A Novel and Efficient Method for the Synthesis of Methyl (R)-10-Hydroxystearate and FAMEs from Sewage Scum

In this work, the transesterification of methyl estolides (ME) extracted from the lipid component present in the sewage scum was investigated. Methyl 10-(R)-hydroxystearate (Me-10-HSA) and Fatty Acid Methyl Esters (FAMEs) were obtained in a single step. A three-level and four factorial Box–Behnken experimental design were used to study the effects of methanol amounts, catalyst, temperature, and reaction time on the transesterification reaction using aluminum chloride hexahydrate (AlCl3·6H2O) or hydrochloric acid (HCl) as catalysts. AlCl3·6H2O was found quite active as well as conventional homogeneous acid catalysts as HCl. In both cases, a complete conversion of ME into Me-10-HSA and FAMEs was observed. The products were isolated, quantified, and fully characterized. At the end of the process, Me-10-HSA (32.3%wt) was purified through a chromatographic separation and analyzed by NMR. The high enantiomeric excess (ee > 92%) of the R-enantiomer isomer opens a new scenario for the valorization of sewage scum.

Esterification catalyzed by efficient solid acid synthesized from PTSA and UiO–66(Zr) for biodiesel production

P–toluenesulfonic acid (PTSA) is a typical homogeneous acid for biodiesel production. Due to the shortcomings of high deliquescence and non–recyclability, it is necessary to synthesize the recyclable solid acid. For...

POTASSIUM CHLORIDE IMPREGNATED ON ACTIVATED GREEN MUSSEL SHELLS (KCL/ AGMS): AN ACTIVE CATALYST TOWARDS KNOEVENAGEL CONDENSATION

Knoevenagel condensation represents one of the most important C-C bond forming reactions in organic chemistry. The typical reaction was carried out commonly in the presence of homogeneous acid as well as basic catalysts. With the problems like corrosive and high catalyst amount, the search for a new heterogeneous catalyst is an attractive research topic in this area. KCl supported on activated green mussel shell (KCl/AGMS) was prepared by impregnation method and characterized by some analytical instrumentations (IR, XRD, SEM, EDAX). The prepared materials shows an incredible catalytic ability in Knoevenagel condensation of ethyl acetoacetate with aromatic aldehydes to produce condensed products 3a-3d in medium to good yields (60-94%). The findings disclose a mild route for the synthesis of Knoevenagel products using a cost-effective and green catalyst.

Microwave-Assisted Homogeneous Acid Catalysis and Chemoenzymatic Synthesis of Dialkyl Succinate in a Flow Reactor

Two new continuous flow systems for the production of dialkyl succinates were developed via the esterification of succinic acid, and via the trans-esterification of dimethyl succinate. The first microwave-assisted continuous esterification of succinic acid with H2SO4 as a chemical homogeneous catalyst was successfully achieved via a single pass (ca 320 s) at 65–115 °C using a MiniFlow 200ss Sairem Technology. The first continuous trans-esterification of dimethyl succinate with lipase Cal B as an enzymatic catalyst was developed using a Syrris Asia Technology, with an optimal reaction condition of 14 min at 40 °C. Dialkyl succinates were produced with the two technologies, but higher productivity was observed for the microwave-assisted continuous esterification using chemical catalysts. The continuous flow trans-esterification demonstrated a number of advantages, but it resulted in lower yield of the target esters.

Mechanism and theory of d-glucopyranose homogeneous acid catalysis in the aqueous solution phase

Theoretical study of the mechanism of acid hydrolysis of β-d-glucopyranose in the aqueous solution.