Characteristics and Kinetics Study of Glycerolabietate from Glycerol and Abietic Acid from Rosin

Rosin is a natural resin from the coniferous tree sap, which separated from its oil content (terpenes). Rosin is brittle. Therefore modifications are needed to improve its mechanical properties. The main content of rosin is abietic acid which has a carboxylic group, so it can form an ester group when reacted with polyhydric alcohol (polyalcohol) such as glycerol. The research aimed to study the kinetics of the esterification reaction between the hydroxyl group in glycerol and the carboxylic group in abietic acid from rosin at various reaction temperatures and reactant compositions. This reaction is carried out in a three-neck flask at atmospheric pressure without a catalyst. The reaction temperatures used were 180˚C, 200˚C, and 220˚C, and the ratio of rosin and glycerol was 1:1, 1:3, and 1:5. The reaction kinetics calculations were analyzed with acid number data over the reaction time using three different models. The calculations showed that this reaction involves positioning a hydroxyl group on glycerol, which the primary and secondary hydroxyl groups contribute to forming a rosin ester (glycerolabietate). The rate of reaction constants of primary hydroxyl of glycerol and abietic acid were in the range 6.25x10-4 - 3.90x10-3 g/(mgeq.min), while reaction rate constants of secondary hydroxyl and abietic acid were in the range 1.06x10-5 - 1.15x10-4 g/(mgeq.min). FTIR analysis showed a change in the hydroxyl, carboxylate, and ester groups which were assigned by a shift of wavenumber and a difference of intensity at 3200-3570 cm-1, 1697.36 cm-1, and 1273.02 cm-1.

A Simple Synthesis Route for Selectively Methylated β-Cyclodextrin Using a Copper Complex Sandwich Protecting Strategy

This communication reports a novel synthesis route for the preparation of monofunctionalized β-cyclodextrin in a single stage. The approach involves only the in-situ protection of secondary hydroxyl groups as an excellent alternative to the classical procedure involving a series of five steps of protection and deprotection of hydroxyl groups (both primary and secondary ones) belonging to β-cyclodextrin.

Assembly of Platinum Nanoparticles and Single-atom Bismuth for Selective Oxidation of Glycerol

Selective oxidation of the secondary hydroxyl group of glycerol to dihydroxyacetone (DHA) is an extremely challenging yet important reaction. The main difficulty is that three hydroxyl groups in glycerol are...

Changed reactivity of secondary hydroxyl groups in C8-modified adenosine – lessons learned from silylation

Synthesis of site-specifically modified oligonucleotides has become a major tool for RNA structure and function studies. Reporter groups or specific functional entities are required to be attached at a pre-defined site of the oligomer. An attractive strategy is the incorporation of suitably functionalized building blocks that allow post-synthetic conjugation of the desired moiety. A C8-alkynyl modified adenosine derivative was synthesized, reviving an old synthetic pathway for iodination of purine nucleobases. Silylation of the C8-alkynyl modified adenosine revealed unexpected selectivity of the two secondary sugar hydroxyl groups, with the 3'-O-isomer being preferentially formed. Optimization of the protection scheme lead to a new and economic route to the desired C8-alkynylated building block and its incorporation in RNA.

Selective Protection of Secondary Alcohols by Using Formic Acid as a Mild and Efficient Deprotection Reagent for Primary tert-Butyldimethylsilyl Ethers

A mild, efficient, and environmentally friendly method for the selective protection of secondary hydroxyl groups is described. The method involves the protection of both primary and secondary hydroxyl groups as tert-butyldimethylsilyl (TBDMS) ethers and selective deprotection of the primary TBDMS group with formic acid in acetonitrile/water. The rates of desilylation of primary and secondary TBDMS ethers by different concentrations of formic acid are determined. Formic acid of 5–20% concentration is found to selectively deprotect primary TBDMS ethers while keeping more than 95% of their secondary counterparts intact.