Oxalation, diethyl oxalate

Ethyl oxalate Diethyl oxalate (COOCjHs) C H NCaH CHaCHjOH ... 

M-Butyl formate. Ethyl iso-butyrate IsO -butyl acetate Ethyl butyrate -Propyl propionate Iso-amyl formate, -But> l acetate Iso-propyl butyrate Iso-butyl propionate n-Propyl -butyrate -Butyl propionate Iso-butyl isobutyrate Ethyl lactate Iso-butyl butyrate Cycloheicyl formate -Butyl -butyrate Iso-propyl lactate. Cyclohexyl acetate Diethyl oxalate Di-iao-propyl oxalate... 

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. 

Successful results have been obtained (Renfrew and Chaney, 1946) with ethyl formate methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and iso-amyl acetat ethyleneglycol diacetate ethyl monochloro- and trichloro-acetates methyl, n-propyl, n-octyl and n-dodecyl propionates ethyl butyrate n-butyl and n-amyl valerates ethyl laurate ethyl lactate ethyl acetoacetate diethyl carbonate dimethyl and diethyl oxalates diethyl malonate diethyl adipate di-n-butyl tartrate ethyl phenylacetate methyl and ethyl benzoates methyl and ethyl salicylates diethyl and di-n-butyl phthalates. The method fails for vinyl acetate, ieri.-butyl acetate, n-octadecyl propionate, ethyl and >i-butyl stearate, phenyl, benzyl- and guaicol-acetate, methyl and ethyl cinnamate, diethyl sulphate and ethyl p-aminobenzoate. 

One route to o-nitrobenzyl ketones is by acylation of carbon nucleophiles by o-nitrophenylacetyl chloride. This reaction has been applied to such nucleophiles as diethyl malonatc[l], methyl acetoacetate[2], Meldrum s acid[3] and enamines[4]. The procedure given below for ethyl indole-2-acetate is a good example of this methodology. Acylation of u-nitrobenzyl anions, as illustrated by the reaction with diethyl oxalate in the classic Reissert procedure for preparing indolc-2-carboxylate esters[5], is another route to o-nitrobenzyl ketones. The o-nitrophenyl enamines generated in the first step of the Leimgruber-Batcho synthesis (see Section 2.1) are also potential substrates for C-acylation[6,7], Deformylation and reduction leads to 2-sub-stituted indoles. 

The reduction of o-nitrophenyl acetic acids or esters leads to cyclization to oxindoles. Several routes to o-nitrophenylacetic acid derivatives arc available, including nitroarylation of carbanions with o-nitroaryl halides[2l,22] or trif-late[23] and acylation of o-nitrotoluenes with diethyl oxalate followed by oxidation of the resulting 3-(u-nitrophenyl)pyruvate[24 26]. 

Diethyl oxalate (29.2 g, 0.20mol) and 4-bromo-2-nitrotoluene (21.6 g, O.lOmol) were added to a cooled solution of sodium cthoxide prepared from sodium (4.6 g, 0.20 mol) and ethanol (90 ml). The mixture was stirred overnight and then refluxed for 10 min. Water (30 ml) was added and the solution refluxed for 2h to effect hydrolysis of the pyruvate ester. The solution was cooled and concentrated in vacuo. The precipitate was washed with ether and dried. The salt was dissolved in water (300 ml) and acidified with cone. HCl. The precipitate was collected, washed with water, dried and recrystallizcd from hexane-EtOAc to give 15.2 g of product. 

An Organic Syntheses preparation of 4-nitroindole may involve a related reaction. The condensation occurs in the presence of diethyl oxalate which may function by condensation at the methyl group. If this is the case, it must subsequently be lost by deacylation[17]. 

Acylation of ketones (Sec tion 21 4) Diethyl carbo nate and diethyl oxalate can be used to acylate ketone enolates to give p keto esters... 

The manufacture of prednisolone (30) follows a similar route. 11-Oxo-progesterone (34) is treated with two molar equivalents of diethyl oxalate and sodium methoxide in /-butanol. The product (39) is acidified and treated with... 

ROOC—COOH, are not. The dialkyl esters are characterized by good solvent properties and serve as starting materials in the synthesis of many organic compounds, such as pharmaceuticals, agrochemicals, and fine chemicals (qv). Among the diesters, dimethyl, diethyl, and di- -butyl oxalates are industrially important. Their physical properties are given in Table 7. 

Oxalates. Stable oxalates of Pu(III), Pu(IV), and Pu(VI) are known. However, only the Pu(III) and Pu(IV) oxalates are technologically important (30,147). Brilliant green plutonium(III) oxalate [56609-10-0] precipitates from nitric acid solutions containing Pu(III) ions upon addition of oxaUc acid or sodium oxalate. The composition of the precipitate isPu2(C20 2 10H2O. A homogeneous oxalate precipitation by hydrolysis of diethyl oxalate at... 

Primary synthesis of arylazopyrimidines is used (52JCS3448). It is exemplified in the condensation of phenylazomalondiamidine with diethyl oxalate to give the azopyrimidine (833) (66JCS(C)226). Finally, 5-phenylazopyrimidine may be made by the condensation of pyrimidin-5-amine with nitrosobenzene (5UCS1565) but the reaction seems to have been overlooked for many years. 

Cellulose for chromatography is purified by sequential washing with chloroform, ethanol, water, ethanol, chloroform and acetone. More extensive purification uses aqueous ammonia, water, hydrochloric acid, water, acetone and diethyl ether, followed by drying in a vacuum. Trace metals can be removed from filter paper by washing for several hours with O.IM oxalic or citric acid, followed by repeated washing with distilled water. 

Fractionally distd through a 4-ft column packed with glass helices. Ppted as its oxalate from diethyl ether soln. After crystn from 95% EtOH, the salt was decomposed with aqueous saturated NaOH, and the free base was distd, dried over BaO and redistd [McBride and Kruse 7 Am Chem Soc 79 572 1957]. Distn and storage should be under nitrogen. 

Difunctional electrophiles such as diethyl carbonate and diethyl oxalate also react with perfluorooctyllithium and perfluoroalkyletherlithium compounds to yield ketones, diketones, and keto esters [39, 79] (equations 38 1). 

Mixed Claisen condensations (Section 21.3) Diethyl carbonate, diethyl oxalate, ethyl formate, and benzoate esters cannot form ester enolates but can act as acylating agents toward other ester enolates. 

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