Alcohol Backbone Research Articles

Sequestration of Cr (VI) from water using agar-polyvinyl alcohol based cation exchanger

Present study focuses on the use of a biodegradable and cost-effective cation exchanger for removal of Cr (VI) metal ions from water sources. Semi-IPN was prepared through grafting of acrylamide onto agar-polyvinyl alcohol backbone in presence of boric acid and ammonium per sulphate as crosslinker-initiator system. Graft copolymer was converted to cation exchanger through phosphorylation. Characterization was done using methods such as FTIR, SEM-EDX and XRD. Semi-IPN exhibited higher thermal resistance. The findings revealed that the optimum conditions for Cr (VI) removal are pH = 4.0; contact time (min) = 360; adsorbent dose (mg) = 125 and metal ion concentration(mg/L) =2. The adsorption kinetics of Cr (VI) ions are best fit by the pseudo second order kinetic with 0.99 R2 and Kf (rate constant) was found to be 0.97 thereby supporting the Freundlich isotherm. The adsorption isotherm models used in this study were consistent with the Freundlich model, but the pseudo second order model was the most accurate description of the adsorption kinetics. The present investigation showed an excellent potential with 85 % adsorption capacity for the removal of Cr (VI). Moreover, reusability studies showed that the cation exchanger can be used effectively up to four cycles.

Nonionic nontoxic antimicrobial polymers: indole-grafted poly(vinyl alcohol) with pendant alkyl or ether groups

A series of new nonionic antimicrobial polymers with a biodegradable polyvinyl alcohol (PVA) backbone grafted with indole units and different hydrophobic alkyl or ether groups were synthesized by facile esterification.

Mammalian Toxicity Testing of Semilinear and Branched Alcohol Ethoxylates

AbstractAlcohol ethoxylates (AE) are commonly used nonionic surfactants with widespread adoption in consumer and industrial applications. The toxicology profile of this general class of molecules has been extensively reported previously. This report serves to make accessible previously unpublished toxicological data from 59 toxicology studies on AE produced from branched and semilinear alcohols produced by ExxonMobil, with alcohol backbones ranging from C9 to C15. Information on acute oral toxicity, acute dermal toxicity, genetic toxicity, skin irritation, eye irritation, skin sensitization, and oral repeat‐dose toxicity are presented here. These data significantly enrich the database on the toxicity of branched AE and support that the degree of branching presents no unique toxicological hazards in relation to that of semilinear AE in this report, as well as in comparison with similar data published on a range of linear, semilinear, and branched AE.

Dynamic bonded supramolecular binder enables high-performance silicon anodes in lithium-ion batteries

Silicon-based lithium ion battery is reckoned as an ideal choice owing to its ultrahigh theoretical capacity and rich natural resources. However, its practical application is largely hampered by the low Coulombic efficiency (CE) and fast capacity decay arising from the substantial volumetric variations and the unstable solid-electrolyte interphase (SEI). Herein, we propose a binder-based optimization, where a three-dimensional (3D) binder network is devised with organic polyvinyl alcohol (PVA) backbones cross-linked by a functional boric acid (BA). Apart from the improved mechanics, B–OH bond is able to set a chemical bridge between the binder and Si surface by dehydration with Si–OH group, which enables the coherent link with Si surface. More importantly, the electron deficient B element readily accepts electrons during the cell formation and thus facilitates the buildup of an effective SEI film. The obtained lithium borate species significantly reduce the interfacial side reactions and improve the initial Coulombic efficiency (ICE). After optimization of the key parameters, a high ICE (92.76%) with excellent rate capability (~2920.73 mAh g−1 at 10 C) is obtained. After 500 cycles, the Si anode retained a capacity of ~1883.7 mAh g−1, massively outperforming the pure PVA-based Si counterpart (~317.9 mAh g−1).

Enzymatic Synthesis and Stereocomplex Formation of Chiral Polyester Containing Long-Chain Aliphatic Alcohol Backbone.

Herein we demonstrated a novel lipase-catalyzed synthesis of isotactic D-/L-poly(aspartate-octanediol) ester containing long chain alcohols backbone and discovered their stereocomplex feature with an increased Tm for the first time. Simple design of monomer structures not only overcomes the inherent selectivity limitation of enzyme used, but also achieves totally isotactic polyester products. By crystallizing the mixed enantiopure isotactic polyesters in different solvents, the formation of amorphous mixture, homocrystallites or stereocomplex crystallites were observed, respectively. This study is expected to open up a new way to prepare various stereocomplex polyesters containing a long-chain aliphatic alcohol backbone and a wide variety of functional groups.

In-situ crosslinked SPPO/PVA composite membranes for alkali recovery via diffusion dialysis

Diffusion dialysis (DD) integrated with cation exchange membranes (CEMs) is eco-friendly separation process, which has been extensively used for base recovery in various separation industries. The development of cost-effective and suitable CEMs is highly desirable to enhance process efficiency. In this work, we describe the development of SPPO/PVA composite membranes (SPVA) composed of sulfonated poly (2, 6-dimethyl-1, 4-phenylene oxide) (SPPO) and polyvinyl alcohol (PVA) backbones crosslinked with glutaraldehyde (GA). The flux was improved via PVA while SPPO catalyzed the in-situ crosslinking else induced cation channels. The anion selectivity was tuned by various amounts of GA. The physio-chemical properties of the prepared membranes such as water uptake(WR), cation exchange capacity (CEC) and mechanical stability, confirmed the appropriateness of prepared membranes for DD application. The influence of GA concentration on the base recovery and the separation factor was explored and discussed in details. The membranes showed WR within the range of 56–85% with CEC values of 1.37–1.42 mmol g−1, respectively. The base recovery (mentioned as UOH−) and separation factor (S) were found in the range of 0.00255–0.0107 m h−1 and 45–261, respectively. Moreover, the representative membranes (SPVA-50 and SPVA-100) displayed excellent operational stability for ten consecutive cycles and validated the membrane's potential for long term application.

Optimized Association of Short Alkyl Side Chains Enables Stiff, Self-Recoverable, and Durable Shape-Memory Hydrogel.

This work reports a self-healing and shape-memory hydrogel integrating multiple mechanical properties. The network configuration is featured as entangled networks cross-linked by distributed association of very short alkyl chains (hexyl, six carbons). These cross-linking knots are interconnected by the long hydrophilic polyvinyl alcohol backbone. The optimal aggregation of hexyl side chains leads to the broadened distribution in bonding strength as verified by static and dynamic mechanical characterization. These structural features contribute to high strength, toughness, stiffness, and yet fast recoverability. Furthermore, the hydrophobic and supramolecular nature of aggregated alkyl chains offers high durability and solvent-assistant healing function. Finally, distributed association of hexyl side chains confers a broadened temperature-dependent modulus, allowing for encoding stepwise shape recovery from a temporary shape at different temperatures and/or times.

Synthesis and characterization of chain-extended and branched polyurethane copolymers as form stable phase change materials for solar thermal conversion storage

In this work, polyethylene glycol (PEG) based polyurethane copolymer was synthesized using linear chain extension and branching methods. In linear chain extension, multiple PEG molecules were linked using urethane bonds. In branching, polyvinyl alcohol (PVOH) backbone was grafted with PEG molecules as branches and cross-linked to other PVOH molecules. 4,4′-Diphenylmethane di-isocyanate (MDI) was used as both chain extender and cross-linker. The resulting copolymers were characterized for chemical composition, microscopic morphology, crystalloid structure and thermal properties. Based on the results from characterizations, a detailed discussion on the phase change mechanism in polyurethanes is presented. 1H NMR and FT-IR results confirmed the chain extension and branching. 1H NMR spectra displayed characteristic signal of the urethane. DSC results revealed solid-solid phase change behavior of copolymers with high latent heat. Crystalline nature of spherulite lamellae structures was verified by observing birefringence using POM microscope and XRD peaks. Polyurethane copolymers had maximum latent heat absorption capacity of 144.14 kJ kg−1 at melting temperature of 51 ℃ and had maximum heat release capacity of 117.5 kJ kg−1 at freezing temperature of 33 ℃. Polyurethane copolymers were thermally stable up to 200 ℃. Polyurethane copolymers satisfied all criteria for use as form stable solid-solid phase change material (SSPCM) in solar thermal conversion storage.

SYNTHESIS AND COMPUTATIONAL CALCULATIONS OF NOVEL CHIRAL BIS-1,2,3-TRIAZOLE DERIVATIVES

The one-pot synthesis of novel bis-1,2,3-triazole derivatives from homopropargyl alcohol backbones is described. The key intermediates chiral 2-benzothiophenyl (-)-1 and 2-benzofuranyl (-)-2 substituted homopropargyl alcohols are synthesized from their corresponding carboxyaldehyde derivatives by O-propargylation and enzymatic resolution. Enantiomerically enriched homopropargyl alcohol derivatives are reacted with diiodo benzene and sodium azide via one-pot synthesis method and novel chiral bis-benzofuranyltriazole (-)-3 and bis-benzothiophenyltriazole (-)-4 are constructed without isolation of potentially toxic and unstable organic azide intermediates. Article DOI: https://dx.doi.org/10.20319/mijst.2017.32.165176 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Improving mechanical and electrical properties of poly(vinyl alcohol-g-acrylic acid) nanocomposite films by reinforcement of thermally reduced graphene oxide

Graphene has drawn an astounding research interest in recent years, owing to its exceptional properties. The scaled-up and trustworthy production of graphene derivatives, such as graphene oxide (GO) and thermally reduced graphene oxide (TRGO), offer wide variety of possibilities to synthesize graphene-based polymer materials for various applications. In the present work, poly(vinyl alcohol-g-acrylic acid) films were prepared by grafting polyacrylic acid chains onto polyvinyl alcohol backbone employing a free radical polymerization system in the presence of crosslinking agent, N,N′-methylenebisacrylamide (MBA). The graphene was homogeneously dispersed into the prepared polymer using thermal mechanical agitation technique. The so prepared nanocomposites were undertaken for structural and morphological characterization using FTIR, SEM, XRD, Raman Spectroscopy, DLS, Zetasizer and AFM analysis, respectively. The electrical conductive and mechanical properties of prepared nanocomposite films were also investigated.

Stereoselective synthesis of benzofuran and benzothiophene substituted dihydropyran derivatives via ring closing metathesis

Ring closing metathesis reactions have been applied to diene and enyne systems derived from homoallylic alcohol backbones are described. The key intermediates 2-benzofuranyl 1a and 2-benzothiophenyl 1b substituted homoallylic alcohols were synthesized from their corresponding carboxaldehyde derivatives. Racemic 2-heteroaryl-substituted homoallylic alcohols are successfully resolved to give the corresponding enantiopure acetates and alcohols with 80–99% ee through enzymatic resolution by various lipases. Enantiomerically enriched diene and enyne skeletons derived from homoallylic alcohols were subjected to the ring closing metathesis via first and second generation Grubbs’ catalysts and the corresponding chiral heteroaryl-substituted dihydropyran derivatives were obtained with good yields (41–96%).

Isoquinoline-substituted triazole and pyran derivatives: synthesis and computational studies

The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazoles from isoquinoline-substituted homopropargyl alcohol backbone is described (42%-88% yields). A ring closing metathesis reaction and an intramolecular Pauson-Khand reaction of enyne system derived from a homopropargyl alcohol backbone to afford the corresponding isoquinoline-substituted dihydropyran and cyclopentenone-pyran, respectively, are also described (54% and 78% yields). Information about the structural, electronic, and physico-chemical properties of the novel compounds, obtained by density functional theory application, is also reported.

Chemoenzymatic synthesis of novel 1,4-disubstituted 1,2,3-triazole derivatives from 2-heteroaryl substituted homopropargyl alcohols

The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazoles from homopropargyl alcohol backbones is described. The key intermediates 2-benzothiophenyl 1a and 2-benzofuranyl 1b substituted homopropargyl alcohols were synthesized starting from their corresponding carboxyaldehyde derivatives. The racemic heteroaryl-substituted homopropargyl alcohol derivatives are successfully resolved to give the corresponding enantiopure acetates and the alcohols with 84–99% ee by applying chemoenzymatic methods using various lipases. Enantiomerically enriched homopropargyl alcohol derivatives were reacted with various aromatic and aliphatic halides and sodium azide via a one-pot synthesis method and novel chiral benzothiophenyltriazoles 3a–9a and benzofuranyltriazoles 3b–9b were constructed without the isolation of potentially unstable organic azide intermediates.

Linear, Mannitol-Based Poly(anhydride-esters) with High Ibuprofen Loading and Anti-Inflammatory Activity.

Sugar alcohols, such as mannitol and xylitol, are biocompatible polyols that have been used to make highly cross-linked polyester elastomers and dendrimers for tissue engineering and drug delivery. However, research that utilizes the secondary hydroxyl groups as sites for pendant bioactive attachment and subsequent polymerization is limited. This work is the first report of a linear, completely biodegradable polymer with a sugar alcohol backbone and chemically incorporated pendant bioactives that exhibits sustained bioactive release and high bioactive loading (∼70%). With four pendant esters per repeat unit, this poly(anhydride-ester) has high loading and biodegrades into three biocompatible products: bioactive, sugar alcohol, and alkyl-based diacid. Ibuprofen serves as a representative bioactive, whereas mannitol is a representative polyol. Polymerization was achieved through reaction with (trimethylsilyl)ethoxyacetylene. Drug release via polymer degradation was quantified by high performance liquid chromatography. Additionally, a cytocompatibility study with fibroblast cells was performed to elucidate the polymer's suitability for in vivo use and a cyclooxygenase-2 (COX-2) assay was performed on the degradation media to ensure that released ibuprofen retained its anti-inflammatory activity. This work enables the future development of novel, biodegradable polymers exhibiting two key features: (i) polymer backbones with easily modified pendant groups, such as targeting moieties, and (ii) high drug loading using a multitude of bioactive classes.

Regioselective one-pot synthesis of 1,4-disubstituted 1,2,3-triazole derivatives

Abstract The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazole derivatives derived from homopropargyl alcohol backbones has been accomplished. Triazoles are obtained in good yields from a variety of readily available aromatic and aliphatic halides without isolation of potentially unstable organic azide intermediates.

Chemoenzymatic route to various spirocyclic compounds based on enantiomerically enriched tertiary allylic, homoallylic, and homopropargylic alcohols

A ring closing metathesis (RCM) reaction of dienes and an intramolecular Pauson–Khand (PKR) reaction of enynes derived from tertiary allyl, homoallyl, and homopropargyl alcohol backbones to afford the corresponding spirocyclic dihydrofuran and dihydropyrans and spirocyclic cyclopentenone pyrans, respectively, are described. Cyclopent-2-ene anchored tertiary allyl, homoallyl, and homopropargyl alcohols 1a–c have been efficiently resolved via enzymatic resolution with high ee (up to 90%) with 44%, 40%, and 43% chemical yields, respectively. Moreover, the cyclohex-2-ene anchored tertiary allyl, homoallyl, and homopropargyl alcohols 3a–c have also been resolved in the same manner with high ee (up to 97%) and in 42%, 45%, and 49% chemical yields. Enantiomerically enriched dienes derived from tertiary homoallyl alcohols yield the corresponding enantiomerically enriched spirocyclic dihydropyran derivatives via RCM with 74% and 78% chemical yields and with 90% and 97% ee, respectively. Moreover, enantiomerically enriched enynes derived from tertiary homoallyl alcohols afford the corresponding enantiomerically enriched cyclopentenone pyrans with spirocyclic motifs via PKR with 80% and 81% chemical yields, respectively, and as single diastereomers.

Synthesis and biological evaluation of optically active conjugated γ- and δ-lactone derivatives

An efficient synthesis of racemic and both enantiomeric forms of heteroaryl substituted γ- and δ-lactone derivatives derived from allyl and homoallyl alcohol backbones has been accomplished via ring closing metathesis reaction. 2-Heteroaryl substituted allyl and homoallyl alcohols have been efficiently resolved through enzymatic method with high ee (97–99%) and known stereochemistry. Antimicrobial and antioxidant activities of target lactones were evaluated.

Stereoselective synthesis of optically active cyclopenta[c]pyridines and tetrahydropyridines

The intramolecular Pauson–Khand and ring closing metathesis (RCM) reactions of nitrogen containing chiral enynes and dienes are described. The enyne and diene systems comprised of N-propargylated and N-allylated units are constructed on chiral homoallylic or homopropargylic alcohol backbones, respectively, via SN2 and/or modified Mitsunobu reactions. The racemic homoallylic and homopropargylic alcohol derivatives were successfully resolved in high ee (93–99%) by applying chemoenzymatic methods using various lipases such as PS-C II, Lipozyme, and CAL-B. Each enantiomerically enriched enyne afforded the most conformationally stable diastereomeric cyclopenta[c]pyridine ring system as the sole product, whereas enantiomerically enriched dienes gave tetrahydropyridine derivatives as a result of intramolecular Pauson–Khand and RCM reactions, respectively.

Stereoselective synthesis of optically active dihydrofurans and dihydropyrans via a ring closing metathesis reaction

A ring closing metathesis reaction of dienes and a ring closing enyne metathesis reaction derived from allyl, homoallyl and homopropargyl alcohol backbones are described. 2-Heteroaryl substituted allyl, homoallyl and homopropargyl alcohols have been easily and efficiently resolved through enzymatic resolution with high ee (93–99%) and known stereochemistry. Enantiomerically enriched dienes derived from allyl and homoallyl alcohols afforded the corresponding enantiomerically enriched dihydrofuran and dihydropyran derivatives, respectively, with chemical yields which varied between 72% and 88%. On the other hand, enantiomerically enriched enynes derived from homoallyl and homopropargyl alcohols gave the corresponding optically active dihydropyrans with conjugated diene units with chemical yields between 70% and 80%. A subsequent Diels–Alder reaction of the dihydropyran derivatives with a diene unit with tetracyanoethylene resulted in the formation of a diastereomeric dihydroisochromene ring system as the sole product.

Development of a Photolabile Carbonyl-Protecting Group Toolbox

New salicyl alcohol derived photolabile carbonyl protecting groups have been developed, and the effect of substituents on the photochemical properties of photolabile protecting groups (PPGs) has been studied. The 3-(dimethylamino)phenyl groups at the α position prove to be important to the efficiency of the deprotection reactions, as shown in the photo reactions of the acetal 9. On the other hand, expansion of the salicyl alcohol's benzene skeleton to naphthalene does not improve the photochemical properties of PPGs. A neutral protecting protocol has been generalized to new PPGs with α,α-diaryl salicyl alcohol backbone. Thus, installation of PPGs onto aldehydes is readily achieved at 140 °C without using any other chemical reagents. These PPGs are stable under acidic conditions typical for hydrolyzing acetals and constitute orthogonal protecting groups with traditional 1,3-dioxane/1,3-dioxolane for carbonyl compounds. Highly efficient release of carbohydrate molecules is demonstrated, which can be potentially useful in site-specific release and immobilization of carbohydrates for preparation of high-density microarrays. With the enriched PPG toolbox, PPGs are divided into three subgroups based on their UV absorption profiles. PPGs from different subgroups can be sequentially removed by using different UV irradiation wavelengths. For PPGs absorbing UVA (λ >315 nm), photochemical deprotection can be carried out with sunlight in high yields.