Oxalic acid, preparation

Carbon(II) oxide (carbon monoxide) is prepared under laboratory conditions from formic or oxalic acid (prepare it only in one of these ways). 

NBS oxalic acid standards Oxalic acid preparations... 

Tertiary butyl alcohol, trimethyl carbinol, tertiary butanol. 2-methyl-2-propanol, Me3COH. Colourless prisms, m.p. 25°C, b.p. 83°C. Prepared by absorbing isobutene (2-methylpropene) in sulphuric acid, neutralizing and steam distilling the liquor. Converted to isobutene by heating with oxalic acid. Potassium-/-buloxide is a very strong base. 

Melbylpropene, isobutylene, isobutene, Me2C CH2 Prepared by heating r-butanol with oxalic acid. 

CHjCOCOOH. A colourless liquid with an odour resembling that of ethanoic acid, m.p. 13 C, b.p. 65 C/lOmm. It is an intermediate in the breakdown of sugars to alcohol by yeast. Prepared by distilling tartaric acid with potassium hydrogen sulphate. Tends 10 polymerize to a solid (m.p. 92 C). Oxidized to oxalic acid or ethanoic acid. Reduced to ( + )-Iactic acid. 

The reaction usually proceeds with explosive violence and a better method of preparation is to heat, gently, moist crystals of ethane-dioic acid (oxalic acid) and potassium chlorate(V) ... 

The oxalate is prepared in a similar way, using a solution of 1 2 g. of oxalic acid in about 15 ml. of water. On stirring the mixed solutions with a rod, the oxalate crystallises out. 

Anhydrous oxalic acid may be prepared by heating the finely-powdered A.R. crystallised acid, spread upon large clock glasses, in an electric oven at 105° for 6 hours, allowing to cool in a desiccator and storing in a tightly stoppered bottle. 

The dialkyl oxalate thus prepared is hydroly2ed to oxaUc acid and the corresponding alcohol. 

Because of the structural requirements of the bielectrophile, fully aromatized heterocycles are usually not readily available by this procedure. The dithiocarbamate (159) reacted with oxalyl chloride to give the substituted thiazolidine-4,5-dione (160) (see Chapter 4.19), and the same reagent reacted with iV-alkylbenzamidine (161) at 100-140 °C to give the 1 -alkyl-2-phenylimidazole-4,5-dione (162) (see Chapter 4.08). Iminochlorides of oxalic acid also react with iV,iV-disubstituted thioureas in this case the 2-dialkylaminothiazolidine-2,4-dione bis-imides are obtained. Thiobenzamide generally forms linear adducts, but 2-thiazolines will form under suitable conditions (70TL3781). Phenyliminooxalic acid dichloride, prepared from oxalic acid, phosphorus pentachloride and aniline in benzene, likewise yielded thiazolidine derivatives on reaction with thioureas (71KGS471). 

The tetrahydropyranyl ether, prepared from a phenol and dihydropyran (HCl/ EtOAc, 25°, 24 h), is cleaved by aqueous oxalic acid (MeOH, 50-90°, 1-2 h). ... 

H0(CH2)20H, oxalic acid, CH3CN, 25°, 95% yield.Note that ketals prepared with oxalic acid from enones retain the olefin regiochemistry. ... 

In general, imines are too reactive to be used to protect carbonyl groups. In a synthesis of juncusol, however, a bromo- and an iodocyclohexylimine of two identical aromatic aldehydes were coupled by an Ullman coupling reaction modi-fied by Ziegler. The imines were cleaved by acidic hydrolysis (aq. oxalic acid, THF, 20°, 1 h, 95% yield). Imines of aromatic aldehydes have also been prepared... 

Carbon monoxide is produced by incomplete combustion of carbon and its compounds. In the laboratory it can be prepared by careful dehydration of formic or oxalic acid with sulphuric acid ... 

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°. 

The tetrahydropyranyl ether, prepared from a phenol and dihydropyran (HCl/EtOAc, 25°, 24 h) is cleaved by aqueous oxalic acid (MeOH, 50-90°, 1-2 h). Tonsil, Mexican Bentonite earth, HSZ Zeolite, and H3[PW,204o] have also been used for the tetrahydropyranylation of phenols. The use of [Ru(ACN)3(triphos)](OTf)2 in acetone selectively removes the THP group from a phenol in the presence of an alkyl THP group. Ketals of acetophenones are also cleaved. ... 

In context with the formation of peraminosubstituted 1,4,5,8-tetraazaful-valenes of type 85 it must be mentioned that the bis-vinylogous compounds 94 can be easily prepared by reaction of acetamidine with bisimidoylchlo-rides derived from oxalic acid (96S1302). In the course of a complex reaction a cyclic ketene aminal was produced it immediately underwent an oxidative dimerization to yield deeply colored TAFs. Tlieir high chemical stability can be compared with that of indigoid dyes and manifests itself, for example, by the fact that they are soluble in hot concentrated sulfuric acid without decomposition. Tire same type of fulvalene is also available by cy-... 

Phenylacetaldehyde can also be prepared by treating sodium cinna-mate with bromine, and then adding oxalic acid. The sodium salt of phenylbromolactic acid results. On steam distillation this gives ofif CO, and yields phenylacetaldehyde (the reaction is probably more complicated than the equation indicates) — ... 

It can be prepared artificially in various ways for example, by distilling oxalic acid with glycerine, when at about 130° formic acid comes over according to the equation—... 

A) Preparation of 4-Acetyl-7-Chloro-1,2,3,4-Tetrahydro-1-Methyl-5H-1,4-Bemodiazepin-5-one A mixture of 68.5 g (0.37 mol) of 5-chloro-N-methylanthranilic acid, 51 g (0.51 mol) of calcium carbonate, 76 g (0.37 mol) of bromoethylamine hydrobromide and 2.5 liters of water was stirred and heated under reflux for 3 hours. A solution of 23.4 g (0.26 mol) of anhydrous oxalic acid in 250 ml of water was slowly added to the refluxing mixture. The precipitated calcium oxalate was filtered off, and the filtrate adjusted to pH 7 with concentrated ammonium hydroxide. The filtrate was then concentrated to dryness in vacuo and the residue heated on the steam bath with 400 ml of 6 N ethanolic hydrogen chloride until the residue was crystalline. Filtration gave 122 g of N-(aminoethyl)-5-chloro-N-methylanthranilic acid hydrochloride as a solid. 

The treatment of kasuganobiosamine with dimethyl ester of oxalic acid followed by concentrated aqueous ammonia gave two kinds of amides. The amide (11a) with pK a 7.6 was identical with the amide of kasugamycinic acid, which was prepared from kasugamycinic acid by treatment with anhydrous hydrogen chloride-methanol followed by concentrated aqueous ammonia. The other isomer (lib) with pK a 7.8, was named amide of isokasugamycinic acid. 

B. 2-Methylcyclopenlane-l,3,5-trione hydrate. A mixture of 200 g. (0.89 mole) of the keto ester prepared above, 910 ml. of water, and 100 ml. of 85% phosphoric acid is healed under reflux for 4 hours and then cooled in an ice-salt bath to —5°. The trione mixed with oxalic acid separates and is collected by filtration and dried under reduced pressure. The dried material is extracted with boiling ether (250-300 ml.) under reflux, and the ethereal extract is separated from the undissolved oxalic acid. The original aqueous filtrate is also extracted with ether in a continuous extractor. The two extracts are combined, and ether is removed by distillation. The crude trione separates as a dark brown solid and is crystallized from ca. 250 ml. of hot water. The once-crystallized, faintly yellow product weighs 95-105 g. (74-82%), m.p. 70-74°. This product is used in the next step without further purification. A better specimen, m.p. 77-78°, which is almost colorless, can be obtained by recrystallization from hot water after treatment with Norit activated carbon. 

Procedure B. Prepare an approximately 0.05 M solution of oxalic acid by dissolving about 1.6 g of the compound and making up to 250 mL in a graduated flask. Standardise the solution with standard (0.02M) potassium permanganate solution using the procedure described in Section 10.94 (Method B). 

Furo[3,4-e)(l,2,4]triazines 204 (91 MI 1) were prepared by the reaction of 199 or its analogues with aroylhydrazines in the presence of ammonium acetate in acetic acid. Similarly, the respective 3,3 -bis(furo[3,4-e](l,2,4]triazine) was prepared by reacting 199 with oxalic acid hydrazide (91MI5). 

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