Synthesis of New Liquid Crystalline Diglycidyl Ethers

Abstract

The phenolic Schiff bases I–VI were synthesized by condensation reactions between various diamines, namely o-dianisidine, o-tolidine and ethylenediamine with vanillin or p-hydroxybenzaldehyde and subsequent reactions between these phenolic Schiff bases and epichlorohydrin to produce new diglycidyl ethers Ia–VIa. The structures of these compounds were confirmed by CHN, FT-IR, 1H-NMR, and 13C-NMR spectroscopy. Their thermotropic liquid crystalline behavior was studied using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). All the diglycidyl ethers prepared exhibit nematic mesophases, except for Va and VIa, which did not show any transition mesophases, but simply flow to liquids.

Preparation and Characterization of Di-, Tri-, and Tetranuclear Schiff Base Complexes Derived from Diamines and 3,4-Dihydroxybenzaldehyde

“…Chemical shifts for 13 C NMR of EDH 4 and MPDH 4 in DMSO are described in Table 4 . The signals assigned to the chemical shifts of methylene and methyl groups for the two ligands, respectively, were observed at 60.99 (CH 2 ) and at 19.8 and 20.1 (CH 3 ) ppm [ 18 ], while the signals of aromatic carbons were located at 113.6–161.2 and 110.8–146.8 ppm, respectively [ 18 , 19 ]. The signals observed at 167.2 and 150.6–152.7 ppm, respectively, were attributed to the chemical shifts of azomethine carbons which confirms the formation of the Schiff bases [ 20 – 22 ].…”

Biobased epoxy thermosets from vanillin-derived oligomers

“…Another strategy found in the literature consists in synthesizing aromatic epoxy monomers from various biobased aromatic molecules such as furans [13,14], 4-hydroxybenzoic acid [15], cinnamic acid [16], catechin [11,17], gallic acid [18], eugenol [19], vanillic acid [20] and vanillin [21][22][23]. Among them, vanillin and derivatives are especially interesting as vanillin is the only monoaromatic compound currently industrially produced from lignin [24].…”

New vanillin-derived diepoxy monomers for the synthesis of biobased thermosets

“…In a first step, a diacetal was prepared from vanillin and pentaerythritol and in a second step, a diglycidyl ether was formed. In another work, vanillin was reacted with a diamine to obtain a dienamine that was glycidylated in a second step [26]. In a previous paper [4], our team investigated the functionalization of vanillin and its derivatives at different oxidation states, getting rid of the ''coupling'' step.…”