Chemically and enzymatically catalyzed synthesis of C₆–C₁₀ alkyl benzoates

Abstract

The esterification of benzoic acid with n-hexanol, n-octanol, 2-ethyl hexanol and n-decanol was investigated in detail. An analysis of the reaction kinetics of esterification in the presence of different commercially available chemical catalysts was carried out. The effects of catalyst type and loading on the reaction rate were studied. Although the considered reaction is bimolecular, it showed a first-order behavior, and a linear dependence with respect to the catalyst concentration was observed. Hence, a new approach is presented to describe the reaction kinetics accurately over a wide range. The application of biotechnological synthesis applying different enzymes as catalysts offers an interesting alternative besides chemical synthesis. Especially an esterase from Bacillus subtilis immobilized on Sepabeads EC-EP showed high stability and was applied for 2 days in the synthesis of hexyl benzoate. Nevertheless, the chemical reaction route remains superior with respect to the catalyst activities under the applied conditions, which were 25 kU/g for the chemical reaction and 0.7 kU/g for the best enzymatic conversion.

Scaleup of Lipase-Catalyzed Polyester Synthesis

“…6 Generally, enzymes used as catalysts can offer the following advantages: high enantio-and regioselectivity, 7 possible catalyst recycling, 8,9 no organic solvents needed, 10 low reaction temperatures, 11,12 replacement of potentially toxic catalysts and no protection/deprotection steps. 13 Especially peroxidases, 14 cellulases and lipases can be used in order to prepare well-defined polymeric structures. A first example of lipase catalyzed polymerization is the reaction of divinylsebacate with glycerol carried out by Kobayashi and co-workers.…”

“…As biocatalysts could already replace chemical catalysts in many fields, such as synthesis of acrylamide using nitrile hydratase in whole cells of Rhodococcus rhodochrous, l - tert -Leucine by leucine dehydrogenase or surfactant production by Novozym 435, research is also done with the aim of using enzymes as catalysts in polymer synthesis . Generally, enzymes used as catalysts can offer the following advantages: high enantio- and regioselectivity, possible catalyst recycling, , no organic solvents needed, low reaction temperatures, , replacement of potentially toxic catalysts and no protection/deprotection steps . Especially peroxidases, cellulases and lipases can be used in order to prepare well-defined polymeric structures.…”

Synthesis and biological evaluation of propargyl acetate derivatives as anti-mycobacterial agents

“…In the present work, propargyl acetate derivatives 3a-h were prepared by acylation of propargyl alcohols 1 with acid anhydrides 2 in H 2 SO 4 (Scheme 1) [20]. …”

Novozym-435 as efficient catalyst for the synthesis of benzoic and (hetero)aromatic carboxylic acid esters

“…In contrast, Krause et al reported the esterification of benzoic acid and n-hexanol in a solventless system using several lipases, including Novozym-435, although they claimed that all tested enzymes gave negligible chemical yields. 10 We have recently reported about new reaction conditions for the esterification of benzoic acid with 1-heptanol obtaining excellent yields by using the commercially available Novozym-435 and cyclohexane as the solvent. 11 Due to a loss of catalytic activity in the esterification of benzoic acid, recycling of the immobilized lipase was not feasible for more than 4 cycles.…”