Formation Of Nitriles Research Articles

Effect of the post treatments for biowaste‐based digestates on water solubility of nutrients and iron‐cyanide (Fe‐CN) complex mobility

AbstractWith recent policy developments, an increase in organic waste utilization is expected. However, the use of organic amendments to reduce the mobility of iron‐cyanide (Fe‐CN) complexes and simultaneously promote vegetation growth has not been studied before. Therefore, we evaluated the effect of (a) drying, (b) composting, and (c) pelletizing on the ability of digestates (biowastes from an anaerobic treatment of municipal organic waste) to provide easily available nutrients and stabilize Fe‐CN complexes.Extraction with deionized water resulted in a considerably higher nutrient and carbon elution from air‐dried and oven‐dried digestates (50% dry matter [DM] of total K, 11% DM Mg, 7% DM Ca, and 6% DM C). Mixer‐pelletized digestates stand out among the composted samples (42% of total K, 3% DM C, 5% DM P, 1.5% DM Mg, and 1% DM Ca). The adsorption experiment showed the highest significant tot. CN conc. reduction using noncomposted, air‐dried (100%), and oven‐dried (82%) digestates. Significant correlations have been found for Mg, Ca, and dissolved organic carbon elution and slightly acidic pH as well as CN adsorption. The Fourier transform infrared analysis revealed Fe‐CN complexation on inorganic (K2Mn[FeII (CN)6] and NH4Fe[FeII (CN)6]) and organic constituents indicating formation of nitriles. Air‐ and oven‐dried digestates showed the most promising results in terms of nutrients' availability and ability to decrease Fe‐CN complex mobility.

Structural diversification during glucosinolate breakdown: mechanisms of thiocyanate, epithionitrile and simple nitrile formation.

SummarySecondary metabolism is characterized by an impressive structural diversity. Here, we have addressed the mechanisms underlying structural diversification upon damage‐induced activation of glucosinolates, a group of thioglucosides found in the Brassicales. The classical pathway of glucosinolate activation involves myrosinase‐catalyzed hydrolysis and rearrangement of the aglucone to an isothiocyanate. Plants of the Brassicaceae possess specifier proteins, i.e. non‐heme iron proteins that promote the formation of alternative products by interfering with this reaction through unknown mechanisms. We have used structural information available for the thiocyanate‐forming protein from Thlaspi arvense (TaTFP), to test the impact of loops protruding at one side of its β‐propeller structure on product formation using the allylglucosinolate aglucone as substrate. In silico loop structure sampling and semiempirical quantum mechanical calculations identified a 3L2 loop conformation that enabled the Fe2+ cofactor to interact with the double bond of the allyl side chain. Only this arrangement enabled the formation of allylthiocyanate, a specific product of TaTFP. Simulation of 3,4‐epithiobutane nitrile formation, the second known product of TaTFP, required an alternative substrate docking arrangement in which Fe2+ interacts with the aglucone thiolate. In agreement with these results, substitution of 3L2 amino acid residues involved in the conformational change as well as exchange of critical amino acid residues of neighboring loops affected the allylthiocyanate versus epithionitrile proportion obtained upon myrosinase‐catalyzed allylglucosinolate hydrolysis in the presence of TaTFP in vitro. Based on these insights, we propose that specifier proteins are catalysts that might be classified as Fe2+‐dependent lyases.

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.

NH3⋅H2O: The Simplest Nitrogen-Containing Ligand for Selective Aerobic Alcohol Oxidation to Aldehydes or Nitriles in Neat Water.

Aqueous ammonia (NH3⋅H2O) has been shown to serve as the simplest nitrogen‐containing ligand to effectively promote copper‐catalyzed selective alcohol oxidation under air in water. A series of alcohols with varying electronic and steric properties were selectively oxidized to aldehydes with up to 95 % yield. Notably, by increasing the amount of aqueous ammonia in neat water, the exclusive formation of aryl nitriles was also accomplished with good‐to‐excellent yields. Additionally, the catalytic system exhibits a high level of functional group tolerance with −OH, −NO2, esters, and heteroaryl groups all being amenable to the reaction conditions. This one‐pot and green oxidation protocol provides an important synthetic route for the selective preparation of either aldehydes or nitriles from commercially available alcohols.

Photoinduced Nitrile Formation from O‐(Arylcarbonyl) oxime: Usage as a Photoremovable Protecting Group

AbstractEmploying a photoremovable protecting group is a useful technique to achieve precise conditional control over a biological function. This Communication reports the development of a photoremovable protecting group for the nitrile moiety. In the process, O‐(arylcarbonyl) oxime was photochemically converted into the corresponding nitrile in the presence of a carbazole photosensitizer by means of an electron transfer from the excited carbazole to the arylcarbonyl unit. A variety of alkyl and (hetero) aryl nitriles were generated from the corresponding O‐(arylcarbonyl) oximes. Moreover, a self‐contained variant, in which O‐(arylcarbonyl) oxime and carbazole units were covalently bonded, exhibited photochemical nitrile formation even in a highly diluted aqueous solution (0.1 mM), thus demonstrating that this molecular motif is potentially applicable in biological systems.

Formation of odorous and hazardous by-products from the chlorination of amino acids

The formation of odorous aldehydes and N-chloraldimines, and also nitriles, which are potentially hazardous to human health, was investigated in studies of the chlorination of amino acids (AAs) in both operational drinking water treatment plants and laboratory-based experiments. In the drinking water treatment plants studied, the concentration of total free AAs did not significantly change after treatment, even though good removal of DOC was observed. However, free AAs still contributed less than 3% of total nitrogen in the treated drinking waters, and no aldehydes, N-chloraldimines or nitriles of interest were detected in the treated waters, presumably due to the low concentrations of the precursor AAs in these water samples. Laboratory formation potential experiments showed that carboxylic acids can form from the degradation of aldehydes and nitriles. Volatile carboxylic acids could result in odour issues and some carboxylic acids may be of potential health concern. Therefore, carboxylic acids should also be considered as potential by-products of interest in distribution systems with long contact times of ≥ 7days. A higher proportion of nitrile formation, and promotion of carboxylic acid formation, was observed when the chlorine to AA ratio was greater than 4 compared to when this ratio was 2.8, indicating that the Cl:AA ratio is an important factor in DBP formation pathways. This suggests that results from laboratory formation studies undertaken at these low Cl:AA ratios cannot be directly applied to ‘real’ water systems, which typically have Cl:AA ratios that are orders of magnitude higher than 4. Laboratory formation potential experiments also showed that the short-term rate of formation of aldehydes and N-chloraldimines was reduced in the presence of ammonia, although formation over longer timescales (e.g. 7 days) was not significantly different between chlorination and chloramination experiments. Therefore, the use of chloramination instead of chlorination does not appear to reduce the formation of these by-products from AAs.

Molecular identification and characterization of rhodaneses from the insect herbivore Pieris rapae

The association of cabbage white butterflies (Pieris spec., Lepidoptera: Pieridae) with their glucosinolate-containing host plants represents a well-investigated example of the sequential evolution of plant defenses and insect herbivore counteradaptations. The defensive potential of glucosinolates, a group of amino acid-derived thioglucosides present in plants of the Brassicales order, arises mainly from their rapid breakdown upon tissue disruption resulting in formation of toxic isothiocyanates. Larvae of P. rapae are able to feed exclusively on glucosinolate-containing plants due to expression of a nitrile-specifier protein in their gut which redirects glucosinolate breakdown to the formation of nitriles. The release of equimolar amounts of cyanide upon further metabolism of the benzylglucosinolate-derived nitrile suggests that the larvae are also equipped with efficient means of cyanide detoxification such as β-cyanoalanine synthases or rhodaneses. While insect β-cyanoalanine synthases have recently been identified at the molecular level, no sequence information was available of characterized insect rhodaneses. Here, we identify and characterize two single-domain rhodaneses from P. rapae, PrTST1 and PrTST2. The enzymes differ in their kinetic properties, predicted subcellular localization and expression in P. rapae indicating different physiological roles. Phylogenetic analysis together with putative lepidopteran rhodanese sequences indicates an expansion of the rhodanese family in Pieridae.

Gut Glucosinolate Metabolism and Isothiocyanate Production.

The glucosinolate‐myrosinase system in plants has been well studied over the years while relatively little research has been undertaken on the bacterial metabolism of glucosinolates. The products of myrosinase‐based glucosinolate hydrolysis in the human gut are important to health, particularly the isothiocyanates, as they are shown to have anticancer properties as well as other beneficial roles in human health. This review is concerned with the bacterial metabolism of glucosinolates but is not restricted to the human gut. Isothiocyanate production and nitrile formation are discussed together with the mechanisms of the formation of these compounds. Side chain modification of the methylsulfinylalkyl glucosinolates is reviewed and the implications for bioactivity of the resultant products are also discussed.

Leaching and degradation kinetics of glucosinolates during boiling of Brassica oleracea vegetables and the formation of their breakdown products

Domestic processing methods, such as boiling, significantly affect the glucosinolate content and the formation of breakdown products in Brassica vegetables. Here, we comprehensively describe the effect of aqueous heat treatment on the degradation and leaching kinetics of glucosinolates on the formation of their enzymatic and non-enzymatic hydrolysis and breakdown products. The results were correlated with the inactivation kinetics of myrosinase and epithiospecifier protein activity in the Brassica oleracea vegetables kohlrabi, white cabbage, and red cabbage. Short-term heating increased isothiocyanate formation due to inactivation of the epithiospecifier protein. Myrosinase was inactivated shortly after that. Boiling led to leaching of glucosinolates and their hydrolysis products into the boiling water. Heating to 99 °C resulted in thermally-induced glucosinolate breakdown and nitrile formation, both in vegetables and boiling water. Finally, kinetic modeling not only revealed differences in myrosinase inactivation among the vegetables, but also glucosinolate leaching and degradation kinetics differed between individual glucosinolates and vegetables.

The effect of chewing on oral glucoraphanin hydrolysis in raw and steamed broccoli

Chewing disrupts broccoli cells, and myrosinase can effectively hydrolyze the glucosinolate glucoraphanin into the biological active sulforaphane. The influence of chewing time and steaming time on glucoraphanin hydrolysis as well as sulforaphane and sulforaphane nitrile formation in broccoli was studied.To study the effect of chewing time on differently steamed broccoli, broccoli was chewed for 11 s, 22 s, 30 s and 40 s by volunteers. To determine the effect of steaming time, raw and steamed broccoli samples were chewed for 22 s. Glucoraphanin, sulforaphane and sulforaphane nitrile were analyzed in all samples. Longer chewing times of raw, 0.5-min and 1-min steamed broccoli, which contained active myrosinase, lead to a higher hydrolysis. The highest hydrolysis rate of glucoraphanin was found in 0.5-min steamed broccoli (38%) and 2-min steamed samples which contained the highest sulforaphane concentration. This could lead to a recommendation to steam broccoli for a short time before consumption.

Intensifying sulforaphane formation in broccoli sprouts by using other cruciferous sprouts additions.

Sulforaphane is a significant chemopreventive compound which is the predominant glucosinolate in broccoli sprouts. However, the existence of the epithiospecifier protein could direct the hydrolysis of glucosinolates toward sulforaphane nitrile formation instead of sulforaphane. Therefore, the study aimed on improving the yielding of sulforaphane in broccoli sprouts with a new method of the united hydrolysis of cruciferous sprouts. According to the results, the addition of radish, rocket and rape sprouts to broccoli sprouts could promote the hydrolysis of the glucoraphanin to anticancer effective sulforaphane to 2.03, 2.32 and 1.95-fold, respectively, compared to single broccoli sprouts. Meanwhile, the formation of non-bioactive sulforaphane nitrile in these three groups decreased greatly. However, the addition of mustard sprouts had no positive effect. These observations could make a contribution to the potential chemoprotective effects of broccoli sprouts.

Differences in the enzymatic hydrolysis of glucosinolates increase the defense metabolite diversity in 19 Arabidopsis thaliana accessions

Plants of the order Brassicales produce glucosinolates (GS), a group of secondary metabolites that are part of an elaborate defense system. But it is not the GS itself rather its enzymatic hydrolysis products that cause the bioactive effects protecting the plants against pests and pathogens. Thus the enzymatic hydrolysis and a variety of additional influential factors determine the structural outcome of the GS degradation process. To evaluate the possible diversity of defense metabolites a range of 19 Arabidopsis thaliana accessions were selected showing divergence in their geographical origin, in their phenotype, and in their GS profile. These particular accessions accumulate several alkenyl GS, hydroxyalkyl GS, methylthioalkyl GS, and methylsulfinylalkyl GS in their rosette leaves whereas the indole GS contents are relatively invariant, as analyzed by UHPLC-DAD. After tissue disruption the enzymatic formation of GS hydrolysis products was examined and breakdown products were identified and quantified by GC-MS. Great differences in the amount and structure of volatile enzymatic degradation products could be observed in the different accessions, with strong variation in formation of epithionitriles, nitriles, and isothiocyanates. The occurrence of specific GS hydrolysis products was put in relation to relative gene expression profiles of myrosinases and specifier proteins as measured by RT-qPCR, and in relation to relative protein abundance of epithiospecifier protein. Dependent on the different GS profiles and reliant on degradation protein abundance and composition the ecotypes strongly varied in their ability to form isothiocyanates, nitriles and epithionitriles, thus increasing the plants' equipment of defense metabolites.

Unexpected nitrile formation in bio-based mesoporous materials (Starbons®).

The bio-based mesoporous materials made from polysaccharides, Starbons® can be modified by two different routes to give high levels of N-content, unexpectedly including significant quantities of nitrile groups which can improve the materials performance in applications including metal capture.

Exploiting λ-Orthogonal Photoligation for Layered Surface Patterning.

We exploit λ-orthogonal photoligation of nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) chemistry to generate complex, interconnected surface modifications via a simple layered surface patterning approach. By judicious choice of activating chromophores, we introduce a one pot reaction where nitrile imine formation can be triggered independently of other tetrazoles present. When irradiated with visible light, a tetrazole bearing a pyrene chromophore undergoes quantitative elimination of nitrogen to release nitrile imine (which subsequently undergoes trapping with a dipolarophile in a 1,3 dipolar cycloaddition) whereas a tetrazole bearing a phenyl moiety remains unreacted. Subsequent irradiation of the solution with UV light yields the N-phenyl containing nitrile imine quantitatively, while the pyrene pyrazoline adduct remains unchanged. This λ-orthogonal photoligation was subsequently exploited for the generation of layered patterned surfaces. Specifically, the visible light active tetrazole was grafted to a silicon wafer and subsequently photolithographically patterned with a dipolarophile modified with a UV-active tetrazole. Various electron deficient olefins were then patterned in a spatially resolved manner relying on different light activation. The desired functionality was successfully imaged on the silicon wafers using time-of-flight-secondary ion mass spectrometry (ToF-SIMS), demonstrating that a powerful mask-less lithographic platform technology has been established.

Secrets of Plasma-Deposited Polyoxazoline Functionality Lie in the Plasma Phase

Plasma deposited polyoxazoline thin films share many valuable properties with polyoxazoline prepared via conventional organic chemistry; they are biocompatible, non-cytotoxic and low fouling. What is more, they bind biomolecules covalently, support cell adhesion, and are generated in a solvent free, single step process. Here, we show that the secret for plasma deposited polyoxazolines’ unique set of properties lies in both the chemical fragmentation processes occurring in the plasma phase itself and the recombination events subsequently occurring at the plasma-activated surface. In situ plasma mass spectroscopy was used to elucidate the complex composition of the oxazoline plasma phase at nominal powers ranging from 2 to 50W. This confirmed the stability of the un-opened monomer, but also revealed the formation of nitrile, isocyanate, and imine species. In correlation with post-plasma surface characterization data, the mass spectroscopy results indicate that reactive functional groups were plasma-generate...

Chemopreventive glucosinolate accumulation in various broccoli and collard tissues: Microfluidic-based targeted transcriptomics for by-product valorization.

Floret, leaf, and root tissues were harvested from broccoli and collard cultivars and extracted to determine their glucosinolate and hydrolysis product profiles using high performance liquid chromatography and gas chromotography. Quinone reductase inducing bioactivity, an estimate of anti-cancer chemopreventive potential, of the extracts was measured using a hepa1c1c7 murine cell line. Extracts from root tissues were significantly different from other tissues and contained high levels of gluconasturtiin and glucoerucin. Targeted gene expression analysis on glucosinolate biosynthesis revealed that broccoli root tissue has elevated gene expression of AOP2 and low expression of FMOGS-OX homologs, essentially the opposite of what was observed in broccoli florets, which accumulated high levels of glucoraphanin. Broccoli floret tissue has significantly higher nitrile formation (%) and epithionitrile specifier protein gene expression than other tissues. This study provides basic information of the glucosinolate metabolome and transcriptome for various tissues of Brassica oleracea that maybe utilized as potential byproducts for the nutraceutical market.

Cultivar-Specific Changes in Primary and Secondary Metabolites in Pak Choi (Brassica Rapa, Chinensis Group) by Methyl Jasmonate.

Glucosinolates, their hydrolysis products and primary metabolites were analyzed in five pak choi cultivars to determine the effect of methyl jasmonate (MeJA) on metabolite flux from primary metabolites to glucosinolates and their hydrolysis products. Among detected glucosinolates (total 14 glucosinolates; 9 aliphatic, 4 indole and 1 aromatic glucosinolates), indole glucosinolate concentrations (153–229%) and their hydrolysis products increased with MeJA treatment. Changes in the total isothiocyanates by MeJA were associated with epithiospecifier protein activity estimated as nitrile formation. Goitrin, a goitrogenic compound, significantly decreased by MeJA treatment in all cultivars. Changes in glucosinolates, especially aliphatic, significantly differed among cultivars. Primary metabolites including amino acids, organic acids and sugars also changed with MeJA treatment in a cultivar-specific manner. A decreased sugar level suggests that they might be a carbon source for secondary metabolite biosynthesis in MeJA-treated pak choi. The result of the present study suggests that MeJA can be an effective agent to elevate indole glucosinolates and their hydrolysis products and to reduce a goitrogenic compound in pak choi. The total glucosinolate concentration was the highest in “Chinese cabbage” in the control group (32.5 µmol/g DW), but indole glucosinolates increased the greatest in “Asian” when treated with MeJA.

Copper-Catalyzed Cascade Transformation of Homopropargyl Azides into Trifluoromethylated Nitriles via C-C Cleavage.

A cascade reaction of homopropargyl azides in the presence of a Cu catalyst was achieved, affording 3-(trifluoromethyl)but-3-enenitriles with good yields and excellent regioselectivity. This reaction appears to be the first direct conversion of homopropargyl azides into trifluoromethylated nitriles. Mechanistic studies indicate that the transformation proceeds by addition of a CF3 radical to the alkyne, C-C cleavage by 1,4-aryl radical migration, and nitrile formation. This protocol provides a novel strategy for transforming azides into nitriles via C-C cleavage derived from radical migration.

Formation of nitrile species on Ag nanostructures supported on a-Al2O3: a new corrosion route for silver exposed to the atmosphere

The aging of supported Ag nanostructures upon storage in ambient conditions (air and room temperature) for 20 months has been studied. The samples are produced on glass substrates by pulsed laser deposition (PLD); first a 15 nm thick buffer layer of amorphous aluminum oxide (a-Al2O3) is deposited, followed by PLD of Ag. The amount of deposited Ag ranges from that leading to a discontinuous layer up to an almost-percolated layer with a thickness of <6 nm. Some regions of the as-grown silver layers are converted, by laser induced dewetting, into round isolated nanoparticles (NPs) with diameters of up to ∼25 nm. The plasmonic, structural and chemical properties of both as-grown and laser exposed regions upon aging have been followed using extinction spectroscopy, scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. The results show that the discontinuous as-grown regions are optically and chemically unstable and that the metal becomes oxidized faster, the smaller the amount of Ag. The corrosion leads to the formation of nitrile species due to the reaction between NOx species from the atmosphere adsorbed at the surface of Ag, and hydrocarbons adsorbed in defects at the surface of the a-Al2O3 layer during the deposition of the Ag nanostructures by PLD that migrate to the surface of the metal with time. The nitrile formation thus results in the main oxidation mechanism and inhibits almost completely the formation of sulphate/sulphide. Finally, the optical changes upon aging offer an easy-to-use tool for following the aging process. They are dominated by an enhanced absorption in the UV side of the spectrum and a blue-shift of the surface plasmon resonance that are, respectively, related to the formation of a dielectric overlayer on the Ag nanostructure and changes in the dimensions/features of the nanostructures, both due to the oxidation process.

Understanding Reactivity Patterns in Light‐Induced Nitrile Imine Mediated Tetrazole–Ene Cycloadditions

AbstractA rationale for predicting photochemical tetrazole activation in the popular nitrile imine mediated tetrazole–ene cycloaddition (NITEC) reaction, based on a combined theoretical and experimental study, is reported. DFT calculations of three tetrazole derivatives reveal that the efficiency of intersystem crossing is determined by the chromophore moiety. This species is critical in dictating the reactivity of the tetrazoles towards nitrile imine formation, yet mere inspection of the chromophore moiety's absorptivity is insufficient for predicting the tetrazole's photochemical reactivity.