Reaction Of Nitriles Research Articles

HCN emission by a Polydesmid Millipede Detected Remotely by Reactive Adsorption on Gold Nanoparticles Followed by Laser Desorption/Ionization Mass Spectrometry (LDI-MS).

Hydrocyanic acid (HCN) is a well-known defensive allomone in the chemical arsenal of millipedes in the order Polydesmida. The presence of HCN in the headspace vapor of adult Xystocheir dissecta (Wood, 1867), a common millipede from the San Francisco Bay Area, was traced by laser desorption/ionization-mass spectrometry (LDI-MS). To accomplish this, the headspace vapor surrounding caged, live millipedes was allowed to diffuse passively over gold-nanoparticle (AuNP) deposits placed at various distances from the emitting source. The stainless steel plates with AuNP deposits were removed and irradiated by a 355-nm laser. The gaseous ions generated in this way were detected by time-of-flight mass spectrometry. The intensity of the mass spectrometric peak detected at m/z 249 for the Au(CN)2- complex anion was compared to that of the residual Au- signal (m/z 197). Using this procedure, HCN vapors produced by the live millipedes could be detected up to 50 cm away from the source. Furthermore, the addition of H2O2, as an internal oxygen source for the gold cyanidation reaction that takes place in the AuNP deposits, significantly increased the detection sensitivity. Using the modified H2O2 addition procedure, HCN could now be detected at 80 cm from the source. Moreover, we found a decreasing intensity ratio of the Au(CN)2-/Au- signals as the distance from the emitting source increased, following an exponential-decay distribution as predicted by Fick's law of diffusion. Graphical abstract.

Ag2O-catalysed nucleophilic isocyanation: selective formation of less-stable benzylic isonitriles

Both primary and secondary benzylic isonitriles were exclusively produced by the Ag2O-catalysed reaction of benzylic phosphates and trimethylsilyl cyanide without formation of the thermodynamically favoured regioisomers, benzylic nitriles.

Gas chromatography-mass spectrometric identification of cyanide using a nucleophilic substitution based derivatization with S-phenyl benzenethiosulfonate.

A novel, simple and efficient analytical method for GC-MS based identification of cyanide has been developed using a single step nucleophilic substitution based derivatization of cyanide in aqueous medium. The nucleophilic substitution reaction of cyanide with S-phenyl benzenethiosulfonate results in the formation of phenyl thiocyanate as a cyanide derivative and it was found that the relative response of the resultant cyanide derivative was much higher than that of the cyanide derivatives resulting from disulfide based derivatizing agents. The sample preparation protocol for the identification of cyanide in aqueous samples was also optimized with the new derivatizing agent. Derivatization followed by liquid-liquid extraction was employed for the preparation of aqueous samples containing cyanide salts. The resultant samples were subjected to GC-MS analysis for the identification of the cyanide derivative. Under optimized conditions, the detection and quantification limits for cyanide aqueous samples were found to be 0.075 μg mL-1 and 0.25 μg mL-1 respectively. The calibration curve had a linear relationship with y = 0.086x - 0.076 and r2 = 0.997 for the working range of 0.25 μg mL-1 to 50 μg mL-1. The intraday RSDs were between 2.24 and 8.17%, and the interday RSDs were between 2.22 and 12.85%. The method can also be successfully employed for the identification of hydrogen cyanide in aqueous medium. The applicability of the present method was demonstrated by analysing a real sample from apple seed extraction.

Two three-dimensional Sc(III)-MOFs: Synthesis, crystal structure and catalytic property

Two new three-dimensional (3D) Sc(III)-based metal organic frameworks (MOFs) [Sc2(OH)2(TDC)2]·4H2O (1) and [Sc3O(fum)3(H2O)3(NO3)]·DMF (2) (H2TDC = 2,5-thiophenedicarboxylic acid, H2fum = fumaric acid) have been hydrothermally synthesized. For 1, TDC2− ligands connect infinite one-dimensional (1D) -Sc-OH-Sc-OH- chains to form open-framework with rhombic channels along the a axis. In 2, flexible fum2− ligands link adjacent trimer [Sc3O(COO)6(H2O)3] secondary building units showing hexagonal-closed circular pores with a diameter of approximate 9.9 Å. Furthermore, the desolvated material la can retain the framework, presenting good catalytic activity, significant universality and substrate-selectivity for Strecker-type reactions of trimethylsilyl cyanide (TMSCN) and various aromatic aldimines, especially for N-benzyl 4-methoxybenzaldimine.

Kinetics of Thiocyanate Formation by Reaction of Cyanide and Its Iron Complexes with Thiosulfate

Reactions between cyanide and compounds, which contain S–S bonds, in aqueous media result in formation of thiocyanate. In this work, we studied the kinetics of reactions of thiosulfate with free cyanide and its complexes under environmental conditions. Rates of reactions between cyanide species and thiosulfate decrease in the following order: CN− > HCN > [Fe(CN)6]3− > [Fe(CN)6]4−. However, at neutral and slightly acidic pH range, reaction of thiosulfate with iron-cyanide complexes outcompetes its reaction with free cyanide, which exists in equilibrium with complexed cyanide. At environmentally relevant conditions, the characteristic time of reaction between free cyanide and thiosulfate was found to be tens of thousands of years, while for iron-cyanide complexes it was found to be hundreds to millions of years. Examples of application of kinetic parameters for calculation of rates of cyanide consumption in industrial (coke oven wastewater) and non-polluted natural aquatic system (Delaware Great Marsh) are provided.

EXPERIENCING A SYNTHESIS ONE-POT OF 1,2,4-OXADIAZOLE MEDIATED BY MICROWAVE OVEN: GREEN CHEMISTRY IN FOCUS

1,2,4-oxadiazoles are compounds that have attracted the attention of many researchers due to their wide range of biological activities, for example, anti-inflammatory, antimicrobial, antitumor etc. The syntheses are based mostly on the use of amidoximes and acylating agents as the initial reactants. This work aims to describe a one-pot reaction for the synthesis of 1,2,4-oxadiazols, mediated by microwave irradiation, employing home-use microwave oven, in the discipline of heterocyclic Chemistry in the postgraduate. The methodology consisted of the reaction of nitriles, hydroxylamine hydrochloride, potassium carbonate and different esters to obtain 1,2,4-oxadiazole. The reactions include two sequential procedures: base-promoted intermolecular addition of hydroxylamine to nitrile to lead to amidoxime, then treatment of the amidoxime with esther to form 1,2,4-oxadiazoles in good yields. This method represents a direct and simple protocol for the synthesis of 3,5-disubstituted 1,2,4-oxadiazoles. It was initially discussed with the students the chemistry of the oxadiazoles, one-pot reactions and green chemistry through atheoretical-expository-dialogue strategy. In the course of the didactic intervention the students, through a thematic seminary, presented the results of the analysis of the spectra from the different techniques used. With the skills acquired from completing this laboratory work, the students become well-prepared to perform spectroscopic analyzes in subsequent experiments encountered in the organic chemistry laboratory.

Synthesis of α‐Aminonitriles and 5‐Substituted 1H‐Tetrazoles Using an Efficient Nanocatalyst of Fe3O4@SiO2–APTES‐supported Trifluoroacetic Acid

Fe3O4@SiO2–APTES‐supported trifluoroacetic acid nanocatalyst was used for the one‐pot synthesis of α‐aminonitriles via a three‐component reaction of aldehydes (or ketones), amines, and sodium cyanide. This method produced a high yield of 75–96% using only a small amount of the catalyst (0.05 g) in EtOH at room temperature. The catalyst was also employed for the synthesis of 5‐substituted 1H‐tetrazoles from nitriles and sodium azide in EtOH at 80°C. The tetrazoles were produced with good‐to‐excellent yields in a short reaction time of 4 h. Both synthetic methods were carried out in the absence of an organic volatile solvent. Because the supported trifluoroacetic acid generated a solid acid on the surface, thus the acid corrosiveness was not a serious challenge. This heterogeneous nanocatalyst was magnetically recovered and reused several times without significant loss of catalytic activity.

Reaction Kinetics of Cyanide Binding to a Cobalt Schiff-Base Macrocycle Relevant to Its Mechanism of Antidotal Action.

The Co(II/III)-containing macrocycle, cobalt 2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]-heptadeca-1(17)2,11,13,15-pentaenyl cation, or CoN4[11.3.1], is a potential cyanide-scavenging agent. The rate of reduction of Co(III)N4[11.3.1] by ascorbate is reasonably facile under pseudo-first-order conditions; a second-order rate constant of 11.7(±0.4) M-1 s-1 was determined at 25 °C and pH 7.4, along with the activation parameters for the reaction (ΔH⧧ = 53.9(±0.8) kJ mol-1; ΔS -79(±3) J mol-1 K-1). It follows that any cyanide-decorporating capability of the cobalt complex should depend more on the cyanide-binding characteristics of Co(II)N4[11.3.1] than the oxidized form. The kinetics of the reaction of cyanide with Co(II)N4[11.3.1] under anaerobic pseudo-first-order conditions is rapid and resulted in a linear dependence on the cyanide concentration, kHCN = 8 × 104 M-1 s-1, with a nonlinear intercept of 420 s-1 at 10 °C, pH 7.6. The observed reaction rate increases significantly with increasing pH. A rate law is suggested, kobs = k'[X] + (kHCN + kCNKa/[H+])[HCN], where kCN is estimated to be ∼2 × 106 M-1 s-1. Activation parameters for the reaction with HCN (ΔH⧧ = 10.7(±0.4) kJ mol-1; ΔS⧧ = -153(±1) J mol-1 K-1) suggest an associative mechanism. In the presence of excess oxygen, i.e., at higher levels than free oxygen in vivo, the reaction rate was too fast to be measured, and the final product was the oxidized complex, Co(III)N4[11.3.1], where any cyanide ligands had been lost. This is much more rapid than the oxidation of the parent compound by oxygen, for which a second-order rate constant of 0.5(±0.02) M-1 s-1 at 25 °C was obtained. The study has gone some way toward enhancing our understanding of the reaction of Co(II)N4[11.3.1] with cyanide. The fast reaction rate implies a high efficacy of the cyanide-scavenging capability of the complex and further supports the suggestion stemming from our previous work that Co(II)N4[11.3.1] could prove to be a better and more cost-effective cyanide antidote than the FDA-approved hydroxocobalamin.

One-pot three-component synthesis of α-amino nitriles using ZnO as a heterogeneous, reusable, and eco-friendly catalyst

Various forms of α-amino nitrile molecules are found to exert strong impacts on the synthesis of multiple organic compounds such as pharmaceuticals, amino acids, agrochemical agents, and pesticides. Spherical ZnO nanoparticles (NPs) prepared by a simple co-precipitation method are an efficient heterogeneous catalyst for the synthesis of vital intermediate α-amino nitriles. The present protocol was investigated via one-pot synthesis of α-amino nitriles over ZnO NPs using a three-component coupling reaction of aldehydes, amines, and trimethylsilyl cyanide in acetonitrile. The feasibility of our synthesis approach was assessed with respect to the purity and yield of synthesized products in relation to several controlling variables (e.g., ZnO molar ratio, reaction time, amines/aldehydes types, and solvent). The qualitative characteristics of α-amino nitrile products were evaluated by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and mass spectroscopic analysis. A high yield (81–95%) of pure α-amino nitriles within a short reaction time (45–75 min) along with good recyclability of the catalyst (e.g., without significant loss in performance over five cycles) was confirmed as the distinctive merits of this new eco-friendly synthetic method. This study confirms that various amines including sterically crowded secondary amines should react efficiently with benzenoid plus non-benzenoid aldehyde to yield α-amino nitriles. The selected route is very fast as well as economical. Hence, this method can be used for large-scale production of a variety of biologically important molecules through α-amino nitriles.

HCN on Tap: On-Demand Continuous Production of Anhydrous HCN for Organic Synthesis.

A continuous process for the on-demand generation, separation, and reaction of hydrogen cyanide (HCN) using membrane separation technology was developed. The inner tube of the reactor is manufactured from a gas-permeable, hydrophobic fluoropolymer (Teflon AF-2400) membrane. HCN is formed from aqueous reagents within the inner tube and then diffuses through the membrane into an outer tubing containing organic solvent. This technique enabled the safe handling of HCN for three different organic transformations without the need for distillation.

Iron (III)‐porphyrin Complex FeTSPP as an efficient catalyst for synthesis of tetrazole derivatives via [2 + 3]cycloaddition reaction in aqueous medium

The metal complex (5,10,15,20‐tetrakis‐(4‐sulfonatophenyl)‐porphyrin‐iron (III) chloride (FeTSPP) was new employed in an environmentally benign protocol as an efficient catalyst for a “click” chemistry approach for the synthesis of tetrazole and guanindinyltetrazole derivatives via [2 + 3] cycloaddition reaction of nitriles and azide derivatives in aqueous medium. The synthesized compounds were obtained in excellent yield, short reaction times and a recoverable catalyst.

Prebiotic Syntheses Under Shock in the Water - Formamide - Potassium Bicarbonate - Sodium Hydroxide System.

Syntheses under shock in nitrogen bubbled samples of the water - formamide - bicarbonate - sodium hydroxide system at pH8.63, 9.46 and 10.44 were performed in the stainless steel preservation capsules. The maximum temperature and pressure in the capsules reached 545K and 12.5GPa respectively. Using the LC-MS-MS analysis, the 21 synthesis products have been identified, including amines and polyamines, carboxamide, acetamide and urea derivatives, compounds containing aniline, pyrrolidine, pyrrole, imidazole, as well as alcohol groups. It was found that the Fischer-Tropsch-type syntheses with catalysis on the surface of the stainless steel of the conservation capsule associated with the adsorbed hydrogen cyanide reactions and transamidation processes play the main role in the shock syntheses. Formation reactions of all the above-mentioned compounds have been suggested. It was proposed that hydrogen cyanide, ammonia, isocyanic acid, aminonitrile, aminoacetonitrile, as well as adsorbed species H(a), CH(a), CH2(a), CHOH(a), NH2(a) and H2CNH(a) are especially important for the formation of the products. A reduction reaction of adsorbed bicarbonate with hydrogen to formaldehyde has been first postulated. In the studied system also classical reactions take place - Wöhler's synthesis of urea and Butlerov's synthesis of methenamine. It was suggest that material of meteorites may be an effective catalyst in the Fischer-Tropsch-type syntheses at falling of the iron-nickel meteorites in the water - formamide regions on the early Earth. It was concluded that life could have originated due to the impact of meteorites on alkaline water-formamide lakes located near volcanoes on the early Earth.

Ab initio investigations of isopropyl cyanide reaction mechanisms and kinetics of formation on an icy grain model

AbstractIsopropyl-cyanide (iso-PrCN) was recently observed in Sagittarius B2 with an abundance higher than its straight-chain structure isomer (n-PrCN). Here we study theoretically by means of [UMP2(full)/aug-cc-pVTZ/Amber] a hybrid ab initio/molecular mechanics methodology, the routes leading to its formation on a formaldehyde doped water ice grain model of the interstellar medium. The reaction path and the energetics are calculated, the mechanism is found to be exothermic by ∼ 30 kcal/mol and the barrier is ∼ 70 kcal/mol. We use the CVT/ZCT semiclassical method to predict the kinetics of the reaction path starting from initially adsorbed HCN and CH2CHCH3 molecules colliding from the gas phase over the temperature range [100–500K].

Reversal of Diastereoselectivity in a Masked Acyl Cyanide (MAC) Reaction: Synthesis of Protected erythro-β-Hydroxyaspartate Derivatives.

Using Garner's aldehyde as a substrate, one-pot MAC hydroxyhomologation reactions proceeded in good yields and with anti selectivity for the first time (dr up to 9:1). The products were used to prepare a panel of protected derivatives of erythro-β-hydroxyaspartic acid and erythro-β-hydroxyasparagine as single enantiomers in a few steps.

Double and Single Hydroboration of Nitriles Catalyzed by a Ruthenium–Bis(silyl)xanthene Complex: Application to One-Pot Synthesis of Diarylamines and N-Arylimines

A ruthenium complex bearing a bis(silyl)xanthene chelate ligand xantsil, i.e. Ru[κ3(Si,O,Si)-xantsil](CO)(PCyp3) (1a, Cyp = cyclopentyl), was found to catalyze both double and single hydroboration reactions of nitriles with pinacolborane (HBpin) and 9-borabicyclo[3.3.1]nonane (9-BBN) to give bis(boryl)amines 2 and N-borylimines 3, respectively, in mostly >99% yields. By combination of these reactions with subsequent palladium-catalyzed deborylative C–N coupling reactions of 2 and 3 with a 1:1 mixture of bromoarenes and KOtBu, one-pot synthetic routes to tertiary N,N-diarylamines 4 and N-arylaldimines 5 from nitriles were developed.

An efficient transformation of methyl ethers and nitriles to amides catalyzed by Iron(III) perchlorate hydrate

An efficient and inexpensive synthesis of N-substituted amides from the reaction of nitriles with methyl ethers catalyzed by Fe(ClO4)3·H2O is described. Fe(ClO4)3·H2O is an economically efficient catalyst for the Ritter Reaction under solvent-free conditions. A range of methyl ethers (benzyl, sec-alkyl and tert-butyl ethers) were reacted with nitriles to provide the corresponding amides in high–excellent yields.

Heterogeneous copper-catalyzed three-component reaction of 2-aminopyridines, acetophenones and benzyl cyanide towards 3-cyanoimidazo[1,2-a]pyridines

The heterogeneous three-component reaction of 2-aminopyridines, acetophenones and benzyl cyanide was achieved in NMP at 120 °C by using an MCM-41-anchored L-proline‑copper(I) complex [MCM-41-L-Proline-CuI] as catalyst under air, yielding a wide variety of 3-cyanoimidazo[1,2-a]pyridines in moderate to high yields. The new heterogeneous copper catalyst exhibited higher catalytic activity than CuI, and could be recycled at least eight times with almost constant activity.

A cascade process for directly converting nitriles (RCN) to cyanamides (RNHCN) via SO2F2-activated Tiemann rearrangement.

A simple, mild and practical process for the direct conversion of nitriles to cyanamides was newly discovered and exhibited a wide substrate scope as well as great functional group-tolerability (36 examples). In this efficient strategy, the in situ generated amidoximes obtained from the reaction of nitriles with hydroxylamine subsequently underwent Tiemann rearrangement, producing the corresponding cyanamides with great isolated yields under SO2F2. Additionally, the control experiments reportedly shed light on the tentative mechanism involved in the formation and elimination of the key intermediate: a sulfonyl ester.

Lewis adduct formation of hydrogen cyanide and nitriles with arsenic and antimony pentafluoride.

The reactions of hydrogen cyanide, butyronitrile, cyclopropanecarbonitrile, pivalonitrile and benzonitrile with arsenic pentafluoride and antimony pentafluoride result in the formation of 1 : 1 Lewis adducts, while malononitrile yielded both 1 : 1 and 1 : 2 Lewis adducts. All adducts were isolated and characterized by multinuclear NMR and vibrational spectroscopy, and in most cases by their X-ray crystal structures.

Continuous flow synthesis of amines from the cascade reactions of nitriles and carbonyl-containing compounds promoted by Pt-modified titania catalysts

A Pt-modified titania-based catalyst was successfully applied in the synthesis of amines employing several carbonyl containing molecules and nitriles.