29 research outputs found
Hydrogen production via dehydrogenation of alcohols using ruthenium hexamethylenetetramine complex
No full textBeing a zero-carbon source, the hydrogen economy is considered to be better than the fuel economy as it produces only water vapor even after complete combustion. Still, it suffers from two major drawbacks, namely (1) the production of green hydrogen from sustainable resources and (2) the storage and transportation of hydrogen. The use of liquid organic hydrogen carriers (LOHCs) such as alcohols, amines, etc. has been found to be a better and more secure way to store and transport hydrogen. Catalytic hydrogenation and dehydrogenation of LOHCs using transition metal complexes are known as the best methods to load and unload hydrogen for storage and transportation. Here, in this article, we show the amount of hydrogen produced during the catalytic dehydrogenation of LOHCs like alcohols using a very simple and cheap gas burette method. The dehydrogenative oxidation of alcohols was done using a well-defined [Ru(p-cym)HMTA]Cl2 complex with a catalyst loading of 0.5 mol%. Hydrogen estimation was done for different alcohol substrates. A comparison was made between theoretical and experimental yields of the released hydrogen
Synthesis of a Water-Soluble Ruthenium Complex and Its Catalytic Activity for Acceptorless Alcohol Dehydrogenation in Aqueous Medium
No full textThe synthesis of a ruthenium complex bearing a PN-chelating ligand is described. The complex, in the presence of KOH, enabled the synthesis of ketones from secondary alcohols in the absence of a hydrogen acceptor in aqueous medium. This synthetic protocol, which uses water as the medium, is green and has a high atom economy as it avoids the use of an acceptor and produces hydrogen as the sole byproduct. Mechanistic investigations revealed that the catalytic cycle involves a phosphine dissociative pathway.</jats:p
Well-Defined Ruthenium Complex for Acceptorless Alcohol Dehydrogenation in Aqueous Medium
No full textAcceptorless and base-free dehydrogenation of alcohols and amines using ruthenium-hydride complexes
No full textAn efficient, operatively simple, acceptorless, and base-free dehydrogenation of secondary alcohols and nitrogen-containing heterocyclic compounds was achieved by using readily available ruthenium hydride complexes as precatalysts. The complex RuH2(CO)(PPh3)3 (1) and Shvo’s complex (2) showed excellent activities for the dehydrogenation of secondary alcohols and nitrogen containing heterocycles. In addition to complexes 1 and 2, the complex RuH2(PPh3)4 (3) also showed moderate to excellent activity for the acceptorless dehydrogenation of nitrogen-containing heterocyclic compounds. Kinetic studies on the oxidation reaction of 1-phenylethanol using complex 1 were carried out in the presence and the absence of external triphenylphosphine (PPh3). External addition of PPh3 had a negative influence on the rate of the reaction, which suggested that dissociation of PPh3 occurred during the course of the reaction. Hydrogen was evolved from the oxidation reaction of 1-phenylethanol by using 1 mol% of 1 (88%) and 2 (92%), which demonstrated the possible usage of the catalytic systems in hydrogen generation
ChemInform Abstract: Acceptorless and Base‐Free Dehydrogenation of Alcohols and Amines Using Ruthenium‐Hydride Complexes.
No full text
ChemInform Abstract: Tandem Synthesis of Amides and Secondary Amines from Esters with Primary Amines under Solvent‐Free Conditions.
No full textTandem Synthesis of Amides and Secondary Amines from Esters with Primary Amines under Solvent‐Free Conditions
No full textExtending the Chemistry of Hexamethylenetetramine in Ruthenium-Catalyzed Amine Oxidation
No full textA very efficient,
highly atom economical, and environmentally benign oxidation of primary
and secondary amines using an in situ catalyst system generated from
commercially available ruthenium(II) benzene dichloride dimer and
hexamethylenetetramine has been demonstrated. Mechanistic studies
revealed that hexamethylenetetramine acted as a source of hydride
to generate the active ruthenium hydride catalyst and amine oxidation
involves a dehydrogenative pathway. In comparison to reported catalyst
systems for the dehydrogenative oxidation of amines, this synthetic
protocol makes use of a simple ruthenium precursor and a cheaper additive;
it is very selective, leading to the exclusive formation of nitrile/imine
compounds. Further, it releases hydrogen as the only side product,
suggesting the potential application of the developed catalyst system
in hydrogen storage
