Previous Page Purification of Inorganic and Metal-Organic Chemicals

399

Lithium picrate [18390-55-11 M 221.0. Recrystd three times from EtOH and dried under vacuum at 45O for 48h [D'Aprano and Sesta JPC 91 2415 19871. The necessary precautions should be taken in case of EXPLOSION. Lithium perchlorate [7791-03-91 M 106.4. Crystd from water or 50% aq MeOH. Rendered anhydrous by heating the trihydrate at 170-180° in an air oven. It can then be recrystd twice from acetonitrile and again dried under vacuum [Mohammad and Kosower JACS 93 2713 19711. Lithium salicylate [552-38-51 M 144.1. Crystd from EtOH (2ml/g) by partial evaporation. Lithium sulphate (anhydrous) evaporation.

[10377-48-71 M 109.9.

Crystd from H 2 0 (4ml/g) by partial

Lithium tetrafluoroborate [14283-07-91 M 93.7. Dissolve in THF just below its solubility, filter from insol material and evap to dryness in a vacuum below 50°. Wash the residue with dry Et20, and pass dry N2 gas over the solid and finally heat in an oven at 80-90°. Solubility in Et2O: 1.9 (1.3)g in 1001111 at 25O, in THF: 71g in lOOml at 25O. It is hygroscopic and is an irritant. [JACS 74 5211 1952, 75 1753 19531. Lithium thiocyanate (lithium rhodanide) [556-65-01 M 65.0. It crystallises from H20 as the dihydrate but on drying at 38-42O it gives the monohydrate. It can be purified by allowing an aqueous soln to crystallise in a vac over P2O5. The crystals are collected, dried out in vacuum at 80°/P205 in a stream of pure N2 at llOo. [JCS 1245 19361. Lithium trimethylsilanolate (trimethylsilanol Li salt) [20O4- 14-01 M 96.1, m 120°(dec i n air). Wash with Et20 and pet ether. Sublimes at 180°/lmm as fine transparent needles. [JOC 17 1555 19521.

Magnesium

[7439-95-41 M 24.3, m 651°, b 11000, d 1.739. slowly oxidises in moist air and tarnishes. If dark in colour do not use. Shiny solid should be degreased by washing with dry Et20, dry and keep in a N2 atmosphere. It can be activated by adding a crystal of I2 in the Et20 before drying and storing. Magnesium acetate [16674-78-51 M 214.5, m 80°. Crystd from anhydrous acetic acid, then dried under vacuum for 24h at loo0 Magnesium benzoate (3H20) [553-70-81 M 320.6. Crystd from water (6ml/g) between 100° and Oo. Magnesium bromide (anhydrous) [7789-84-61 M 184.1. Crystd from EtOH. Magnesium chloride (6H2O) [7791-18-61 M 203.3. Crystd from hot water (0.3mVg) by cooling. Magnesium dodecylsulphate /3097-08-31 M 555.1. Recrystd three times from EtOH and dried in a vacuum. Magnesium ethylate (magnesium ethoxide) [2414-98-41 M 114.4. Dissolve ca Ig of solid i n 12.8ml of absolute EtOH and 201111 of dry xylene and relux in a dry atmosphere (use CaC12 in a drying tube at the top of the condenser). Add lOml of absolute EtOH and cool. Filter solid under dry N2 and dry in a vacuum. Alternatively dissolve in absolute EtOH and pass through molecular sieves (40 mesh) under N2, evap under N2, and store in a tightly stoppered container. [JACS 68 889 19641.

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Purification of Inorganic and Metal-Organic Chemicals

g6

Magnesium D-gluconate [3632-91-51 M 414.6, [a] +13.5O, [a] +11.3O (c 1, HzO). Cryst from dilute EtOH to give ca trihydrate, and then dry at 9 8 O in high vacuum. Insol in EtOH and solubility in H 2 0 is 16% at 25O. Magnesium iodate (4H20) [7790-32-11 M 446.2. Crystd from water (Smug) between 100° and Oo. Magnesium iodide [10377-58-91 M 278.1. Crystd from water (1.2mYg) by partial evapn in a desiccator. Magnesium ionophore I (ETH 1117), (N,Nr-diheptyl-N,N'-dimethyl-l,4-butanediamide) [75513-72-31 M 340.6. Purified by flash chromatography (at 40 kPa) on silica and eluting with EtOHhexane (4:l). IR has v(CHCI3) 1630cm-'. [ H C A 63 2271 19801. It is a good magnesium selectophore compared with Na, K and Ca [AC 52 2400 19801. Magnesium ionophore I1 (ETH 5214), [N,N"-octamethylene-bis(N'-heptyl-N"-methyl methylmalonamide)] [119110-38-8] M 538.8. Reagent ( c a 700mg) can be purified by flash chromatography on Silica Gel 60 (30g) and eluting with CH2C12-Me2CO (4:l). [AC 61 574 19891. Magnesium lactate [18917-93-61 M 113.4. Crystd from water (6ml/g) between 100O to Oo. Magnesium nitrate (6H20)[13446-18-91 M 256.4. Crystd from water (2.5mVg) by partial evapn in a desiccator. Magnesium perchlorate (2H20) [10034-81-81 M 259.2. Crystd from water. Coll, Nauman and West [JACS 81 1284 19591 removed traces of unspecified contaminants by washing with small portions of Et20. EXPLOSIVE in contact with organic materials. Magnesium succinate [556-32-11 M 141.4. Crystd from water (OSmYg) between 100O and Oo. Magnesium sulphate (anhydrous) [7487-88-91 M 120.4. Crystd from warm water (Iml/g) by cooling. Magnesium trifluoromethanesulphonate [60871-83-21 M 322.4, m >300°. Wash with CH2C12 and dry at 125O/2h and 3mmHg. [TET LE7T 24 169 19831. Magon [3-hydroxy-4-(hydroxyphenylazo)-2-naphthoyl2,4-dimethylanilide; Xylidyl Blue 111 [523-67-11 M 411.5, m 246-247O.Suspend in H2O and add aqueous NaOH until it dissolves, filter and acidify with dil HCl. Collect the dye, dissolve in hot EtOH (sol is l 0 0 m g L at ca 25O) concentrate to a small volume and allow to cool. Sol in H 2 0 of the Na salt is 0.4mg/ml. [ACA 16 155 1957; AC 28 202 19561. Manganese (111) acetate (2H20)[19513-05-41 M 268.1. Wash the acetate with AcOH then thoroughly with Et2O and dry in air to obtain the dihydrate. The anhydrous salt can be made by stimng vigorously a mixt of the hydrated acetate (ca 6g) and Ac2O (22.5ml) and heat carefully (if necessary) until the mixture is clear. It is set aside overnight for the material to crystallise. Filter the solid, wash with Ac2O and dry over P2O5. The dihydrate can also be obtained from the di-and terra- hydrate mixture of the divalent acetate by adding 5OOml of Ac20 and 48g of the hydrated acetate and refluxing for 2Omin, then add slowly 8.0g of KMn04. After refluxing for an additional 30min, the mixture was cooled to room temperature and 85ml of H 2 0 added. It should be noted that larger amounts of H 2 0 change the yield and nature of the manganese acetate and the yields of reactions that use this reagent, e.g. formation of lactones from olefines. The Mn(OAc)3.2H20 is then filtered off after 16h, washed with cold AcOH and air dried. [JACS 90 5903,5905 1968,91138 19691. Manganese (11) acetylacetone [14024-58-91 M 253.2, m -250O. Purify by stirring 16g of reagent for a few min with l00ml absolute EtOH and filter by suction as rapidly as possible through coarse filter paper. Sufficient EtOH is added to the filtrate to make up for the loss of EtOH and to redissolve any solid that separates. Water (ljml) is added to the filtrate and the solution is evaporated with a stream of N2 until reduced to half its vol. Cool for a few min and filter off the yellow crystals, dry under a stream of N2, then in a

Purification of Inorganic and Metal-Organic Chemicals

401

vacuum at room temp for 6-8h. These conditions are important for obtaining the dihydrute. A vacuum to several mm of Hg or much lower pressure for several days produces the anhydrous complex. The degree of hydration can be established by determining the loss in weight of lOOg of sample after heating for 4h at 100° and 72 theoretical plates with total reflux and 0.35% take-off. The apparatus is under N2 at a rate of 12 bubbledmin fed into the line using an Hg manometer to control the pressure. Sensitive to H20. [JACS 73 4252 1951; JOC 48 3667 19831. Methyl triethoxysilane [ 2 0 3 1 - 6 7 - 6 1 M 178.31, b142-144S0/742mm, 1 4 1 ° / 7 6 5 , 141S0/775mm, d0.8911, n 1.3820. Repeated fractionation in a stream of N2 through a 3' Heligrid packed Todd column. Hydrolysed by H20 and yields cyclic polysiloxanes on hydrolysis in the presence of acid in C6H6. [JACS 77 1292, 3990 19551. Methyl trimethoxysilane [185-55-31 M 136.2, b 102°/760mm, d 1.3687, n 1.3711. Likely impurities are 1,3-dimethyltetrarnethoxy disiloxane (b 3 1O/1 mm) and cyclic polysiloxanes, see methyl triethoxysilane. [JOC 16 1400 1952, 20 250 19551. Methyl trimethylsilylacetate [2916-76-91 M 146.3, b 65-6S0/50mm, d 0.89. Dissolved in EtzO, shaken with 1M HCl, washed with H20, aqueous saturated NaHCO3, H20 again, and dried (a ppte may be formed in the NaHC03 s o h and should be drawn off and discarded). The solvent is distd off and the residue is fractionated through a good column. IR (CHC13) v 1728cm-I. [JOC 32 3535 1967,45 237 19801. Methyl 2-(trimethylsilyl)propionate [55453-09-31 M 160.3, b 155-157O/atm, d 0.89. Dissolve in Et20, wash with aqueous NaHC03, H20,O.lM HCl, H20 again, dry (MgS04), evaporated and distil. [JCS Perk I 541 1985; TET 39 3695 19831. Methyl triphenoxyphosphonium iodide [ I 7579-99-61 M 452.2, m 146O. Gently heat the impure iodide with good grade Me2CO The saturated solution obtained is decanted rapidly from undissolved salt and treated with an equal volume of dry Et20. The iodide separates as beautiful flat needles which are collected by centrifugation, washed several times with dry Et20, and dried in a vacuum over P2O5. For this recrystn it is essential to minimise the time of contact with Me2CO and to work rapidly and with rigorous exclusion of moisture. If the crude material is to be used, it should be stored under dry EtzO, and dried and weighed in vucuo immediately before use. [JCS Perk 1 982 1974; JCS 224 19531.

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Purification of Inorganic and Metal-Organic Chemicals

Methyl triphenylphosphonium bromide [ I 779-49-31 M 357.3, m 229-230°(corr), 227-229O, 230-233O. Wash with C6H6 and dry in a vacuum over P2O5. [ B 87 1318 1954; JACS 79 6295 1957; JOC 24 1494 19591. The iodide crysts from H20 has m 187.5-188.5O [JCS 1130 1953; B 580 44 19531. N -Me thyl-N -trimethylsilyl acetamide [74479-74-31 M 145.3, b 48-49O/1 lmm, 84O/13 mm, 105-107°/35mm (solid at room temp), d 0.90, n 1.4379. Likely impurity is Et3N.HCl which can be detected by its odour. If it is completely soluble in C6H6, then redistil, otherwise dissolve in this solvent, filter and evaporate first in a vacuum at 12mm then fractionate, all operations should be carried out in a dry N2 atmosphere. [JACS 88 3390 1966; B 96 1473 19631.

N-Methyl-N-trimethylsilyl trifluoroacetamide j24589-78-41 M 199.3, b 78-79°/130mm. Fractionate through a 40mm Vigreux column. Usually it contains cu 1% of methyl trifluoroacetamide and 1% of other impurities which can be removed by gas chromatography or fractionating using a spinning band column. [JC 42 103 1969, 103 91 19751. Methyl vinyl dichlorosilane [124-70-91 M 141.1, 43-45.5°/11-11.5mm, 91°/742mm, 92S0/743.2mm, 92.5-93°/atm, d 1.0917, n 1.444. Likely impurities are dichloromethylsilane, butadienyl-dichloromethylsilane. Fractionate through a column packed with metal filing (20 theoretical plates) at atmospheric pressure. [Isvest Akad SSSR Otd Chem 1474 1957 and 767 19581. Molybdenum hexacarbonyl [13939-06-51 M 264.0, m 150°(dec), b 156O. Sublimed in a vacuum before use [Connor et al. JCSDT 51 1 19861. Molybdenum hexafluoride [7783-77-91 M 209.9, b 35°/760mm. Purified by low-temperature trapto-trap distillation over predried NaF. [Anderson and Winfield JCSDT 337 19861. Molybdenum trichloride [13478-18-71 M 202.3. Boiled with 12M HCl, washed with absolute EtOH and dried in a vacuum desiccator. Molybdenum trioxide [1313-27-51 M 143.9. Crystd from water (5OmVg) between 70° and Oo. Monocalcium phosphate (HzO) [7758-23-81 M 154.1. Crystd from a near-saturated soln in 50% aqueous reagent grade phosphoric acid at 100° by filtering through fritted glass and cooling to room temperature. The crystals were filtered off and this process was repeated three times using fresh acid. For the final crystn the solution was cooled slowly with constant stirring to give thin plate crystals that were filtered off on fritted glass, washed free of acid with anhydrous acetone and dried in a vacuum desiccator [Egan, Wakefield and Elmore, JACS 78 1811 19-56].

1-Naphthyl phosphate disodium salt

[2183-17-71 M 268.1. The free acid has m 157-158O (from Me2CO/C&). The free acid is crystd several times by adding 20 parts of boiling C6H6 to a hot solution of 1 part of free acid and 1.2 parts of Me2CO. [JACS 77 4002 19551. The monosodium salt was ppted from a soln of the acid phosphate in MeOH by addition of an equivalent of MeONa in MeOH. [JACS 72 624 19-50]. 2-Naphthyl phosphate monosodium salt [14463-68-41M 246.1. Recrystd from H20 (10ml) containing NaCl (0.4g). The salt is collected by centrifugation and dried in a vacuum desiccator, m 203-205O (partially resolidifies and melts at 244O). Crystd from MeOH (m 222-223O). The free acid is recrystd several times by addition of 2.5 parts of hot CHC13 to a hot solution of the free acid (1 part) in Me2CO (1.3 parts), m 177-178O.. [JACS 73 5292 1951,77 4002 19551. Neodynium chloride 6H2O [13477-89-91 M 358.7, m 124O. Forms large purple prisms from conc solns of dilute HCI. Soluble in H 2 0 (2.46 parts in 1 part of H20) and EtOH.

Purification of Inorganic and Metal-Organic Chemicals

405

Neodynium nitrate (6H2O) [16454-60-71 M 438.4, m 70-72O. Crystallises with 5 and 6 molecules of H20 from conc solutions in dilute HNO3 by slow evaporation; 1 part is soluble in 10 parts of H20.

[1313-97-91 M 336.5. Dissolved in HC104, ppted as the oxalate with doubly Neodymiun oxide recrystd oxalic acid, washed free of soluble impurities, dried at room temperature and ignited in a platinum crucible at higher than 850° in a stream of oxygen [Tobias and Garrett JACS 80 3532 19581. Neon [7440-01-91 M 20.2. Passed through a copper coil packed with 60/80 mesh 13X molecular sieves which is cooled in liquid N2, or through a column of Ascarite (NaOH-coated silica adsorbent). Neopentoxy lithium [3710-27-81 M 94.1. Recrystd from hexane [Kress and Osborn JACS 109 3953 1987. Nickel (11) acetate (4H20) [60f8-89-91 M 248.9, d 1.744. Recryst from aqueous AcOH as the green tetrahydrate. Soluble in 6 parts of H20. It forms lower hydrates and should be kept in a well closed container. [ Z Anorg Allegem Chem 343 92 19661. Nickel (11) acetylacetonate [3264-82-21 M 256.9, m 229-230°, b 220-235°/11mm, d1 1.455. Wash the green solid with H20, dry in a vacuum desiccator and recrystallise from MeOH. [JPC 62 440 19581. The complex can be conveniently dehydrated by azeotropic distn with toluene and the crystals may be isolated by concentrating the toluene solution. [JACS 76 1970 19541. Nickel bromide [ f 3462-86-91 M 218.5. Crystd from dilute HBr (0.5ml /g) by partial evaporation in a desiccator. Nickel chloride (6H2O) [7791-20-01 M 237.7. Crystd from dilute HCl. Nickel nitrate (6H2O) [13478-00-71 M 290.8, m 57O. evaporation in a desiccator.

Crystd from water (0.3ml/g) by partial

Nickelocene [bis-(cyclopentadieny1)nickel 111 [ f 271 -28-91 M 188.9, m 173-174O(under N2). Dissolve in Et20, filter and evaporate in a vacuum. Purify rapidly by recrystn from pet ether using a solid C02-Me2CO bath, m 171-173O(in an evacuated tube). Also purified by vacuum sublimation. [JACS 76 1970 1954; JINC 2 95, 110 19561. Nickel (11) phthallocyanine [14055-02-8] M 571.3, m >300°. Wash well with H 20 and boiling EtOH and sublime at high vacuum in a slight stream of C02. A special apparatus is used (see reference) with the phthallocyanine being heated to red heat. The sublimate is made of needles with an extremely bright red lustre. The powder is dull greenish blue in colour. [JCS 1719 19361. Nickel potassium sulphate see potassium nickel sulphate. Nickel sulphate (7H20) [lolo-98-11 M 280.9. Crystd from warm water (0.25mVg) by cooling. Nickel 5,10,15,20-tetraphenylporphyrin [ I41 72-92-01 M 671.4, I,,, 414(525)nm. Purified by chromatography on neutral (Grade I) alumina, followed by recrystn from CH2C12/MeOH [Yamashita JPC 91 3055 1987. Niobium (V) chloride [10026-12-71 M 270.2, rn 204.7-209S0, b -250°(begins to sublime at 125O), d 2.75. Yellow very deliquescent crystals which decompose in moist air to give HCl. Should be kept in a dry box flushed with N2 in the presence of P2O5. Wash with CC14 and dry over P2O5. The yellow crystals usually contain a few small dirty white pellets among the yellow needles. These should be easily picked out. Upon grinding in a dry box, however, they turn yellow. NbCI5 has been sublimed and fractionated in an electric furnace. [fnorg Synth 7 163 1963; JCS S233 19491.

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Purification of Inorganic and Metal-Organic Chemicals

Nitric acid [ 7 6 9 7 - 3 7 - 2 1 M 63.0, m -42O, b 83O, d25 1.5027; [Constant boiling acid has composition 68% HNO3 + 32% H 2 0 , b 120S0, d 1.411. Obtained colourless (approx. 92%) by direct distn of fuming HNO3 under reduced pressure at 40-50° with an air leak at the head of the fractionating column. Stored in a desiccator kept in a refngerator. Nitrite-free HNO3 can be obtained by vac distn from urea. Nitric oxide [10102-43-91 M 30.0, b -151.8O. Bubbling through 10M NaOH removes N02. It can also be freed from NO2 by passage through a column of Ascarite followed by a column of silica gel held at -197OK. The gas is dried with solid NaOH pellets or by passing through silica gel cooled at -78O, followed by fractional distillation from a liquid N2 trap. This purification does not eliminate nitrous oxide. Other gas scrubbers sometimes used include one containing conc H2SO4 and another containing mercury. It is freed from traces of N2 by a freeze and thaw method. TOXIC. p-Nitrobenzenediazonium EXPLOSIVE when dry.

fluoroborate [456-27-91 M 236.9.

Crystd from water.

Can be

Nitrogen [7727-37-91 M 28.0, b -195.8O. Cylinder N2 can be freed from oxygen by passage through Fieser's soln [which comprises 2g sodium anthraquinone-2-sulphonate and 15g sodium hydrosulphite dissolved in lOOml of 20% KOH (Fieser, JACS 46 2639 1924)] followed by scrubbing with saturated lead acetate soln (to remove any H2S generated by the Fieser soln), conc H2SO4 (to remove moisture), then soda-lime (to remove any H2SO4 and CO;?). Alternatively, after passage through Fieser's solution, N2 can be dried by washing with a soln of the metal ketyl from benzophenone and Na wire in absolute ethyl ether. [If ether vapour in N2 is undesirable, the ketyl from liquid Na-K alloy under xylene can be used]. Another method for removing 0 2 is to pass the nitrogen through a long tightly packed column of Cu turnings, the surface of which is constantly renewed by scrubbing it with ammonia (s.g. 0.880) s o h The gas is then passed through a column packed with glass beads moistened with conc H2SO4 (to remove ammonia), through a column of packed KOH pellets (to remove H2SO4 and to dry the N2). and finally through a glass trap packed with chemically clean glass wool immersed in liquid N2. Nitrogen has also been purified by passage over Cu wool at 723OK and Cu(I1) oxide [prepared by heating Cu(N03)2.6H20 at 903OK for 24h] and then into a cold trap at 77OK. A typical dry purification method consists of a mercury bubbler (as trap), followed by a small column of silver and gold turnings to remove any mercury vapour, towers containing anhydrous CaS04, dry molecular sieves or Mg(C104)2, a tube filled with fine Cu turnings and heated to 40O0 by an electric furnace, a tower containing soda-lime, and finally a plug of glass wool as filter. Variations include tubes of silica gel, traps containing activated charcoal cooled in a Dry-ice bath, copper on Kieselguhr heated to 250°, and Cu and Fe filings at 4 0 0 O . Nitrophenolarsonic acid [121-19-71 M 350.1. Crystd from water. Nitroso-R-salt see l-nitroso-2-naphthol-3,6-disulphonicacid, disodium salt, hydrate.

l-Nitroso-2-naphthol-3,6-disulphonicacid, disodium salt, hydrate [525-05-31 M 377.3, m >30O0. Purified by dissolution in aqueous alkali and precipitation by addition of HCl. Nitrosyl chloride [2696-92-61 M 65.5, b -So.Fractionally distilled at atmospheric pressure in an allglass, low temperature still, taking the fraction boiling at - 4 O and storing it in sealed tubes. Nitrous oxide [10024-97-21 M 44.0, b -88.5O. Washed with conc alkaline pyrogallol solution, to remove 0 2 , C02, and N02, then dried by passage through columns of P2O5 or Drierite, and collected in a dry trap cooled in liquid N2. Further purified by freeze-pump-thaw and distn cycles under vacuum [Ryan and Freeman JPC 81 1455 19771.

Octadecyl isonicotinate

see hydrogen ionophore IV, ETH 1778

Purification of Inorganic and Metal-Organic Chemicals

Octadecyl trichlorosilane [I 12-04-91 M 387.9, b 159-162°/13mm, 0.98. Purified by fractional distillation. [ J A C S 69 2916 19471.

407

185-199°/2-3mm, d:'

Octadecyl trimethylammonium bromide [1120-02- I] M 392.5, m -250°dec, 230-240°(dec). Cryst from EtOH or H20 (sol 1 in 1OOOparts). Very soluble in Me2CO. [ J A C S 68 714 19461. Octamethyl cyclotetrasiloxane 556-67-21 M 296.6, m 17-19O, 17.58O, 18.5O; b 74°/20mm, 3 i 176.4°/760mm, d249*30.9451, n D 1.3968. Solid has two forms, m 16.30° and 17.65O. Dry over CaH2 and distil. Further fractionation can be effected by repeated partial freezing and discarding the liquid phase. [ J A C S 76 399 1954,75 6313 19541. Octamethyl trisiloxane 1107-51-71 M 236.5, m -goo, b 151.7O/747mm, 153°/760mm. Distil twice, the middle fraction from the first distillation is again distilled, and the middle fraction of the second distillation is used. [JACS 68 358, 691 1946, JCS 1908 19531. Octaphenyl cyclotetrasiloxane [546-56-51 M 793.2, m 201-202O, 203-204O, b 330340°/lmm. Recryst from AcOH or C6H6 or EtOAc. It forms two stable polymorphs and both forms as well as the mixture melt at 200-201°. There is a metastable form which melts at 187-189O. [JACS 67 2173 1945,69488 19471. Octyl trichlorosilane [ 5 2 8 3 - 6 6 - 9 1 M 247.7, b 96.5°/10mm, 112°/15mm. 1 1 9 ° / 2 8 m m , 229°/760mm, d 1.0744, n 1.4453. Purified by repeated fractionation using a 15-20 theoretical plates glass column packed with glass helices. This can be. done more efficiently using a spinning band column. The purity can be checked by analysing for C1 [ca 0.5-lg of sample is dissolved in 25ml of MeOH, diluted with H20 and titrated with standard alkali. [JACS 68 475 1946,80 1737 19-58], Orange I [tropaeolin 000 Nrl] (4-(4-hydroxy-l-naphthylazo)benzenesulphonicacid sodium salt) [523-44-41 M 350.3, m >260°(dec). Purified by dissolving in the minimum volume of H20, adding, with stirring, a large excess of EtOH. The salt separates as orange needles. It is collected by centrifugation or filtration, washed with absolute EtOH (3 x) and Et2O (2x) in the same way and dried in a vacuum desiccator over KOH. The free acid can be recrystallised from EtOH. [ B 64 86 19311. The purity can be checked by titration with titanium chloride [ J A C S 68 2299 19461. Orange I1 [tropaeolin 000 Nr2] (4-(2-hydroxy-l-naphthylazo)benzenesulphonic acid sodium salt) [633-96-51 M 350.3. Purification is as for Orange I. The solubility in H20 is 40gL at 25O. [ H C A 35 2579 19521. Also purified be extracting with a small volume of water, then crystd by dissolving in boiling water, cooling to ca 80°,adding two volumes of EtOH and cooling. When cold, the ppte is filtered off, washed with a little EtOH and dried in air. It can be salted out from aqueous solution with sodium acetate, then repeatedly extracted with EtOH. Meggy and Sims [ J C S 2940 19561, after crystallising the sodium salt twice from water, dissolved it in cold water (1 lml/g) and conc HCl added to ppte the dye acid which was separated by centrifugation, redissolved and again ppted with acid. After washing the ppte three times with 0.5M acid it was dried over NaOH, recrystd twice from absolute EtOH, washed with a little Et20, dried over NaOH and stored over conc H2SO4 in the dark. Orange G (l-phenylazo-2-naphthol-6,8-disulphonic acid disodium salt) [1936-15-81 M 452.4. Recryst from 75% EtOH, dry for 3h at 1 loo and keep in a vacuum desiccator over H2SO4. The free acid crystallises from EtOH or conc HCl in deep red needles with a green reflex. [ J A C S 48 2483 1923, J C S 292 19381. Orange RO [5850-86-21 M 364.4. Salted out three times with sodium acetate, then repeatedly extracted with EtOH. Osmium tetroxide (osmic acid) [ 2 08 I 6 - I 2 - O]M 524..2, m 40.6O, b 59.4O/6 0 m m , 71.5°/100mm, 109.3°/400mm, 130°/760mm, d 5.10. It is VERY TOXIC and should be manipulated in a good fume cupboard. It attacks the eyes severely and is a good oxidising agent. It is volatile

408

Purification of Inorganic and Metal-Organic Chemicals

and has a high vapour pressure (1 lmm) at room temp. It sublimes and dists well below its boiling point. It is sol in C6H6, H20 (7.24% at 25O), CCl4 (375% at 25O), EtOH and Et20. It is estimated by dissolving a sample in a glass stoppered flask containing 25ml of a solution of KI (previously saturated with C02) and acidified with 0.35M HCI. After gentle shaking in the dark for 30min, the solution is diluted to 200ml with distilled H20 satd with C02 and titrated with standard thiosulphate using Starch indicator. This method is not as good as the gravimetric method. Hydrazine hydrochloride (0.1 to 0.3g) is dissolved in 3M HCl (10ml) in a glass stoppered bottle. After warming to 55-65O, a weighed sample of Os04 solution is introduced, and the mixture is digested on a water bath for lh. The mixture is transferred to a weighed glazed crucible and evaporated to dryness on a hot plate. A stream if H2 is started through the crucible and the crucible is heated over a burner for 20-30 min. The stream of H2 is continued until the crucible in cooled to room temperature, and then the H2 is displaced by C02 in order to avoid rapid combustion of H2. Finally the crucible is weighed. [Handbook of Preparative Inorganic Chemistry (ed Brauer) Vol I1 1603 1965; JACS 60 1822 19381.

Oxygen [7782-44-71 M 32.00, m -218.4O, b -182.96O, d-lg3 1.149, d-252-51.426. Purified by passage over finely divided platinum at 673OK and Cu(I1) oxide (see under nitrogen) at 973O, then condensed in liquid N2-cooled trap. HIGHLY EXPLOSIVE in contact with organic matter.

Palladium (11) acetate

[3375-31-31 M 244.5, m 205Odec. Recrystd from c H c i 3 as purple crystals. It can be washed with AcOH and H20 and dried in air. Large crystals can be obtained by dissolving in C6H6 and allowing to evaporate slowly at room temp. It forms green adducts with nitrogen donors, dissolved in KI s o h but is insoluble in aqueous saturated NaCl, and NaOAc. Soluble in HCI to form PdC@. [Chemistry & Ind ustry (London) 544 1964; JCS 658 19701.

Palladium (11) acetyl acetone [14024-61-41 M 304.6. Recrystd from CgH6-pet ether and sublimed in vacuo. It is soluble in heptane, C6H6 (1.2% at 20°, 2.2 at 40°), toluene (0.56% at 20°, 1.4% at 40°) and acetylacetone (1.2% at 20°, 0.05% at 40O). [JINC 5 295 195718; Inorg Synth 5 105 19571. Palladium (11) chloride [7647-10-11 M 177.3, m 678-680O. The anhydrous salt is insoluble in H20 and dissolves in HCl with difficulty. The dihydrate forms red hygroscopic crystals that are readily reduced to Pd. Dissolve in conc HCI through which dry C12 was bubbled. Filter this solution which contains H2PdC14 and H2PdC16 and on evaporation yields a residue of pure PdC12. [Handbook of Preparative Inorganic Chemistry (ed Brauer) Vo12 1582 1965; Org Synth Col Vol I11 685 19551. Palladium (11) cyanide [2035-66-71 M158.1. A yellow solid, wash well with H20 and dry in air. [Inorg Chem 2 245 19461. Palladium tetrakis(tripheny1phosphine)

see tetrakis(tripheny1phosphine) palladium.

Palladium (11) trifluoroacetate [42196-31-61 M 332.4., m 210°(dec). Suspend in trifluoroacetic acid and evaporate on a steam bath a couple of times. The residue is then dried in vacuum (40-80°) to a brown powder. [JCS 3632 1965; JACS 102 3572 19801. Pentafluorophen 1 dimethylchlorosilane (Flophemesyl chloride) [20082-71-71 M 260.7, b 89-90°/10mm, d p l . 4 0 3 , n i o 1.447. If goes turbid on cooling due to separation of some LiCl, then dissolve in Et20, filter and fractionate. [JC 89 225 1974, 132 548 1977,]. Perchloric acid [7601-90-31 M 100.5, d 1.665. The 72% acid has been purified by double distn from silver oxide under vacuum: this frees the acid from metal contamination. Anhydrous acid can be obtained by adding gradually 400-5OOml of oleum (20% fuming H2S04) to 100-12Oml of 72% HC104 in a reaction flask cooled in an ice-bath. The pressure is reduced to lmm (or less), with the reaction mixture at 20-25O. The temperature is gradually raised during 2h to 85O, the distillate being collected in a receiver cooled in Dry-ice.

Purification of Inorganic and Metal-Organic Chemicals

409

For further details of the distillation apparatus [see Smith JACS 75 184 19531. HIGHLY EXPLOSIVE, a strong protective screen should be used at all times.

Phenylarsonic acid [98-05-51 M 202.2, m 155-158°(dec). Crystd from HzO (3ml/g) between 90° and

OO. Phenyl boric acid (benzeneboronic acid) [ 9 8 - 8 0 - 6 1 M 121.9, m ca 43O, 215-216O (anhydride), 217-220°. It recrystallises from H20, but can convert spontaneously to benzeneboronic anhydride or phenylboroxide on standing in dry air. Possible impurity is dibenzeneborinic acid which can be removed by washing with pet ether. Heating in an oven at 110°/760mm lh converts it to the anhydride m 214216O. Its solubility in H20 is 1.1% at Oo and 2.5% at 2 5 O and in EtOH it is 10% (w/v). It has a pKa25 of 8.64 in H20. [Gilman and Moore J A C S 80 3609 19583. If the acid is required, not the anhydride, the acid (from recrystallisation in H20) is dried in a slow stream of air saturated with H20. The anhydride is converted to the acid by recrystallisation from H20. The acid gradually dehydrates to the anhydride if left in air at room temperature with 30-40% relative humidity. The melting point is usually that of the anhydride because the acid dehydrates before it melts [Washburn et al. Org Synrh Coll Vol IV 68 19631. Phenyl

dimethyl

chlorosilane

(chlorodimethylphenylsilane) [768-33-21 M 170.7, 1.032, n i 5 1.032. Fractionate through a 1.5 x 18 inch column packed with stainless steel helices; better use a spinning band column. [JACS 74 386 1952; 70 1115 1948; JCS 494 19531.

79O/15mm, 189-191°/739mm, 196°/760mm, d':

1,2-Phenylenephosphorochloridate (2-chloro-1,3,2-benzodioxaphosphole-2-oxide) [ 1 4 9 9 17-81 M 190.5, m 52O. 58-59O, 59-61°, b 80-81°/1-2mm, 118°/10mm, 122°/12mm, 125°/16mm, 155O/33mm. Distil in a vacuum, sets to a colourless solid. It is soluble in pet ether, benzene and slightly soluble in Et20. [JCSC 2092 1970;A 454 109 19271. Phenylmercuric hydroxide [ I 00-57-21 M 294.7, m 195-203O. Crystd from dilute aqueous NaOH. Phenylmercuric nitrate [8003-05-21 M 634.4, m 178-188O. Crystd from water. Phenylphosphinic acid [1779-48-21 M 142.1, m 70°, 71°, 83-85O,86O. Crystallises from H20 (sol, 7.7% at 25O). Purified by placing the solid in a flask covered with dry Et20, and allowed to stand for 1 day with intermittent shaking. EtzO was decanted off and the process repeated. After filtration, excess Et20 was removed in vacuum. pKal = 1.92. [ A 181 265 1876;A C 29 109 1957; NMR: J A C S 78 5715 19561. Phenylphosphonic acid [1571-33-11 M 158.1, m 164.5-166°. Best recryst from H 2 0 by concentrating an aqueous soln to a small volume and allowing to crystallise. Wash the crystals with ice cold H20 and dry in a vacuum desiccator over H2SO4. [JACS 78 1045 19541. pKa values in H 2 0 at 25O are 1.83 and 7.07, and in 50% EtOH 3.15 and 8.26. [JACS 75 2209 19531. [IR: A C 23 853 19511. Phenylphosphonic dichloride (P,P-dichlorophenyl phosphine oxide) [824- 72-61 M 195.0, b 83-84°/lmm, 135-136O/23mm,d y 1.977, n 1.5578. Fractionally distilled using a spinning band column. [JACS 76 1045 1954; NMR: J A C S 78 3557, 5715 1956; IR: A C 23 853 19511.

i'

Phenylphosphonous acid

[121-70-0] M 141.1, m 71O. Crystd from hot water.

Phenylphosphonous dichloride (P,P-dichloro phenyl phosphine) [644-97-31 M 179.0, 6870°/lmm, 224-226O/atm,d y 1.9317, . n g 1.5962. Vacuum distilled by fractionating through a 20cm column packed with glass helices (better use a spinning band column) [JACS 73 755 1951; NMR: JACS 78 3557 1956; IR: A C 23 853 19511. It forms a yellow Ni complex: Ni(C6H5C12P)4 (m 91-92O, from H 2 0 ) [ J A C S 79 3681 19.571 and a yellow complex with molybdenum carbonyl: M O ( C O ) ~ . ( C ~ H ~(m C~~P)~ 106-110°dec)[JCS 2323 19591.

410

Purification of Inorganic and Metal-Organic Chemicals

Phenyl phosphor0 chloridate (diphenyl phosphoryl chloride) [2524-64-31 M 268.6, b 1 4 1O/lmm, 194°/13mm, 275O/216mm, 314-316/272mm, d t o 1.2960, n3615490. Fractionally distilled under a good vacuum, better use a spinning band column. [JACS 81 3023 1959; IR: JCS 475,481 19521. Phenyl phosphoryl dichloride [ 7 7 0 - 1 2 - 7 1 M 211.0, m -lo, b 103-104°/2mm, 110111°/lOmm, 130-134°/21mm, 241-243O/atm, d l o 1.4160, n3: 1.5216. Fractionally distilled under as good a vacuum as possible using an efficient fractionating column or a spinning band column. It should be redistilled if the IR is not very good [IR: JCS 475, 481 1952; JACS 60 750 1938,80 727 19581. Phenylthio trimethylsilane (trimethyl phenylthio silane) [4551-15-9] M 182.4, b 9599O/12mm, d i 0 0.97. Purification is as for phenyl trimethyl silylmethyl sulphide. Phenyl trimethoxylsilane (trimethoxysilyl benzene) [2996-92-11 M 198.3, b 103°/20mm, 35 130.5-131°/45mm, d 4 1.022, 'n; 1.4698. Fractionate through an efficient column but note that it forms an azeotrope with MeOH which is a likely impurity. [JACS 75 2712 1953; J Gen Chem USSR (Engl Edn) 25 1079 19551. Phenyl trimethylsilane (trimethylphenyl silane) [768-32-11 M 150.3, b 67.3O/20mm, 9899O/80rnm, 170.6°/738mm, dT0.8646. If the sample is suspect, then wash with H20 and distil using a Podbielniak Heligrid column or better a spinning band column. [JACS 71 2923 1949,73 4770 1951,75 2821 19531. Phenyl trimethylsilylmethyl sulphide [(phenylthiomethyl trimethylsilane] [17873-08-41 M 196.4, b 48°/0.04mm, 113-115°/12mm, 158S0/52mm, d 30 , 0.9671, n g 1.5380. If the sample is suspect then add H20, wash with 10% aqueous NaOH, H20 again, dry (anhydrous CaC12) and fractionally distil through a 2ft column packed with glass helices. [JACS 76 3713 19541. Phosgene [75-44-51 M 98.9, b 8.2O/756mm. Dried with Linde 4A molecular sieves, degassed and distilled under vacuum. HIGHLY TOXIC, should not be inhaled. Phosphonitrilic chloride (tetramer) [1832-07-11 M (115.9)4. Purified by zone melting, then crystd from pet ether (b 40-60O) or n-hexane. [van der Huizen et al. JCSDT 1317 19861. Phosphonitrilic chloride (trimer) (hexachlorocyclotriphosphazine) [940- 71-61 M (115.9)3, m 112.8O, 113-114O. Purified by zone melting, by crystallisation from pet.ether, n-hexane or benzene, and by sublimation. [van der Huizen et al. JCSDT 1311 1986; Meirovitch JPC 88 1522 19841. Phosphoric acid (7664-38-21 M 98.0, m 42.3O. Pyrophosphate can be removed from phosphoric acid by diluting with distilled H20 and refluxing overnight. By cooling to 1 l o and seeding with crystals obtained by cooling a few millilitres in a Dry-ice/acetone bath, 85% orthophosphoric acid crystallises as H3P04.H20. The crystals are separated using a sintered glass filter. It has pKa25 values of 2.15, 7.20 and 12.37 in H20. P h o s p h o r u s (red) [7723-14-01 M 31.0, m 590°/43atm, ignites at 200°, d 2.34. Boiled for 15min with distilled H20, allowed to settle and washed several times with boiling H20. Transferred to a Buchner funnel, washed with hot H20 until the washings are neutral, then dried at 100° and stored in a desiccator. Phosphorus (white) [7723-14-01 M 31.0, m 590, d 1.82. Purified by melting under dilute H2SO4dichromate mixture and allowed to stand for several days in the dark at room temperature. It remains liquid, and the initial milky appearance due to insoluble, oxidisable material gradually disappears. The phosporus can then be distilled under vacuum in the dark [Holmes TFS 58 1916 19621. Other methods include extraction with dry CS2 followed by evaporation of the solvent, or washing with 6M HN03, then H20, and drying under vacuum. POISONOUS.

Purification of Inorganic and Metal-Organic Chemicals

41 1

Phosphorus oxychloride [10025-87-31 M 153.3, b 105.5O, n 1.461, d 1.675. Distilled under reduced pressure to separate from the bulk of the HCI and the phosphoric acid, the middle fraction being distilled into ampoules containing a little purified mercury. These ampoules are sealed and stored in the dark for a 4-6 weeks with occasional shaking to facilitate reaction of any free chloride with the mercury. The POCl3 is then again fractionally distilled and stored in sealed ampoules in the dark until used [Herber JACS 82 792 19601. Lewis and Sowerby [JCS 336 19.571 refluxed their distilled POCl3 with Na wire for 4h, then removed the Na and again distilled. Phosphorus pentabromide [7789-69-71 M 430.6, m