Subsequent Acid Hydrolysis Research Articles

Film-Forming Capability and Antibacterial Activity of Surface-Deacetylated Chitin Nanocrystals: Role of Degree of Deacetylation.

Developing sustainable food-active packaging materials is a major issue in food preservation applications. Chitin nanocrystals (ChNCs) are regarded as unique bioderived nanomaterials due to their inherent nitrogen moiety. By tuning the chemical functionality of this nanomaterial, it is possible to affect its properties, such as film-forming capability and antibacterial activity. In this work, surface-deacetylated chitin nanocrystals (D-ChNCs) with different degrees of deacetylation (DDs) were prepared by partial deacetylation of native chitin and subsequent acid hydrolysis, and their film-forming capability and antibacterial activity were studied systematically. The D-ChNCs showed favorable film-forming ability and antibacterial activity, which are closely related to their DD. With the increase in DD (from 5.7% to 45.4%), the formed transparent films based on ChNCs showed gradually increased elongation at break (from 0.5% to 2.5%) and water contact angle (from 25.5° to 87.0°), but decreased break strength (from 3.13 to 0.89 MPa), Young's modulus (from 0.84 to 0.24 MPa), and water vapor permeability (from 4.7 × 10-10 to 4.1 × 10-10g/m s Pa). Moreover, the antibacterial activity of the D-ChNCs against E. coli and S. aureus also increased with the increase of DD. This study also found that the depolarization and potential dissipation of the bacterial cell membrane induced by the contact between amino-rich D-ChNCs and bacteria through electrostatic attraction are the possible mechanisms causing bacterial cell death. This study provides a basis for understanding the effects of DD on the film-forming capability and antibacterial activity of ChNCs, which is conducive to the design of novel active packaging films based on ChNCs.

Nanocrystalline cellulose from Arctic brown algae Laminaria digitata and Saccharina latissima

Nanocrystalline cellulose (NCC) was successfully obtained from two Arctic brown algae species, Laminaria digitata and Saccharina latissima. The production process involved a sequential extraction of non-cellulosic compounds, an environmentally friendly bleaching process with hydrogen peroxide, and subsequent acidic hydrolysis, resulting in the formation of nanosized rod-like particles. Comprehensive assessments were conducted to evaluate the influence of hydrolysis conditions, specifically using hydrochloric and sulfuric acids, on the key characteristics of the nanocellulose. The resulting NCC was characterized using various techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA, DTG), scanning electron microscopy (SEM), laser diffraction, and low-temperature nitrogen sorption. The obtained algal NCC demonstrated a yield of 76–91%, a degree of polymerization of 150–230 units, and a crystallinity index of 69–80%. The choice of acid during the production significantly influenced the thermal stability, particle size distribution, and porous properties of the samples. Remarkably, the algal NCC, acquired in the form of stable gel-like suspensions, exhibited robust stability during extended storage. These materials showcase promising potential for applications in biomedicine, serving as versatile components for hydro/aerogels, matrices, and fillers in the development of advanced medical dressings.

18F]Fluoromisonidazole synthesis method: development and optimization by cartridge purification

Abstract [18F]Fluoromisonidazole ([18F]FMISO) as nitroimidazole derivative with 18F radioisotope is a widely known and studied hypoxia marker for PET imaging. A number of automated synthesis modules and purification strategies for production of [18F]FMISO have been described in recent years. The goal of this work was to develop [18F]FMISO synthesis process with Synthera module with solid phase extraction (SPE) Sep-Pak purification cartridges. To adjust the reaction conditions we synthesized [18F]FMISO under different reaction conditions and using various reversed-phase (RP) purification cartridges (HLB light, HLB plus, tC18, C18 environmental, Chromafix PS-RP). The synthesis was performed by nucleophilic substitution of commercial 1-(2′-nitro-1′-imidazolyl)-2-O-tetrahydropyranyl-3-O-toluenesulfonylpropanediol precursor and subsequent acidic hydrolysis. Further, the product mixture was purified by passing through the SPE cartridge. The produced [18F]FMISO was retained on the cartridge, while the impurities passed through the cartridge into a waste. The retained [18F]FMISO was then eluted with small amounts of ethanol in water and eluates were collected in the final product vial. The product sample was subjected to quality control tests, while for waste sample chemical and radiochemical tests were performed. We have developed an efficient synthesis method of [18F]FMISO with cartridge purification with good radiochemical yield (RCY) and high chemical and radiochemical purity in accordance with the Ph. Eur. Monograph for Fluoromisonidazole (18F) injection.

Green acidic catalyst from cellulose extracted from sugarcane bagasse through pretreatment by electron beam irradiation and subsequent sulfonation for sugar production

The objective of this research is to prepare a green acidic catalyst from cellulose derived from sugarcane bagasse (SB). Initially, SB was pretreated by electron beam irradiation with a dose of 50 kGy to 200 kGy and subsequent acid hydrolysis to obtain cellulose. The cellulose derived from SB was carbonized at different temperatures for 4 h and then sulfonated with heating at 120°C under reflux. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to confirm the successful preparation of acidic catalyst by irradiation pretreatment and subsequent sulfonation. The cellulose derived from irradiated SB at the lowest dose of 50 kGy was used as a representative irradiated sample for comparison with non-irradiation. Scanning electron microscope image of sulfonated biochar was observed pores with various sizes. The existence of sulfur atom onto sulfonated biochar surface was investigated by Energy dispersive X-ray spectroscopy. After sugar production by sulfonated biochar as an acidic catalyst, the total sugar content was measured by a phenol-sulfuric acid method using a UV-Vis spectrophotometer. The total sugar with 94.51 ± 1.35% content was found when the acidic catalyst was performed. It was remarkable to note that sulfonated biochar prepared from cellulose derived from SB after pretreatment and sulfonation exhibited outstanding result for being as an acidic catalyst for sugar production.

Intensification of delignification and subsequent hydrolysis of sustainable waste as banana peels for the HMF production using ultrasonic irradiation

The present work deals with the intensification of delignification of banana peels and subsequent acid hydrolysis and HMF production using ultrasound assisted approach. The delignification by conventional method was only 45.78% which increased to 92% for ultrasound clearly demonstrating intensification. The study into effect of operating parameters in the ultrasound-assisted acid hydrolysis on the yields of reducing sugars established optimum conditions as 4% acid concentration (v/v%), solid to solvent ratio of 0.0143, temperature of 80°C, power of 110 W, duty cycle of 70% and time as 3 h. Comparison of sugar yields using conventional approach, ultrasonic horn, and ultrasonic bath indicated that the yield of reducing sugars were 4 times more in ultrasonic horn and 2 times more in ultrasonic bath than conventional method. The studies for conversion of sugars to 5-hydroxymethylfurfural using acid catalyzed hydrothermal treatment revealed the best yield as 50 g/L after 1 h of treatment with 5% sulphuric acid for the approach of ultrasound assisted delignification and acid hydrolysis followed by hydrothermal treatment whereas the conventional approach resulted in much lesser yield of 6.1 g/L. The obtained results demonstrated that there was significant intensification in HMF yield based on using ultrasound for both alkaline pretreatment and acid hydrolysis.

Unexploited Design and Application of Dynamic Covalent Networks: Phenol-yne Click Reaction and Porous Film Generation

Dynamic covalent networks (DCNs) have attracted great attention because of their capacity for reprocessing and remolding, based on macromolecular architecture transformations or rearrangements through dynamic exchange reactions. Here, a new dynamic exchange reaction between a phenol and an enol-one motif yielded from the phenol-yne click reaction is introduced, and the phenol-yne click reaction is facilely integrated into the fabrication of a novel DCN. To expand the scope of material recycling, another degradable DCN prepared using the same click reaction but with a degradable diacetal motif is introduced. After thermal fusion of these two DCNs and subsequent acidic hydrolysis, a porous polymer film with a porosity of 46% is afforded, which is verified to possess excellent oil absorption capacity and recyclability. The strategic design and fabrication of porous polymer films provide an entirely new pathway for the application of DCNs.

Effects of ultrasonic-assisted alkaline pretreatment on xylose production from pineapple peel waste

The pineapple industry generates large amounts of unusable waste (peel and core) with adverse environmental impacts. This experimental study aims to systemize the potential of ultrasonic-assisted alkaline pretreatment for xylose production from pineapple peel waste. The best condition for single alkaline pretreatment (1 % NaOH w/v, 100 °C, 60 min) has obtained hemicellulose, cellulose, and lignin composition at 34.80 %, 32.16 %, and 8.66 %, respectively, retained in the biomass. Meanwhile, a combination of alkaline (1 % NaOH, w/v) and ultrasonic (frequency 40 kHz, 45 min) pretreatment has obtained the percentage yield of hemicellulose and lignin at 51.15 % and 7.15 %, respectively. Both single alkaline and ultrasonic-assisted alkaline pretreated samples were subsequently hydrolyzed with 2 % H2SO4 (w/v). After acid hydrolysis for 30 min, the maximum xylose concentration of 48.85 g.L-1 was achieved by using ultrasonic-assisted alkaline pretreatment, while single alkaline pretreatment contributed to the lowest yield of xylose (37.11 g.L-1). It is shown that the ultrasonic-assisted alkaline treatment is more favorable than single alkaline pretreatment as it can produce high xylose concentration after the subsequent hydrolysis. These results indicated that ultrasonic-assisted alkaline pretreatment and its subsequent acid hydrolysis were appropriate for producing xylose from pineapple peel waste.

Expression of acid cleavable Asp-Pro linked multimeric AFP peptide in E. coli

BackgroundDifficult to express peptides are usually produced by co-expression with fusion partners. In this case, a significant mass part of the recombinant product falls on the subsequently removed fusion partner. On the other hand, multimerization of peptides is known to improve its proteolytic stability in E. coli due to the inclusion of body formation, which is sequence specific. Thereby, the peptide itself may serve as a fusion partner and one may produce more than one mole of the desired product per mole of fusion protein. This paper proposes a method for multimeric production of a human alpha-fetoprotein fragment with optimized multimer design and processing. This fragment may further find its application in the cytotoxic drug delivery field or as an inhibitor of endogenous alpha-fetoprotein. ResultsMultimerization of the extended alpha-fetoprotein receptor-binding peptide improved its stability in E. coli, and pentamer was found to be the largest stable with the highest expression level. As high as 10 aspartate-proline bonds used to separate peptide repeats were easily hydrolyzed in optimized formic acid-based conditions with 100% multimer conversion. The major product was represented by unaltered functional alpha-fetoprotein fragment while most side-products were its formyl-Pro, formyl-Tyr, and formyl-Lys derivatives. Single-step semi-preparative RP-HPLC was enough to separate unaltered peptide from the hydrolysis mixture. ConclusionsA recombinant peptide derived from human alpha-fetoprotein can be produced via multimerization with subsequent formic acid hydrolysis and RP-HPLC purification. The reported procedure is characterized by the lower reagent cost in comparison with enzymatic hydrolysis of peptide fusions and solid-phase synthesis. This method may be adopted for different peptide expression, especially with low amino and hydroxy side chain content.

X-RAY STRUCTURAL ANALYSIS OF COTTONS AND HERBACEOUS CELLULOSE

It was found that the extrusion treatment of cotton cellulose in an aqueous medium, followed by drying and grinding on a hammer mill leads to a decrease in the crystallite size in the transverse direction ([110] and [100]) as a result of mechanical destruction of cellulose macromolecules, and the subsequent acid hydrolysis of cellulose in H2SO4 solutions to an increase in the size of crystallites in the transverse direction ([110], [110] and [100]) due to co-crystallization processes. It is shown that alkaline cooking of cellulose-containing material, followed by extrusion processing, washing, drying and grinding on a hammer mill leads to an increase in the transverse dimensions of crystallites in the [110] and [100] directions for flax cellulose and in the [110], [110] and [100] – for cellulose from oats and alfalfa as a result of partial removal of lignin and hemicelluloses from the cellulose-containing material.
 Differences were revealed in the sizes of the coherent scattering regions and the parameters of the crystallographic cell of cellulose samples from cotton and herbaceous plants (flax, oats, and alfalfa), as well as between samples from oats and alfalfa obtained under the same conditions with the same type of feedstock (straw).
 It has been established that the proposed stepwise technology for processing cotton and linen fibers leads to a slight decrease in the degree of crystallinity and the average degree of polymerization, which indicates that the developed technology for obtaining high-viscosity powder celluloses for various purposes is promising.
 Correlation coefficients are established between the values of the degree of ordering of the structure of cellulose samples from various plant raw materials, calculated using X-ray diffraction analysis and FT-IR spectroscopy, which make it possible to adequately compare all the known literature and experimental data.

Surface Modification of Magnetite with PBS Using a Ricinoleic‐Toluene Diisocyanate Fragment as the Binder Structure

AbstractMagnetite nanoparticles are widely used in current medicine because their magnetite properties allow several uses as drug delivery systems, contrasts in imaging tests, and even for magnetohyperthermia. However, magnetic nanoparticles possess meager Zeta potential, presenting a strong tendency to agglomerate. For clinical use, they must be covered with a biocompatible material to maintain colloidal stability, without, however, altering its magnetic properties. Thus, for biomedical applications in general, magnetic nanocomposites are more interesting than pure magnetite. The present work applies poly(butylene succinate) (PBS), as a coating on magnetite nanoparticles, aiming to increase their biocompatibility. PBS is a polymer obtained from renewable sources, being entirely suitable for pharmacological uses. In this work, the synthesis of ricinoleic acid from natural castor oil is carried out through the saponification method and subsequent acid hydrolysis. In turn, the synthesis of magnetite nanoparticles is performed by coprecipitation. Then, by an acid‐base reaction, the nanoparticles are treated with ricinoleic acid. Soon afterward, toluene diisocyanate is used to produce bonding between the modified particles and PBS. Fourier‐transform infrared spectroscopy confirms the synthesis of the material. Also, scanning electron microscopy and dynamic light scattering experiments are performed. The obtained results allow inferring the success in the preparation of the pursued hybrid material.

Modified Rhamnogalacturonan-Rich Apple Pectin-Derived Structures: The Relation between Their Structural Characteristics and Emulsifying and Emulsion-Stabilizing Properties.

In the context of the increasing interest in natural food ingredients, the emulsifying and emulsion-stabilizing properties of three rhamnogalacturonan-rich apple pectin-derived samples were assessed by evaluating a range of physicochemical properties. An apple pectin (AP74) was structurally modified by a β-eliminative reaction to obtain a RG-I-rich pectin sample (AP-RG). Subsequent acid hydrolysis of AP-RG led to the generation of pectin material with partially removed side chains (in particular arabinose depleted) (AP-RG-hydrolyzed), thus exhibiting differences in rhamnose, arabinose, and galactose in comparison to AP-RG. All samples exhibited surface activity to some extent, especially under acidic conditions (pH 2.5). Furthermore, the viscosity of the samples was assessed in relation to their emulsion-stabilizing properties. In a stability study, it was observed that the non-degraded AP74 sample at pH 2.5 exhibited the best performance among all the apple pectin-derived samples evaluated. This emulsion presented relatively small oil droplets upon emulsion production and was less prone to creaming than the emulsions stabilized by the (lower molecular weight) RG-I-rich materials. The AP-RG and AP-RG-hydrolyzed samples presented a slightly better emulsion stability at pH 6.0 than at pH 2.5. Yet, neither pectin sample was considered having good emulsifying and emulsion-stabilizing properties, indicated by the presence of coalesced and flocculated oil droplets.

Acute toxicity tests and dyeing potentials of three azo dyes from Pyocyanin, produced by Pseudomonas aeruginosa from farmlands

The admiration for colours by man has made dyes to have very useful applications on a great variety of materials. Pyocyanin (PCN) or 5-methyl-1-hydroxyphenazine, a phenazine derivative biosynthesized by Pseudomonas aeruginosa isolated from the stressed soil of a farmland at Awka was used to prepare three azo dyes namely, pyocyanin azophenol, pyocyanin azo-1-naphthol and pyocyanin azo-2-naphthol. The PCN was treated with SOCl2 to convert it to the chloro analogue. Treatment of chloro analogue with NaCN in ethanol and subsequent acid hydrolysis gave the carboxylic acid from which the amide was obtained after treatment with (NH4)2CO3 and heat. The amide was converted to the amine by Hoffman’s amide degradation. The amine was diazotized and coupled with phenol, 1-naphthol and 2-naphthol to give the three azo dyes respectively. UV-VIS and infrared spectra of the compounds agreed with the assigned structures. Acute Toxicity (LD50) tests showed the compounds to be reasonably non-toxic. Dyeing potentials of the Pyocyanin (PCN), PCN azophenol, PCN azo-1-naphthol and PCN azo-2-naphthol by mordant dyeing on cotton, silk and nylon textile materials showed them to have blue, dark green, purplish-brown and red colours respectively. The dyes were reasonably fast to light, washing, rubbing, alkali and acid. Pyocyanin, Pyocyanin azophenol, Pyocyanin azo-1-naphthol and pyocyanin azo-2-naphthol produced from Pseudomonas aeruginosa isolated from farmland soil can be used effectively to dye cotton, silk and nylon textile materials.

Effect of Oil Content in Tea-seed Pancake on the Determination of Tea Saponin

According to the national standard for the determination of tea saponin content in tea-seed pancake (GB/T 35131-2017), tea saponin was obtained by extracting oil with ethanol and removing solvent. The actual samples of tea-seed pancake did not completely remove the oil, and some of the residual oil content was as high as 9%. Due to the long period of national standard determination, people often use ethanol to extract tea saponin directly, instead of subsequent acid hydrolysis or alkali hydrolysis steps, so as to realize the rapid evaluation of tea-seed pancake quality. In this case, the residual oil has a greater impact on the results. If it was still tested according to the national standard method, the result will be much higher than the actual result. In this work, petroleum ether extraction process was selected before ethanol extraction to remove the residual oil. Experimental results showed that, the accuracy of the determination was effectively improved.

Interaction of Proteins with a Planar Poly(acrylic acid) Brush: Analysis by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D)

We describe the preparation of a poly(acrylic acid) (PAA) brush, polymerized by atom transfer radical polymerization (ATRP) of tert-butyl acrylate (tBA) and subsequent acid hydrolysis, on the flat gold surfaces of quartz-crystal microbalance (QCM) crystals. The PAA brushes were characterized by Fourier transform infrared (FT-IR) spectroscopy, ellipsometry and water contact angle analysis. The interaction of the PAA brushes with human serum albumin (HSA) was studied for a range of ionic strengths and pH conditions by quartz-crystal microbalance with dissipation monitoring (QCM-D). The quantitative analysis showed a strong adsorption of protein molecules onto the PAA brush. By increasing the ionic strength, we were able to release a fraction of the initially bound HSA molecules. This finding highlights the importance of counterions in the polyelectrolyte-mediated protein adsorption/desorption. A comparison with recent calorimetric studies related to the binding of HSA to polyelectrolytes allowed us to fully analyze the QCM data based on the results of the thermodynamic analysis of the binding process.

Is Steam Explosion a Promising Pretreatment for Acid Hydrolysis of Lignocellulosic Biomass?

For the production of sugars and biobased platform chemicals from lignocellulosic biomass, the hydrolysis of cellulose and hemicelluloses to water-soluble sugars is a crucial step. As the complex structure of lignocellulosic biomass hinders an efficient hydrolysis via acid hydrolysis, a suitable pretreatment strategy is of special importance. The pretreatment steam explosion was intended to increase the accessibility of the cellulose fibers so that the subsequent acid hydrolysis of the cellulose to glucose would take place in a shorter time. Steam explosion pretreatment was performed with beech wood chips at varying severities with different reaction times (25–34 min) and maximum temperatures (186–223 °C). However, the subsequent acid hydrolysis step of steam-exploded residue was performed at constant settings at 180 °C with diluted sulfuric acid. The concentration profiles of the main water-soluble hydrolysis products were recorded. We showed in this study that the defibration of the macrofibrils in the lignocellulose structure during steam explosion does not lead to an increased rate of cellulose hydrolysis. So, steam explosion is not a suitable pretreatment for acid hydrolysis of hardwood lignocellulosic biomass.

Improved preparation of vitexin from hot water extract of Basella alba, the commercially available vegetable Malabar spinach ("Tsurumurasaki" in Japanese) and the application to semisynthesis of chafuroside B.

Hot water extraction of D-arabinofuranosylvitexin from the raw leaves of commercially available Basella alba "Tsurumurasaki" and subsequent acidic hydrolysis was improved to be a procedure using a high-pressure steam sterilizer to afford vitexin. The amount was estimated to be 14.1 mg from 1g of dry weight of the raw leaves, whose recovery was calculated to be 95% based on the estimated content of D-arabinofuranosylvitexin in B. alba raw leaves. The product was dehydratively cyclized between hydroxy groups on the carbohydrate and flavone skeletons under modified Mitsunobu reaction conditions in N,N-dimethylformamide to give chafuroside B, which is known to be a bioactive Oolong tea polyphenol. Through these transformations, 10.2 mg of chafuroside B could be semisynthesized from 1g of dry weight of the raw leaves, and the efficiency was improved compared to that from the extraction from Oolong tea (3.4μg from 1g of dry weight).

Analysis of polyphenols in apple pomace: A comparative study of different extraction and hydrolysis procedures

Apple pomace is a potential source of bioactive polyphenols. The objective of this study was to compare different methods for extraction of phenolic compounds. The content of free polyphenolic compounds in aqueous-methanol extracts was 5.56 mg gallic acid equivalents (GAE)/g dry weight (DW) pomace, with the major free phenolic compounds identified as chlorogenic acid, quercetin-3-O-galactoside, quercetin-3-O-rhamnoside, and phloridzin. Different order of sequential base and acid hydrolysis of the residue and then extraction by diethyl ether/ethyl acetate yielded 6.82–8.12 mg GAE/g DW of bound polyphenols. The major phenolics in the residue, after aqueous-methanol was subjected to base hydrolysis, were phloridzin, 4-hydroxybenzoic acid, and quercetin-3-O-galactoside, and subsequent acid hydrolysis further released significant amounts of 4-hydroxybenzoic acid and isoferulic acid. Extraction of the residue remaining after aqueous-methanol extraction subjected to acid hydrolysis released mainly 4-hydroxybenzoic acid, protocatechuic acid and isoferulic acid, and subsequent base hydrolysis further released significant amounts of protocatechuic acid, catechin and 4-hydroxybenzoic acid. Extracts obtained after direct acid or base hydrolysis yielded 5.55 mg GAE/g DW and 10.62 mg GAE/g DW, respectively. The absolute amounts of the individual phenolic compounds were different in different fractions after either direct base or acid hydrolysis. Regardless of the hydrolysis procedures, the extractions with higher phenolics contents showed the stronger antioxidant activities, as measured by oxygen radical absorbance capacity (ORAC). This work shows that extraction and hydrolysis procedure have substantial effects on the recovery of phenolics from apple pomace.

Stable Isotope Dilution LC-HRMS Assay To Determine Free SN-38, Total SN-38, and SN-38G in a Tumor Xenograft Model after Intravenous Administration of Antibody-Drug Conjugate (Sacituzumab Govitecan).

Antibody-drug conjugates (ADCs) have gained significant interest over the past few years due to their targeted delivery, higher efficacy, decreased toxicity and improved therapeutic index over conventional anticancer therapies. Sacituzumab govitecan (SG) is an ADC composed of a Trop-2-targeted antibody conjugated to the cytotoxic payload SN-38. SG is currently being evaluated in clinical trials of several solid cancers. In this nonclinical study, we have developed a highly sensitive and selective approach to measure free and total SN-38 and its glucuronidation metabolite (SN-38G) using stable isotope dilution (SID) ultrahigh-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). An efficient and fast hydrolysis procedure (2 h at 100 °C) was established to release SN-38, conjugated to the antibody by carbonate linkage. The assay involves the extraction of free SN-38, SN-38G by protein precipitation, and subsequent acid hydrolysis of the protein layer to release antibody-bound SN-38. The developed UHPLC-HRMS method resulted in good linearity (r2 ≥ 0.997), accuracy (RE ≤ ± 9.1%), precision (CVs ≤ 7.7%), and extraction recoveries (85.6-109.3%). The validated method was applied in the plasma and tumor of mice bearing human brain (U251) and breast (MDA-MB-468) tumor xenografts treated with a single dose (0.5 mg) of SG for 6 h. Results revealed the presence of trace level of SN-38G and free SN-38 in plasma, which suggests an improved therapeutic index of SG. The established method makes a significant contribution to the assessment of SG in different cancers.

Manganese‐Catalyzed Transfer Hydrogenation of Nitriles with 2‐Butanol as the Hydrogen Source

AbstractWe report herein the first example of a homogeneous manganese catalyzed transfer hydrogenation of nitriles using 2‐BuOH as the hydrogen source. Compound fac‐[(CO)3Mn{iPr2P(CH2)2PiPr2}Br] (Mn‐1, 3 mol %) exhibited catalytic activity in the presence of KOtBu (10 mol %) for the transfer hydrogenation of benzonitrile to yield a mixture of benzylamine (BA) and N‐sec‐butylidenebenzylamine (SBA). Subsequent acidic hydrolysis yielded isolated benzylamine hydrochloride in 96 %. The title system featured reversible formation of N‐benzylidenebenzylamine (BBA) prior to formation of SBA. A series of amine hydrochlorides was prepared following this methodology (39–92 % isolated yields, 4 examples). Best substrates for this transformation are electron‐rich aromatic nitriles, nonetheless electron‐deficient aromatic as well as aliphatic nitriles were also hydrogenated. Mechanistic studies suggested coordinatively unsaturated Mn‐hydride species performing catalytic turnover.

Alkali metal trifluoroacetates for the nucleophilic trifluoromethylation of fullerenes

Fullerene C60 readily reacts with potassium and cesium trifluoroacetates yielding C60(CF3)–M+ salts, and subsequent acid hydrolysis gives ortho-C60(CF3)H. The reaction rate and the probability of the alternative reaction pathways strongly depend on the particular metal cation. Thus, the reactivity increases in the order Li < Na < K≈Cs, in correlation with the decreasing thermal stability. Furthermore, the sodium and, especially, lithium salts tend to effect CF2- rather than CF3-functionalization of the fullerene, in good accordance with the hard/soft acids and bases theory. The nucleophilic trifluoromethylation is found to be applicable to other pristine fullerenes like C70 as well as to fullerene derivatives like p7mp-C70(CF3)10. It enables selective preparation of low trifluoromethylated fullerenes via regioselective consecutive trifluoromethylation under accurately controlled solution-phase conditions.