The Effect of Molecular Weight on the Solubility Properties of Biocompatible Poly(ethylene succinate) Polyester

Poly(ethylene succinate) (PES) is one of the most promising biodegradable and biocompatible polyesters and is widely used in different biomedical applications. However, little information is available on its solubility and precipitation properties, despite that these solution behavior properties affect its applicability. In order to systematically study these effects, biodegradable and biocompatible poly(ethylene succinate) (PES) was synthesized using ethylene glycol and succinic acid monomers with an equimolar ratio. Despite the optimized reaction temperature (T = 185 °C) of the direct condensation polymerization, relatively low molecular mass values were achieved without using a catalyst, and the Mn was adjustable with the reaction time (40–100 min) in the range of ~850 and ~1300 Da. The obtained crude products were purified by precipitation from THF (“good” solvent) with excess of methanol (“bad” solvent). The solvents for PES oligomers purification were chosen according to the calculated values of solubility parameters by different approaches (Fedors, Hoy and Hoftyzer-van Krevelen). The theta-solvent composition of the PES solution was 0.3 v/v% water and 0.7 v/v% DMSO in this binary mixture. These measurements were also allowed to determine important parameters such as the coefficients A (=0.67) and B (=3.69 × 104) from the Schultz equation, or the Kη (=8.22 × 10−2) and α (=0.52) constants from the Kuhn–Mark–Houwink equation. Hopefully, the prepared PES with different molecular weights is a promising candidate for biomedical applications and the reported data and constants are useful for other researchers who work with this promising polyester.

The cyclone separator application on physicochemical characterization of coconut shell-liquid smoke grade C

The further processing of coconut shell pyrolysis into liquid smoke has been developed in recent years. However, the common technology by directly condensing the smoke has many impurity compounds which decreases the yield of liquid smoke produced. Hence, in this study the cyclone separator was applied to increase the quality of physicochemical content in coconut shell-liquid smoke (CS-LS) grade C. The physical parameters analyzed were yield, pH, density and color. The chemical parameters was analyzed by GC-MS. The result showed that CS-LS processing with cyclone separator was able to increase the total yield into 3.33%, with better color, pH and density compared to the CS-LS produced using common method (direct condensation). The application of cyclone separator was also able to increase the phenolic compounds (97%), alcoholic compounds (92%), cycloalkene compounds (91%) and also decreased the benzoic acid, carbonyl and ester up to 100% compared with common method for CS-LS grade C production.

Synthesis of Novel N-(R)-2-(1-Adamantyl)-1H-Benzimidazole-5(6)-Carboxamide, Carbohydrazide and 1,3,4-Oxadiazole Derivatives

: A novel series of benzimidazole-5(6)-carboxamide 3a-g, carbohydrazide 5a-e and 1,3,4-oxadiazole 6a-g derivatives bearing adamantane moiety were synthesized. The synthesis of benzimidazole heterocycle was performed by direct condensation/cyclization reaction of 1-adamantanecarboxylic acid with methyl 3,4-diaminobenzoate in Trimethylsilyl Polyphosphate (PPSE). The obtained Methyl 2-(1-adamantyl)-1H-benzimidazole-5(6)-carboxylate was converted to desired carboxamide and carbohydrazide derivatives in two different ways. In the first case, the synthesized ester after hydrolysis was converted to acid chloride and subsequently coupled with different aromatic and heterocycle amines to give carboxamide derivatives. In the second case, treatment with hydrazine hydrate gave corresponding 2-(1-adamantyl)-1Hbenzimidazole-5(6)-carbohydrazide which was coupled with some acyl chlorides to give appropriate carbohydrazide derivatives and with some aromatic acids to give 1,3,4-oxadiazole derivatives.