White plate

CifiHijClNj. White plates m.p. 125 C. Diazepam is one of several benzodiazepines which are very widely used as minor tranquillizers for allaying anxiety, as hypnotics or, in sufficiently high dosage given intravenously, as pre-anaesthetic sedatives. 

Aminophenol. This compound forms white plates when crystallized from water. The base is difficult to maintain in the free state and deteriorates rapidly under the influence of air to pink-purple oxidation products. The crystals exist in two forms. The a-form (from alcohol, water, or ethyl acetate) is the more stable and has an orthorhombic pyramidal stmcture containing four molecules per unit cell. It has a density of 1.290 g/cm (1.305 also quoted). The less stable P-form (from acetone) exists as acicular crystals that turn into the a-form on standing they are orthorhombic bipyramidal or pyramidal and have a hexamolecular unit (15,16,24) (see Tables 3—5). 

Propargyl triphenyl phosphonium bromide [2091-46-5] M 381.4, m 179°. Recrystallises from 2-propanol as white plates. Also crystallises from EtOH, m 156-158°. IR has V 1440, 1110cm (P-C str). [Justus Liebigs Ann Chem 682 62 1965 J Org Chem 42 200 1977]. 

B-Norcholesterol Acetate (71). A test tube containing 2 g (4.4 mmoles) of (70) is placed in an oil bath at 150° and the temperature of the bath is slowly raised. At 170°, the liquified mass begins to froth and after 15 min the evolution of CO2 is essentially complete. The melt is allowed to stand at 180° for an additional 15 min. After cooling to room temperature and trituration with 5 ml of acetone, long white plates separate. The crystals are removed by filtration and washed with 70% acetone-water to yield 1.74 g (94%) of (71) mp 77-79°. 

Methylsulfinyl -pentyl ketone is prepared by the reaction of the reagent (0.1 mole) and 7.2 g (0.05 mole) of ethyl caproate yielding the crude product as a pasty crystalline mass. The material is dissolved in hot isopropyl ether (20 ml), petroleum ether (30 ml) is added, and the solution cooled to -15°. Filtration yields approx. 6 g of white plates, mp 40-44°. Recrystallization from isopropyl ether affords pure product, mp 45-47°. 

The product was purified as follows. 60 g of product was dissolved in 3N aqueous hydrochloric acid, the solution was treated with charcoal and filtered. The filtrate was neutralized by the gradual addition of aqueous concentrated ammonia at 0°C to 5°C under stirring whereupon the product precipitated in white plates as the neutralization proceeded. The precipitate was filtered by suction, washed on the filter with 50 ml of ice cold water and dried at room temperature, MP 60°C. 

Matheson, Coleman, and Bell mabsolute ethanol contEflining 0.02% glacial acetic acid (Note 6) and filtered by suction. The ffiltrate was cooled, and the white plates of mercuric acetate were collected by suction filtration and stored under vacuum. 

Chloride salt (la). The pyridinium mesylate from above was dissolved in 200 ml of methylene chloride, and was shaken with 50 ml of saturated NaCl solution in a separatory funnel for ca 2 min. The methylene chloride phase was removed, the brine phase was washed once with 20 ml of methylene chloride, and the organic phases were combined. This procedure was repeated twice using fresh brine. The methylene chloride phase was filtered and evaporated to dryness, affording the crude chloride salt. Recry-stalllzation of the salt from THE/chloroform (ca. 20 1) gives white plates with mp = 192-193 ... 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

To a cooled solution of 3,4-dimethoxyphenylethylamine 5.4 g in 20 cc of acetic acid, 4.8 g of bromine in 15 cc of acetic acid is slowly added with stirring. Separation of the product will begin rapidly, and after setting overnight the crystals can be collected and recrystallized from ethanol. Addition of sodium hydroxide to an aqueous solution will precipitate the free base as white plates. Yield 7 g, mp 202-204°. 

Aminophenol. This compound forms white plates when crystallized from water. The base is difficult to maintain in the free state and deteriorates rapidly under the influence of air to pink-purple oxidation products. 

Tri-m-tolyl tellurium iodide 5 separates from water in scales which sinter at 154° C. and melt at 156° to 157° C., and from ether in scales softening at 158° C. and melting at 160° to 161° C. The corresponding picrate forms small needles from alcohol, M.pt. 152° to 153° C. The bromide is an amorphous powder. The chloride yields a mercurichloride, (CH3.C6H4)3TeCl.HgCl2, white plates, M.pt. 159° to 160° C. 

The white plate is used by most investigators for standardization, but there may be instances where the colored standard is preferred. Whichever is chosen, that same plate must be used throughout the discoloration study. Additionally, the exact specifications of the standardization plate should be indicated in any scientific report. 

The titration is then repeated, all but 2 c.cs. of the volume of glucose solution used in the first determination being run in at once, and the remainder in drops until the blue colour just vanishes. The end point is more easily observed when the dish is slightly tilted. Several determinations are made until concordant results are obtained. If the end point is indistinct, a dilute acetic acid solution of potassium ferrocyanide spotted on a white plate may be used as external indicator. A brown coloration is observed so long as copper is present in solution. 

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