Dimethyl oxalate

The above example serves to iUustrate the basis of the procedure employed for the characterisation of aUphatic esters, viz., hydrolysis to, and identification of, the parent acids and alcohols. Most esters are liquids a notable exception is dimethyl oxalate, m.p. 54°. Many have pleasant, often fruit-hke, odours. Many dry esters react with sodium, but less readily than do alcohols hydrogen is evolved particularly on warming, and a sohd sodio derivative may separate on coohng (e.j/., ethyl acetate yields ethyl sodioacetoacetate ethyl adipate gives ethyl sodio cj/cZopentanone carboxylate). 

Oxahc acid reacts with various metals to form metal salts, which are quite important as the derivatives of oxahc acid. It also reacts easily with alcohols to give esters. Crystalline dimethyl oxalate is, for example, produced by the reaction of oxahc acid dihydrate and methanol under reflux for a few hours. When oxahc acid is treated with phosphoms pentachloride, oxalyl chloride, ClCOCOCl, is formed (6). 

In addition to the Hquid-phase -butyl nitrite (BN) process, UBE Industries has estabHshed an industrial gas-phase process using methyl nitrite (50—52). The oudine of the process is described in Eigure 4 (52). This gas-phase process is operated under lower reaction pressure (at atmospheric pressure up to 490 kPa = 71 psi) and is more economical than the Hquid-phase process because of the foUowing reasons owing to the low pressure operation, the consumption of electricity is largely reduced (—60%) dimethyl oxalate (DMO) formation and the methyl nitrite (MN) regeneration reaction are mn... 

Dimethyl carbonate [616-38-6] and dimethyl oxalate [553-90-2] are both obtained from carbon monoxide, oxygen, and methanol at 363 K and 10 MPa (100 atm) or less. The choice of catalyst is critical cuprous chloride (66) gives the carbonate (eq. 20) a palladium chloride—copper chloride mixture (67,68) gives the oxalate, (eq. 21). Anhydrous conditions should be maintained by removing product water to minimize the formation of by-product carbon dioxide. 

Dimethyl oxalate [553-90-2] M 118,1, m 54 , b 163-165 , d 1.148. Crystd repeatedly from EtOH. Degassed under nitrogen high vacuum and distd. 

Reactions of perfluorophenyllithium with dimethyl oxalate give a mixture of products whose composition depends upon experimental conditions [55] (equation 11)... 

Table 1. Effect of Temperature of Decomposition of the Product of Reaction of Pentafluorophenyllithium with Dimethyl Oxalate on Product Distribution [JJ]...

Cyclocondensation of 2-aminomethylpiperidine 422 and dimethyl oxalate yielded perhydropyrido[l,2-n]pyrazine-3,4-dione 423 (00T1005). 

Dimethyl oxalate and diethyl oxalate can also be hydrolysed to yield oxalate ion ... 

Diethyl oxalate is usually preferred because of its slower rate of hydrolysis. Satisfactory results are obtained in the precipitation of calcium, magnesium, and zinc thorium is precipitated using dimethyl oxalate. 

Precipitation of calcium oxalate may also be made from homogeneous solution either by use of urea as reagent or by the use of dimethyl oxalate. Both procedures lead to satisfactory separations from magnesium. 

Note. Unless pure dimethyl oxalate is used, immediate precipitation of some fine calcium oxalate will occur. Impure dimethyl oxalate should be recrystallised from ethanol and stored in a desiccator. 

Dimethyl oxalate in homogeneous pptn. 426 2,9-Dimethyl-l,10-phenanthroline see... 

Assumed tto be similar to that of other esters (like dimethyl oxalate) in Table 1. Assumed to equal that of O,. ... 

Two of these forms suggest possible bimolecular rate-controlling steps. The kinetic data cannot be used to decide between them, although other tests might. For example, one could test whether dimethyl oxalate reacts with OCl , and the monomethyl ester with HOC1. 

Dimethylmercury 6,6-Dimethyl-2-methylene-bicyclo[3.1.1 ]heptane 2,4-Dimethyloctane Dimethyl oxalate 21.07... 

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