Methyl benzoate nitration

Methyl m-nitrobenzoate has been prepared by the esterification of m-nitrobenzoic acid 1 this method is, however, obviously much less satisfactory than nitration of methyl benzoate. Nitration by means of fuming nitric acid has also been applied to methyl benzoate,2 but the use of the ordinary nitration mixture of concentrated sulfuric add and concentrated nitric acid is more satisfactory. 

The preparation of a number of miscellaneous acids is described. m-Nitrobenzoic acid. Although m-nitrobenzoic acid is the main product of the direct nitration of benzoic acid with potassium nitrate and concentrated sulphuric acid, the complete separation of the small quantity of the attendant para isomer is a laborious process. It is preferable to nitrate methyl benzoate and hydrolyse the resulting methyl w-nitrobenzoate, which is easily obtained in a pure condition ... 

Methyl m-nitrobenzoate. In a 1 htre round-bottomed or bolt-head flask, fitted with a mechanical stirrer, place 102 g. (94 ml.) of pure methyl benzoate (Section IV,176) support a separatory funnel containing a mixture of 62 -5 ml, of concentrated sulphuric acid and 62 -5 ml. of concentrated nitric acid over the mouth of the flask. Cool the flask in an ice bath to 0-10°, and then run in the nitrating mixture, with stirring. 

Into a 2-1. round-bottom flask fitted with a mechanical stirrer, are placed 400 cc. of concentrated sulfuric acid cooled to o°, and 204 g. (1.5 mols.) of pure methyl benzoate (Note 1). The mixture is cooled by means of an ice bath to o-io° and then, with stirring, there is added gradually by means of a dropping funnel a mixture of 125 cc. concentrated nitric acid (sp. gr. 1.42) and 125 cc. concentrated sulfuric acid. During the addition of the nitrating acid, which requires about one hour, the temperature of the reaction mixture should be kept within the range 5-15° (Note 2). 

The nitration of methyl benzoate runs unusually smoothly, but it is essential to keep the temperature within the specified limits, otherwise the yield falls at 50°, 193 g. of solid product is obtained, while at 70° the yield falls to 130 g. 

On diluting the methyl alcoholic filtrate with water, 10-20 cc. of oil separates more of this oil is formed by nitrating at higher temperatures, amounting to 57 cc. at 50° and 100 cc. at 70°. The oil consists not merely of methyl o-nitrobenzoate with some of the meta compound but contains also traces of dinitrobenzoic ester and nitrophenolic compounds. Unchanged methyl benzoate does not appear to be present. 

Nitro is the most electron-withdrawing of these groups and some of the other compounds are nearly as reactive (in the meta position, of course) as benzene itself. It is easy to nitrate methyl benzoate and the m-nitro ester can then be hydrolysed to m-nitrobenzoic acid very easily. 

Vinyl acetate-ethyl acetate Propane-propylene Ethanol-isopropanol Hydrochloric acid-water Nitric acid-water Close-boiling Close-boihng Close-boihng Maximum-boiling azeotrope Maximum-boiling azeotrope Phenol, aromatics Acrylonitrile Methyl benzoate Sulfuric acid, calcium chloride for salt process Sulfuric acid, magnesium nitrate for salt process Alternative to simple distillation Alternative to simple distillation, adsorption Alternative to simple distillation Sulfuric acid process rehes heavily on boundary curvature Sulfuric acid process rehes heavily on boundary curvature... 

Q Wliat products result when (a) ethylbenzene, (b) methyl benzoate and (c) A, A -dimethylaniline are nitrated with mixed acid ... 

Remove the ether by simple distillation or by evaporation on the steam bath under an aspirator tube. See Fig. 5 in Chapter 5 or Fig. 9 in Chapter 3 or use a rotary evaporator (Fig. 7 in Chapter 10). When evaporation ceases, add 2-3 g of anhydrous sodium sulfate to the residual oil and heat for about 5 min longer. Then decant the methyl benzoate into a 50-mL round-bottomed flask, attach a stillhead, dry out the ordinary condenser and use it without water circulating in the jacket, and distill. The boiling point of the ester is so high (199°C) that a water-cooled condenser is liable to crack. Use a tared 25-mL Erlenmeyer as the receiver and collect material boiling above 190°C. A typical student yield is about 7 g. See Chapter 36 for the nitration of methyl benzoate. 

Prelab Exercise Draw the complete mechanism for the nitration of methyl benzoate. Show the resonance forms that make the methyl ester group a meta director and deactivator of the aromatic ring. 

Benzene and somewhat less reactive aromatic compounds such as methyl benzoate can be nitrated with a mixture of nitric and sulfuric acids, which ionizes completely to generate the nitronium and hydronium ions ... 

METHYL BENZOATE (93-58-3) Combustible liquid (flash point 181°F/83°C). Incompatible with strong acids, nitrates, oxidizers. 

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