Ketene

Ketenes ( stress on the second syllable: ketenes ) are a group of organic compounds with the general formula RR'C = C = O. R and R ' can be any residue. Ketene ( Ethenon ) is the simplest representative of this group of substances with the formula CH2 = C = O. Ketenes are very reactive, almost all dimerize immediately to the correct diketene.

Production

Industrially it generates ketene by catalytic high-temperature pyrolysis of acetone or acetic acid at 700 ° C.

Generally ketenes by reaction of carboxylic acid halides, carry at least one α -position hydrogen, with bases such as triethylamine in situ accessible:

Reactions

Ketenes are highly reactive due to their cumulated double bonds. From ketenes formed by reaction with:

• Alcohols, a carboxylic acid ester
• Carboxylic acids, a carboxylic acid anhydride
• Primary amines, an amide
• Water is a carboxylic acid
• Enolizable carbonyl compounds enolacetate

Ketene dimerizes rapidly at room temperature to diketene, from which it can be recovered by heating again.

Acetic anhydride is industrially produced mainly from ketene and acetic acid.