Dimethylammonium Dimethylcarbamate Research Articles

Branched Tertiary Amines from Aldehydes and α-Olefins by Combined Multiphase Tandem Reactions.

This study presents the transformation of olefins to branched amines by combining a hydroformylation/aldol condensation tandem reaction with the reductive amination in a combined multiphase system that can be recycled 9 times. The products are branched amines that are precursors for surfactants. Since the multiphase hydrofomylation/aldol condensation system has already been studied, the first step was to develop the partial hydrogenation of unsaturated aldehydes together with a subsequent reductive amination. The rhodium/phosphine catalyst is immobilized in a polar polyethylene phase which separates from the product phase after the reaction. Reaction and catalyst recycling are demonstrated by the conversion of the C14 -aldehyde 2-pentylnonenal with the dimethylamine surrogate dimethylammonium dimethylcarbamate to the corresponding tertiary amine with yields up to 88 % and an average rhodium leaching of less than 0.1 % per recycling run. Furthermore, the positive influence of a Bronsted acid and carbon monoxide on the selectivity are discussed. Finally, the two PEG based systems have been merged in one recycling approach, by using the product phase of the hydroformylation aldol condensation reaction for the reductive amination reaction. The yields are stable during a nine recycling runs and the leaching low with 0.09 % over the two recycling stages.

Permeabilization of Haematococcus pluvialis and solid-liquid extraction of astaxanthin by CO2-based alkyl carbamate ionic liquids

Haematococcus pluvialis (H. pluvialis) microalgae are well known for their high content of astaxanthin, which is a super potent antioxidant with various remedial effects. Ionic liquids (ILs) have been proposed as a promising solvent to permeabilize the robust microalgal cell wall for an effective extraction of bioactive compounds. Nonetheless, the removal of ILs from the extracted compounds requires the additional treatment steps that complicate the overall extraction process and the recycling of ILs. To address these shortcomings, we demonstrated a sustainable extraction system that utilizes CO2-based alkyl carbamate ILs to permeate H. pluvialis cells and extract astaxanthin. This class of ILs is readily distillable for an easy recovery of ILs from the extraction medium. Among the tested CO2-based alkyl carbamate ILs [dimethylammonium dimethylcarbamate (DIMCARB), dipropylammonium dipropylcarbamate (DPCARB), dibutylammonium dibutylcarbamate (DBCARB) and diallyammonium diallycarbamate (DACARB)], DIMCARB gave the best performance of astaxanthin extraction. The optimized extraction conditions [100% (w/w) of DIMCARB, 75 min and 45 °C] resulted in the high yield of astaxanthin (27.99 mg/g). The capability of DIMCARB to permeabilize the amorphous trilayered structure of cell wall was verified by the presence of pores on the cell surface of H. pluvialis as shown in the microscope images. The performance and recyclability of DIMCARB extraction system were also evaluated by conducting three successive rounds of astaxanthin extraction with the recycled DIMCARB solutions. In addition, the antioxidant capacity of the extracted astaxanthin was well retained, showing that this type of distillable IL was suitable for the extraction of phytonutrients from algal source.

Symmetrical and unsymmetrical substituted 2,5-diarylidene cyclohexanones as anti-parasitic compounds

Symmetrical and unsymmetrical bis-aryl-α,β-unsaturated ketones were synthesized in moderate to excellent yield by treating cyclohexanone with various aldehydes. Dimethylammonium dimethylcarbamate (DIMCARB) was used as both catalyst and reaction medium for the synthesis of monoarylidenes cycloadduct intermediates, which was further used to produce diarylidene cyclohexanones. All the 34 compounds synthesized were evaluated for their anti-proliferative activity, particularly against promastigote of Leishmania amazonensis, epimastigoteand trypomastigoteof Trypanosoma cruzi. Eighteen compounds displayed anti-leishmanial activity against promastigotes of L. amazonensis with IC50 values ranging from 2.8 to 10 μM. In addition, two compounds exhibited significant antitrypanosomal activity against epimastigotes of T. cruzi with IC50 values of 5.2 ± 0.8 and 3.0 ± 0.0 μM, while five compounds exhibited activity from 15.0 ± 1.4 to 30.2 ± 1.8 μM against trypomastigote of T. cruzi. Moreover, all compounds were more selective against the parasites than the epithelial cells. The unsymmetrical compounds 16, 28, 30 and 33 can be considered as favorable anti-parasitic lead molecule having IC50 and EC50 values in the low-micromolar range, better than the reference drug benznidazole, and low cytotoxicity against Vero cells. The potent compounds were screened in silico against 17 enzymes of T. cruzi and best scoring were found against Dihydroorotate Dehydrogenase.

Electrochemical Reduction of CO2 with an Oxide‐Derived Lead Nano‐Coralline Electrode in Dimcarb

AbstractElectroreduction of CO2 in the distillable ionic liquid dimethylammonium dimethylcarbamate (dimcarb) has been investigated with an oxide‐derived lead (od‐Pb) electrode. Compared with unmodified polycrystalline Pb, where H2 is the dominant electrolysis product, od‐Pb possesses impressive catalytic properties for the reduction of CO2 in dimcarb (mixing molar ratio of CO2 and dimethylamine (DMA) >1 : 1.8), with faradaic efficiencies for the generation of H2, CO, and [HCOO]− of approximately 15, 10, and 75 %, respectively. These efficiencies are independent of the applied potential in the range of −1.34 to −3.34 V vs. Cc0/+ (where Cc+=cobaltocenium). Thorough analysis of the properties of od‐Pb, we demonstrate that its intrinsically high catalytic activity towards CO2 reduction compared to bulk Pb is attributable to an increased surface roughness and greater surface area (ca. 10 times higher), rather than the existence of residual metal oxides that are known to suppress the hydrogen evolution reaction, preferred crystal orientation, or the existence of metastable active sites.

Optimized one-pot synthesis of monoarylidene and unsymmetrical diarylidene cycloalkanones

Ionic liquid dimethylammonium dimethylcarbamate (DIMCARB) catalyzed reaction for the synthesis of monoarylidene and unsymmetrical diarylidene cycloalkanones has been developed. Catalytic amount of DIMCARB was used in green solvent (water and ethanol) for different reaction of cyclic and acyclic ketones with different electron donating and withdrawing substituted aldehydes. Yields were recorded from low to excellent. This synthetic methodology provides mild, efficient, and environmentally friendly access to unsymmetrical curcuminoid analogs, avoiding the use of excess catalysts, chlorinated organic solvent, and high temperature reaction. It is green and environmentally sound alternative to the existing protocols for the synthesis of pharmaceutically important unsymmetrical natural product analogs.

Electrochemical Reduction of CO2 at Metal Electrodes in a Distillable Ionic Liquid.

The electroreduction of CO2 in the distillable ionic liquid dimethylammonium dimethylcarbamate (dimcarb) has been investigated with 17 metal electrodes. Analysis of the electrolysis products reveals that aluminum, bismuth, lead, copper, nickel, palladium, platinum, iron, molybdenum, titanium and zirconium electroreduce the available protons in dimcarb to hydrogen rather than reducing CO2 . Conversely, indium, tin, zinc, silver and gold are able to catalyze the reduction of CO2 to predominantly carbon monoxide (CO) and to a lesser extent, formate ([HCOO](-) ). In all cases, the applied potential was found to have a minimal influence on the distribution of the reduction products. Overall, indium was found to be the best electrocatalyst for CO2 reduction in dimcarb, with faradaic efficiencies of approximately 45 % and 40 % for the generation of CO and [HCOO](-) , respectively, at a potential of -1.34 V versus Cc(+/0) (Cc(+) =cobaltocenium) employing a dimethylamine to CO2 ratio of less than 1.8:1.

Tandem amine and ruthenium-catalyzed hydrogenation of CO2 to methanol.

This Communication describes the hydrogenation of carbon dioxide to methanol via tandem catalysis with dimethylamine and a homogeneous ruthenium complex. Unlike previous examples with homogeneous catalysts, this CO2-to-CH3OH process proceeds under basic reaction conditions. The dimethylamine is proposed to play a dual role in this system. It reacts directly with CO2 to produce dimethylammonium dimethylcarbamate, and it also intercepts the intermediate formic acid to generate dimethylformamide. With the appropriate selection of catalyst and reaction conditions, >95% conversion of CO2 was achieved to form a mixture of CH3OH and dimethylformamide.

Synthesis of calixarene-based ketocyanine fluorophores

Cup-shaped calix[4]arenes bearing one or two ketocyanine fluorophore fragments at the wide rim of the macrocycle are synthesized by condensation of formyl calix[4]arenes with arylmethylene(hetarylmethylene)cyclopentanones in the presence of the ionic liquid, dimethylammonium dimethylcarbamate (DIMCARB) and characterized using UV–vis and fluorescence spectroscopy. Strong positive solvatofluorochromism for the calixarene ketocyanines is observed.

ChemInform Abstract: Protection‐, Salt‐, and Metal‐Free Syntheses of [n]‐Shogaols by Use of Dimethylammonium Dimethyl Carbamate (DIMCARB) Without Protecting Groups.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Protection-, Salt-, and Metal-Free Syntheses of [n]-Shogaols by Use of Dimethylammonium Dimethyl Carbamate (DIMCARB) without Protecting Groups

Shogaols, the pungent principle of ginger, exhibit interesting bioactivities. Practical preparation of shogaols is highly desired. Here we report the protection/deprotection-, salt-, and metal-free synthesis of shogaol in three steps by use of dimethylammonium dimethyl carbamate (DIMCARB), in which DIMCARB smoothly promoted Mannich-type condensation of the ketone donor with the aldehyde acceptor through the iminium cation intermediate.

A Strategic, 'Green' Approach to Organic Chemistry with Microwave Assistance and Predictive Yield Optimization as Core, Enabling Technologies

Since 1988, we have pursued enabling technologies and methods as tools for ‘green’ synthetic chemistry. The developed technologies comprise hardware including catalytic membranes and continuous and batch microwave reactors that have established global markets, as well as interactive, predictive software for optimization of yields and translation of conditions. New methods include ‘green’ reactions such as a catalytic symmetrical etherification, Pd-catalyzed coupling processes and a multi-component cascade for aniline derivatives. Reactions and workup were facilitated through solvent-free conditions, aqueous media at high temperature and dimethylammonium dimethylcarbamate (dimcarb) as a ‘distillable’ protic ionic liquid, as well as by non-extractive techniques for product isolation. The technologies and methods were designed for use alone or in various combinations as desired. Consolidation of individual operations or processes into unit steps was achieved through multi-tasking: media, reactants, catalysts, and conditions were selected to serve several purposes at various stages of a reaction. The tools were used to establish a technology platform comprising structurally diverse oligomers, macrocycles, and rod-like molecules supplementary to those available through phenol-formaldehyde chemistry. Dienone precursors were assembled from versatile building blocks containing complementary ‘male’ or ‘female’ fittings that were connected through inherently ‘green’ Claisen–Schmidt-type reactions. Isoaromatization afforded Horning-crowns, macrocyclic phenolic derivatives that were hybrids of calixarenes and crown ethers. Preliminary studies of organic substrates in salt water, with and without CO2, called into question proposals for disposal of anthropogenic CO2 by deep-sea dispersal.

Direct Preparation of Monoarylidene Derivatives of Aldehydes and Enolizable Ketones with DIMCARB.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Direct preparation of monoarylidene derivatives of aldehydes and enolizable ketones with DIMCARB.

[reaction: see text] Aryl alpha,beta-unsaturated ketones and aldehydes were synthesized, in moderate to excellent yields, with use of dimethylammonium dimethyl carbamate (DIMCARB) as a recyclable reaction medium and as a catalyst.

Zum dynamischen Strukturverhalten des Dimethylamin—Kohlendioxid-Komplexes (Dimcarb) / On the Dynamic Structure Behaviour of the Dimethylamine—Carbondioxide Complex (Dimcarb)

Abstract Dimcarb, a liquid distillable 1 .8 :1-dimethylamine-carbondioxide complex which can be used as a preparatively profitable dimethylamine source, displays unusual properties in view of a salt ("dimethylammonium dimethylcarbamate"). The dynamic structure behaviour has been investigated by1'H, 13C, and 15N NMR spectroscopy: At ambient temperature dimcarb underlies a rapid dimethylamine change between ammonium and carbamate functionality (⊿G ≠ about 58 kJ/mol). On further temperature decreasing prototropic interactions between dimethylammonium and dimethylamine as well as dimethylcarbamate and dimethylcarbamic acid species are additionally revealed. Timely averaged, ionic structures predominate, obviously dimethylammonium dimethylcarbamate combinations as intimate ion pairs. Involved dimethylcarbamic acid can be trapped as methylester in high yield by reaction of dimcarb with diazomethane. Moreover, the dimethylcarbamic acid trimethylsilylester, obtained from dimcarb with the aid of trimethyl-chlorosilane, affords a crystalline product by methanolysis at -78 °C. probably dimethylcarbamic acid, which decomposes above -50 °C under carbondioxide elimination and regeneration of dimcarb.

Dimethylammonium-dimethylcarbamat (Dimcarb) - ein vorteilhaftes Reagens für die Willgerodt-Kindler-Reaktion

Dimethylammonium Dimethylcarbamate - A Useful Reagent for the Willgerodt-Kindler Reaction Dimethylammonium dimethylcarbamate (dimcarb), easily accessible from dimethylamine and carbon dioxide, is a useful reagent for the Willgerodt-Kindler synthesis of N,N-dimethylthiocarboxamides. Moreover, dimcarb displays some unusual properties, and generally behaves as a preparatively useful dimethylamine source.