Also purified by sublimation in vucuo onto an ice-cold finger [Woon et al. JACS 108 7990 19861.

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