Hyperbranched,
multifunctional polycarbonate polyols based on CO2, cyclohexene
oxide (CHO), and the “inimer”
(initiator–monomer) (4-hydroxymethyl)cyclohexene oxide
(HCHO) were prepared in one-pot syntheses. The related linear poly(hydroxymethyl
cyclohexene carbonate) structures based on protected HCHO and postpolymerization
deprotection were also synthesized as model compounds. The content
of hydroxyl functionalities was adjustable for both linear and hyperbranched
terpolymer systems. All CO2/epoxide polymerizations were
catalyzed by the (R,R)-(salcy)-Co(III)Cl
complex. The polycarbonates obtained were comprehensively investigated
using various 1D and 2D NMR techniques, SEC, FT-IR, UV–vis
spectroscopy, and contact angle measurements. Rigid polyols with molecular
weights between 3600 and 9200 g mol–1 and moderate
dispersity between 1.18 and 1.64 (M
w/M
n) were obtained. In addition, the materials
were examined with respect to their thermal properties, intrinsic
viscosity, and their three-dimensional structure. Glass transition
temperatures in the range of 113–141 °C (linear) and 72–105
°C (hyperbranched) were observed. The intrinsic viscosity of
the hyperbranched systems is in the range of 5.69–11.51 cm3 g–1 and mirrors their compact structure.
The hyperbranched polyols were also studied regarding their successful
reaction with phenyl isocyanate to convert the free hydroxyl groups
into urethanes.
Pyrazolines and pyrazoles are common and important motifs of pharmaceutical agents and agrochemicals. Herein, the first electrochemical approach for their direct synthesis from easily accessible hydrazones and dipolarophiles up to decagram scale is presented. The application of a biphasic system (aqueous/organic) even allows for the conversion of highly sensitive alkenes, wherein inexpensive sodium iodide is employed in a dual role as supporting electrolyte and mediator. In addition, mechanistic insight into the reaction is given by the isolation of key step intermediates. The relevance of the presented reaction is underlined by the synthesis of commercial herbicide safener mefenpyr‐diethyl in good yields.
To demonstrate the technical application potential of electrochemical reactions, we developed a synthetic method to access commercially available herbicide safener mefenpyr-diethyl. In a simple undivided electrolysis cell with non-hazardous aqueous...
Pyrazoline und Pyrazole sind häufige und wichtige Bestandteile vieler Pharmaka und Agrochemikalien. Diese Arbeit zeigt den ersten elektrochemischen Ansatz zu deren direkter Synthese aus leicht zugänglichen Hydrazonen und Dipolarophilen bis in den Dekagrammbereich. Die Anwendung eines zweiphasigen Systems (wässrig/organisch) ermöglicht auch die Umsetzung hochempfindlicher Alkene, wobei kostengünstiges Natriumiodid gleichzeitig als Leitsalz und Mediator eingesetzt wird. Darüber hinaus wurden entscheidende Zwischenstufen isoliert, die einen Einblick in den Reaktionsmechanismus geben. Die Relevanz der vorgestellten Reaktion wird durch die Synthese des kommerziellen Herbizidsafeners Mefenpyr-Diethyl in guter Ausbeute unterstrichen.
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