Carboalkoxylation Explained

In industrial chemistry, carboalkoxylation is a process for converting alkenes to esters. This reaction is a form of carbonylation. A closely related reaction is hydrocarboxylation, which employs water in place of alcohols

A commercial application is the carbomethoxylation of ethylene to give methyl propionate:[1]

C2H4 + CO + MeOH → MeO2CC2H5The process is catalyzed by Pd[C<sub>6</sub>H<sub>4</sub>(CH<sub>2</sub>PBu-t)<sub>2</sub>]2. Under similar conditions, other Pd-diphosphines catalyze formation of polyethyleneketone.

Methyl propionate ester is a precursor to methyl methacrylate, which is used in plastics and adhesives.[2]

Carboalkoxylation has been incorporated into various telomerization schemes. For example carboalkoxylation has been coupled with the dimerization of 1,3-butadiene. This step produces a doubly unsaturated C9-ester:[3]

2CH2=CH-CH=CH2 + CO + CH3OH → CH2=CH(CH2)3CH=CHCH2CO2CH3

Hydroesterification

Related to carboalkoxylation is hydroesterification, the insertion of alkenes and alkynes into the H-O bond of carboxylic acids. Vinyl acetate is produced industrially by the addition of acetic acid to acetylene in the presence of zinc acetate catalysts: Presently, zinc acetate is used as the catalyst:

Notes and References

  1. Ahmad . Shahbaz . Bühl . Michael . 2021-08-04 . Computational modelling of Pd-catalysed alkoxycarbonylation of alkenes and alkynes . Physical Chemistry Chemical Physics . en . 23 . 30 . 15869–15880 . 1463-9084 . 10.1039/D1CP02426D . 34318843 . 2021PCCP...2315869A . 236472958 . free. 10023/23678 . free .
  2. Book: Scott D. Barnicki . Synthetic Organic Chemicals . Handbook of Industrial Chemistry and Biotechnology . James A. Kent . New York . Springer . 2012 . 12th . 978-1-4614-4259-2.
  3. 10.1021/cr010328q . Palladium-Catalyzed Reppe Carbonylation . 2001 . Kiss . Gabor . Chemical Reviews . 101 . 11 . 3435–3456 . 11840990.