Preparation of Ketene From Glacial Acetic Acid. Methyl Acetate, and Ethyl Acetate

Abstract

Laboratory studies were carried out to determine whether nlethyl and ethyl acetates could be pyrolyzed to give yields and conversions to ketene comparable to those obtainable from acetic acid. Acetic acid was pyrolyzed to ketene and water in the presence of 0.33% triethyl phosphate or phosphoric acid catalyst a t 680"-760°C. and 140-160 mm. H g absolute. Maxirnum yield obtained was 80.6y0 and maximum conversion 34.5%. Methyl acetate was cracked to ketene and methanol a t 610°-6850C. and 95-400 mm. absolute, using triethyl phosphate, phosphoric acid, sulphuric acid, dimethyl sulphate, butyl borate, and silica gelboric acid a s catalysts. High yields could be obtained only with phosphates in 2.3% concentration. Maximum yield to ketene, including keterle recovered as acetic acid, was 76% (conversion 31-34Yo). lklaximunl yield to nlethanol was 81.3% (conversion 33-34%). Methyl acetate containing 18% methanol was also cracked but results were poorer. Ethyl acetate, in the presence of 0.33% triethyl phosphate, was pyrolyzed to ketene, ethylene, and water a t 630"-685°C. and 140-190 mm. absolute. Maximum yield of ketene, includi~ig: ketene recovered as acetic acid, was 85.8y0. Maxinlum conversion to ketene was 35.4% and to ketene plus acetic acid 85.7%. Yields to ethylene were nearly quantitative.

An Atom-Efficient Route to Ethyl 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylate (DFMMP)—A Key Building Block for a Novel Fungicide Family

“…On an industrial scale ketene is produced by thermal cracking of acetic acid. Lab-scale synthesis of ketene is well-documented and can be generated in situ by various methods over thermal cracking of different carbonyl compounds . Due to its high reactivity and instability, the formation of ketene by thermal cracking must be performed in direct proximity, and it should be used in further chemical conversions within seconds.…”

Mechanistic Investigation of the Pyrolysis of Brown Grease

“…Most of the previous attempts to obtain a higher value fuel have focused on anaerobic digestion to biogas, or esterification to biodiesel [10,11,13,14]. Brown grease can also undergo pyrolysis to a kerosene-like mixture of hydrocarbons under relatively mild conditions [15][16][17]. e pyrolysis reaction, our concern, is defined as a high-temperature reaction in the absence of oxygen [18][19][20][21].…”

The thermal decomposition of fluorinated esters. III. Esters without β hydrogen atoms

“…Two such esters have been examined, methyl trifluoroacetate and 2,2,2 trifluoroethyl trifluoroacetate, in which fluorine replaces hydrogen a t the ,b carbon. In addition the decomposition of methyl acetate has been studied under the same conditions to compare the behavior of unfluorinated esters without 0 hydrogen, since previously published work on this ester refers to either catalyzed [5] or high-temperature [6] conditions.…”