Methyl acetal

D methyl ACETATE 253-423 5 8575E400 -4 9733E403 -3.2652E-02 3 1157E400 1 72755-05... 

METHYL ACETATE 2.2064E402 -3 4664E- 03 4.0393E-02 5.4I58E401... 

Here again the odour of methyl acetate is similar, and the student must decide for himself what reliance he can place on the difference. 

Methyl formate. Ethyl formate Methyl acetate Iso-propyl formate Ethyl acetate Methyl propionate "-Propyl formate Iso-propyl acetate Methyl iso-butyrate Iso-butyl formate. Ethyl propionate M-Propyl acetate. Methyl butyrate. ... 

Methyl acetate. An anhydrous product of 99 per cent, purity (b.p. 56-5-57°) i.s available coniniercially this is comparatively cheap so that purification of inferior products is not worth while. It is appreciably soluble in water (ca. 24 per cent, at 20°). The pure compound has b.p. 57°/760 mm. 

If it is desired to purify an inferior product, 1 litre of it is refiuxed for 6 hours with 85 ml. of acetic anhydride and then distilled through a fractionating column the liquid passing over at 56-57° is collected. The distillate is shaken with 20 g. of anhydrous potassium carbonate for 10 minutes, filtered and redistilled. The resulting methyl acetate has a purity of 99- 9 %. 

Ethyl acetate. Use 58 g. (73-5 ml.) of absolute ethyl alcohol, 225 g. of glacial acetic acid and 3 g. of concentrated sulphuric acid. Reflux for 6-12 hours. Work up as for n-propyl acetate. B.p. 76- 77°. Yield 32 g. Much ethyl acetate is lost in the washing process. A better yield may be obtained, and most of the excess of acetic acid may be recovered, by distilhng the reaction mixture through an efficient fractionating column and proceeding as for methyl acetate. 

Ethyl n-butyrate. Use a mixture of 88 g. (92 ml.) of n-butyric acid, 23 g. (29 ml.) of ethanol and 9 g. (5 ml.) of concentrated sulphuric acid. Reflux for 14 hours. Pour into excess of water, wash several times with water, followed by saturated sodium bicarbonate solution until all the acid is removed, and finally with water. Dry with anhydrous magnesium sulphate, and distU. The ethyl n-but3rrate passes over at 119 5-120-5°, Yield 40 g. An improved yield can be obtained by distilhng the reaction mixture through an efficient fractionating column until the temperature rises to 125°, and purifying the crude ester as detailed above under methyl acetate. 

Similar activation takes place in the carbonylation of dimethyl ether to methyl acetate in superacidic solution. Whereas acetic acid and acetates are made nearly exclusively using Wilkinson s rhodium catalyst, a sensitive system necessitating carefully controlled conditions and use of large amounts of the expensive rhodium triphenylphosphine complex, ready superacidic carbonylation of dimethyl ether has significant advantages. 

The Pd-catalyzed reductive carbonylation of methyl acetate with CO and H2 affords acetaldehyde. The net reaction is the formation of acetaldehyde from MeOH, CO, and H2P4]. Methyl formate (109) is converted into AcOH under CO pressure in the presence of Lil and Pd(OAc)2[95],... 

Esters can participate m hydrogen bonds with substances that contain hydroxyl groups (water alcohols carboxylic acids) This confers some measure of water solubil ity on low molecular weight esters methyl acetate for example dissolves m water to the extent of 33 g/100 mL Water solubility decreases as the carbon content of the ester increases Fats and oils the glycerol esters of long chain carboxylic acids are practically insoluble m water... 

Acetyl chloride Acetic anhydnde Methyl acetate Acetamide... 

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