Thursday, April 30, 2020
Uranyl nitrate experiments (total mass of uranyl nitrate is 8.26 grams).
- Ammonium uranyl carbonate (Handbook of Preparative Inorganic Chemistry page 1449)
- Hydroxylamine Potassio-uranate (NH3OH)(NH3OK)UO4
- Thallium Uranyl Carbonate
- Uranyl Hypophosphite
- Peruranic Acid
Ammonium Uranyl Carbonate (NH4)4[UO2(CO3)3]
- The (NH4)2U2O7 is precipitated from an aqueous solution of 4 g. of UO2(NO3)2•6H2O by addition of conc. ammonia
- Ammonium diuranate = 624.129 grams per mole (Wikipedia)
- The fine yellow powder is suction-filtered and washed with water.
- The precipitate stirred with an excess of cone. (NH4)2CO3 solution for about 10 minutes (the flask is on a 70°C water bath).
- The clear supernatant liquid is decanted and allowed to stand overnight.
- Yellow crystals precipitate; these are filtered with suction and dried in air.
- The residue of undissolved (NH4)2U2O7 is treated several times with the mother liquor at 70°C, as described above, until crystals no longer form on cooling.
- Yield: 5-8 g.
Hydroxylamine Potassio-uranate (NH3OH)(NH3OK)UO4•H2O
- Formed when a 10 per cent, caustic potash solution is added to a solution containing uranyl nitrate and hydroxylamine hydrochloride until the precipitate first formed is redissolved.
- 2 molar equivalents hydroxylamine HCl for every equivalent uranyl nitrate
- Molar mass hydroxylamine HCl = 69.49 grams per mole
- 2 molar equivalents = 0.0025378 x 2 = 0.0050756 moles = 0.35270 grams of hydroxylamine hydrochloride
- Molar Mass uranyl nitrate = 394.04 grams per mole
- 1 gram (5 mLs of solution) is 0.0025378 moles
- Reddish-yellow cubic crystals separate slowly from the liquid.
- The corresponding sodium compound, (NH3OH)(NH3ONa)UO4•H2O, yields minute prismatic crystals, while the mother-liquor, on further concentration, deposits orange-red prisms of the salt, (NH3ONa)2UO4•6H2O.
- Note: It took a large excess of hydroxylamine hydrochloride to dissolve the potassium diuranate precipitate. I do not know if this was due to my adding a large excess of potassium hydroxide thinking this was what the instructions said to do. After attempting the experiment I would say the better way to do it would be to add KOH solution until the potassium diuranate fully precipitates. Then add in solid hydroxylamine hydrochloride with stirring until the potassium diuranate precipitate dissolves.
Thallium Uranyl Carbonate Tl4UO2(CO3)3
- The compound separates as a crystalline precipitate on the addition of thallous nitrate to a solution containing uranium in presence of a carbonate.
- To produce TlNO3 solution pure thallium metal is dissolved in dilute nitric acid.
- M.P. = 206°C, B.P. = 433°C
- Solubility in water
- 0°C = 4 grams per 100 grams H2O, density = 1.035 grams per mL
- 15°C = 8 grams per 100 grams H2O, density = 1.065 grams per mL
- 30°C = 14 grams per 100 grams H2O, density = 1.115 grams per mL
- 104.5°C = 593.9 grams per 100 grams H2O, density = 3.191 grams per mL
- It is extremely insoluble in water, and the crystals, which are characteristic, may serve for the microchemical detection of uranium.
Uranyl Hypophosphite UO2(H2PO2)2
- Uranyl Hypophosphite is obtained as a yellow crystalline powder when freshly precipitated ammonium diuranate is digested with aqueous hypophosphorous acid. It is insoluble in water, soluble in acids.
- On heating, it loses water between 100° and 200° C., and at higher temperatures decomposes with explosive violence, yielding hydrogen and a residue containing uranium monophosphide (caution: likely to be pretty fucking poisonous; release of phosphine with water/acids?).
- The anhydrous salt, UO2(H2PO2)2, may be prepared by agitating solutions of 1 molecular proportion of uranyl nitrate and 4 molecular proportions of sodium hypophosphite.
- Sodium Hypophosphite =
- It separates in yellow microcrystalline prisms, insoluble in water, but readily soluble in excess of either reagent. A pale yellow trihydrate has also been obtained.
Peruranic Acid H4UO6
- The hydrate, peruranic acid, UO4•2H2O, is obtained as a yellowish-white precipitate by the addition of dilute hydrogen peroxide to a solution of uranyl nitrate or acetate, excess of the uranyl salt being allowed to remain unacted upon.
- The precipitate may be dried at 100° C. without loss of oxygen.
- The precipitation has been investigated by Mazzucchelli. It is hindered by the presence of chlorides, sulphates, acetates, oxalates, or tartrates, owing to the tendency to form soluble complexes. In presence of alkali or alkaline earth metals no precipitation occurs owing to the formation of soluble peruranates.
- Peruranates of the alkali metals are obtained by acting on alkaline solutions of uranyl nitrate with hydrogen peroxide. They are soluble in water, but may be precipitated by the addition of alcohol. Corresponding peruranates of the heavier metals may be obtained by double decomposition with solutions of the sodium salt.
- The precipitate is very slightly soluble in water and in a solution of ammonium chloride. In the former the solubility, expressed in grams of UO3 per litre of solution, is 0.0061 at 20° C. and 0.0084 at 90° C.
- The hydrate decolorises permanganate in dilute sulphuric acid solution, the ratio of active oxygen to uranium being 1:1.
- When strongly ignited, the hydrate loses water and oxygen, leaving a residue of urano-uranic oxide.
- The compound (Na2O2)2.UO4•8H2O is prepared by adding hydrogen peroxide to a solution of uranic acid or peruranic acid in aqueous sodium hydroxide.
- It gradually separates from the concentrated solution without the addition of alcohol, and forms yellow needle-shaped crystals.
- If only a small quantity of the alkali is present, the addition of alcohol first precipitates a deep red oil which gradually becomes crystalline and has the composition Na2O2.(UO4)2•6H2O.
- The solution of sodium peruranate gradually undergoes decomposition, hydrogen peroxide being liberated. Like most peruranates, it yields ozonised oxygen when treated with concentrated sulphuric acid.
- A solution of ammonium uranyl carbonate treated with hydrogen peroxide yields the compound (NH4)2CO3.UO4•2H2O.
Miscellaneous Notes on Important Uranium Compounds and Their Chemistry
- Ammonium Diuranate Properties and Reactions
- It is a deep yellow powder, which may be dried at 100° C.
- It is insoluble in ammonium hydroxide solution, and this fact is sometimes made use of in the analytical separation of uranium.
- When fused with ammonium chloride, uranous oxide is formed.
- It is known commercially as "uranium yellow" (see also sodium diuranate) and is used in making fluorescent "uranium glass."
- Urano-Uranic Oxide a.k.a. Triuranium Octoxide a.k.a. The "Green Oxide of Uranium"
- Formed by thermal decomposition of ammonium diuranate at temperatures >900°C.
- To obtain pure urano-uranic oxide, free from alkali, the following method may be used:
- Sodium uranyl acetate (100 g.) is dissolved in a mixture of water (4 L) and hydrochloric acid (50 c.c.), and precipitated by adding concentrated ammonia solution (300 c.c.).
- The precipitate is washed ten times with a 2% ammonium chloride solution.
- The precipitate is redissolved in hydrochloric acid.
- The precipitation with ammonia and washing are repeated twice more.
- The final precipitate, on calcination, yields pure urano-uranic oxide.
- Uranium Trioxide Properties and Reactions
- UO3 is obtained when ammonium diuranate, ammonium uranyl carbonate, or uranic acid is heated to a temp not exceeding 300°C.
- 450°F = 232.222°C
- Uranium trioxide is slightly basic. The salts formed by interaction with acids are of the type UO2R'2.
- Uranium trioxide acts towards strong bases as an acid anhydride, similar to chromic anhydride, and produces stable uranates. In contact with water it readily forms uranic acid, UO2(OH)2.
- Two well-defined hydrates are known: the monohydrate, UO3•H2O and the dihydrate, UO3•2H2O. The former is also known as uranic acid, H2UO4, or uranyl hydroxide, UO2(OH)2, and acts both as an acid and a base.
- It may be obtained in the amorphous condition by heating an alcoholic solution of uranyl nitrate for some time at a temperature just below its boiling-point, and then washing the yellow precipitate produced with boiling water.
- Potassium Diuranate (KOH + A Uranyl Salt)
- The trihydrate, K2U2O7•3H2O, is obtained by drying at 100° C. the yellow precipitate formed when excess of potassium hydroxide is added to a solution of a uranyl salt.
- According to Stolba, if the precipitate is allowed to dry in air at ordinary temperature, the hexahydrate, K2U2O7•6H2O, is formed.
- Sodium Diuranate (NaOH + A Uranyl Salt)
- Sodium Diuranate, Na2U2O7•6H2O, is generally known as "uranium yellow." It may be formed by adding excess of sodium hydroxide to a solution of a uranyl salt, and drying the resulting yellow precipitate in air.
- When dried over sulphuric acid it loses nearly all its water.
- It is obtained in the anhydrous condition by heating together uranyl chloride, sodium chloride, and ammonium chloride, or by strongly heating the hexahydrate.
- The uranium yellow of commerce, which is used in staining and painting glass and porcelain and for making uranium glass, is obtained in two colours: light yellow, by decomposing the solution of sodium uranyl carbonate with sulphuric acid, and orange yellow, by decomposing with excess of sodium hydroxide.
- Uranyl Sulfate UO2SO4
- The trihydrate, UO2SO4•3H2O, crystallises from a solution of uranyl hydroxide in dilute sulfuric acid.
- It can also be made by triturating potassium hydrogen sulphate with uranyl hydroxide, taking up with water, and concentrating the solution.
- It forms yellowish-green prismatic crystals, which under the microscope show a beautiful fluorescence. They have density at 16.5° C. = 3.280.
- In the air the crystals slowly effloresce; on heating they lose more water, and at 115° C. yield the monohydrate. This hydrate, in moist air, takes up water again and reforms the trihydrate.
Wednesday, April 15, 2020
Azide Solubilities at 0 oC and 20 oC in grams / 100 mL
- Ammonium Azide 16 / 25.3
- Barium Azide 12.5 / 17.4
- Cesium Azide - / 307
- Calcium Azide - / 45
- Lead Azide - / 0.0249
- Lithium Azide 61.3 / 67.2
- Mercury(I) Azide - / 0.02727
- Potassium Azide 41.4 / 50.8
- Silver Azide - / 0.0007931
- Sodium Azide 38.9 / 40.8
- Thallium(I) Azide 0.171 / 0.364
Chlorate Solubilities at 0 oC and 20 oC in grams / 100 mL
- Ammonium Chlorate - / 28.7
- Barium Chlorate 20.3 / 33.9
- Cadmium Chlorate 299 / 322
- Cesium Chlorate 3.8 (10 oC)/ 6.2
- Calcium Chlorate - / 209
- Cobalt Chlorate 135 / 180
- Copper Chlorate - / 242
- Lead Chlorate - / 144
- Lithium Chlorate 241 / 372
- Magnesium Chlorate 114 / 135
- Mercuric Chlorate 282 / 407
- Nickel Chlorate 111 / 133
- Potassium Chlorate 3.3 / 7.3
- Rubidium Chlorate 2.1 / 5.4
- Silver Chlorate 10.4 (10 oC) / 15.3
- Sodium Chlorate 79.6 / 95.9
- Strontium Chlorate - / 175
- Thallous Chlorate 2 / 3.92
- Zinc Chlorate 145 / 200
Sunday, April 5, 2020
1. Reduction of Phenylacetic Acid to Phenethyl Alcohol with BH4 and I2 in THF (HPLC grade anhydrous). From: "Selective Reduction of Carboxylic Acids into
Alcohols Using NaBH4, and I2" by J. V. Bhaskar Kanth and Mariappan Periasamy, School of Chemistry, University of Hyderabad, Journal of Organic Chemistry, 1991, Vol 56, pages 5964-5965.
- Phenylacetic Acid = 136.15 grams per mole
- 10 mmol = 1.3615 grams in 20 mL of THF (solution)
- Sodium Borohydride = 37.83 grams per mole
- 12 mmol = 0.45396 grams in 20 mL of THF (suspension)
- Iodine (0.5 I2) = 253.80894 grams per mole
- 5 mmol of I2 = 1.2690447 grams
- 5 mmol of I = 0.63452235 grams in 20 mL of THF
- A solution of the carboxylic acid is added slowly added to the suspension of NaBH4 at room temperature over the course of 10 mins..
- The solution is stirred until the evolution of hydrogen gas ceases.
- Iodine in THF is added slowly over the course of 10 minutes at the temperature mentioned in the table. Additional hydrogen evolves.
- The contents were further stirred for 1 hour.
- 5 mL of 3N HCl is added carefully and the mixture extracted with ether.
- Dilute ~3 mL of 31% HCl to 10 mL volume
- The extracts are combined, washed with 3 x 10 mL portions of 3N NaOH, then brine, and then dried with magnesium sulfate.
- 50 mL of 3M NaOH = 6 grams in 50 mLs
- Evaporate the organic layer to obtain the pure alcohol.
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