Neat Reaction Research Articles

Lithium Imide Synergy with 3d Transition‐Metal Nitrides Leading to Unprecedented Catalytic Activities for Ammonia Decomposition

AbstractAlkali metals have been widely employed as catalyst promoters; however, the promoting mechanism remains essentially unclear. Li, when in the imide form, is shown to synergize with 3d transition metals or their nitrides TM(N) spreading from Ti to Cu, leading to universal and unprecedentedly high catalytic activities in NH3 decomposition, among which Li2NHMnN has an activity superior to that of the highly active Ru/carbon nanotube catalyst. The catalysis is fulfilled via the two‐step cycle comprising: 1) the reaction of Li2NH and 3d TM(N) to form ternary nitride of LiTMN and H2, and 2) the ammoniation of LiTMN to Li2NH, TM(N) and N2 resulting in the neat reaction of 2 NH3⇌N2+3 H2. Li2NH, as an NH3 transmitting agent, favors the formation of higher N‐content intermediate (LiTMN), where Li executes inductive effect to stabilize the TMN bonding and thus alters the reaction energetics.

Lithium imide synergy with 3d transition-metal nitrides leading to unprecedented catalytic activities for ammonia decomposition.

Alkali metals have been widely employed as catalyst promoters; however, the promoting mechanism remains essentially unclear. Li, when in the imide form, is shown to synergize with 3d transition metals or their nitrides TM(N) spreading from Ti to Cu, leading to universal and unprecedentedly high catalytic activities in NH3 decomposition, among which Li2NH-MnN has an activity superior to that of the highly active Ru/carbon nanotube catalyst. The catalysis is fulfilled via the two-step cycle comprising: 1) the reaction of Li2NH and 3d TM(N) to form ternary nitride of LiTMN and H2, and 2) the ammoniation of LiTMN to Li2NH, TM(N) and N2 resulting in the neat reaction of 2 NH3⇌N2+3 H2. Li2NH, as an NH3 transmitting agent, favors the formation of higher N-content intermediate (LiTMN), where Li executes inductive effect to stabilize the TM-N bonding and thus alters the reaction energetics.

H2O2 in WERSA: an efficient green protocol for ipso-hydroxylation of aryl/heteroarylboronic acid

A mild, green, economic and efficient protocol has been developed for ipso-hydroxylation of aryl/heteroarylboronic acids to phenols using 30% aqueous H2O2 as an oxidant and WERSA (water extract of rice straw ashes) as a neat reaction medium.

Facile access to amides and hydroxamic acids directly from nitroarenes.

A new method for synthesis of amides and hydroxamic acids from nitroarenes and aldehydes is described. The MnO2 catalyzed thermal deoxygenation of nitrobenzene resulted in formation of a reactive nitroso intermediate which on reaction with aldehydes provided amides and hydroxamic acids. The thermal neat reaction in the presence of 0.01 mmol KOH predominantly led to formation of hydroxamic acid whereas reaction in the presence of 1 mmol acetic acid produced amides as the only product.

Green Chemistry Starting from 2H-Pyran-2-one Derivatives

In this review with broad coverage of recent literature references we present some general aspects of green chemistry as well as a brief overview of transformations of 2H-pyran-2-ones and fused pyran-2-ones under green condition. The emphasis is given on microwave-assisted transformations under various conditions, such as aqueous condition, neat reactions, reactions in ionic liquids and, to provide a comparison, also the reactions under high pressure are presented. Keywords: Aqueous conditions, high pressure chemistry, ionic liquids, microwave chemistry, neat reactions, 2H-Pyran-2-ones, organocatalysis.

A highly efficient and green cascade synthesis of 3-methyl-substituted-4-hydroxy-1-methyl-quinolin-2(1H)-ones under solvent- and catalyst-free conditions

An expeditious and green protocol for the synthesis of 3,3′-methanediylbis(4-hydroxy-1-methylquinolin-2(1H)-one) (MDBHQ) derivatives and 3-((2-amino-6-oxocyclohex-1-enyl)methyl)-4-hydroxy-1-methylquinolin-2(1H)-one (AOCHQ) derivatives has been developed via a cascade Knoevenagel–Michael reaction. The products were obtained in high yield under neat reaction conditions without any work-up or chromatographic purification. The generality and functional tolerance of this environmentally benign protocol is demonstrated.

ChemInform Abstract: CeCl3·7H2O—SiO2: Catalyst Promoted Microwave Assisted Neat Synthesis, Antifungal and Antioxidant Activities of α‐Diaminophosphonates.

AbstractTen α‐diaminophosphonates of dapsone (IV) are synthesized in good to excellent yields by a one‐pot three‐component reaction under neat reaction conditions.

CeCl3·7H2O-SiO2: Catalyst promoted microwave assisted neat synthesis, antifungal and antioxidant activities of α-diaminophosphonates

CeCl3·7H2O supported on silica (CeCl3·7H2O-SiO2) is used as a heterogeneous, efficient and recyclable catalyst for a three component one-pot reaction of an amine, aldehydes and diethyl phosphite to synthesize α-diaminophosphonate derivatives under microwave irradiation exploiting neat reaction conditions. Ten α-diaminophosphonates (6a–j) of 4,4′-sulfonyldianiline (Dapsone) (3) were synthesized and structural elucidation was confirmed by spectral data. Antifungal and antioxidant activities were evaluated include minimum inhibitory concentrations and IC50 values, respectively of the titled compounds. Compounds 6h, 6i exhibited promising antioxidant activity at lower IC50 values 53.7 μg/mL, 53.2 μg/mL, respectively as compared with standard IC50 value 51.6 μg/mL.

ChemInform Abstract: Solvent‐Free, Highly Efficient One‐Pot Multi‐Component Synthesis of 1‐Amido‐ and 1‐Carbamato‐alkyl Naphthols/Phenols Catalyzed by Ethylammonium Nitrate as Reusable Ionic Liquid under Neat Reaction Condition at Ambient Temperature.

A solvent-free, environmentally clean, mild, and simple one-pot multi-component protocol has been developed for the efficient synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols in excellent yields via one-pot three-component condensation of various aldehydes, amides/carbamates/urea, and naphthols/phenols using ethylammonium nitrate (EAN) as a reusable ionic liquid catalyst under neat reaction condition at ambient temperature.

From Conventional Reaction Conditions to Microwave-Assisted Catalytic Transformations of Various Substrates. State of the Art in 2012 (Part A: General)

Microwave irradiation as a modern approach to various organic transformations, specially in combination with the use of homogeneous or heterogeneous catalysts, is a well-established strategy for the preparation of a range of important compounds. However, due to the recent enormous expansion of the field of modern, catalytic transformations of different types, we present the title subject in the form of two reviews (Part A: General and Part B: Catalysis). In Part A, we provided a general overview of the underlying principles of the application of microwaves in organic synthesis. Furthermore, we presented a selection of examples of catalyst-free applications of principles of the green chemistry, such as use of water as the solvent, application of neat reaction conditions and reactions taking place on solid supports. In Part B [1], we described the reactions carried out using microwaves in the combination with various types of catalysts (transition-metal-catalyzed transformation, organocatalysis, phase-transfer catalysis, the use of inorganic catalysts and ionic liquids, etc.). In addition, we looked at the syntheses and transformations of different organic targets with the emphasis on heterocycles, especially on those containing a 2H-pyran-2-one moiety in their structure. A particular interest is also dedicated to the environmentally benign reaction conditions.

ChemInform Abstract: Direct Amide Bond Formation from Carboxylic Acids and Amines Using Activated Alumina Balls as a New, Convenient, Clean, Reusable and Low Cost Heterogeneous Catalyst.

For the first time, we have used activated alumina balls (3–5 mm diameter) for amide synthesis from carboxylic acids (unactivated) and amines (unactivated) under neat reaction conditions that produce no toxic by-products and has the advantages of being low-cost, easily available, heterogeneous, reusable and environmentally benign with no troublesome/hazardous disposal of the catalyst.

Solvent-free, highly efficient one-pot multi-component synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols catalyzed by ethylammonium nitrate as reusable ionic liquid under neat reaction condition at ambient temperature

A solvent-free, environmentally clean, mild, and simple one-pot multi-component protocol has been developed for the efficient synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols in excellent yields via one-pot three-component condensation of various aldehydes, amides/carbamates/urea, and naphthols/phenols using ethylammonium nitrate (EAN) as a reusable ionic liquid catalyst under neat reaction condition at ambient temperature.

Controlling Product Composition of Metathesized Triolein by Reaction Concentrations

AbstractTriolein was used as a model material to investigate the effect of concentration on self metathesis of vegetable oils. The metathesis reaction using Grubbs' second generation catalyst (used at a level of 2.5 mol % of triolein) was carried out at 38 °C using dichloromethane as the solvent. The products from three reaction concentrations were investigated: neat, 10 and 20 mmol/L. The products from the reactions were separated by column chromatography and the fractions were characterized by 1H‐NMR, 13C‐NMR, MS and FTIR. Mono‐cyclic and multi‐cyclic triacylglycerol‐based compounds and different level aliphatic triacylglycerol‐like oligomers were produced, but the compositions of the products were found to be significantly controlled by the reaction concentrations. Cyclic compounds were favorably produced at lower reaction concentrations, whereas, linear oligomers were favorably produced at higher reaction concentrations. Cyclic compounds were formed mainly from adjacent fatty acid chains on the glycerol backbone. In the neat reactions, only linear oligomers were produced. The trans/cis ratios increased as concentration was increased.

Kinetic Study of Thermal 1,3‐Dipolar Cycloaddition of Azomethine Ylides by Using Differential Scanning Calorimetry

AbstractThe kinetics of 1,3‐dipolar cycloaddition involving azomethine ylides, generated from thermal 1,2‐prototropy of the corresponding imino ester, employing differential scanning calorimetry (DSC), is surveyed. Glycine and phenylalanine derived imino esters have different behavior. The first one prefers reacting with itself at 75 °C, rather than with the dipolarophile. However, the α‐substituted imino ester gives the cycloadduct at higher temperatures. Thermal dynamic analysis, by using 1H NMR spectroscopy, of the neat reaction mixture of the glycine derivative reveals the presence of signals corresponding to the dipole in small abundance. The non‐isothermal and isothermal DSC curves of the cycloaddition of phenylalaninate and diisobutyl fumarate are obtained from freshly prepared samples. The application of known kinetic models and mathematical multiple non‐linear regressions (NLR) allow the determintion and comparison of Ea, lnA, reaction orders, and reaction enthalpy values. Finally a rate equation for each different temperature studied can be established for this particular thermal cycloaddition.

ChemInform Abstract: Expedient Approach for the Synthesis of Novel Indenothiophene Derivatives.

AbstractAll products are isolated by simple work‐up and purified by recrystallization.

Syntheses of Novel Protein Products (Milkglyde, Saliglyde, and Soyglyde) from Vegetable Epoxy Oils and Gliadin

The aqueous alcohol-soluble fraction of wheat gluten is gliadin. This component has been implicated as the causative principle in celiac disease, which is a physiological condition experienced by some infants and adults. The outcome of the ingestion of whole wheat products by susceptible individuals is malabsorption of nutrients resulting from loss of intestinal vili, the nutrient absorption regions of the digestive system. This leads to incessant diarrhea and weight loss in these individuals. Only recently has this health condition been properly recognized and accurately diagnosed in this country. The culprit gliadin is characterized by preponderant glutamine side-chain residues on the protein surface. Gliadin is commercially available as a wheat gluten extract, and in our search for new biobased and environmentally friendly products from renewable agricultural substrates, we have exploited the availability of the glutamine residues of gliadin as synthons to produce novel elastomeric nonfood products dubbed "milkglyde", "saliglyde", and soyglyde from milkweed, salicornia and soybean oils. The reaction is an amidolysis of the oxirane groups of derivatized milkweed, salicornia, and soybean oils under neat reaction conditions with the primary amide functionalties of glutamine to give the corresponding amidohyroxy gliadinyl triglycerides, respectively. The differential scanning calorimetry, thermogravimetric analyses, and rheological data from a study of these products indicate properties similar to those of synthetic rubber.

Zn(OAc)2•2H2O‐catalyzed synthesis of α‐aminophosphonates under neat reaction

AbstractA series of novel α‐aminophosphonates have been prepared by one‐pot three‐component condensation in the presence of a zinc acetate (Zn(OAc)2•2H2O) catalyst at 50°C under solvent‐free conditions with excellent yields. The major advantages of the present method are high yields, a short reaction time, and solvent‐free reaction conditions. Their antimicrobial activity was evaluated, and some of them showed significant activity. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:160–165, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20765

Direct amide bond formation from carboxylic acids and amines using activated alumina balls as a new, convenient, clean, reusable and low cost heterogeneous catalyst

For the first time, we have used activated alumina balls (3–5 mm diameter) for amide synthesis from carboxylic acids (unactivated) and amines (unactivated) under neat reaction conditions that produce no toxic by-products and has the advantages of being low-cost, easily available, heterogeneous, reusable and environmentally benign with no troublesome/hazardous disposal of the catalyst.

Synthesis of new thieno[2,3‐d]pyrimidines, thieno[3,2‐e]pyridines, and thieno[2,3‐d][1,3]oxazines

Abstracto‐Aminothiophene dicarbonitrile 1 on neat reaction with cyclic ketones in anhydrous ZnCl2 yielded mixture of fused aminopyridine 3 and iminospirooxazine 4 derivatives. Similarly, pyrimidine derivatives 5 and 8 were obtained by the reaction of this intermediate 1 with formic acid and DMF‐DMA followed by hydrazine hydrate, respectively. The reaction of o‐amino‐thiophene dicarboxamide 2 at ambient temperature with cyclic ketones yielded spiropyrimidine 10 as a sole product in quantitative yield. The regioselective anellated pyrimidine 9, 11, and dihydropyrimidine 12 derivatives were also obtained by the reaction with aromatic aldehydes in presence of piperidine and iodine respectively. J. Heterocyclic Chem., (2012).

ChemInform Abstract: Iodine‐Catalyzed Amination of Benzoxazoles: A Metal‐Free Route to 2‐Aminobenzoxazoles under Mild Conditions.

A facile metal-free route of oxidative amination of benzoxazole by activation of C–H bonds with secondary or primary amines in the presence of catalytic iodine in aqueous tert-butyl hydroperoxide proceeds smoothly at ambient temperature under neat reaction condition to furnish the high yield of the aminated product. This user-friendly method to form C–N bonds produces tertiary butanol and water as the byproduct, which are environmentally benign. The application of the methodology is demonsrated by synthesizing therapeutically active benzoxazoles.