Triethyl amine was successfully examined as a potent N-base surrogate for Knoevenagel condensation to produce cinnamic acids without compromising product yield.

5-(Hydroxymethyl)­furfural (HMF) is a trending biogenic platform molecule for the production of multiple energy, fuel, and chemical products, and it can be synthesized by using C6 sugars and/or its oligomers and polymers. In the present paper, the heterogeneous solid acid catalyst DICAT-1, with characteristic properties, exhibited one-pot conversion of sucrose into 5-HMF. The DICAT-1 triggered in-situ hydrolysis, isomerization, and dehydration of sucrose to yield 5-HMF in the presence of the low boiling point (LBP) green solvent isopropyl alcohol (IPA) in combination with the cosolvent DMSO. Of the tested solvents water, IPA, DMF, DMSO, and IPA:DMSO, the use of IPA in combination with DMSO shows the profound effect on sucrose dehydration. Exploration of DICAT-1 in the presence of IPA:DMSO (70:30 v/v) resulted in a 5-HMF yield of >77%. The central composite design model (CCD) was used to find out the best operating conditions for the solvent ratio and catalyst concentration. Moreover, the process intensification study depicted the remarkable effect of solvent, reaction temperature, time, sucrose concentration, catalyst concentration, and autogenous pressure of the solvent on the yield of 5-HMF. In- process analysis was conducted by using HPLC, and the product was characterized by using HPLC, ATR-FTIR, GC-MS, and LC-MS. The plausible reaction mechanism for the DICAT-1-mediated sucrose to 5-HMF conversion was also proposed. Characteristic properties of DICAT-1 such as the porosity and presence of accessible −SO3H acid active sites favor the one-pot conversion. Moreover, the catalyst recyclability test for five consecutive runs showed consistent 5-HMF yields. Thus, DICAT-1 was found to be an efficient and robust catalyst for sucrose dehydration in the IPA:DMSO solvent mixture.

In this work, effect of salt on cellulose pyrolysis behaviour using chemical percolation devolatilization (CPD) model has been investigated. The distributed activation energy model (DAEM) has been used to determine the kinetics of pure and NaCl-loaded cellulose pyrolysis in a thermogravimetric analyser (TGA). A number of these experiments were performed for a range of heating rates (5–100 °C min−1) and for different concentrations of NaCl in cellulose (0.25–2 mass/%) which showed a pronounced effect of salt on the primary pyrolysis reactions of cellulose. These data were then used in a two-component DAEM to calculate the kinetic parameters for the chemical percolation devolatilization model (CPD) for both pure and NaCl-loaded cellulose. The optimized kinetic parameters for the pure and NaCl-loaded cellulose were used in the CPD model, and the product yield was predicted. The CPD predictions showed that the fraction of gases and char in the pyrolysis products increased in the presence of salt. The amount of char for pure cellulose was 6.97% which increased to 16.4% in the presence of 0.25% NaCl. The amount of gases produced as a result of pure cellulose pyrolysis was 9.63% and this amount increased with addition of NaCl to 22.85% and then further increases with an increase in NaCl concentration. Amount of tar produced for pure cellulose was 83.4%, and this amount reduced to 60.7% with addition of 0.25% NaCl. The presence of NaCl accelerates cellulose decomposition and favours the formation of gases and char.

k-Carrageenan is a major constituent of red seaweeds composed of inherent repeating sulfated galactan units having potential to produce 5-hydroxymethyl furfural (5-HMF). The presence of inherent alkali sulfate functionality generates catalytically active acid sites on the backbone of k-carrageenan. In the present study, catalyst-free synthesis of 5-HMF was studied by inducing acid active sites on alkali-sulfated functionalities of k-carrageenan. The presence of −SO 3 H active sites on acid-imparted k-carrageenan were accountable for the self-catalytic property to deconstruct k-carrageenan into galactose units and further dehydration into 5-HMF. A plausible mechanism for the self-catalytic deconstruction of k-carrageenan into 5-HMF has been proposed. The comparative study of catalytic and noncatalytic reactions in DMSO resulted 43% and 41% yield of 5-HMF, respectively. Of the tested solvents (DMF, DMSO, IPA, TBA, and IAA), DMSO was found as the best solvent for deconstruction. Furthermore, the ease of solvent recovery is achieved by using IPA as a green solvent in combination with DMSO, which resulted in 50% yield of 5-HMF. The use of a catalyst-free protocol by using IPA as a green and low boiling reaction medium promotes development of green processes.

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