3 research outputs found
Biobased Methacrylic Acid via Selective Catalytic Decarboxylation of Itaconic Acid
We
report a biobased route to methacrylic acid via selective decarboxylation
of itaconic acid utilizing catalytic ruthenium carbonyl propionate
in an aqueous solvent system. High selectivity (>90%) was achieved
at low catalyst loading (0.1 mol %) with high substrate concentration
(5.5 M) at low temperature (200–225 °C) and pressure (≤425
psig) relative to previous contributions in this area. Direct decarboxylation
of itaconic acid was achieved as opposed to the conjugate base reported
previously, thereby avoiding basification and acidification steps.
Also investigated was catalytic manganeseÂ(II) oxalate (5 mol %), but
low yield (4.8%) and evolution of carbon monoxide via oxalate decomposition
was problematic. Attempts at stabilization of the catalyst with triphenylphosphine
were unsuccessful, but it exhibited greater catalytic efficacy (14.0%
yield) than the manganese catalyst (4.8% yield) at 5 mol %. Neither
carbon monoxide nor propylene (excessive decarboxylation) were detected
during ruthenium-catalyzed decarboxylation. In addition, cosolvents
such as tetraglyme lowered vapor pressures within the reaction vessel
by >100 psig while minimizing decomposition of starting acids.
In
combination, these findings represent improvements over existing methodologies
that may facilitate sustainable production of methacrylic acid, an
important petrochemically based monomer for the plastics industry
Parameters Governing Ruthenium Sawhorse-Based Decarboxylation of Oleic Acid
Ruthenium-catalyzed decarboxylation
of 9-cis-octadecenoic is a
path to produce biobased olefins. Here, a mechanistic study of this
reaction was undertaken utilizing a closed reaction system and a pressure
reactor. The proposed mechanism of an isomerization followed by a
decarboxylation reaction was consistent with a mathematical kinetic
model. That same model was able to accurately predict CO<sub>2</sub> evolution. Additionally, computational chemistry was used to determine
that the barrier of the oleic acid decarboxylation reaction is 249
kJ mol<sup>–1</sup>. Using the new information, the efficacy
of the decarboxylation reaction was improved to an overall catalytic
efficiency of 850 total turnovers
Parameters Governing Ruthenium Sawhorse-Based Decarboxylation of Oleic Acid
Ruthenium-catalyzed decarboxylation
of 9-cis-octadecenoic is a
path to produce biobased olefins. Here, a mechanistic study of this
reaction was undertaken utilizing a closed reaction system and a pressure
reactor. The proposed mechanism of an isomerization followed by a
decarboxylation reaction was consistent with a mathematical kinetic
model. That same model was able to accurately predict CO<sub>2</sub> evolution. Additionally, computational chemistry was used to determine
that the barrier of the oleic acid decarboxylation reaction is 249
kJ mol<sup>–1</sup>. Using the new information, the efficacy
of the decarboxylation reaction was improved to an overall catalytic
efficiency of 850 total turnovers