Acid washing

In early designs, the reaction heat typically was removed by cooling water. Crude dichloroethane was withdrawn from the reactor as a liquid, acid-washed to remove ferric chloride, then neutralized with dilute caustic, and purified by distillation. The material used for separation of the ferric chloride can be recycled up to a point, but a purge must be done. This creates waste streams contaminated with chlorinated hydrocarbons which must be treated prior to disposal. 

Set aside (preferably overnight), and then filter off the acid, wash it with water and dry. Yield of crude acid, 12 g. m.p. 223-226°. 

To obtain the free acid, dissolve the potassium salt in 50 ml. of cold water, filter the solution if a small undissolved residue remains, and then boil the clear solution gently whilst dilute sulphuric acid is added until the separation of the acid is complete. Cool the solution and filter off the pale orange-coloured crystals of the benzilic acid wash the crystals on the filter with some hot distilled water, drain well, and then dry in a desiccator. Yield of crude acid, 4 g. Recrystallise from benzene (about 50 ml.) to which a small quantity of animal charcoal has been added, filtering the boiling solution through a preheated funnel fitted w ith a fluted filter-paper, as the benzilic acid readily crystallises as the solution cools alternatively, recrystallise from much hot water. The benzilic acid is obtained as colourless crystals, m.p. 150°. 

The hydrochloric acid washing removes any unchanged alcohol which may be present. 

Dissolve 50 g. of piperonal and 75 g. of malonic acid in a mixture of 160 ml. of pyridine and 2-5 ml. of piperidine contained in a 500 ml. round-bottomed flask, and heat under reflux for 1 hour on a water bath. A rapid evolution of carbon dioxide takes place. Complete the reaction by boiling the solution for 5 minutes. Cool, pour into excess of water containing enough hydrochloric acid to combine with the pyridine, filter ofiFthe piperonylacrylic acid, wash with a little water, and dry. The yield is almost quantitative and the acid is practically pure. It may be recrystallised from glacial acetic acid m.p. 238°. 

Reflux 6 8 g. of the dimethyl ester with a solution of 3 2 g. of sodium hydroxide in 150 ml. of 80 per cent, methanol for 2 hours on a water bath. When cold, filter oflF the solid and wash it with a little cold methanol. Dissolve the solid in 350 ml. of warm water, add concentrated hydrochloric acid to the solution at 60° until acidic to litmus, filter off the precipitated acid, wash with a little water and dry at 100°. The resulting hexadecane-1 16 dicarboxylic acid, m.p. 122°, weighs 5-3 g. Recrystallisation from absolute methanol raises the m.p. to 124 -5°. 

Purification of charcoal. Heat Norit charcoal on a water bath for 6 hours with 10 per cent, nitric acid, filter, wash free from acid, and dry at 100°. If the acid-washed form of Norit charcoal is available, it may be used directly without further purification. 

C. Palladium on carbon catalyst (5 per cent. Pd). Suspend 41-5 g. of nitric acid - washed activated carbon in 600 ml. of water in a 2-litre beaker and heat to 80°. Add a solution of 4 1 g. of anhydrous palladium chloride (1) in 10 ml. of concentrated hydrochloric acid and 25 ml. of water (prepared as in A), followed by 4 ml. of 37 per cent, formaldehyde solution. Stir the suspension mechanically, render it alkaUne to litmus with 30 per cent, sodium hydroxide solution and continue the stirring for a further 5 minutes. Filter off the catalyst on a Buchner funnel, wash it ten times with 125 ml. portions of water, and dry and store as in B. The yield is 46 g. 

Oxidation of galactose (or a galactose-containing sugar) to mucic acid. Dissolve 1 g. of galactose or lactose in a mixture of 10 ml. of water and 5 ml. of concentrated nitric acid contained in a small evaporating dish, and evaporate the solution to dryness on a water bath. Stir the cold residue with 10 ml. of cold water, filter off the mucic acid, wash it with cold water, dry and determine the m.p. (212-213° with decomposition). 

B. With 70 per cent, sulphuric acid. Reflux 1 g. of the substance (e.g., benzanilide) with 10-15 ml. of 70 per cent, sulphuric acid (4 3 by volume) for 30 minutes. Allow to cool and wash down any acid which has sublimed into the condenser with hot water. Filter off the acid, wash it with water, and examine for solubility, etc. Render the filtrate alkaline... 

Interesting note, using CuCk for the first time.. NO OLIVE GREEN color appeared. Stayed slightly yellow -dark brown... All the way through the rxn. Never came close to Green (light, dark or olive). When rxn finished solution was very dark reddish-brown, even when acid washed it stayed dark reddish brown. 

This is my version, but may be better done. First one, evaporate methanol, better with vacuum. Then we have two layers similar in volume, we add 100 of solvent and 50 cc of basic solution (sodium carbonate, bicarbonate or 10 % NaOH ). We shake it and may be we will have little more precipitate or tar. Also may be we can t see separation, then w/e add a bit more solvent without shaking to see separation. We make two more extractions with 50 cc of solvent. Even if we can t see separation, we can add enough HCI and shake, this will forme some tar and layers will be distincts, so we can separate and make a basic wash. Sometimes I ve done first an acid wash, but I can t sure it s better. I m thinking now may be is better to do all extraction as Strike s top 3. Add acid solution, like 250 cc (less PdClz and no CuCI) 15% HCI, extract and make a basic wash. 

METHOD 2 [89]--1M MDA or benzedrine and 1M benzaldehyde is dissolved in 95% ethanol (Everclear), stirred, the solvent removed by distillation then the oil vacuum distilled to give 95% yellow oil which is a Schiff base intermediate. 1M of this intermediate, plus 1M iodomethane, is sealed in a pipe bomb that s dumped in boiling water for 5 hours giving an orangy-red heavy oil. The oil is taken up in methanol, 1/8 its volume of dH20 is added and the solution refluxed for 30 minutes. Next, an equal volume of water is added and the whole solution boiled openly until no more odor of benzaldehyde is detected (smells like almond extract). The solution is acidified with acetic acid, washed with ether (discard ether), the MDMA or meth freebase liberated with NaOH and extracted with ether to afford a yield of 90% for meth and 65% for MDMA. That s not a bad conversion but what s with having to use benzaldehyde (a List chemical) Strike wonders if another aldehyde can substitute. 

Turmeric paper (gives a rose-brown coloration with boric acid) wash tbe ground root of turmeric with water and discard tbe washings. Digest with alcohol and filter, using the clear filtrate to impregnate white, unsized paper, which is then dried. 

Acrylamide copolymers are effective iron ore pellet binders (118). When the ore slurry in water has a pH above 8, anionic polymers are effective. If the ore is acid washed to remove manganese, then a cationic polymer is effective. 

A high percentage of the ammonia can be recovered from the spin-bath effluent and by washing prior to the final acid bath. During acidification, remaining ammonia is converted to the sulfate and recovered when the acid wash Hquor is treated with carbonate to recover the copper. Ammonia residuals in the large volumes of washwater can only be removed by distillation. Overall about 75—80% of the ammonia requited to dissolve the cellulose can be recovered. 

Pyrolysis. Heating in the absence of oxygen releases moisture at low temperatures, carbon dioxide at temperatures >200° C, and a variety of gaseous products at very high temperatures. Acid washing of the raw coal is used to remove extractable cations, followed by treatment with selected cations. Yields of CO2, CO, CH, H2, and H2O depend on the amounts of inorganic species in the coal (42). 

This resia was temporarily accepted, primarily because of its improved resistance to acid washes. However, the relatively high cost of the diamine precluded widespread commercial acceptance. 

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