8- -, dihydrate, crystal

Fig. 1. Fquilihrium phase diagram, Na2S202 and H2O, where the dashed line is an extension of dihydrate crystal phase (24).

LiB02 2H20 or Li20 20 4H2O, becomes the stable soHd phase. Dihydrate crystals are orthorhombic having a density of 1.825 g/mL and a stmctural formula Li[B(OH)4]. In solution above 150°C a hemihydrate, LiB02 1 /2H2O, forms and the anhydrous salt crystallizes above 225°C. 

Chlorination of lime slurried in strong NaOCl solution, followed by cooling to — 15°C, precipitates about 80% of the av CI2 as large hexagonal crystals of a triple salt Ca(OCl)2 NaOCl NaCl -12H20 [64147-46-2] (182). The recovered triple salt, free of much of the lime impurities, is treated with chlorinated lime slurry to produce neutral calcium hypochlorite dihydrate crystals [22464-76-2]. 

Crystal growth modifiers have been employed to improve filterabiHty and water retention of Ca(OCl)2 2H20, which typically crystallizes as fine plates. Addition of zinc dust or salts produces larger square- and diamond-shaped, untwinned dihydrate crystals (215). Coarse prismatic crystals are obtained by use of carbohydrates and carboxyHc acids and thek salts (216). 

The dihydrate crystallizes as the solution cools. Such salts are stable in alkaline solution but hydrolyse in acid solution to imidodisulfate (and then more slowly to sulfamic acid) ... 

The solid is collected on a Buchner funnel and washed with three 30-cc. portions of cold water. The alloxantin is dissolved by boiling the wet solid for fifteen minutes with 250 cc. of water, and the hot solution is filtered to remove the sulfur (Note 2). Alloxantin dihydrate crystallizes from "the filtrate in glistening plates which should be pressed as dry as possible on a Buchner filter, washed with about 30 cc. of ether, and dried in a vacuum desiccator (Note 3). The yield is 8-10 g. (55-69 per cent of the theoretical amount) (Note 4). The product melts with decomposition at 234-238° (Note 5), and is pure enough for most purposes. 

The formula (5.14) has been applied, for example, by Hutchison and McKay144 to determine the proton coordinates in Nd(III)-doped lanthanum nicotinate dihydrate crystals, and by Balmer et al.101) to localize the charge compensator H+ in Co(II)-doped a-Al203. 

With this data, the computer program is capable of predicting the operation of a hemihydrate - dihydrate crystallizer installation. 

Figure 15. Flowsheet for computer model of hemlhydrate dihydrate crystallizer.

Reaction with copper(II) chloride at 2 1 ratio produces yellow orthorhombic crystals of cupric ammonium chloride, which reacts with water to form blue dihydrate crystal, ammonium tetrachlorodiaquocuprate(II) ... 

Figure 4. Packing of the molecules in the diphenylguanidinium 5-nitrouracilate dihydrate crystal structure. The dashed lines represent hydrogen bonds.

Presence of water in the reaction mixture has significant importance because dihydrates crystallized in both cases. Single crystal X-ray analysis of (6)-3b-DBTACa.2H20 confirmed that one of the water molecules coordinated to the central calcium ion while the other one sticked to the remote carboxylic group by H-bond as it is showed in Scheme 3. [24]... 

Edetic acid is obtained as crystals from water Edetate sodium is a powder Edetate disodium is composed of dihydrate crystals Edetate trisodium is obtained as monohydrate crystals from water Edetate calcium disodium is a tetrahydrate powder. All materials are white in color, and odorless. 

Upper right mescaline sulfate (also called, mescaline hemi-sulfate dihydrate) crystals and a straight pin for size comparison. The crystals look like tiny, translucent glass rods, but upon closer examination they appear more like a pile of lumber (left). The photo at the bottom enlarges this "lumber pile ten times. 

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