Crystals, crystalline solids

White crystals, crystalline solid, or light pink liquid which slowly turns brown on exposure to air. Phenol has an acrid or sweet, tarry-like odor resembling wet newspaper or cardboard. Sharp burning taste. At 40 °C, the average odor threshold concentration and the lowest concentration at which an odor was detected were 31 and 9.5 pg/L, respectively. At 25 °C, the lowest concentration at which a taste was detected was <2 pg/L (Young et al., 1996). Leonardos et al. (1969) and Nagata and Takeuchi (1990) reported odor threshold concentrations of 47 ppmv and 5.6 ppbv, respectively. 

Crystalline solids A solid whose atoms, ions, or molecules are arranged in an orderly, geometric, three-dimensional structure (lattice) is called a crystalline solid. The individual pieces of a crystalline solid are called crystals. Crystalline solids are divided into five categories based on the types of particles they contain atomic solids, molecular solids, covalent network solids, ionic solids, and metallic solids. Noble gases are atomic solids whose properties reflect the weak dispersion forces between the atoms. 

Boron trioxide is not particularly soluble in water but it slowly dissolves to form both dioxo(HB02)(meta) and trioxo(H3B03) (ortho) boric acids. It is a dimorphous oxide and exists as either a glassy or a crystalline solid. Boron trioxide is an acidic oxide and combines with metal oxides and hydroxides to form borates, some of which have characteristic colours—a fact utilised in analysis as the "borax bead test , cf alumina p. 150. Boric acid. H3BO3. properly called trioxoboric acid, may be prepared by adding excess hydrochloric or sulphuric acid to a hot saturated solution of borax, sodium heptaoxotetraborate, Na2B407, when the only moderately soluble boric acid separates as white flaky crystals on cooling. Boric acid is a very weak monobasic acid it is, in fact, a Lewis acid since its acidity is due to an initial acceptance of a lone pair of electrons from water rather than direct proton donation as in the case of Lowry-Bronsted acids, i.e. 

For solids which melt above 100° and are stable at this temperature, drying may be carried out in a steam oven. The crystals from the Buchner funnel should then be placed on a clock glass or in an open dish. The substance may sometimes be dried in the Buchner funnel itself by utilising the device illustrated in Fig. 77, <33, 1. An ordinary Pyrex funnel is inverted over the Buchner funnel and the neck of the funnel heated by means of a broad flame (alternatively, the funnel may be heated by a closely-fltting electric heating mantle) if gentle suction is applied to the Alter flask, hot (or warm) air will pass over the crystalline solid. 

Dissolve 2 5 g. of hydroxylamine hydrochloride and 4 g. of crystallised sodium acetate in 10 ml. of water in a small flask or in a test-tube. Warm the solution to about 40° and add 2 5 g. of cyclohexanone. Stopper the vessel securely with a cork and shake vigorously for a few minutes the oxime soon separates as a crystalline solid. Cool in ice, filter the crystals at the pump, and wash with a little cold water. RecrystaUise from light petroleum, b.p. 60-80°, and dry the crystals upon filter paper in the air. The yield of pure cycZohexanone oxime, m.p. 90°, is 2 -5 g. 

Introduce 197 g. of anhydrous brucine or 215 g. of the air-dried dihydrate (4) into a warm solution of 139 g. of dZ-acc.-octyl hj drogen phthalate in 300 ml. of acetone and warm the mixture vmder reflux on a water bath until the solution is clear. Upon cooling, the brucine salt (dA, IB) separates as a crystalline solid. Filter this off on a sintered glass funnel, press it well to remove mother liquor, and wash it in the funnel with 125 ml. of acetone. Set the combined filtrate and washings (W) aside. Cover the crystals with acetone and add, slowly and with stirriug, a slight excess (to Congo red) of dilute hydrochloric acid (1 1 by volume about 60 ml.) if the solution becomes turbid before the introduction of... 

Transfer the crude dinitrobenzene to a 250 ml. flask fitted with a reflux condenser, add 80-100 ml. of methylated (or rectified) spirit and heat on a water bath until all the crystalline solid dissolves. If the resulting solution is not quite clear, filter it through a fluted filter paper on a large funnel which has previously been warmed or through a warm Buchner funnel. Colourless crystals of m-dinitrobenzene (15 g.) are deposited on cooling. If the m.p. is below 89-90°, recrystaUisation is necessary. 

Dissolve 200 g. of sodium nitrite in 400 ml. of water in a 2-litre beaker provided with an efficient mechanical stirrer, and add 40 g. of copper powder (either the precipitated powder or copper bronze which has been washed with a little ether). Suspend the fluoborate in about 200 ml. of water and add it slowly to the well-stirred mixture. Add 4-5 ml. of ether from time to time to break the froth. The reaction is complete when all the diazonium compound has been added. Transfer the mixture to a large flask and steam distil until no more solid passes over (about 5 litres of distillate). Filter off" the crystalline solid in the steam distillate and dry upon filter paper in the air this o-dinitrobenzene (very pale yellow crystals) has m.p. 116° (t.c., is practically pure) and weighs 29 g. It may be recrystallised from alcohol the recrystallised solid melts at 116-5°. 

Dimethylaminomethylindole (gramine). Cool 42 5 ml. of aqueous methylamine solution (5 2N ca. 25 per cent, w/v) contained in an 100 ml. flask in an ice bath, add 30 g. of cold acetic acid, followed by 17 -2 g. of cold, 37 per cent, aqueous formaldehyde solution. Pour the solution on to 23 -4 g. of indole use 10 ml. of water to rinse out the flask. Allow the mixture to warm up to room temperature, with occasional shaking as the indole dissolves. Keep the solution at 30-40° overnight and then pour it, with vigorous stirring, into a solution of 40 g. of potassium hydroxide in 300 ml. of water crystals separate. Cool in an ice bath for 2 hours, collect the crystalline solid by suction flltration, wash with three 50 ml. portions of cold water, and dry to constant weight at 50°. The yield of gramine is 34 g. this is quite suitable for conversion into 3-indoleacetic acid. The pure compound may be obtained by recrystaUisation from acetone-hexane m.p. 133-134°. 

Sodium iodide [7681-82-5] Nal, occurs as colorless crystals or as a white crystalline solid. It has a salty and slightly bitter taste. In moist air, it gradually absorbs as much as 5% water, which causes caking or even Hquefaction (dehquescence). The soHd slowly becomes brown when exposed to air because some iodide is oxidized to iodine. Water solutions are neutral or slightly alkaline and gradually become brown for the same reason. Aqueous solutions are stabilized with respect to oxidation by raisiag the pH to 8—9.5 (see Iodine and iodine compounds). 

Cane sugar is generally available ia one of two forms crystalline solid or aqueous solution, and occasionally ia an amorphous or microcrystalline glassy form. Microcrystalline is here defined as crystals too small to show stmcture on x-ray diffraction. The melting poiat of sucrose (anhydrous) is usually stated as 186°C, although, because this property depends on the purity of the sucrose crystal, values up to 192°C have been reported. Sucrose crystallines as an anhydrous, monoclinic crystal, belonging to space group P2 (2). 

A crystalline solid is never perfect in that all of tire lattice sites are occupied in a regular manner, except, possibly, at the absolute zero of temperature in a perfect crystal. Point defects occur at temperatures above zero, of which the principal two forms are a vacant lattice site, and an interstitial atom which... 

In spite of theii easy interconversion in solution, a and p fonns of carbohydrates are capable of independent existence, and many have been isolated in pure fonn as crystalline solids. When crystallized from ethanol, D-glucose yields a-D-glucopyianose, mp 146°C, [a]o -1-112.2°. Crystallization from a water-ethanol mixture produces P-d-glucopyranose, mp 148-155°C, +18.7°. In the solid state the two fonns do not... 

The alkali metal halides are all high-melting, colourless crystalline solids which can be conveniently prepared by reaction of the appropriate hydroxide (MOH) or carbonate (M2CO3) with aqueous hydrohalic acid (HX), followed by recryslallization. Vast quantities of NaCl and KCl are available in nature and can be purihed if necessary by simple crystallization. The hydrides have already been discussed (p. 65). 

After anilide 30 (1.12 g, 4.46 mmol) is hydrolized in 6 M HCl at 100 °C (by TLC analysis), toluene (5 mL) is added and then aldehyde 5 (0.74 mL, 8.92 mmol) is added dropwise at the same temperature. The reaction was stirred for 2 h and then cooled to room, temperature. The aqueous layer is removed and neutralized with aqueous NaOH to afford 31 as a crystalline solid. The crude product is purified by silica gel chromatography (hexanesiethyl acetate, 5 1) to give 31 (802 mg, 70%) as colorless crystals, mp 103 °C. 

The washed benzene layer is diluted with an equal volume of ether and alcoholic hydrochloric acid is added until the mixture is acid to Congo red. A white crystalline solid forms which is dissolved in 300-400 cc of alcohol and diluted with ether to the point where precipitation starts. A few drops of butanone are added, the solution is cooled to -10°C, and filtered to recover the crystals which separate. The product is obtained in the form of white needles melting at IbS -IBO C, in good yield. 

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