Drying oxalic acid

Esters of bomeol are obtained by the action of dry oxalic acid on turpentine under suitable conditions. From these, borneol is obtained by saponification and is oxidised to camphor. Some other acids produce a similar result, as, for example, salicylic and chlorobenzoic acids. 

By heatmg equal freights of dry oxalic acid and glycerin together to 75° C., when the oxalic acid splits into formic acid and carbonic anhydride —... 

In a reaction kettle constructed as shown in Figure 36 (page 333), a mixture of 138 grams (1.0 mole) of p-nitroaniline and 225 grams (2.5 moles) of dry oxalic acid (anhydrous ) is heated with good stirring at 110°C. The two compounds should be finely pulverized and intimately mixed beforehand, and six steel balls of 25 mm. diameter should... 

Aurin is prepared by heating phenol with oxalic acid and sulphuric acid 6 parts of phenol, 3 parts sulphuric acid, and 4 parts of dried oxalic acid are heated for about twenty-four hours to 120°-130°. 

This radical, in die isolated condition, constitutes dry oxalic acid) and in combination with hydrogen and other radicals it enters into the composition of nearly all organic acids. Acids containing one atom of oxatyl are monobasie, those containing two atoms are dibaaie, and those containing three are tri-baaio. 

The bestmethod d preparing this substance is the one proposed by Geriiardt namety, by heating dried oxalic acid with phosphorus pentac oride when the Mowing reaction takes plaoo... 

Startg. aldehyde added to a stirred soln. of SnCl4 and dicyclohexylcarbodiimide in benzene, after 2 hrs. coned, in vacuo, the residue treated at 0° with a mixture of glycol, dry oxalic acid, and acetonitrile, warmed during 20 min. to room temp. product. Y 97%. F. e. s. N.H. Andersen and H. Uh, Synth. Commun. 3, 125 (1973). 

It follows that liquids of high boiling point should not be distilled from drying agent systems which have appreciable vapour pressures. An extreme case of this action is the dehydration of oxalic acid dihydrate by distillation over toluene or over carbon tetrachloride. 

Diethyl oxalate. Reflux a mixture of 45 g. of anhydrous oxalic acid (1), 81 g. (102-5 ml.) of absolute ethyl alcohol, 190 ml. of sodium-dried benzene and 30 g. (16-5 ml.) of concentrated sulphuric acid for 24 hours. Work up as for Diethyl Adipate and extract the aqueous laj er with ether distil under atmospheric pressure. The yield of ethyl oxalate, b.p. 182-183°, is 57 g. 

Chemical Treatment. The most iavolved regeneration technique is chemical treatment (20) which often follows thermal or physical treatment, after the char and particulate matter has been removed. Acid solution soaks, glacial acetic acid, and oxalic acid are often used. The bed is then tinsed with water, lanced with air, and dried ia air. More iavolved is use of an alkaline solution such as potassium hydroxide, or the combination of acid washes and alkaline washes. The most complex treatment is a combination of water, alkaline, and acid washes followed by air lancing and dryiag. The catalyst should not be appreciably degraded by the particular chemical treatment used. 

Dry air is blown through the solution to remove the excess of ammonia, and the solution is then dissolved in its own volume of absolute alcohol. A sample of this solution is titrated with standard oxalic acid, litmus being used as an outside indicator (Note 3). The amount of oxalic acid (Note 4) necessary to form the acid salt is placed in a large evaporating dish and dissolved in 4 1. of 95 per cent alcohol. The amine solution is then slowly run into the acid with constant stirring. During the addition of the last half of the amine solution, the container must be cooled in order to avoid the formation of the neutral oxalate,... 

Recrystd aniline was dropped slowly into an aqueous soln of recrystd oxalic acid. Aniline oxalate was filtered off, washed several times with water and recrystd three times from 95% EtOH. Treatment with satd Na2C03 soln, regenerated aniline which was distd from the soln, dried and redistd under reduced pressure [Knowles Ind Eng Chem 12 881 7920]. 

Morpholine [110-91-8] M 87.1, f -4.9", b 128.9", d 1.0007, n 1.4540, n 5 1.4533, pK 8.33. Dried with KOH, fractionally distd, then refluxed with Na, and again fractionally distd. Dermer and Dermer [J Am Ghent Soc 59 1148 1937] ppted as the oxalate by adding slowly to slightly more than 1 molar equivalent of oxalic acid in EtOH. The ppte was filtered and recrystd twice from 60% EtOH. Addition of the oxalate to cone aq NaOH regenerated the base, which was separated and dried with solid KOH, then sodium, before being fractionally distd. 

Neodymium oxide [1313-97-9] M 336.5, m 2320°. Dissolved in HCIO4, ppted as the oxalate with doubly recrystd oxalic acid, washed free of soluble impurities, dried at room temperature and ignited in a platinum crucible at higher than 850° in a stream of oxygen [Tobias and Garrett J Am Chem Soc 80 3532 1958]. 

Potassium tetraoxaiate (2H2O) [oxalic acid hemipotassium salt] [6100-20-5 (2H2O) 127-96-8 (anhydr)] M 254.2. Crystd from water below 50°. Dried below 60° at atmospheric pressure. 

Chromomycin A3 [7059-24-7] M 1183.3, m 185 dec, [a] -57 (c 1, EtOH). Dissolve reagent (lOg) in EtOAc and add to a column of Silica Gel (Merck 0.05-0.2microns, 4x70cm) in EtOAc containing % oxalic acid. Elute with EtOAc+1% oxalic acid and check fractions by TLC. Pool fraction wash with H2O thoroughly, dry and evaporate. Recryst from EtOAc. The hepta-acetate has m 214°, [a] -20° (c 1, EtOH). [Tetrahedron 23 421 7967 J Am Chem Soc 91 5896 1969.]... 

On methylation apomorphine yields apo-i/i-coDEiNE (i/i-apocodeme, anocodeine, apomorphine methyl ether), CigHigOaN. C2H5. OH, crystallising in brilliant plates, m.p. 104-5-106-5°, or 122-5-124-5 dry), — 90° (EtOH), which is also produced when codeine or i/i-codeine is heated with oxalic acid or phosphoric acid. It stands in the same relation to codeine as apomorphine to morphine. 

Androst-4-ene-3,17-dione. Testosterone (0.58 g, 2 mmoles) is dissolved in a solution prepared from 3 ml of benzene, 3 ml of dimethyl sulfoxide, 0.16 ml (2 mmoles) of pyridine and 0.08 ml (1 mmole) of trifluoroacetic acid. After addition of 1.24 g (6 mmoles) of dicyclohexylcarbodiimide, the sealed reaction flask is kept overnight at room temperature. Ether (50 ml) is added followed by a solution of 0.54 g (6 mmoles) of oxalic acid in 5 ml of methanol. After gas evolution has ceased ( 30 min) 50 ml of water is added and the insoluble dicyclohexylurea is removed by filtration. The organic phase is then extracted twice with 5 % sodium bicarbonate and once with water, dried over sodium sulfate and evaporated to a crystalline residue (0.80 g) which still contains a little dicyclohexylurea. Direct crystallization from 5 ml of ethanol gives androst-4-ene-3,17-dione (0.53 g, 92%) in two crops, mp 169-170°. 

To a solution of dihydronaphthalene 41 (250 mg, 0.77 mmol) in CH2CI2 (5 mL) was added methyl trifluoromethanesulfonate (227 mg, 1.38 mmol). The mixture was stirred at rt until the starting material had been completely consumed as judged by TLC analysis (3 h). The mixture was cooled to 0°C and a solution of NaBHt (111 mg, 2.92 mmol) in 4 1 MeOH THF (3 mL) was slowly added. The mixture was warmed to rt then quenched with saturated aqueous ammonium chloride (50 mL). The resulting mixture was extracted with CH2CI2 (3 X 50 mL) and the combined organic extracts were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The resulting material was dissolved in 4 1 THF/H2O (5 mL) and oxalic acid (485 mg, 3.85 mmol) was added. The reaction... 

A solution of tetrahydropapaverine (4.43 g) and 1,5-pentamethylene diacrylate (1.30 g) in dry benzene (15 ml) was stirred under reflux for 4B hours excluding light. The solvent was removed in vacuo and the residual pale red oil dissolved in chloroform (10 ml). Addition of ether (ca 400 ml), followed by saturated ethereal oxalic acid solution (ca 500 ml) gave a floc-culent white precipitate, which was filtered off, washed with ether and dried. Crystallization (twice) from ethanol gave N,N -4,10<)ioxa-3,11 <)ioxotridecvlene-1,13-bis-tetrahydropapa-verlne dioxalate as a white powder (3.5 g 51% MP 117°to 121°C). 

To a solution of 1-(2,3-epoxypropoxy)-2-(2-tetrahydrofurfuryloxy)benzene in methanol are added tert-butylamine and water, the mixture is allowed to stand at 25°-30°C for 72 hours, and then the methanol is distilled off. The residue is dissolved in toluene and the solution is extracted twice with 5% oxalic acid. The aqueous extract is dried over potassium carbonate and concentrated to give Bufetrol. 

Hydrolysis A suspension of 1 g of the 6a,9a-difluoroprednisoione 17a,21-methylortho-butyrate in 10 cc of methanol is treated with 2 cc of a 2 N aqueous solution of oxalic acid and heated on a water bath at 40°-50°C for about 5-10 minutes and, afterwards, the mixture is concentrated under vacuum. The residue is then shaken with water, the insoiubie product is filtered off and then dried. The solid materiai is recrystailized from acetone-ether and 6a, 9a-difiuoroprednisolone 17-butyrate is obtained, MP 193°-196°C. 

Synthesis of 9-oxo-11 CH,1 Sol-bis-(2-tetrahydropyranytoxy)-16,16-dimethyl-prosta-trans-2, trans-13-dienoicacid 4gof ethyl 9a-hydroxy-1 la,1 5a-bis-(2-tetrahydropyranyloxy )-16,16-dimethyl-prosta-trans-2,trans-13-dienoate were dissolved In 130 ml of a mixture of ethanol-water (3 1), mixed with 3.9 g of potassium hydroxide and stirred at 25°C for 2 hours. The reaction mixture was acidified with aqueous solution of oxalic acid to pH 5, and diluted with 100 ml of water, extracted with ethyl acetate. The extracts were washed with water, dried over sodium sulfate and concentrated under reduced pressure to obtain 3,88 g of 90 -hydroxy-11a,15a-bis-(2-tetrahydropyranyloxy)-16,16-dimethyl-prosta-trans-2,trans-13-dienoic acid. 

The ethyl acetate is dried with anhydrous sodium sulfate, filterad and dried off. The oily residue is dissolved in 600 cc of methanol the di-oxalate is precipitated by the addition of a solution of oxalic acid in methanol. Yield 85%, melting point 190°C to 192°C (crystallized by methanol). Microcrystalline substance, creamy white color. 

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