Rhomb

If desired, the 3,5-dinitrobenzoic acid may be re crystallised from water as almost colourless rhombs, m.p. 204 . 

Crocetin is a dicarboxyUc acid that forms brick red rhombs from acetic anhydride that melt with decomposition at about 285°C. It is very sparingly soluble in water and most organic solvents but soluble in pyridine and similar organic bases as well as in dilute sodium hydroxide. 

Anthrimide [l,l -imino-bis-anthraquinone] [82-22-4] M 429.4, m >250 (dec). Crystd from chlorobenzene (red needles) or nitrobenzene (red rhombs)... 

Bilirubin [635-65-4] M 584.7, e450nm t OO in CHCI3, pKE t 3 0. An acyclic tetrapyrrole bile pigment with impurities which can be eliminated by successive Soxhiet extraction with diethyl ether and MeOH. It crystallises from CHCI3 as deep red-brown rhombs, plates or prisms, and is dried to constant weight at 80 under vacuum, [Gray et al. J Chem Soc 2264, 2276 1961.]... 

Arecoline, CgHj 302N. This, the most important alkaloid of areca nut, is an odourless, alkaline oil, b.p. 209°, volatile in steam, miseible with most organic solvents and water, but extractable from the latter by ether in presence of dissolved salts. The salts are crystalline, but usually deliquescent the hydrobromide, B. HBr, forms slender prisms, m.p. 177-9°, from hot alcohol the aurichloride, B. HAUCI4, is an oil, but the platinichloride, B2. H2PtClg, m.p. 176°, crystallises from water in orange-red rhombs. The methiodide forms glancing prisms, m.p. 173-4°. 

Conhydrine, CgHj, ON. This oxygenated alkaloid was isolated by Wertheim. It crystallises in colourless leaflets, has a coniine-like odour, can be sublimed and is strongly basic, m.p. 121°, b.p. 226°, Wd 4" 10°- It is soluble in alcohol or chloroform, moderately so in water and in ether, from which it crystallises readily. The salts are crystalline the aurichloride small rhombs or pri.sims, m.p. 133° the benzoyl derivative m.p. 132°. 

Ephedrine, CjqHjsON, crystallises from ether in rhombs, m.p. 118-9°, [a]n"° + 51 2° (EtOH), and, unlike ephedrine, is sparingly soluble in water. The hydrochloride, B. HCl, crystallises in colourless, slender needles, m.p. 181-2°, + 62-05° (HjO), and, unlike the ephedrine salt,... 

Delphinine, C34H47O9N (Walz) or C33H45O9N (J. and C.). The alkaloid crystallises in rhombs, or six-sided plates, m.p. 198-200°, [a]f ° + 25° (EtOH), shows mutarotation in alcoholic solution, and forms an acid oxalate, B. H2C2O4, m.p. 168° dry), a hydrochloride, B. HCl, m.p. 208-210°, and a monobenzoyl derivative, m.p. 171-3°. On alkaline hydrolysis it yields one molecule each of acetic and benzoic acids. The basic, hydrolytic product of this action is delphonine, C24H3g07N, which is amorphous, but can be distilled at a bath temperature of 140° and a pressure of 0-001 to 0-0001 mm. The brittle, possibly semi-crystalline resin so obtained, has m.p, 76-8° and [a]f ° - - 37-5 (EtOH). 

There was obtained a mixture of N-(2 -diethylamino-2 -methylethyl)phenthiazine and N-(2 -diethylamino-1 -methylethyDphenthiazine in the form of a viscous yellow oil, BP 202° to 205°C/2 mm. This oil was treated in ethereal solution with ethereal hydrogen chloride and gave a white solid which was fractionally crystallized from ethylene dichloride. The less soluble fraction, N-(2 -diethylamino-2 -methylethyl)phenthiazine hydrochloride formed colorless rhombs, MP 223° to 225°C. The more soluble N-(2 -diethylamino-1 -methylethyl)-phenthiazine hydrochloride was obtained as colorless prismatic needles, MP 166° to 168°C. 

Knoop hardness It is a measure of hardness is measured by a calibrated machine that forces a rhomb-shape, pyramidal diamond indenter having specified edge angles under specific small loading conditions into the surface of the test material the long diagonal in the material is measured after removal of the load. 

Uranyl Nitrate (Uranium Nitrate, UNH, Yellow Salt). U02(N03)2.6H20, mw 502.18, N 5.58% yellow rhomb crysts, greenish luster by reflected light mp 60.2°, bp 118°, d 2.807g/cc, RI 1.4967. Sol in 1.5p w, freely in ale and eth. Prepd by the action of nitric acid on U octoxide. When shaken, rubbed, or crushed, the crysts show remarkable triboluminescence with occasional detonations. It is highly toxic, and a severe fire and expln risk when shocked or heated,... 

Phenyl-tetrazole. Mw 146.17, N 38.34% white (C6H5).C.NH,N rhomb-pyramidal crysts ... 

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