Air-dried

Another method, which is especiafly suitable for low melting point solids or solids which decompose at low temperatures, is to place the material on a porous plate or pad of drying paper, and to cover the latter with another sheet of Alter paper perforated with a number of holes or with a large clock glass or sheet of glass supported upon corks. The air drying is continued until the solvent has been completely eliminated. 

Introduce 197 g. of anhydrous brucine or 215 g. of the air-dried dihydrate (4) into a warm solution of 139 g. of dZ-acc.-octyl hj drogen phthalate in 300 ml. of acetone and warm the mixture vmder reflux on a water bath until the solution is clear. Upon cooling, the brucine salt (dA, IB) separates as a crystalline solid. Filter this off on a sintered glass funnel, press it well to remove mother liquor, and wash it in the funnel with 125 ml. of acetone. Set the combined filtrate and washings (W) aside. Cover the crystals with acetone and add, slowly and with stirriug, a slight excess (to Congo red) of dilute hydrochloric acid (1 1 by volume about 60 ml.) if the solution becomes turbid before the introduction of... 

Concentrate the combined filtrate and washings (W) to about half the original volume, and pour it into sUghtly more than the calculated amount of dilute hydrochloric acid (use a mixture of 30 ml. of concentrated hydrochloric acid and 30 ml. of ice-water) then add about 300 ml. of water. Collect the active aec.-octyl hydrogen phthalate (crude lA) as above (5). The weight of the air-dried ester is about half that of the dl-ester originally used (7). 

Commercial brucine is usually the tetrahydrate Cj,H2404Nj,4Hj0 upon air drying, this loses two molecules of water of crystallisation and passes into the dihydmte. 

I) When working with larger quantities of material, it is more convenient (and a better yield is obtained) to purify the air-dried product by distillation under diminished pressure. Use the apparatus pictured in Fig. II, 19, 4, and add a few fragments of porous porcelain to the solid. No air inlet can be employed to prevent bumping since this may lead to explosive decomposition. Collect the pure m-nitrophenol at I60-I65°/I2 mm. always allow the flask to cool before admitting air otherwise the residue may decompose with explosive violence. The recovery is over 90 per cent, of the pure m-nitroplienol. 

To prepare pure anhydrous o-benzoylbenzoic acid, dissolve the air-dried (or the moist) product in about 175 ml. of benzene contained in a 500 ml. round-bottomed flask fitted with a reflux condenser and heat on a water bath. Transfer the benzene solution to a separatory funnel, run oflF any water present, and dry with anhydrous magnesium sulphate. Concentrate the benzene solution to about 75 ml. and add light petroleum, (b.p. 60-80°) to the hot solution until a slight turbidity is produced. Allow to cool spontaneously to room temperature, then cool in ice to about 5°, collect the crystals and dry. The yield of pure, anhydrous o-benzoylbenzoic acid, m.p. 128°, is 32 g. 

Amino-3 5-diiodobenzoic acid. In a 2 litre beaker, provided with a mechanical stirrer, dissolve 10 g. of pure p-aminobenzoic acid, m.p. 192° (Section IX,5) in 450 ml. of warm (75°) 12 -5 per cent, hydrochloric acid. Add a solution of 48 g. of iodine monochloride (1) in 40 ml. of 25 per cent, hydrochloric acid and stir the mixture for one minute during this time a yellow precipitate commences to appear. Dilute the reaction mixtiue with 1 litre of water whereupon a copious precipitate is deposited. Raise the temperature of the well-stirred mixture gradually and maintain it at 90° for 15 minutes. Allow to cool to room tempera-tiue, filter, wash thoroughly with water and dry in the air the yield of crude acid is 24 g. Purify the product by dissolving it in dilute sodium hydroxide solution and precipitate with dilute hydrochloric acid the yield of air-dried 4-amino-3 5-diiodobenzoic acid, m.p. >350°, is 23 g. 

The following is an alternative method of purifying the crude aspirin. Dissolve the solid in about 30 ml. of hot alcohol and pour the solution into about 75 ml. of warm water if a sohd separates at this point, warm the mixture until solution is complete and then allow the clear solution to cool slowly. Beautiful needle-like crystals will separate. The yield is 13 g. The air-dried crude product may also be recrystallised from benzene or from ether - light petroleum (b.p. 40-60°). 

Seaweeds. The eadiest successful manufacture of iodine started in 1817 using certain varieties of seaweeds. The seaweed was dried, burned, and the ash lixiviated to obtain iodine and potassium and sodium salts. The first process used was known as the kelp, or native, process. The name kelp, initially apphed to the ash of the seaweed, has been extended to include the seaweed itself. About 20 t of fresh seaweed was used to produce 5 t of air-dried product containing a mean of 0.38 wt % iodine in the form of iodides of alkah metals. The ash obtained after burning the dried seaweed contains about 1.5 wt % iodine. Chemical separation of the iodine was performed by lixiviation of the burned kelp, followed by soHd-Hquid separation and water evaporation. After separating sodium and potassium chloride, and sodium carbonate, the mother Hquor containing iodine as iodide was treated with sulfuric acid and manganese dioxide to oxidize the iodide to free iodine, which was sublimed and condensed in earthenware pipes (57). 

Zinc arc spraying is an inexpensive process in terms of equipment and raw materials. Only 55—110 g/m is required for a standard 0.05—0.10 mm Zn thickness. It is more labor intensive, however. Grit blasting is a slow process, at a rate of 4.5 m /h. AppHcation of an adhesive paint layer is much quicker, 24 m /h, although the painted part must be baked or allowed to air dry. Arc sprayed 2inc is appHed at a rate of 9—36 m /h to maintain the plastic temperature below 65°C. The actual price of the product depends on part complexity, number of parts, and part size. A typical price in 1994 was in the range of 10—32/m. ... 

Substituted heat-reactive resins are most widely used in contact-adhesive appHcations and, to a lesser extent, in coatings (77,78) -butylphenol, cresol, and nonylphenol are most frequendy used. The alkyl group increases compatibiHty with oleoresinous varnishes and alkyds. In combination with these resins, phenoHcs reduce water sensitivity. Common appHcations include baked-on and electrical insulation varnishes, and as modifiers for baking alkyds, rosin, and ester gum systems. Substituted heat-reactive resins are not used for air-dry coatings because of theh soft, tacky nature in the uncured state substituted nonheat-reactive phenoHcs are the modifying resin of choice in this case. 

PhenoHcs that are not heat-reactive may be incorporated into both air-dried and baked oleoresinous coatings. AppHcations vary widely and include clear and pigmented exterior varnishes, aluminum-maintenance paints, 2inc-rich primers, can coatings, insulation varnishes, and concrete paints. As modifiers in a great variety of appHcations, they enhance the performance of oleoresinous and alkyd coatings. 

Crystalline TSP is a dodecahydrate with somewhat variable composition between the limits of (Na PO I2H2O) 0.25NaOH and (Na PO I2H2O) l/TNaOH. It is manufactured by crystallisation below 60°C from a solution with an Na20/P20 mole ratio slightly lower than 3.25. Crystals are isolated by centrifugation and air-dried at ca 40°C to minimise dehydration. 

Llthol Reds. Lithol Red or Pigment Red 49 1/7103-38-4] is one of the most important of the precipitated salt pigments. They comprise a family of sodium (PR 49), barium (PR 49 1), calcium (PR 49 2), and strontium (PR 49 3) salts of dia2oti2ed Tobias acid or 2-naphthylamine-l-sulfonic acid coupled with 2-naphthol. The most popular are the barium and calcium salts, the former being yellower in shade. These reds are used where brightness, bleed resistance, and low cost ate of primary importance. They are neither resistant to heat nor chemicals, and are used primarily in printing inks and some inexpensive air-dried industrial paints where good durabiUty is not requited. 

Other minor raw materials are used for specific needs. Eumaric acid [110-17-8] the geometric isomer of maleic acid, is selected to maximize thermal or corrosion performance and is the sole acid esterified with bisphenol A diol derivatives to obtain optimum polymer performance. CycloaUphatics such as hydrogenated bisphenol A (HBPA) and cyclohexanedimethanol (CHDM) are used in selective formulations for electrical apphcations. TetrahydrophthaUc anhydride [85-43-8] (THPA) can be used to improve resiUence and impart useful air-drying properties to polyester resins intended for coating or lining apphcations. 

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