Secondary Alcohols Research Articles

Synthesis of plantain peel powder-based biofilm

The present study investigated the use of ripe plantain peel powder, crude glycerol, vinegar, egg shell powder and cassava starch as source raw materials for producing plantain peel-based biodegradable biofilm (P-BF). The synthesized biofilm was characterized by chemical test (FTIR, GC-MS, morphology test, water absorption property, biodegradation test, solubility test and swelling test) and mechanical test (ultimate tensile test, flexural, hardness test, % elongation and thermogravimetric analysis). Results showed successful production of P-BF. A non-plantain bioplastic (NP-BF) served as control. The FTIR analysis showed eight functional groups; ether, ethene, amine, carboxylic acid, nitriles, methylene, cyclic ester, primary, secondary and tertiary alcohols common to hydrocarbons. The biodegradation test showed the P-BF degraded at the same pace as NP-BF which degraded on the 6th day of the test. The mechanical test showed P-BF had higher thermal stability and water absorption property compared to the NP-BF. However, P-BF showed lower ultimate tensile test, flexural, hardness test, percentage elongation compared to the NP-BF. Morphology test showed that there was uneven distribution of constituents materials in P-BF compared to the NP-BF which affected its mechanical properties. In conclusion, the study successfully produced plantain peel-based biodegradable biofilm with good mechanical properties, biodegradability, thermal stability, fair water absorption property.

Chiral ferrocenylimine alcohols and corresponding reduced ferrocenyl secondary amine alcohols: synthesis, X-crystal structures and characterization

Chiral ferrocenylimine alcohols and corresponding reduced ferrocenyl secondary amine alcohols: synthesis, X-crystal structures and characterization

Description and genome analysis of a novel archaeon isolated from a syntrophic pyrite-forming enrichment culture and reclassification of Methanospirillum hungatei strains GP1 and SK as Methanospirillum purgamenti sp. nov.

The archaeal isolate J.3.6.1-F.2.7.3T was obtained from an anaerobic enrichment culture, where it may play an important role in methane production during pyrite formation. The new isolate formed a species-level clade with Methanospirillum hungatei strains GP1 and SK, which is separate from the type strain JF-1T. Cultivation-independent surveys indicate the occurrence of this phylogenetic group in sediments and anaerobic digesters. The abundance of this clade appears to be negatively affected by high nitrogen loads, indicating a sensitivity to certain nitrogen compounds that is not known in M. hungatei JF-1T. The relatively large core genome of this Methanospirillum clade is indicative of niche specialization and efficient control of horizontal gene transfer. Genes for nitrogenase and F420-dependent secondary alcohol dehydrogenase contribute to the metabolic versatility of this lineage. Characteristics of the new isolate such as the ability to utilize 2-propanol as an electron donor or the requirement for acetate as a carbon source are found also in the strains GP1 and SK, but not in the type strain M. hungatei JF-1T. Based on the genomic differences to related species, a new species within the genus Methanospirillum is proposed with the name M. purgamenti sp. nov. The determined phenotypic characteristics support this proposal and indicate a metabolic adaptation to a separate ecological niche.

Visible Light‐Promoted Aerobic Oxidation of α‐Silyl Styrenes with Alcohols

Comprehensive SummaryA mechanistically distinctive visible‐light‐promoted metal‐free aerobic oxidation of alkenyl silanes with alcohols was disclosed to efficiently construct α‐alkoxy ketones under mild conditions. The primary, secondary, and tertiary alcohols could be used as reactants. The protocol could be carried out on a gram‐scale. Various derivatizations of products could be conducted. Mechanistic studies indicated the reaction was initiated by single‐electron oxidation of the alkenyl silanes, rather than radical addition to alkenyl silanes.

Iron-Catalyzed sp3 C-H Alkylation of Fluorene with Primary and Secondary Alcohols: A Borrowing Hydrogen Approach.

The utilization of earth-abundant, cheap, and nontoxic transition metals in important catalytic transformations is essential for sustainable development, and iron has gained significant attention as the most abundant transition metal. A mixture of FeCl2 (3 mol %), phenanthroline (6 mol %), and KOtBu (0.4 eqivalent) was used as an effective catalyst for the sp3 C-H alkylation of fluorene using alcohol as a nonhazardous alkylating partner, and eco-friendly water was formed as the only byproduct. The substrate scope includes a wide range of substituted fluorenes and substituted benzyl alcohols. The reaction is equally effective with challenging secondary alcohols and unactivated aliphatic alcohols. Selective mono-C9-alkylation of fluorenes with alcohols yielded the corresponding products in good isolated yields. Various postfunctionalizations of C-9 alkylated fluorene products were performed to establish the practical utility of this catalytic alkylation. Control experiments suggested a homogeneous reaction path involving borrowing hydrogen mechanism with the formation and subsequent reduction of 9-alkylidene fluorene intermediate.

TsOH-catalyzed dehydroxylative cross-coupling of alcohols with phenols: rapid access to propofol derivatives.

Modification of the parent structure of molecules often alters their physicochemical properties and biological activities. Herein, a practical, efficient, and highly regioselective C-H alkylation of phenols with alcohols via dehydroxylative cross-coupling was developed to produce para-alkylated phenols with excellent regioselectivities and yields, using which propofol derivatives were rapidly synthesized. This process is performed under mild and simple conditions and is well-compatible with a variety of alcohols (secondary and tertiary benzylic alcohols as well as allyl alcohols) as alkylated agents. In addition, high aryl ether derivatives were also obtained using this catalytic system.

Phosphotungstic Acid-Supported Hercynite: A Magnetic Nanocomposite Catalyst for the Selective Esterification of Chloroacetic Acid.

This study presents the synthesis and characterization of a novel phosphotungstic acid-functionalized hercynite@SiO2 magnetic core-shell through a three-step procedure. The characterization involved various analyses including Fourier-transform infrared spectroscopy, P-XRD, TGA-DSC, EDAX, inductively coupled plasma optical emission spectroscopy, elemental mapping, scanning electron microscopy, transmission electron microscopy, and value stream mapping. The catalytic performance of the hercynite@SiO2-PTA nanomagnetic composite was examined in the esterification of chloroacetic acid. Results indicate that the developed procedure enables the production of chloroacetic acid esters using a wide range of primary, secondary, and tertiary aliphatic and aromatic alcohols with good to excellent yields and high selectivity. The significance of this work lies in its straightforward synthesis method, minimal time requirement, reduced utilization of hazardous chemicals, and cost-effectiveness. Additionally, the catalyst exhibited magnetic recyclability for up to five cycles with negligible loss in activity. Notably, the synthesized catalyst demonstrated nontoxicity and environmental friendliness.

Assessment of Accelerated Aging Effect of Bio-Oil Fractions Utilizing Ultrahigh-Resolution Mass Spectrometry and k-Means Clustering of van Krevelen Compositional Space.

Bio-oils contain a substantial number of highly oxygenated hydrocarbons, which often exhibit low thermal stability during storage, handling, and refining. The primary objectives of this study are to characterize the hydroxyl group in bio-oil fractions and to investigate the relationship between the type of hydroxyl group and accelerated aging behavior. A bio-oil was fractionated into five solubility-based fractions, classified in two main groups: water-soluble and water-insoluble fractions. These fractions were then subjected to chemoselective reactions to tag molecules containing hydroxyl groups and analyzed by negative-ion electrospray ionization 21 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The fractions were also subjected to accelerated aging experiments and characterized by FT-ICR MS and bulk viscosity measurements. Extracting insightful information from ultrahigh-resolution data to aid in predicting upgrading methodologies and instability behaviors of bio-oils is challenging due to the complexity of the data. To address this, an unsupervised learning technique, k-means clustering analysis, was used to semiquantify molecular compositions with a close Euclidean distance within the (O/C, H/C) chemical space. The combination of k-means analysis with findings from chemoselective reactions allowed the distinctive hydroxyl functionalities across the samples to be inferred. Our results indicate that the hexane-soluble fraction contained numerous molecules containing primary and secondary alcohols, while the water-soluble fraction displayed diverse groups of oxygenated compounds, clustered near to carbohydrate-like and pyrolytic humin-like materials. Despite its high oxygen content, the water-soluble fraction showed minimal changes in viscosity during aging. In contrast, a significant increase in viscosity was observed in the water-insoluble materials, specifically, the low- and high-molecular-weight lignin fractions (LMWL and HMWL, respectively). Among these two fractions, the HMWL exhibited the highest increase in viscosity after only 4 h of accelerated aging. Our results indicate that this aging behavior is attributed to an increased number of molecular compositions containing phenolic groups. Thus, the chemical compositions within the HMWL are the major contributors to the viscosity changes in the bio-oil under accelerated aging conditions. This highlights the crucial role of oxygen functionality in bio-oil aging, suggesting that a high oxygen content alone does not necessarily correlate with an increase of viscosity. Unlike other bio-oil categorization methods based on constrained molecule locations within the van Krevelen compositional space, k-means clustering can identify patterns within ultrahigh-resolution data inherent to the unique chemical fingerprint of each sample.

Ready Access to [5,6,5]-Trioxa-spiro and Fused Ketals via Ag-Catalyzed Cascade Annulation of 4-Pentyn-1-ols and Aldehydes.

In this study, we unveil the versatility of 4-pentyn-1-ols as carbonyl surrogates for the unprecedented synthesis of diverse oxygen heterocycles, including [5,6,5]-bis-spiroketals (trioxadispiroketals) and [5,6,5]-furano-spiroketals related to bioactive natural products. These reactions commence with the π-activation-induced intramolecular hydroalkoxylation of 4-pentyn-1-ols, yielding cyclic enol ethers, which undergo subsequent three-component annulation with aldehydes in a [2+2+1+1] fashion, resulting in the formation of [5,6,5]-bis-spiroketals. Notably, the distinctive steric features of alkynyl alcohols, particularly those with a secondary or tertiary alcohol functionality, dictate divergent reaction pathways, leading to the formation of [5,6,5]-furano-spiroketals.

Tuning selectivity toward three-carbon product of glycerol electrooxidation in borate buffer through manipulating borate/glycerol molar ratio

Controlling selective glycerol electrooxidation towards the primary or secondary alcohol group, which enables obtained dihydroxyacetone or glyceraldehyde as the main product, is a challenge for an effective glycerol electrolysis system. In this work, we systematically investigated the protective effect of borate-glycerol complexes toward primary and secondary alcohol group oxidation during the glycerol electrooxidation process on NiOx catalyst in borate buffer (pH 9.2). The Raman spectroscopy and high-performance liquid chromatography results indicated that manipulating the borate/glycerol (B/G) ratio could affect selective oxidation towards primary or secondary alcohol group. Five-member ring complex was more likely to form in the electrolyte with the B/G ratio of 0.1, whereas six-member ring complex became more significant in the electrolyte with the B/G ratio of 1.5. The dominance of five- or six-member ring complex could enhance the favored adsorption of primary or secondary alcohol group, thus generating glyceraldehyde or dihydroxyacetone as the main product, respectively. The results in this study highlight the significance of electrolyte property on glycerol electrocatalysis, which is universally applicable to other transition metal electrocatalysts, enabling the development of a highly selective glycerol electrooxidation towards primary or secondary alcohol system at near-neutral pH level.

Constructing p-n heterojunctions of Cl-Cu2O and PANI on three-dimensional nanofiber networks for enhanced photocatalytic degradation of oxytetracycline

A p-n heterojunction was constructed on a bacterial cellulose (BC) film by combining n-type semiconductor chlorine-doped Cu2O (Cl-Cu2O) and p-type semiconductor polyaniline (PANI), creating a ternary composite flexible film of Cl-Cu2O/PANI/BC. The chemical structure, microscopic morphology, and photoelectrochemical properties of Cl-Cu2O/PANI/BC were characterized and analyzed. Compared with pure Cl-Cu2O, the Cl-Cu2O/PANI/BC composite flexible film exhibited a broader response range to visible and near-infrared light, higher carrier concentration, lower impedance value, and substantial reduction in the recombination probability of photogenerated carriers. The process conditions for the photocatalytic degradation of oxytetracycline (OTC) were optimized using the response surface method, and the degradation rate of OTC caused by the Cl-Cu2O/PANI/BC was 96.3 %. In the degradation process of OTC, superoxide radical is the main active species. It was found that OTC molecules degraded via demethylation, secondary alcohol oxidation, decarboxylation, and deamination reactions, finally being degraded into H2O, CO2, and other small organic molecules. Thirteen major intermediates and possible degradation pathways were speculated. The photocatalytic performance of the Cl-Cu2O/PANI/BC was improved owing to the successful construction of the p-n heterojunction. The built-in electric field generated at the interface between the two semiconductors promoted the diffusion of photogenerated holes from the n-type Cl-Cu2O particles to the PANI coating layer on the BC chain, whereas the photogenerated electrons from PANI diffused toward Cl-Cu2O, accelerating the separation efficiency of photoinduced electrons and holes in the two semiconductors and thereby improving the efficiency of photocatalytic degradation. In addition, the three-dimensional network structure of a composite flexible film can help recover the photocatalyst. After performing seven experiments for recovery and reuse, the photocatalytic degradation rate of OTC still remained above 90 %.

Anticandidal Properties of Launaea sarmentosa among the Salt Marsh Plants Collected from Palk Bay and the Gulf of Mannar Coast, Southeastern India.

Tidal wetlands, commonly known as salt marshes, are highly productive ecosystems in temperate regions worldwide. These environments constitute a unique flora composed primarily of salt-tolerant herbs, grasses, and shrubs. This study investigated the therapeutic properties of ten salt marsh plants collected mainly from Palk Bay and Mannar Gulf against Candida disease. This study examined the changes in natural plant products associated with their anti-Candida growth activity during two distinct seasonal changes-monsoon and summer. The potential of the salt marshes to inhibit the growth of five different Candida strains was assessed using four solvents. In phytochemical analysis, the extracts obtained from a Launaea sarmentosa exhibited the highest results compared to the other plant extracts. Fourier transform infrared spectroscopy revealed 12 peaks with alkane, aldehyde, amine, aromatic ester, phenol, secondary alcohol, and 1,2,3,4-tetrasubstituted. Gas-chromatography-mass spectrometry detected 30 compounds. Cyclotetracosane, lupeol, β-amyrin, and 12-oleanen-3-yl acetate showed the highest peak range. In particular, plant samples collected during the monsoon season were more effective in preventing Canda growth than the summer plant samples. In the monsoon season, the salt marsh plant extracted with ethyl acetate showed a high anti-Candida growth activity, while in the summer, the acetone extract exhibited a higher anti-Candida growth activity than the other solvents. The hexane extract of L. sarmentosa showed the highest inhibition zone against all Candidal strains. Furthermore, compounds, such as β-amyrin, lupeol, and oxirane, from the hexane extract of L. sarmentosa play a vital role in anti-Candida activity. This paper reports the potential of tidal marsh plant extracts for developing new antifungal agents for Candida infections.

Metal-Free Switchable Chemo- and Regioselective Alkylation of Oxindoles Using Secondary Alcohols.

In this study, we have disclosed N-alkylation and C-alkylation reactions of 2-oxindoles with secondary alcohols. Interestingly, these chemoselective reactions are tunable by changing the reaction conditions. Utilization of protic solvent and Brønsted acid catalyst afforded C-alkylation, whereas, aprotic solvent and Lewis acid catalyst afforded N-alkylation of 2-oxindoles in good to excellent yields. Regioselectivity is achieved by protecting the N-center of the oxindole and C5 alkylated product is furnished exclusively. This protocol is notable because it demonstrates functionalization at the C7 position of oxindole without the need for any directing group at the N-center. Further, a new protocol has been reported for C-H oxygenation at the benzylic position of one of the C5 alkylated derivative.

Multigram two-step synthesis of difluoromethyl ethers from aliphatic alcohols and glycols

A convenient method for synthesis of alkyl(difluoromethyl)ethers, including subsequent stages of chlorination and fluorination of the O-formyl derivatives was investigated on series of aliphatic alcohols and glycols. Primary and secondary alcohols are converted to the corresponding O-difluoromethyl derivatives in high yield, polydifluoromethyl derivatives of 1,3-propyleneglycol, diethyleneglycole and pentaerythritol can only be successfully obtained with this procedure.

Dual photocatalytic effect of Ag/TiO2 site for the total reduction of N2O and selective oxidation of alcohols to valuable carbonyl compounds

Nitrous oxide (N2O) is an important greenhouse gas emitted by anthropogenic activities, with a concentration that keeps increasing in the atmosphere. To limit its impact, thermal N2O degradation pathway is traditionally considered by main emitting actors. Nevertheless, N2O activation and upgrading as oxygen source in chemical transformations have recently received significant attention. Here, we propose to combine photocatalytic decomposition of N2O into climate neutral products N2 and H2O in the presence of primary or secondary alcohols as reducing agents. This dual reaction which simultaneously combines photoreduction of N2O and alcohols oxidation was extended to the selective transformation of alcohols into valuable ketones and aldehydes using Ag/TiO2 in acetonitrile as dual-reaction site, easily prepared by photodeposition method and loaded with only 0.3 wt% of silver.

Investigation Towards the Asymmetric CBS‐Catalysed Reduction of Aryl Methyl Ketones with Electrochemically in Situ Generated BH3

AbstractThe aim of this investigation was to explore the possibility to perform an asymmetric reduction, utilising a CBS‐type catalyst, of prochiral aryl methyl ketones under electrochemical conditions to generate the needed BH3 upon oxidation of NaBH4 with in situ generated I2 in the anode compartment. Therefore, various electrochemical parameters were optimised to conduct the desired formation of the chiral secondary alcohols in high to quantitative yields with a high stereochemical induction, although the catalyst loading had to be chosen relatively high to concur with the racemic reduction of the ketones by the electrogenerated BH3.

A Formal General Method for the Synthesis of Spiroacetals: Easy Access to Oleocaran/Elmonin Core

A general method for the synthesis of spiroacetals was investigated. Simple symmetrical [n,n]‐spiroacetals (n = 5,6) can be prepared from α,ω‐alkanediols by their conversion to the respective ω‐benzyloxyalkyl bromides, addition of their Grignard reagents to ethyl formate, further oxidation of the resulting secondary alcohols and finally deprotection with spontaneous intramolecular acetalization. Access to the respective unsymmetrical [m,n]‐spiroacetals (m,n = 5,6,7) was similarly achieved by addition of the above Grignard reagent to a ω‐benzyloxyalkanal, followed by the same reaction sequence. This method was further adapted for the synthesis of the unsubstituted structural core of natural spiroacetals oleocaran and elmonin, thus demonstrating its potential.

NNO Pincer-Supported Pd(II)-Catalyzed Reductive N-Alkylation of Challenging Nitroarenes with Alcohols via Borrowing Hydrogen Strategy.

A sustainable catalytic synthesis of selective monoalkylated amines from nitroarenes and alcohols by new palladium(II)-NNO pincer-type complexes has been described. Herein, a series of Pd(II) complexes [Pd(NNO)PPh3] (1-3) are synthesized and characterized by analytical and spectroscopic (IR, NMR, and HR-MS) methods. The solid-state molecular structures of two complexes are established by X-ray single-crystal diffraction. Furthermore, the catalytic N-alkylation of challenging nitroarenes with primary and secondary alcohols has been performed by the well-defined palladium(II) complexes via borrowing hydrogen strategy. The current protocol offers a wide range of monoalkylated amines (26 examples) with a maximum yield of 87% utilizing 1 mol % of catalyst loading. Gratifyingly, the catalytic system works well under mild reaction conditions and atom economy with water is the only byproduct. Furthermore, control experiments confirm the formation of probable intermediates (aniline, aldehyde, and imine), and deuterium labeling authenticates the borrowing hydrogen mechanism. A gram-scale synthesis of an alkylated product clearly demonstrates the synthetic efficacy of the present catalytic methodology.

Diastereoselective Synthesis of Sulfoxide-Functionalized N-Heterocyclic Carbene Ruthenium Complexes: An Experimental and Computational Study.

The synthesis of sulfoxide-functionalized NHC ligand precursors were carried out by direct and mild oxidation from corresponding thioether precursors with high selectivity. Using these salts, a series of cationic [Ru(II)(η6-p-cymene)(NHC-SO)Cl]+ complexes were obtained in excellent yields by the classical Ag2O transmetallation route. NMR analyses suggested a chelate structure for the metal complexes, and X-ray diffractometry studies of complexes 4 b, 4 c, 4dBArF and 4 e unambiguously confirmed the preference for the bidentate (κ2-C,S) coordination mode of the NHC-SO ligands. Interestingly, only one diastereomer, in the form of an enantiomeric pair, was observed both in 1H NMR and in the solid state for the complexes. DFT calculations showed a possible intrinsic energy difference between the two pairs of diastereomer. The calculated energy barriers suggested that inversion of the sulfoxide is only plausible from the higher energy diastereomer together with bulky substituents. Inverting the configuration at the Ru center instead shows a lower and accessible activation barrier to provide the most stable diastereomer through thermodynamic control, consistent with the observation of a single species by 1H NMR as a pair of enantiomers. All these complexes catalyse the β-alkylation of secondary alcohols. Complex 4dPF6 bearing an NHC-functionalised S-Ad group has been further studied with different primary and secondary alcohols as substrates, showing high reactivity and high to moderate β-ol-selectivities.

Engineered digestate-derived biochar mediated peroxymonosulfate activation for oxytetracycline removal in sustainable wastewater remediation

Nowadays, biochar is extensively used in wastewater remediation with the aim of achieving water security and circularity with minimal impacts on ecosystems and the environment. In this study, digestate biochar was prepared and modified using different methods and then employed as a peroxymonosulfate (PMS) activator to oxidize oxytetracycline, a model antibiotic pollutant in wastewater. The optimal biochar catalyst was characterized, spin trapping tests were carried out to confirm the dominant catalytic mechanism, and in silico toxicity prediction was conducted based on structure-activity relationships. Assessment of the catalytic performance of the pristine and engineered biochar showed that nitrogen doping increased oxytetracycline degradation efficiency by 1.92-fold (i.e., 100% oxytetracycline degradation with the engineered biochar compared to 52% with pristine biochar), while pyrrolic nitrogen was identified as a major PMS activation site. It was discovered that several parameters, such as catalyst dose, pH, PMS concentration, and competing ions, affected oxytetracycline degradation efficiencies. Additionally, the toxicity of the degradation intermediate was studied. Scavenger trapping tests showed that 1O2 and SO4•- were the most prevalent species during oxytetracycline degradation in the system, with four possible degradation pathways proposed, including secondary alcohol oxidation, hydroxylation, dehydration, and deamidation. Overall, it is anticipated that this study would contribute to our understanding of metal-free biochar activation of PMS as an attractive treatment scheme for antibiotic-polluted water.