In
industrial chemistry
The chemical industry comprises the companies that produce industrial chemicals. Central to the modern world economy, it converts raw materials (oil, natural gas, air, water, metals, and minerals) into more than 70,000 different products. The ...
, carboalkoxylation is a process for converting
alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
s to
ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...
s. This reaction is a form of
carbonylation
Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbon ...
. A closely related reaction is
hydrocarboxylation
Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbon ...
, which employs water in place of alcohols
A commercial application is the carbomethoxylation of
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds).
Ethylene i ...
to give
methyl propionate
Methyl propionate, also known as methyl propanoate, is an organic compound with the molecular formula CH3CH2CO2CH3. It is a colorless liquid with a fruity, rum-like odor.
Preparation
Methyl propionate can be prepared by esterification of propion ...
:
:C
2H
4 + CO + MeOH → MeO
2CC
2H
5
The process is catalyzed by Pd
6H4(CH2PBu-t)2">6H4(CH2PBu-t)2sub>2. Under similar conditions, other Pd-diphosphines catalyze formation of
polyethyleneketone.
Methyl propionate ester is a precursor to
methyl methacrylate
Methyl methacrylate (MMA) is an organic compound with the formula CH2=C(CH3)COOCH3. This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA ...
, which is used in plastics and adhesives.
Carboalkoxylation has been incorporated into various
telomerization
Telomerization is a reaction that produces a particular kind of oligomer with two distinct end groups. The oligomer is called a telomer. Some telomerizations proceed by radical pathways, many do not. A generic equation is:
: A-B + n M -> A-M_ ...
schemes. For example carboalkoxylation has been coupled with the dimerization of 1,3-
butadiene
1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two viny ...
. This step produces a doubly unsaturated C9-ester:
:2CH
2=CH-CH=CH
2 + CO + CH
3OH → CH
2=CH(CH
2)
3CH=CHCH
2CO
2CH
3
Hydroesterification
Related to carboalkoxylation is hydroesterification, the insertion of alkenes and alkynes into the H-O bond of carboxylic acids.
Vinyl acetate
Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate and ethene-vinyl acetate copolymers, important industrial polymers.
Production
The worldwide production capacity of v ...
is produced industrially by the addition of acetic acid to
acetylene
Acetylene (systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure ...
in the presence of
zinc acetate
Zinc acetate is a salt with the formula Zn(CH3CO2)2, which commonly occurs as the dihydrate Zn(CH3CO2)2·2H2O. Both the hydrate and the anhydrous forms are colorless solids that are used as dietary supplements. When used as a food additive, it has ...
catalysts:
Presently,
zinc acetate
Zinc acetate is a salt with the formula Zn(CH3CO2)2, which commonly occurs as the dihydrate Zn(CH3CO2)2·2H2O. Both the hydrate and the anhydrous forms are colorless solids that are used as dietary supplements. When used as a food additive, it has ...
is used as the catalyst:
:
References
{{Reflist
Chemical reactions
Carbon monoxide