Crystal manufacture

Sakai, K. (1999) Application of habit modification of diastereomeric salt crystals obtained from optical resolution via crystallization manufacture of enantiomerically pure 1-phenylethylamine,./. Org. Synth. Chem. Jpn, 57, 458-465. 

It should be ever present in the reader s mind that for every particular case the appropriate crystallizer manufacturers should be con-... 

Fig. 10 SEM images of unprocessed and SEDS-processed acetaminophen. (A) As received from Sigma Aldrich, 200x magnification. (B) Crystals manufactured by the SEDS process at 40° C, 150 bar pressure, using a feedstock of lOmg/ml acetaminophen in ethanol. (SEM courtesy of S. Desikan, Bristol-Myers Squibb processing by S. Jen and P. Stetsko, Bristol-Myers Squibb.).

Fig. 1. Piezoelectric quartz crystal resonator (left, photo of the optically polished smooth crystal) and schematic description (right). The crystal shown (part no. 151620-10) is produced by International Crystal Manufacturing, see Note 1.

Figure 15.47 Quartz crystal showing the angle of the AT out. (Courtesy of International Crystal Manufacturing, Inc., Oklahoma City, OK, www.lcmfg.com.)...

The most common frequencies for QCM crystals are 5.000 and 10.000 MHz, although crystals from 1 to >30 MHz can be produced. Electrodes for QCM crystals are usually made of gold, but a variety of metal and nonmetal electrodes are available. The International Crystal Manufacturing, Inc., website (www.icmfg.com) has detailed information on QCM crystals and their manufacture. The Gamry Instruments website (www.gamry.com) has an excellent introduction to the QCM with multiple references. 

Crystals are familiar to everyone, common examples being salt and sugar. Less common but more alluring are diamonds and other gemstones. More prosaic are the innumerable crystals manufactured in the bulk, fine chemical and pharmaceutical industries, in both primary products, secondary formulations and their intermediates. As illustrated by the crystal products in Table 1.1, their range is immense and includes some highly sophisticated materials. Similarly, worldwide production rates and value are ever increasing. 

Several well-characterized crystals for frequency doubling or frequency sum up to 0.25 pm which corresponds to the fourth harmonic of the YAG laser frequency (1.053 pm), are proposed by crystal manufacturers with outstanding conversion efficiencies. This upper frequency limitation around 0.25 pm results from the onset of absorption above this frequency and concomitant heating in practically all efficient doubling crystals there are similar limitations towards the mid- and far-IR spectrum because of strong absorption bands there due to IR active lattice modes (phonons, vibrations) and one resorts here to other nonlinear processes and coupling schemes. 

White crystals, m.p. 114" C. Manufactured by reacting aniline with excess ethanoic acid or ethanoic anhydride. Chief use is in the manufacture of dye intermediates such as p-nitro-acetanilide, p-nitroaniline and p-phenylene-diamine, in the manufacture of rubber, and as a peroxide stabilizer. 

BHC is manufactured by chlorination of benzene in the presence of ultra-violet light. The gamma-isomer is obtained from the crude mixture by selective crystallization, and forms colourless crystals, m.p. I13" C. U.S. production 1980 400 tonnes. 

C8H10N4O2. An alkaloid occurring in tea, coffee and guarana, from which it may be prepared by extraction, It is also manufactured by the methylation of theobromine and by the condensation of cyanoacetic acid with urea. Crystallizes with H2O or anhydrous from organic solvents. M.p. (anhydrous) 235"C, sublimes at 176 C. Odourless, and with a very bitter taste. Caffeine acts as a stimulant and diuretic, and is a constituent of cola drinks, tea and coffee. 

CCl3CH(OH)2, C3H3CI3O2. Crystallizes in large, colourless prisms having a peculiar odour m.p. 57"C, b.p. 91-5 C. Manufactured by adding the calculated amount of water to chloral. For other properties see chloral. Its chief use is as a hypnotic. 

C7H6O5. Colourless crystals with one molecule of water, m.p. 253" C, sparingly soluble in water and alcohol. It occurs free in woody tissue, in gall-nuts and in tea, and is a constituent of the tannins, from which it can be obtained by fermentation or by acid hydrolysis. It gives a blue-black colour with Fe and is used in the manufacture 6f inks. On heating it gives pyrogallol. 

Ordinary glucose is ct-glucopyranose monohydrate m.p. 80-85°C and [ajp 4-113-4 . In solution it gives a mixture with the form with [alo 4-52-5 . It is manufactured from starch by hydrolysis with mineral acids, purification and crystallization, and is widely used in the confectionery and other food industries. It is about 70% as sweet as sucrose. 

Crystallizes from water in large colourless prisms containing 2H2O. It is poisonous, causing paralysis of the nervous system m.p. 101 C (hydrate), 189°C (anhydrous), sublimes 157°C. It occurs as the free acid in beet leaves, and as potassium hydrogen oxalate in wood sorrel and rhubarb. Commercially, oxalic acid is made from sodium methanoate. This is obtained from anhydrous NaOH with CO at 150-200°C and 7-10 atm. At lower pressure sodium oxalate formed from the sodium salt the acid is readily liberated by sulphuric acid. Oxalic acid is also obtained as a by-product in the manufacture of citric acid and by the oxidation of carbohydrates with nitric acid in presence of V2O5. 

Crystallizes in colourless needles m.p. 300° (sublimes). Manufactured by the oxidation of p-xylene and used in the production of Terylene (see also polyesters). U.S. production 1980 2-05 megatonnes. 

Two molecules of vitamin A are formed from one molecule of -carotene. Vitamin A crystallizes in pale yellow needles m.p. 64 C. It is optically inactive. It is unstable in solution when heated in air, but comparatively stable without aeration. Vitamin A is manufactured by extraction from fish-liver oils and by synthesis from / -ionone. The role of vitamin A in vision seems to be different from its systemic function. See also relincne and rhodopsin. 

Several manufacturers of transducers and equipment were contacted to give their best solution of the problems. Two instruments and five types of transducers were selected for further experiments. The equipments were very different concerning the possibility for controlling the measuring conditions and the transducer frequencies where from 10 MHz to 25 MHz with different crystal diameters and focussing lenses. 

Testing. Chemical analyses are done on all manufactured abrasives, as well as physical tests such as sieve analyses, specific gravity, impact strength, and loose poured density (a rough measure of particle shape). Special abrasives such as sintered sol—gel aluminas require more sophisticated tests such as electron microscope measurement of a-alumina crystal si2e, and indentation microhardness. 

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