Secondary Alcohols Research Articles

Accumulation mechanisms for contaminants on weak-base hybrid ion exchange resins

Mechanism of hexavalent chromium removal (Cr(VI) as CrO42-) by the weak-base ion exchange (IX) resin ResinTech® SIR-700-HP (SIR-700) from simulated groundwater is assessed in the presence of radioactive contaminants iodine-129 (as IO3-), uranium (U as uranyl UO22+), and technetium-99 (as TcO4-), and common environmental anions sulfate (SO42-) and chloride (Cl-). Batch tests using the acid sulfate form of SIR-700 demonstrated Cr(VI) and U(VI) removal exceeded 97%, except in the presence of high SO42- concentrations (536 mg/L) where Cr(VI) and U(VI) removal decreased to ≥ 80%. However, Cr(VI) removal notably improved with co-mingled U(VI) that complexes with SO42- at the protonated amine sites. These U–SO42- complexes are integral to U(VI) removal, as confirmed by the decrease in U(VI) removal (<40%) when the acid chloride form of SIR-700 was used instead. Solid phase characterization revealed that CrO42- is removed by IX with SO42- complexes and/or reduced to amorphous Cr(III)(OH)3 at secondary alcohol sites. Tc(VII)O4- and I(V)O3- also undergo chemical reduction, following a similar removal mechanism. Oxyanion removal preference is determined by the anion reduction potential (CrO42->TcO4->IO3-), geometry, and charge density. For these reasons, 39% and 69% of TcO4- and 17% and 39% of IO3- are removed in the presence and absence of Cr(VI), respectively.

Photochemical Hydrogen Atom Transfer Catalysis for Dehydrogenation of Alcohols To Form Carbonyls.

Controllable oxidation of alcohols to carbonyls is one of the fundamental transformations in organic chemistry. Herein, we report an unprecedented visible-light-mediated metal-free oxidation of alcohols to carbonyls with hydrogen evolution. By synergistic combination of organophotocatalyst 4CzIPN and a thiol hydrogen atom transfer catalyst, a broad range of alcohols, including primary and secondary benzylic alcohols as well as aliphatic alcohols, were readily oxidized to carbonyls in moderate to excellent yields. A site-selective oxidation has also been achieved by this protocol. Mechanistic investigation indicates that the oxidation proceeds through an oxidative radical-polar crossover process to obtain an α-oxy carbon cation.

From‐Neutral‐to‐Neutral Reductive Radical Coupling of Non‐Activated Alcohols and Styrenes

AbstractA reductive radical coupling reaction between non‐activated aliphatic alcohols and styrenes has been discovered through the use of low‐valent Ti‐mediated C−O bond homolysis. A general application of styrene derivatives in radical coupling reactions remains a challenge in organic synthesis. The preliminary investigation revealed that the resulting benzyl radical intermediate behaves differently depending on minor steric differences around the spin center, which results in a lack of generality. The addition of 1,3,5‐trimethyl‐2,5‐cyclohexadiene uniformly hydrogenated the benzyl radicals irrespective of the steric environments of the attacking radicals. Under the optimal reaction conditions, all tertiary, secondary, and primary alcohols were applicable. In this study, alcohols were successfully used directly as radical sources and reacted with a large number of styrenes.

Aerobic Oxidative Cleavage of C(OH)-C Bonds to Produce Aromatic Aldehydes Catalyzed by CuI -1,10-phenanthroline Complex.

Effective cleavage and functionalization of C(OH)-C bonds is of great importance for the production of value-added chemicals from renewable biomass resources such as carbohydrates, lignin and their derivatives. The efficiency and selectivity of oxidative cleavage of C(OH)-C bonds are hindered by their inert nature and various side reactions associated with the hydroxyl group. The oxidative conversion of secondary alcohols to produce aldehydes is particularly challenging because the generated aldehydes tend to be over-oxidized to acids or the other side products. Noble-metal based catalysts are necessary to get satisfactory aldehyde yields. Herein, for the first time, the efficient aerobic oxidative conversion of secondary aromatic alcohols into aromatic aldehydes is reported using non-noble metal catalysts and environmentally benign oxygen, without any additional base. It was found that CuI -1,10-phenanthroline (Cu-phen) complex showed outstanding performance for the reactions. The C(OH)-C bonds of a diverse array of aromatic secondary alcohols were effectively cleaved and functionalized, selectively affording aldehydes with excellent yields. Detailed mechanism study revealed a radical mediated pathway for the oxidative reaction. We believe that the findings in this work will lead to many explorations in non-noble metal catalyzed oxidative reactions.

Correlation analysis between sleep quality and the mental health status of female sex workers during the COVID-19 pandemic in Hubei Province.

Female sex workers (FSWs) in entertainment venues are subject to condemnation and rejection by their families and the outside world. As a result, they are prone to psychological problems, including anxiety and even suicidal tendencies. The aim of the current study was to understand the sleep and mental health status of local FSWs and to identify associated risk factors, so as to provide a scientific basis for improving the social recognition of FSWs and establishing effective psychological interventions. A stratified cluster random sampling method was used to select women engaged in commercial sex in bathing, sauna, karaoke halls and other entertainment venues. A self-designed questionnaire assessing mental health-related factors was administered face-to-face with the respondents. 90 participants were randomly selected for blood tests to analyze the relationship between biological indicators and sleep quality. The rates of depression, anxiety and somnipathy among FSWs were 32.7%, 43.1% and 8.6%, respectively. The correlation coefficients (r) between sleep quality and depression, anxiety and social support were 0.07, 0.09 and -0.09, respectively. Divorce or widowhood, technical secondary school education, alcohol consumption and exercise were independent risk factors for depression in FSWs (p< 0.05) while living in urban areas and counties and having a sense of social support were protective factors (P< 0.05). Quarantining due to the pandemic and exercise were independent risk factors for anxiety in FSWs (P< 0.05) while living in counties and having a sense of social support were protective factors (P< 0.05). Quarantining due to the pandemic was an independent risk factor for somnipathy in FSWs (P< 0.05) while being married was a protective factor (P< 0.05). NE/NA was a protective factor for sleep disorders (OR=0.042, P=0.05), with an AUC of 0.87. FSWs should appropriately adjust their work form during the pandemic period, maintain a positive and optimistic attitude, establish long-term stable social relationships, and seek a greater sense of social support. The government should provide comprehensive bio-psycho-social interventions to address the mental and physical health status of this population.

Synthesis and Anti-Proliferative Activity of 5-Benzoyl and 5-Benzylhydroxy Derivatives of 3-Amino-2-Arylcarboxamido-Thieno[2-3-b]Pyridines.

3-Amino-2-arylcarboxamido-thieno[2-3-b]pyridines have been previously described as having potent anti-proliferative activity against MDA-MB-231 and HCT116 cancer cell lines. The mechanism by which these molecules prevent cancer cell growth is proposed to be through interfering with phospholipid metabolism via inhibition of PI-PLC, along with other cellular processes. Previously, 5-cinnamyl derivatives of these thieno[2-3-b]pyridines have been shown to have enhanced anti-proliferative activity compared to compounds lacking this moiety, indicating a tethered aromatic ring is important for this western region of the pharmacophore. Herein, we report the synthesis and biological evaluation of a library of 40 novel thieno[2-3-b]pyridine analogues containing shorter benzoyl or secondary benzyl alcohol tethers at the 5-position, in addition to various substituents on the two phenyl rings present on the molecule. Compounds bearing alcohol functionality had improved efficacy compared to their benzoyl counterparts, in addition to a 2-methyl-3-halogen substitution on the 2-arylcarboxamide ring being important for maximising anti-proliferative activity. The most potent molecules 7h and 7i demonstrated IC50 concentrations of 25-50 nM against HCT116 and MDA-MB-231 cells, a similar level of activity as previous thienopyridine compounds bearing cinnamyl moieties, suggesting that these novel derivatives with shorter tethers were able to maintain potent anti-proliferative activity, while allowing for a more concise synthesis.

Stereospecific Cu(I)-Catalyzed C-O Cross-Coupling Synthesis of Acyclic 1,2-Di- and Trisubstituted Vinylic Ethers from Alcohols and Vinylic Halides.

CuI and trans-N,N'-dimethylcyclohexyldiamine catalyze the single-step C-O bond cross-coupling between 1,2-di- and trisubstituted vinylic halides with functionalized alcohols, producing acyclic vinylic ethers. This stereospecific transformation selectively gives each of the (E)- and (Z)-vinylic ether products from the corresponding vinyl halide precursors. This method is compatible with carbohydrate-derived primary and secondary alcohols and several other functional groups. The conditions are mild enough to reliably generate vinylic allylic ethers without promoting Claisen rearrangements.

RuPHOX-Ru catalyzed asymmetric Guerbet reaction of secondary alcohols with primary alcohols

An efficient RuPHOX-Ru catalyzed asymmetric Guerbet reaction of secondary alcohols with a broad scope of primary alcohols has been developed, affording long-chain chiral alcohols in high yields with excellent enantioselectivities (up to 99% yield and 96% ee). In particular, alkyl primary alcohols could also react to give the desired products with good results. The protocol could be performed on a gram-scale, providing an alternative pathway with minimal environmental impact and high atom-economy for the preparation of chiral alcohol products.

2,2′-Biphenol-Derived Phosphoric Acid Catalyst for the Dehydrative Esterification of Carboxylic Acids with Alcohols

AbstractA dehydrative esterification from an equimolar mixture of carboxylic acids and primary or secondary alcohols in toluene at 100 °C was promoted without the necessity to remove water by using a simple 2,2′-biphenol-derived phosphoric acid catalyst (2.5–10 mol%). This reaction was also successfully conducted at the gram scale. To demonstrate the synthetic utility of this catalytic system, pharmaceutically useful substrates and acid-sensitive substrates were examined using these acid–base cooperative phosphoric acid catalysts, which exhibit relatively weak Brønsted acidity.

Application of Prussian Blue Analogue‐Derived Mn−Co Catalysts in the Hydrogenation of CO to Higher Alcohols

AbstractMnxCo3‐x[Co(CN)6]2 Prussian blue analogues were synthesized with Mn : Co ratios in the range from 7 : 10 to 1 : 11 and pyrolyzed at 600 °C to obtain a highly nitrogen‐ and oxygen‐functionalized carbon matrix with embedded reduced Mn and Co species. These catalyst precursors were applied in the CO hydrogenation to higher alcohols at 260 °C and a pressure of 60 bar using a H2/CO ratio of 1. Metallic Co0 formed during pyrolysis was partially transformed into Co2C under reaction conditions. With increasing Co content CO conversion increased up to 10.6 % reaching a total alcohol selectivity of 19 %. Gas chromatograms revealed the expected formation of primary short‐chain alcohols, but also of secondary alcohols, acetic acid and propionaldehyde indicating olefin hydration, carbonylation and hydroformylation as reaction pathways, respectively. The obtained hydrocarbon fractions had a very high olefinicity, which is beneficial for both olefin hydration to secondary alcohols catalyzed by adsorbed carboxylic acids and for hydroformylation. Whereas the carbide‐based reaction pathway and the reductive hydroformylation are assumed to occur at the Co2C/Co0 interface, carbonylation is presumably catalyzed by an additional Co‐based active site. Thus, a unique class of multifunctional catalysts was obtained with highly promising properties bridging the gap between heterogeneous and homogeneous catalysis.

Atmospheric saccharides over the East China Sea: Assessment of the contribution of sea-land emission and the aging of levoglucosan

A one-year observation of aerosols on a remote island was conducted and saccharides were applied to reveal the behaviors of organic aerosol in the East China Sea (ECS). The seasonal fluctuations of total saccharides were relatively small, with annual mean concentration of 64.82 ± 26.88 ng/m3, contributing 10.20 % and 4.90 % to WSOC and OC, respectively. However, the individual species showed significant seasonal variations due to the differences in both the emission sources and the influencing factors between marine and terrestrial areas. Anhydrosugars was the highest species and showed little diurnal variation in air mass from land areas. Primary sugars and primary sugar alcohols showed higher concentrations in blooming spring and summer and were higher in daytime than nighttime due to intense biogenic emissions both in marine and mainland areas. Accordingly, secondary sugar alcohols showed obvious different diurnal variation with ratios of day/night reducing to 0.86 in summer but even increasing to 1.53 in winter, attributing to the additional impact of secondary transmission process. Source appointment suggested that biomass burning emission (36.41 %) and biogenic emission (43.17 %) were the main causes of organic aerosol, while anthropogenic related secondary process and sea salt injection accounted for 13.57 % and 6.85 %, respectively. We further elucidate that the biomass burning emission might be underestimated, as levoglucosan undergoes degradation processes in the atmosphere, which are affected by various atmospheric physicochemical factors, and the degradation degree is particularly severe in remote areas like the oceans. In addition, significantly low ratio of levoglucosan to mannosan (L/M) occurred in air mass from marine area, indicating that levoglucosan was likely be more fully aged after hovering over a large-scale of oceanic area.

Application of methyl itaconate–anthracene adducts (MIAs) in configuration assignment of chiral primary amines by means of 1H NMR

Methyl itaconate–anthracene adducts (MIAs) were previously introduced as chiral derivatizing agents (CDAs) for the determination of chiral secondary alcohols. In this study, they were further employed with chiral primary amines to assign their absolute configuration. Each chiral amine compound was linked to the (R)- and (S)-MIAs through amidation to obtain diastereomeric amides in moderate yield. The modified Mosher's method was applied, where the difference in chemical shift (ΔδSR = δHS−MIA-amide – δHR−MIA-amide) values of each substituent of the chiral amine adducts was utilized to validate the capability of MIAs as CDAs. Finally, the proposed model was successfully achieved, and the MIAs were proven effective for the determination of the absolute configuration of chiral amines.

Steering the Selectivity of Electrocatalytic Glucose Oxidation by the Pt Oxidation State.

Electrocatalytic glucose oxidation can produce high value chemicals, but selectivity needs to be improved. Here we elucidate the role of the Pt oxidation state on the activity and selectivity of electrocatalytic oxidation of glucose with a new analytical approach, using high-pressure liquid chromatography and high-pressure anion exchange chromatography. It was found that the type of oxidation, i.e. dehydrogenation of primary and secondary alcohol groups or oxygen transfer to aldehyde groups, strongly depends on the Pt oxidation state. Pt0 has a 7-fold higher activity for dehydrogenation reactions than for oxidation reactions, while PtOx is equally active for both reactions. Thus, Pt0 promotes glucose dialdehyde formation, while PtOx favors gluconate formation. The successive dehydrogenation of gluconate is achieved selectively at the primary alcohol group by Pt0, while PtOx also promotes the dehydrogenation of secondary alcohol groups, resulting in more complex reaction mixtures.

Steering the Selectivity of Electrocatalytic Glucose Oxidation by the Pt Oxidation State

AbstractElectrocatalytic glucose oxidation can produce high value chemicals, but selectivity needs to be improved. Here we elucidate the role of the Pt oxidation state on the activity and selectivity of electrocatalytic oxidation of glucose with a new analytical approach, using high‐pressure liquid chromatography and high‐pressure anion exchange chromatography. It was found that the type of oxidation, i.e. dehydrogenation of primary and secondary alcohol groups or oxygen transfer to aldehyde groups, strongly depends on the Pt oxidation state. Pt0 has a 7‐fold higher activity for dehydrogenation reactions than for oxidation reactions, while PtOx is equally active for both reactions. Thus, Pt0 promotes glucose dialdehyde formation, while PtOx favors gluconate formation. The successive dehydrogenation of gluconate is achieved selectively at the primary alcohol group by Pt0, while PtOx also promotes the dehydrogenation of secondary alcohol groups, resulting in more complex reaction mixtures.

Copper(I)-BOX Catalyzed Asymmetric 3-Component Reaction for the Synthesis of Trifluoromethylated Propargylic Ethers and Anilines.

An asymmetric 3-component reaction between EthynylBenziodoXoles (EBXs), 2,2,2-trifluorodiazoethane and nucleophiles catalyzed by a Cu(I)-BOX (Bisoxazoline) catalyst is described. This protocol gives access to chiral trifluoromethylated propargyl ethers and anilines, which are valuable building blocks in synthetic and medicinal chemistry. The reaction proceeds with high enantioselectivity and yield with different nucleophiles such as primary, secondary and tertiary alcohols, as well as both electron-rich and electron-poor anilines. Aryl-, alkyl- and silyl-substituted alkynes can be successfully introduced as electrophiles. In case of chiral substrates, high catalyst control was observed, leading to good diastereoselectivity.

Copper (I)‐BOX Catalyzed Asymmetric 3‐Component Reaction for the Synthesis of Trifluoromethylated Propargylic Ethers and Anilines**

AbstractAn asymmetric 3‐component reaction between EthynylBenziodoXoles (EBXs), 2,2,2‐trifluorodiazoethane and nucleophiles catalyzed by a CuI‐BOX (Bisoxazoline) catalyst is described. This protocol gives access to chiral trifluoromethylated propargyl ethers and anilines, which are valuable building blocks in synthetic and medicinal chemistry. The reaction proceeds with high enantioselectivity and yield with different nucleophiles such as primary, secondary and tertiary alcohols, as well as both electron‐rich and electron‐poor anilines. Aryl‐, alkyl‐ and silyl‐substituted alkynes can be successfully introduced as electrophiles. In case of chiral substrates, high catalyst control was observed, leading to good diastereoselectivity.

Novel Strategies for Enantio- and Site-Selective Molecular Transformations.

A strategy for symmetric synthesis based on dynamic chirality of enolates (memory of chirality) has been developed. Asymmetric alkylation, conjugate addition, aldol reaction, and arylation via C-N axially chiral enolate intermediates are described. Asymmetric alkylation and conjugate addition via C-O axially chiral enolate intermediates with a half-life of racemization as short as approx. 1 s. at -78 °C have been accomplished. Organocatalysts for asymmetric acylation and site-selective acylation have been developed. Kinetic resolution of racemic alcohols via remote asymmetric induction by the catalyst is shown. Catalyst-controlled site-selective acylation of carbohydrates and its application to total synthesis of natural glycoside are described. Chemo-selective monoacylation of diols and selective acylation of secondary alcohols with reversal of inherent reactivity are also discussed. Geometry-selective acylation of tetrasubstituted alkene diols is achieved, where acylation takes place independent from the steric environments of the substrates.

Comparative studies of functional groups present in invasive and economically important plant leaf methanolic extracts by using FTIR spectroscopic analysis

Low molecular weight substances known as secondary metabolites (SM) are essential for plants’ interaction with their surroundings but are not necessary for plants to survive. Plants extracts have traditional uses against many pathogens. These substances frequently play a role in plants' defense against biotic (bacteria, fungi, nematodes, insects, or animal grazing) or abiotic (increased temperature and moisture, shade, damage, or heavy metal presence) stresses. The FTIR approach was applied with an FTIR spectroscopy instrument, which is used to identify functional groups and characteristic peak values of phytoconstituents. The chemical properties of these plants can be used to understand their therapeutic potential, which could be a creative way to develop affordable, safe, and effective herbal remedies to treat a variety of ailments. The current study focuses on functional group screening using FTIR. The analysis found that the extract has various typical peak values associated with various functional Groups like alcohol, phenol, alkanes, amino acids, aldehyde, aromatic compound, secondary alcohol, phenol, and carboxylic acids. When compared to the leaf extracts of Callistemon subulatus, Centella asiatica, Catharanthus roseus, Moringa oleifera, and Carica papaya, the leaf extracts of Catharanthu roses, Centella asiatica had the highest number of functional groups. This functional group could positively act as modulating metabolic processes and may act as receptor and enzyme inhibitors.

Catalytic Acceptorless Dehydrogenation (CAD) of Secondary Benzylic Alcohols into Value-Added Ketones Using Pd(II)-NHC Complexes.

For the creation of adaptable carbonyl compounds in organic synthesis, the oxidation of alcohols is a crucial step. As a sustainable alternative to the harmful traditional oxidation processes, transition-metal catalysts have recently attracted a lot of interest in acceptorless dehydrogenation reactions of alcohols. Here, using well-defined, air-stable palladium(II)-NHC catalysts (A-F), we demonstrate an effective method for the catalytic acceptorless dehydrogenation (CAD) reaction of secondary benzylic alcohols to produce the corresponding ketones and molecular hydrogen (H2). Catalytic acceptorless dehydrogenation (CAD) has been successfully used to convert a variety of alcohols, including electron-rich/electron-poor aromatic secondary alcohols, heteroaromatic secondary alcohols, and aliphatic cyclic alcohols, into their corresponding value-added ketones while only releasing molecular hydrogen as a byproduct.

NNN Pincer-Manganese-Catalyzed Guerbet-Type β-Alkylation of Alcohols under Microwave Irradiation

A series of manganese carbonyl complexes based on bis(imino)pyridine ligands of the type R2NNN (R = Cy, iPr, Ph, p-FC6H4) were synthesized. While the complex appears to be an NN bidentate-Mn(I) triscarbonyl species in the solid state, in solution, there is a gradual loss of carbon monoxide leading first to an NNN pincer-Mn(I) biscarbonyl complex, which finally disproportionates to an NNN pincer-Mn(II) dibromide and an NNN pincer-Mn(0) complex. Evidence for this transformation has been obtained from single-crystal X-ray diffraction, IR, EPR, and HRMS analysis. The loss of carbon monoxide is apparently faster with a cyclohexyl-substituted complex than with others. The considered complexes (0.05 mol %) were utilized for catalyzing the β-alkylation of secondary alcohols at 140 °C in air under conventional heating (12 h), as well as under microwave heating (2 h) in the presence of 2.5 mol % of NaOtBu. Among the considered complexes, the catalyst (p-FC6H4NNN)Mn(CO)2Br was found to be highly efficient. While under conventional heating, a maximum of 92% (1840 TON at 153 TOs/h) of the β-alkylated product was obtained; microwave heating provided the β-alkylated product in 85% yield (1700 TON at 850 TOs/h) in just 2 h. The catalytic system has been successfully implemented to alkylate several other secondary alcohols, as well (35 examples). IR, EPR, and HRMS analyses indicate the intermediates in the catalytic cycle to be based both on NNN pincer-Mn(I) biscarbonyl species and on an NNN pincer-Mn(II)/Mn(0) couple. Deuterium labeling studies point to the involvement of C–H bond activation in the rate-determining step (RDS) with a kinetic isotope effect (KIE) of 9.0.