The selective conversion of carbon-oxygen bonds into carbon-nitrogen bonds to form amines is one of the most important chemical transformations for the production of bulk and fine chemicals and pharma intermediates. An attractive atom-economic way of carrying out such C-N bond formations is the direct N-alkylation of simple amines with alcohols by the borrowing hydrogen strategy. Recently, transition metal complexes based on precious metals have emerged as suitable catalysts for this transformation; however, the crucial change towards the use of abundant, inexpensive and environmentally friendly metals, in particular iron, has not yet been accomplished. Here we describe the homogeneous, iron-catalysed, direct alkylation of amines with alcohols. The scope of this new methodology includes the monoalkylation of anilines and benzyl amines with a wide range of alcohols, and the use of diols in the formation of five, six- and seven- membered nitrogen heterocycles, which are privileged structures in numerous pharmaceuticals.

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Iron catalysed direct alkylation of amines with alcohols

Aliphatic amines are of considerable industrial importance and find application in almost every field of modern technology, agriculture, and medicine [1], Lower aliphatic amines (C1 to C6) are important intermediates for the chemical and pharmaceutical industries. A large number of drugs, herbicides, pesticides, dyes, and other chemicals contain amino pups which originate from reactions with such intermediates, Many important applications of higher aliphatic amines (fatty amines) and their derivatives (most important derivatives are quarternary ammonium compounds) are based on their cationic surface activity. Relatively small amounts of such compounds are usually required to achieve the desired changes in surface and colloidal properties. Thus, not surprising, one of the first applications of fatty amines was in the flotation separation of nonmetallic materials such as potash, feldspar, phosphate, and mica. Today, probably the biggest demand for fatty amines lies in the production of fabric softe...

Catalytic Synthesis of Higher Aliphatic Amines from the Corresponding Alcohols

The reductive amination, the reaction of an aldehyde or a ketone with ammonia or an amine in the presence of a reducing agent and often a catalyst, is an important amine synthesis and has been intensively investigated in academia and industry for a century Besides aldehydes, ketones, or amines, starting materials have been used that can be converted into an aldehyde or ketone (for instance, carboxylic acids or organic carbonate or nitriles) or into an amine (for instance, a nitro compound) in the presence of the same reducing agent and catalyst Mechanistically, the reaction starts with a condensation step during which the carbonyl compound reacts with ammonia or an amine, forming the corresponding imine followed by the reduction of the imine to the alkyl amine product Many of these reduction steps require the presence of a catalyst to activate the reducing agent The reductive amination is impressive with regard to the product scope since primary, secondary, and tertiary alkyl amines are accessible and hydrogen is the most attractive reducing agent, especially if large-scale product formation is an issue, since hydrogen is inexpensive and abundantly available Alkyl amines are intensively produced and use fine and bulk chemicals They are key functional groups in many pharmaceuticals, agro chemicals, or materials In this review, we summarize the work published on reductive amination employing hydrogen as the reducing agent No comprehensive review focusing on this subject has been published since 1948, albeit many interesting summaries dealing with one or the other aspect of reductive amination have appeared Impressive progress in using catalysts based on earth-abundant metals, especially nanostructured heterogeneous catalysts, has been made during the early development of the field and in recent years

Transition-Metal-Catalyzed Reductive Amination Employing Hydrogen.

The impact of the electrolyte’s pH on the catalytic activity of platinum group metal-free (PGM-free) catalysts toward the oxygen reduction reaction (ORR) was studied. The results indicate that the ORR mechanism is determined by the affinity of protons and hydroxyls toward multiple functional groups present on the surface of the PGM-free catalyst. It was shown that the ORR is limited by the proton-coupled electron transfer at pH values below 10.5. At higher pH values (>10.5), the reaction occurs in the outer Helmholtz plane (OHP), favoring hydrogen peroxide production. Using a novel approach, the changes in the surface chemistry of PGM-free catalyst in a full pH range were studied by X-ray photoelectron spectroscopy (XPS). The variations in the surface concentration of nitrogen and carbon species are correlated with the electron transfer process and overall kinetics. This study establishes the critical role of the multitude of surface functional groups, presented as moieties or defects in the carbonaceous ...

/pdf/effect-of-ph-on-the-activity-of-platinum-group-metal-free-4alw0zm389.pdf

Effect of pH on the Activity of Platinum Group Metal-Free Catalysts in Oxygen Reduction Reaction

Two iron-based platinum group metal-free catalysts for the oxygen reduction reaction (ORR) were synthesized from novel and low cost organic precursors named niclosamide and ricobendazole. These catalysts have been characterized, incorporated in a gas diffusional electrode and tested in “clean” conditions as well as in operating microbial fuel cell (MFC) for 32 days. Both catalysts demonstrated unprecedented performance yielding a power density 25% higher than that of platinum (Pt) and roughly 100% higher than activated carbon (AC) used as a control. Durability tests were performed and showed that Pt-based cathodes lost their activity within the first week of operation, reaching the level of the supporting AC-based electrode. Fe–ricobendazole, however, demonstrated the highest performance during the long-term study with a power density of 195 ± 7 μW cm−2 (day 2) that slightly decreased to 186 ± 9 μW cm−2 at day 29. Fe–niclosamide also outperformed Pt and AC but the power density roughly decreased with 20% for the 32 days of the study. Accelerated poisoning test using S2− as pollutant showed high losses in activity for Pt. Fe–niclosamide suffered higher losses compared to Fe–ricobendazole. Importantly, Fe–ricobendazole represents a 55-fold cost reduction compared to platinum.

/pdf/iron-based-catalysts-from-novel-low-cost-organic-precursors-fuad3ql9tf.pdf

Iron based catalysts from novel low-cost organic precursors for enhanced oxygen reduction reaction in neutral media microbial fuel cells

1.

Poisoning by means of sulfur containing compounds of dehydrogenating catalysts consisting og different concentrations of platinum on various carriers has been studied, The effect of all the poisons is equal to that an equivalent amount of hydrogen sulfide.




2.

The structure of the poison molecule does not affect its action, suggesting that they are all decomposed at the catalysts surface at about the same rate, with production of hydrogen sulfide.




3.

The amount of organically combined sulfur required to poison the catalysts is proportional to the amount of platinum contained therein.




4.

The amount of sulfur required to lower the activity of catalysts by 70–80% is about 6–7% of the weight of platinum present on the carrier.




5.

The regenerability of platinum catalysts poisoned with one and the same substances varies according to the nature of the carriers.




6.

It has been shown experimentally that the activation energy of the reaction of dehydrogenation of cyclhexane is the same for poisoned and unpoisoned catalyst. The value ofo the pre-exponential terms of the Arrhenius equation is ten times smaller for poisoned than for fresh catalysts. These data, together with crystal lattice data, indicate that poisoning of platinum catalysts is due to occlusion of active centers.

Poisoning of platinum catalysts with a low content of active metal on a carrier, under conditions of dehydrogenation catalysis

http://iopscience.iop.org/article/10.1070/RC1965v034n11ABEH001568/pdf

Catalytic methods of preparing aliphatic and alicyclic amines

1.

It is shown that, in the hydration of olefins and dehydration of alcohols in presence of zinc halides as catalysts, intermediate complexes are formed which later decompose, in a manner dependent on conditions, with formation of the final reaction products.




2.

Both in the reaction of zinc halides with alcohols and in the reaction between hydroxohalozinc acids and the unsaturated hydrocarbons corresponding to these alcohols, the same intermediate complexes are formed. This indicates the existence of a state of equilibrium between the reactions of hydration of olefins and dehydration of alcohols. On the basis of these data and of a detailed investigation of the composition of complexes formed by zinc halides with alcohols and unsaturated hydrocarbons, a possible mechanism is proposed for hydration and dehydration reactions in presence of zinc halides as catalysts.




3.

Comparison between hydration and dehydration reactions catalyzed by zinc halides, on the one hand, and by mineral acids, on the other, shows that they are very similar in mechanism.




4.

On the basis of theoretical considerations and of a study of the properties of the intermediate zinc halide compounds, a possible structure is proposed for the intermediate complexes.

Mechanism of hydration and dehydration reactions in presence of zinc halides

1.

A study has been made of the hydrogenation and dehydrogenation propensities of rhodium and ruthenium catalysts supported on various carriers.




2.

It has been shown that the activity of these catalysts for the hydrogenation of alkenes, cycloalkenes, and the benzene ring is close to that of a platinum catalyst.




3.

The activation energies for the dehydrogenation of cyclohexane over ruthenium and rhodium catalysts have been determined.

Hydrogenation and dehydrogenation of hydrocarbons in presence of ruthenium and rhodium catalysts of low metal content

1.

The formation of amines from alcohols under the influence of ammonia takes place by simple substitution of amino groups for hydroxyl groups in the alcohol molecule with elimination of hydrogen.




2.

Unsaturated hydrocarbons, aldehydes and simple ethers which are formed during the amination of alcohols are products of the side reactions, dehydration and dehydrogenation which occur on the surface of oxide catalysts at elevated temperatures.

N. I. Shuikin

Papers

Poisoning of platinum catalysts with a low content of active metal on a carrier, under conditions of dehydrogenation catalysis

Catalytic methods of preparing aliphatic and alicyclic amines

Mechanism of hydration and dehydration reactions in presence of zinc halides

Hydrogenation and dehydrogenation of hydrocarbons in presence of ruthenium and rhodium catalysts of low metal content

The catalytic amination of alcohols