Six coordination polymers were prepared by linking Mn(SCN) 2 units by three different bis(4-pyridyl) substituited hydrazone derivatives (L) in three different solvents (methanol, ethanol, and acetonitrile) in order to study the effect of the hydrogen bonding ability of L on the formation of solvates rather than interpenetrated solvent-free interpenetrated structures. When the ligand L which cannot act as a hydrogen donor was used, in all three solvents the same product was obtained. This was a [Mn(SCN) 2 L 2 ] n metal− organic framework, consisting of two-dimensional (2D) networks, each interpenetrating two neighboring ones. When the bridging ligands L have additional functional groups capable of acting as hydrogen donors or acceptors, synthesis from acetonitrile yields non-interpenetrating 2D [Mn(SCN) 2 L 2 ] n networks with solvent molecules occupying the voids of the network. Other solvents were found to yield interpenetrated solvent free networks, or they replaced some of the L ligands, forming one-dimensional coordination polymers.
A technique for preparing heterobimetallic frameworks with tunable metal sites is demonstrated by the synthesis of a new two-dimensional metal-organic framework that is constructed from tetra(4-carboxyphenyl)porphyrin and Cd(II) species. The solid can be prepared in the presence of other divalent transition metals to yield the same framework with the smaller metal ions occupying the porphyrin ligands.
Taurine,
2-aminoethane-1-sulfonic acid, is a commercial amino acid
manufactured from either ethylene oxide or monoethanolamine (MEA).
Taurine is a valuable nutritional additive that is widely used in
the production of energy drinks, pet food, nutritional supplements,
and infant formula. The industrial production of taurine from MEA
is a two-step batch process in which the first step is the reaction
of MEA with sulfuric acid to produce the ester 2-aminoethyl hydrogen
sulfate (AES) and the second step is the reaction of AES with a sulfite
reagent. This report summarizes the results of a study of the fundamental
chemistry for this two-step MEA-based chemical route to taurine as
well as the application of this fundamental understanding to a process
design for a scalable and cost-advantaged continuous process that
is capable of commercial-scale production of taurine on a multikiloton
scale. In order to maximize taurine yields, the water formed during
the first esterification step must be effectively removed to avoid
equilibrium limitations on the conversions of MEA and sulfuric acid
to form the solid AES intermediate product. For the second AES sulfonation
step in aqueous medium, we found that operation above 100 °C
under a moderate pressure of an inert gas resulted in significantly
higher taurine yields (>80 mol %) compared to those reported in
current
commercial production technology (typically 55–65 mol %).
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