Previous Page Purification of Organic Chemicals
213
22 1291 19-57], Ethyl cinnamate [ 1 0 3 - 3 6 - 6 1 M 176.2, f.p. 6.7O, b 127O/6mm, 272.7O/768mm, d 1.040, n 1.55983. Washed with aqueous 10% Na2C03, then water, dried (MgS04), and distd. The purified ester was saponified with aqueous KOH, and, after acidifying the soln, cinnamic acid was isolated, washed and dried. The ester was reformed by refluxing for 15h the cinnamic acid (25g) with abs EtOH (23g), conc H2SO4 (4g) and dry benzene (loOml), after which it was isolated, washed, dried and distd under reduced pressure [Jeffery and Vogel JCS 658 19581. Ethyl trans-crotonate [623-70-11 M 114.2, b 137O, d 0.917, n 1.425. Washed with aqueous 5% Na2C03, washed with saturated aqueous CaC12, dried with CaC12 and distd. Ethyl cyanoacetate [105-56-61 M 113.1, b 206.0°, d 1.061, n 1.41751. Shaken several times with aqueous 10% Na2C03, washed well with water, dried with Na2S04 and fractionally distd. Ethyl cyanoformate [ 6 2 3 - 4 9 - 4 1 M 99.1, b 113-114°/740mm, 116.5-116.8°/765.5mm, d i 0 1.0112, nko 1.3818. Dissolve in Et20, dry over Na2S04, filter, evaporate and dgtil [Malachowsky et al. B 70 1016 1937; Adickes et al. Jprukt Chem [2] 133 313 1932; Grundmann et al. A 577 77 19521. Ethylcyclohexane [1678-91-71 M 112.2, b 131.8O, d 0.789, n 1.43304, nt5 1.43073. Purified by azeotropic distn with 2-ethoxyethanol, then the alcohol was washed out with water and, after drying, the ethylcyclohexane was redistd. Ethyl cyclohexanecarboxylate [ 3 2 8 9 - 2 8 - 9 1 M 156.2, b 76-77°/10mm, 92-93O/34mm, d 0.960, n 1.420. Washed with M sodium hydroxide solution, then water, dried with Na2S04 and distd. Ethyl diazoacetate [ 6 2 3 - 7 3 - 4 1 M 114.1, m -22O, b 42O/5mm, 45O/12mm, 85-86°/88mm, 140-141°/720mm, 140-143°/atm, d y . 6 1.0852, n y . 6 1.4588. A very volatile yellow oil with a strong pungent odour. EXPLOSIVE [distillation even under reduced pressure is dangerous and may result in an explosion - TAKE ALL THE NECESSARY PRECAUTIONS IF DISTILLATION IS TO BE CARRIED OUT]. It explodes in contact with conc H2SO4 - trace acid causes rapid decomp. It is slightly sol in H20, but is miscible with EtOH, C6H6, pet ether and Et20. To purify dissolve in Et20 [using CH2C12 instead of Et20 protects the ester from acid], wash with 10% aq Na2C03, dry (MgS04), filter and repeat as many times as possible until the Et2O layer loses its yellow colour, remove the solvent below 20° (vac). Note that prolonged heating may lead to rapid decomp and low yields. It can also be purified by steam distn under reduced pressure but with considerable loss in yield. Place the residual oil in a brown bottle and keep below loo, and use as soon as possible without distilling. [Womack and Nelson Org S p r h Coll Vol I11 392 1955; UV: Miller and White JACS 79 5974 1957; Fieser 1 367 19671. Ethyl dibromoacetate [105-36-21 M 245.9, b 81-82°/14.5mm, nt2 1.4973. Washed briefly with conc aqueous NaHCO3, then with aqueous CaC12. Dried with CaS04 and distd under reduced pressure. Ethyl a,P-dibromo-P-phenylpropionate [5464-70-01 [erythro: 30983-70-11 M 336.0, m 75O. Crystd from pet ether (b 60-80O). Ethyl dichloroacetate [535-15-91 M 157.0, b 131.0-131.5°/401mm, d 1.28, n 1.438. Shaken with aqueous 3% NaHCO3 to remove free acid, washed with distd water, dried for 3 days with CaS04 and distd under reduced pressure. Ethyl 3,3-diethoxypropionate [ I 0 6 0 1 - 8 0 - 6 1 M 190.2, b 58S0/1.5mm, 65O/2mm, 9596O/12mm, d i 0 0.78, nk5 1.4101. Dissolve in dry Et20, and dry with solid NaHC03, filter and distil and carefully fractionate [Dyer and Johnson JACS 56 223 19341. Ethyl 1,3-dithiane-2-carboxylate [20462-00-41 M 192.3, b 75-77°/0.2mm, 96O/0.4mm, d i 0 1.220, nk5 1.5379. Dissolve in CHC13, wash with aqueous K2CO3, 2 x with H20, dry over MgS04, filter,
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Purification of Organic Chemicals
evaporate and distil. [Eliel and Hartman JOC 37 505 1972; Seebach S 1 17 19691.
Ethyl 1,3-dithiolane-2-carboxylate [20461-99-81 M 178.3, b 85°/0.1mm, d i O1.250, n i o 1.538. Dissolve in CHC13, wash with aqueous K2CO3, 2 x with H20, dry over MgS04, filter, evaporate and distil [Hermann et a1 TET LETT 2599 1973; Corey and Erickson JOC 36 3553 19711. Ethylene [74-85-11 M 28.0, m -169.4O, b -102°/700mm. Purified by passage through a series of towers containing molecular sieves or anhydrous CaS04 or a cuprous ammonia s o h , then conc H2SO4, followed by KOH pellets. Alternatively, ethylene has been condensed in liquid nitrogen, with melting, freezing and pumping to remove air before passage through an activated charcoal trap, followed by a further condensation in liquid air. A sputtered sodium trap has also been used, to remove oxygen. Ethylene bis(dipheny1phosphine) (DIPHOS) [ I 663-4521 M 398.4, m 139-140°. Crystd from EtOH [Backvell et al. JOC 52 5430 19871.
Ethylenebis[(o-hydroxyphenyl)glycine] [1170-02-11 M 360.4, m 249O(dec). Purified by extensive Soxhlet extraction with acetone. [Bonadies and Carrano JACS 108 4088 19861. bis(oxyethylenenitrilo)]tetraacetic [Ethylene aminoethy1ether)-tetraacetic acid.
acid
see ethylene
glycol
bis(0-
Ethylene carbonate (1,3-dioxalan-2-one) [96-49-11 M 88.1, m 37O, d 1.32, n40 1.4199. Dried over P2O5 then fractionally distd at lOmm pressure. Crystd from dry ethyl ether. Ethylene chlorohydrin see 2-chloroethanol. Ethylenediamine [107-15-31 M 60.1, f.p. l l . O o , b 117.0°, d 0.897, n 1.45677, n30 1.4513. Forms a constant-boiling (b 118.5O) mixture with water (15%) [hygroscopic and miscible with water]. Recommended purification procedure [Asthana and Mukherjee in Coetzee, 1982 cf p 531: to 1L of ethylenediaminewas added 70g of type 5A Linde molecular sieves and shaken for 12h. The liquid was decanted and shaken for a further 12h with a mixture of CaO (50g) and KOH (15g). The supernatant was fractionally distd (at 20:l reflux ratio) in contact with freshly activated molecular sieves. The fraction distilling at 117.2O /760mm was collected. Finally it was fractionally distilled from sodium metal. All distns and storage of ethylenediamine should be carried out under nitrogen to prevent reaction with C02 and water. Material containing 30% water was dried with solid NaOH (600g/L), heated on a water bath for 10h. Above 60°, separation into two phases took place. The hot ethylenediamine layer was decanted off, refluxed with 40g of sodium for 2h and distd [Putnam and Kobe Trans Electrochem Soc 74 609 19381. Ethylenediamine is usually distd under nitrogen. Type 5A Linde molecular sieves (70g/L), then a mixture of 50g of CaO and 15g of KOHL, with further dehydration of the supernatant with molecular sieves has also been used for drying this diamine, followed by distn from molecular sieves and, finally, from sodium metal. A spectroscopically improved material was obtained by shaking with freshly baked alumina (20gL) before distn. N,N'-Ethylenediaminediacetic acid [5657-17-01 M 176.2, m 222-224O(dec), Ethylenediamine dihydrochloride [333- 18-61 M 133.0. Crystd from water. Ethylenediaminetetraacetic acid (EDTA) [60-00-41 M 292.3, m 253O(dec). Dissolved in aqueous KOH or ammonium hydroxide, and ppted with dil HCl or HNO3, twice. Boiled twice with distd water to remove mineral acid, then recrystd from water or dimethylformamide. Dried at 1loo. Also recrystd from boiling 1N HCI, wash crystals with distd H20 and dried in vacuo. [Ma and Ray Biochemistry 19 751 19801. Ethylene dibromide see 1,2-dibromoethane. Ethylene dichloride see 1,2-dichloroethane. Ethylene dimethacrylate [97-90-51 M 198.2, b 98-10O0/5mm, d 1.053, n 1.456. Distd through
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Purification of Organic Chemicals
a short Vigreux column at about lmm pressure, in the presence of 3% (w/w) of phenyl-6-naphthylamine.
Ethylene dimyristate [627-84-91 M 482.8, m 61.7O. Crystd from benzene-MeOH or ethyl etherMeOH, and dried in a vacuum desiccator.
(Ethylenedinitri1o)tetraacetic acid see ethylenediaminetetraacetic acid. Ethylene dipalmitate [624-03-31 M 538.9, m 69.1°, Ethylene distearate [627-83-81 M 595.0, m 75.3O. Crystd from benzene-MeOH or ethyl ether-MeOH and dried in a vacuum desiccator. Ethylene glycol [107-21-11 M 62.1, b 68O/4mm, 197.9O/760mm, d 1.0986, n15 1.43312, n25 1.43056. Very hygroscopic, and also likely to contain higher diols. Dried with CaO, CaS04, MgS04 or NaOH and distd under vacuum. Further dried by reaction with sodium under nitrogen, refluxed for several hours and distd. The distillate was then passed through a column of Linde type 4A molecular sieves and finally distd under nitrogen, from more molecular sieves. Fractionally distd. Ethylene glycol bis(0-aminoethy1ether)-iV,N'-tetraacetic acid (EGTA) [67-42-51 M 380.4, m >24S0(dec). Dissolved in aq NaOH, pptd by addn of aq HCI, washed with water and dried at 1oOO in vucuo. ueous 5% Na2C03, dried with MgS04 and stored with chromatographic alumina to prevent peroxide formation. Ethylene glycol diethyl ether [ 6 2 9 - 1 4 - 1 1 M 118.2, b 121S0, d 0.842, n 1.392. After refluxing for 12h, a mixture of the ether (2L), conc HCl (27ml) and water (20Oml), with slow passage of nitrogen, the s o h was cooled, and KOH pellets were added slowly and with shaking until no more dissolved. The organic layer was decanted, treated with some KOH pellets and again decanted. It was refluxed with, and distd from sodium immediately before use. Alternatively, after removal of peroxides by treatment with activated alumina, the ether has been refluxed in the presence of the blue ketyl formed by sodium-potassium alloy with benzophenone, then distd. Ethylene glycol dimethyl ether (monoglyrne) Purified by distn from LiAIH4 or sodium.
[110-71-4] M 90.1, b 8S0, d 0.866, n 1.379.
Ethylene glycol monobutyl ether see 2-butoxyethanol. Ethylene glycol monoethyl ether see 2-ethoxyethanol. Ethylene glycol monomethyl ether see 2-methoxyethanol. Ethylene oxide [75-21-81 M 44.0, b 13S0/746mrn, dl0 0.882, n7 1.3597. Dried with CaS04, then distd from crushed NaOH. Has also been purified by its passage, as a gas, through towers containing solid NaOH. Ethylene thiourea [96-45-71 M 102.2, m 203-204O. Crystd from EtOH or amyl alcohol. Ethylene urea [120-93-41 M 86.1, m 131O. Crystd from MeOH (charcoal). Ethylenimine (aziridine) [151-56-41 M 43.1, b 55S0/760mm, d 0.8321. distd from sodium under nitrogen. TOXIC.
Dried with BaO, and
Ethyl ether [ 6 0 - 2 9 - 7 1 M 74.1, b 34.6O/760mm, d 0.714, n15 1.3555, n 1.35272. Usual impurities are water, EtOH, diethyl peroxide (which is explosive when concentrated), and aldehydes. Peroxides [detected by liberation of iodine from weakly acid (HCl) solutions of KI, or by the blue colour in the ether layer when lmg of Na2Cr207 and 1 drop of dil H2SO4 in lml of water is shaken with lOml of ether] can be removed in several different ways. The simplest method is to pass dry ether through a column of activated alumina (80g A1203/7c@ml of ether). More commonly, 1L of ether is shaken repeatedly with 5-1Oml of a s o h comprising
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Purification of Organic Chemicals
6.0g of ferrous sulphate and 6ml of conc H2SO4 in llOml of water. Aqueous 10% Na2S03 or stannous chloride can also be used. The ether is then washed with water, dried for 24h with CaC12, filtered and dried further by adding sodium wire until it remains bright. The ether is stored in a dark cool place, until distd from sodium before use. Peroxides can also be removed by wetting the ether with a little water, then adding excess LiAIH4 or CaH2 and leaving to stand for several hours. (This also dried the ether.) Werner [Analyst 58 335 19331 removed peroxides and aldehydes by adding 8g AgN03 in 60ml of water to 1L of ether, then lOOml of 4% NaOH and shaking for 6min. Fierz-David [Chirnia 1 246 19471 shook 1L of ether with log of a zinc-copper couple. (This reagent was prepared by suspending zinc dust in 5Oml of hot water, adding 5ml of 2M HCl and decanting after 20sec, washing twice with water, covering with 5Oml of water and 5ml of 5% cuprous sulphate with swirling. The liquid was decanted and discarded, and the residue was washed three times with 20ml of ethanol and twice with 20ml of ethyl ether). Aldehydes can be removed from ethyl ether by distn from hydrazine hydrogen sulphate, phenyl hydrazine or thiosemicarbazide. Peroxides and oxidisable impurities have also been removed by shaking with strongly alkaline satd KMnO4 (with which the ether was left to stand in contact for 24h), followed by washing with water, conc H2SO4, water again, then drying (CaC12) and distn from sodium, or sodium containing benzophenone to form the ketyl. Other purification procedures include distn from sodium triphenylmethide or butyl magnesium bromide, and drying with solid NaOH or P2O5.
2-Ethylethylenimine [25449-67-91 M 71.1, b 88.5-89O. Freshly distd from sodium before use. TOXIC. Ethyl formate [109-94-41 M 74.1, b 54.2O, d 0.921, d30 0.909, n 1.35994, n25 1.3565. Free acid or alcohol is removed by standing with anhydrous K2CO3, with occasional shaking, then decanting and distilling from P2O5. Alternatively, the ester can be stood wih CaH2 for several days, then distd from fresh CaH2. Cannot be dried with CaC12 because it reacts rapidly with the ester to form a crystalline compound. Ethyl gallate [831-61-81 M 198.2, m 150-151°, 163-165O. Recryst from 1,2-dichloroethane, UV: hmax (neutral species) 275nm ( E 10 OOO); (anion) 235nm ( E 10 300), 279nm ( E 11 400) and 324nm ( E 8 500) [Campbell and Coppinger JACS 73 2708 19511. 2-Ethyl-1-hexanol [104-76-71 M 130.2, b 184.3O, d 0.833, n 1.431. Dried with sodium, then fractionally distd.
2-Ethylhexyl vinyl ether [37769-62-31 [103-44-61 M 156.3, b 177-17S0/atm. Usually contains amines as polymerization inhibitors. These are removed by fractional distn. Ethyl hydrocupreine hydrochloride (Optochin) [3413-58-91 M 376.9, m 249-251O. Recry st from H20, pKa25 5.5 and 9.95 [W:Heidt and Forbes JACS 55 2701 19331. Ethylidene dichloride see 1,l-dichloroethane. Ethyl iodide [75-03-61 M 156.0, b 72.4O, d 1.933, n l5 1.5682, n25 1.5104. Drying with.P205 is unsatisfactory, and with CaC12 is incomplete. It is probably best to dry with sodium wire and distil [Hammond et al. JACS 82 704 19601. Exposure of ethyl iodide to light leads to rapid decomposition, with the liberation of iodine. Free iodine can be removed by shaking with several portions of dil aq Na2S203 (until the colour is discharged), followed by washing with water, drying (with CaC12, then sodium), and distn. The distd ethyl iodide is stored, over mercury, in a dark bottle away from direct sunlight. Other purification procedures include passage through a 60cm column of silica gel, followed by distn; and treatment with elemental bromine, extraction of free halogen with Na2S203 s o h , followed by washing with water, drying and distn. Free iodine and HI have also been removed by direct distn through a LeBel-Henninger column containing copper turnings. Purification by shaking with alkaline solns, and storage over silver, are reported to be unsatisfactory. Ethyl isobutyrate [ 6 2 3 - 4 8 - 3 1 M 116.2, b llOo, d 0.867, n 1.388. Na2C03, then with saturated aqueous CaC12. Dried with CaS04 and distd.
Washed with aqueous 5%
217
Purification of Organic Chemicals
0.9031, Ethyl isocyanate [109-90-01 M 71.1, b 559.8O/759mm, 59-61°/atm, 60-63O/atm, d:' n;' 1.3808. Fractionate through an efficient column preferably in an inert atmosphere and store in aliquots in sealed tubes [Bieber JACS 74 4700 1952; Slocombe et al. JACS 72 1888 19501. 3-Ethylisothionicotinamide [ I 0605-12-61 M 166.2, m 164-166O(dec). Crystd from EtOH.
Ethyl isovalerate [108-64-51 M 130.2, b 134.7O, d 0.8664, n 1.39621, n25 1.3975. with aqueous 5% Na2C03, then saturated aqueous CaC12. Dried with CaS04 and distd.
Washed
Ethyl levulinate (4-oxopentanoic acid ethyl ester) [ 5 3 9 - 8 8 - 8 / M 144.2, m 37.2O, b 106108°/2mm, 138.8O/8mm, 203-205O/atm, d;' 1.012, nz," 1.423. Stir ester with Na2C03 and charcoal, filter and distil. It is freely soluble in H20 and EtOH [IR, NMR: Sterk M 99 1770 1968; Thomas and Schuette JACS 53 2328 1931; Cox and Dodds JACS 55 3392 19331. Ethyl malonate [105-53-31 M 160.2, b 92O/22mm, 198-199°/760mm, d 1.056, d25 1.0507, n 1.413. If too impure (IR, NMR) the ester (250g) has been heated on a steam bath for 36h with absolute EtOH (125ml) and conc H2SO4 (75ml), then fractionally distd under reduced pressure. Otherwise fractionally distil under reduced pressure and collect the steady boiling middle fraction. Ethyl malonate monoamide [ 7 5 9 7 - 5 6 - 0 1 M 131.1, m 47-50°, 49.5-50°, 50°, b 130135O/2mm. Crystallise from Et20 or by slow evaporation of an aqueous soln as colourless crystals [Snyder and Elston JACS 76 3039 1954; McAlvain and Schroeder JACS 71 45 1949; Rising et al. JBC 89 20 19301. Ethyl mercaptan see ethanethiol. Ethyl methacrylate [97-63-21 M 114.2, b 59°/100mm, d 0.915, n 1.515. Washed successively with 5% aqueous NaN02, 5% NaHS03, 5% NaOH, then water. Dried with MgS04, added 0.2% (w/w) of phenyl-B-naphthylamine, and distd through a short Vigreux column [Schultz JACS 80 1854 19581. Ethyl methyl ether [540-67-01 M 60.1, b 1 0 . 8 O , do 0.725. alumina column (to remove peroxides), then fractionally distd.
Dried with CaS04, passed through an
Ethyl methyl ketone (methyl ethyl ketone, MEK) see 2-butanone. 3-Ethyl-2-methyl-2-pentene [I 9780-67-71 M 112.2, b 114.5°/760mm. GLC on a column of 20% squalene on Chromosorb P at 70°.
Purified by preparative
3 - E t h y l - 4 - m e t h y l p y r i d i n e [ 5 2 9 - 2 1 - 5 1 M 121.2, b 76O/12mm, 194S0/750mm, d 0.947, n 1.510. Dried with solid NaOH, and fractionally distd.
5-Ethyl-2-methylpyridine [ 104-90-51 M 121.2, b 178S0/765mm, d 0.919, n 1.497. by conversion to the picrate, crystn, and regeneration of the free base, then distn.
Purified
N-Ethylmorpholine [IOO-74-31 M 115.2, b 138-139O/763mm, d 0.912, n 1.445. Distd twice, then converted by HCl gas into the hydrochloride (extremely deliquescent) which was crystd from anhydrous EtOH-acetone (1:2) [Henies, Mathias and Rabin BJ85 127 19621. Ethyl nitroacetate [ 6 2 6 - 3 5 -71 M 133.1, n 42-43O/0.2mm, 65O/0.6-2mm, 71-72O/3mm, 9396O/9mm, 194-195O/atm, d:' 1.1953, n;' 1.4260. Purified by repeated distn. IR 1748 (C02), 1570 and 1337 (NOz), and 800cm-l [Hazeldine JCS 2525 19531, pKa,?,zo 5.82. The hydruzine salt crystallises from 95% EtOH or MeOH as yellow crystals m 104-105O [Ungnade and Kissinger JOC 22 1661 1957, Emmons and Freeman JACS 77 4391 19551. Ethyl p-nitrobenzoate [99-77-41 M 195.2, m 5 6 O . Dissolved in ethyl ether and washed with aqueous alkali, then the ether was evaporated and the solid recrystd from EtOH.
218
Purification of Organic Chemicals
Ethyl Orange [13545-67-01M 372.4. Recrystd twice from water. Ethyl orthoformate [ 1 2 2 - 5 1 - 0 1 M 148.2, b 144°/760mm, d 0.892, n 1.391. Shaken with aqueous 2% NaOH, dried with solid KOH andd distd from sodium through a 20cm Vigreux column. o-Ethylphenol [90-00-61M 122.2, f.p. 45.1°, b 210-212O, d 1.020, n 1.537, p-Ethylphenol [123-07-91M 122.2, m 47-48O, b 218.0°/762mm, n25 1.5239. Non-acidic impurities were removed by passing steam through a boiling soln containing 1 mole of the phenol and 1.75 moles of NaOH (as aq 10% soln). The residue was cooled and acidified with 30% (v/v) H2S04, and the free phenol was extracted into ethyl ether. The extract was washed with water, dried with CaS04 and the ether was evapd. The phenol was distd at lOOmm pressure through a Stedman gauze-packed column. It was further purified by fractional crystn by partial freezing, and by zone refining, under nitrogen [Biddiscombe et al. JCS 5764 19633. Alternative purification is via the benzoate, as for phenol. Ethyl phenylacetate [101-97-31M 164.2, b 99-99.3O/14mm, d 1.030, n 1.499. Shaken with saturated aqueous Na2C03 (three times), aqueous 50% CaC12 (twice) and saturated aqueous NaCl (twice). Dried with CaC12 and distd under reduced pressure.
2-Ethyl-2-phenylglutarimidesee 3-ethyl-3-phenyl-2,6-piperidinedione. 3-Ethyl-5-phenylhydantoin [86-35-11M 204.2, m 94O. Crystd from water. N-Ethyl-5-phenylisoxazolinium-3'-sulphonate [4156-16-51 M 253.3, m 220°(dec). [Lamas et al. JACS 108 5543 19861, 3-Ethyl-3-phenyl-2,6-piperidinedione[77-21-41M 217.3, m 8 4 O . Crystd from ethyl ether or ethyl acetate/pet ether. Ethyl propionate [105-37-31 M 102.1, b 99.1°, d 0.891, n15 1.38643, n 1.38394. with anhydrous CuSO4 and distd under nitrogen.
Treated
2-Ethylpyridine [100-71-0]M 107.2, b 148.6O, d 0.942, 4-Ethylpyridine [536-75-41 M 107.2, b 168.2-168.3O, d 0.942. Dried with BaO, and fractionally distd. Purified by conversion to the picrate, recrystn and regeneration of the free base followed by distn. 4-Ethylpyridine-1-oxide [14906-55-91M 123.1, m 109-llOo. Crystd from acetone/ether. Ethyl pyruvate [617-35-61M 116.1, m -50°, b 44-45°/10mm, 56O/20mm, 69-71°/42mm, 63O/23mm, 155S0/760mm, d': 1.047, nLo 1.4052. Shake the ester with lOml portions of satd aq CaC12 s o h (removes ethyl acetate) and the organic layer is removed by centrifugation, decantation and filtration, and is distilled under reduced pressure. Purification of small quantities is carried out via the bisulphite adduct: the ester (2.2ml) is shaken with saturated NaHSO3 (3.6ml), chill in a freezing mixture when crystals separate rapidly (particularly if seeded). After 5min EtOH (1Oml) is added and the crystals are filtered off, washed with EtOH and Et20 and dried. Yield ca 3g of bisulphire udducr. Then treat the adduct (16g) with saturated aqueous MgS04 (32ml) and 40% formaldehyde (5ml) and shake, whereby the ester separates as an oil which is extracted with Et20, the extract is dried (MgS04), filtered, evapd and the residue is distd (b 56O/20mm), and then redistd (b 147S0/750mm) to give 5.5g of pure ester. [Cornforth Org Synrh Col Vol IV 467 19631. 1-Ethylquinolinium iodide see quinolinium ethiodide. Ethyl Red [76058-33-81M 197.4, m 150-152O. Crystd from EtOWethyl ether. Ethyl stearate [Ill-61-51M 312.5, m 33O, b 213-215°/15mm. The solid portion was separated from the partially solid starting material, then crystd twice from EtOH, dried by azeotropic distn with benzene, and fractionally distd in a spinning-band column at low pressure [Welsh TFS 55 52 19591.
219
Purification of Organic Chemicals
Ethyl sulphide [352-93-21 M 90.2, b 92.1°, d 0.835, n15 1.44550. Fractionally distd from sodium metal. Ethyl thioglycolate [623-51-81 M 120.2, b 50-51°/10mm, 55°/17mm, 62.5-64°/22mm, 676S0/24mm, 155-158°/atm, d i 0 1.096, nko 1.457. Dissolve in Et20, wash with H20, dry over Na2S04, filter, evaporate and distil the residue under reduced pressure [Bredereck et al. B 90 1837 1957). The Ni complex [Ni(SCH2CO2Et)2]recrystallised twice from EtOH gives crystals which became black when dried in a vacuum over H2SO4, m 104-105° [Dranet and Cefola JACS 76 1975 19541. N-Ethyl thiourea [625-53-61 M 104.2, m llOo. Crystd from EtOH, MeOH or ether. Ethyl trichloroacetate [515-84-41 M 191.4, b 100-100.5°/30mm, d 1.383. Shaken with saturated aqueous Na2C03 (three times), aqueous 50% CaC12 (three times), saturated aqueous NaCl (twice), then distd with CaC12 and distd under reduced pressure. Ethyl trifluoroacetate [383-63-11 M 142.1, b 61.3O/750, 60-62O/atm, 62-64O/755mm, d i 0 1.191, n i o 1.30738. Fractionate through a long Vigreux column. IR has v at 1800 (C02) and 1000 (OCO) cm-I [Fuson et al. JCP 20 1627 1952; Bergman JOC 23 476 19.581. Ethyl trifluoromethanesulphonate [425-75-21 M 178.1, b 115O/atm, 118-120°/atm, d i O 1.378, n i o 1.336. The ester reacts slowly with H20 and aqueous alkali. If its IR has no OH bands (-3000 cm-I) then purify by redistillation. If OH bands are present then dilute with dry Et20 and shake (carefully) with aqueous NaHC03 until effervescence ceases, then wash with H20 and dry (MgS04), filter, evaporate and distil the residue under slight vacuum then at atmospheric pressure in a N2 atmosphere. IT IS A POWERFUL ALKYLATING AGENT, AND THE FUMES ARE VERY TOXIC - CARRY ALL OPERATIONS IN AN EFFICIENT FUMECUPBOARD. [Gramstad and Hazeldine JCS 173 1956; Howells and McCown Chem Reviews 77 6919771. S-Ethyl trifluorothioacetate [383-64-21 M 158.1, b 88-90°/atm, 90S0/760mm, d i 0 1.255, nko 1.372. If IR is free of OH bands then fractionate, but if OH bands are present then dilute with dry EtzO, wash with 5% KOH and H20, dry over MgS04 and fractionate through an efficient column [Hauptschein et al. JACS 74 4005 19521. Powerjul obnoxious odour. Ethyl vinyl ether [109-92-21 M 72.1, b 35S0, d 0.755. Contains polymerization inhibitors (usually amines, e.g. triethanolamine) which can be removed by fractional distn. Redistd from sodium. LACHRYMATORY. Ethynylbenzene see phenylacetylene.
l-Ethynyl-l-cyclohexanol [ 7 8 - 2 7 - 3 1 124.2, m 30-33O, 32-33O, b 74O/12mm, 767S0/17mm, 171-172°/694mm, 180°/atm, d4 0.9734, n i 5 1.4801. Dissolve in Et20, wash with H20, dilute NaHCO3, H20 again, dry (Na2S04), filter, evaporate and distil the residue. IR (CCl4): 3448 (OH), 2941 (CH), 1449-1123 and 956 cm-l; NMR (CC4) 6: 3.2 (OH), 2.5 ( S H ) , 1.70 (m IOCH2) [Hasbrouck and Kiessling JOC 38 2103 19721. Etiocholane (Sfbandrosterone) [438-23-31 M 260.5, m 78-80°. Crystd from acetone. Etiocholanic acid [438-08-41 M 304.5, m 228-29O. Crystd from glacial acetic acid and sublimes at 160°/0.002mm. The methyl ester has m 99-101O. [Weiland et al. 2 Physiol Chem 161 80 19261. Etioporphyrin I [448-71-51 M 478.7, m 360-363O. Crystd from pyridine or CHC13-pet ether.
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