Liquid filtration phosphating solutions

One gram of 6,7-dihydro-5H-dibenz[c,e] azepine hydrochloride was dissolved in water, made alkaline with concentrated ammonia, and the resultant base extracted twice with benzene. The benzene layers were combined, dried with anhydrous potassium carbonate, and mixed with 0.261 g of allyl bromide at 25°-30°C. The reaction solution became turbid within a few minutes and showed a considerable crystalline deposit after standing 3 A days. The mixture was warmed VA hours on the steam bath in a loosely-stoppered flask, then cooled and filtered. The filtrate was washed twice with water and the benzene layer evaporated at diminished pressure. The liquid residue was dissolved in alcohol, shaken with charcoal and filtered. Addition to the filtrate of 0.3 gram of 85% phosphoric acid in alcohol gave a clear solution which, when seeded and rubbed, yielded 6-allyl-6,7-dihydro-5H-dlbenz[c,e] azepine phosphate, MP about 211°-215°C with decomposition. 

Alkalies. — The solution of 2 gm. of ammonium phosphate in 100 cc. of water is treated with lead acetate solution in slight excess to precipitate the phosphoric acid, and is then filtered. The excess of lead in the filtrate is then precipitated with hydrogen sulphide, the liquid filtered, the filtrate evaporated to dryness, and the residue ignited. The residue should not be soluble in water, nor should it have an alkaline reaction. 

After about half in hour, the excess of lead is eliminated by addition of 40 c.c. of a solution containing 10% of sodium phosphate and 10% of sodium sulphate, and the volume made up to 250 c.c. by means of distilled water. The liquid is mixed, left until the precipitate settles and filtered through a dry filter, exactly 200 c.c. of filtrate being collected. 

In this way, the iron hydroxide and the phosphates of the alkaline earths remain undissolved, whilst the alumina passes into solution. After standing for some time on a water-bath, the liquid is filtered into a platinum or porcelain dish and the residue washed with hot water. The filtrate is boiled for 2-3 minutes with excess of ammonium chloride, the aluminium being thus precipitated as hydroxide, which is collected in a filter supported by means of a small platinum cone in the funnel and washed with hot water containing a little ammonium chloride and ammonia, slight suction being applied at the end of the washing. 

Acetone has been used as the organic solvent but can cause problems due to the formation of acetonides with vicinal diols in slightly acid conditions (lU,15). After the aqueous methanol extraction, the homogenate is filtered and the methanol removed from the filtrate under reduced pressure at 1+0° or below. At this stage it is common to buffer the aqueous residue, usually with potassium phosphate. With some tissues, for example liquid endosperm, it is convenient to extract directly with a buffer solution at about pH 8 resulting in a cleaner extract (16). 

A suspension of Avicel cellulose (0.5 g) in 0.05 mmol/L phosphate buffer (pH 4.5, 10 mL) containing ammonium sulfate (4.72 g) was stirred for 1 h, and a solution of (S)-HNL from Sorghum bicolor (50 pL, 1000 IU/mL, specific activity 70 IU/mg) was added. The mixture was stirred at room temperature for 10 min and filtered, and the immobilized enzyme was suspended in diisopropyl ether (10 mL). After addition of aldehyde (2 mmol) and dry liquid HCN (300 pL, 7.5 mmol), the mixture was stirred until all aldehyde had reacted. After removal of the immobilized enzyme, the filtrate was concentrated to yield the crude cyanohydrin. 

Preparation Method of DaouHewsky. — Fresh pancreas, preferably that of hog, is crushed in a mortar with gravel and water. It is allowed to settle and the decanted liquid is filtered through a sieve. To the filtrate magnesia is added, forming a precipitate which carries down the amylase and other impurides. After filtration the liquid, which contains trypsin free from saccharifying enzyme, is acidified with phosphoric acid and then neutralized with lime. The calcium phosphate formed, which partially carries down with it the lipase, is filtered off and the filtrate, rich in trypsin, is evaporated in a vacuum. The separation of trypsin and amylase can also be accomplished with the aid of collodion diluted with an equal volume of a mixture of alcohol and ether. After the addition of collodion, the pancreatic liquid is stirred, the precipitate formed carrying with it the trypsin, while the amylase remains in solution. 

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