Structure Of Diol Research Articles

A Preliminary Study of Thermosets from Epoxy Resins Made Using Low-Toxicity Furan-Based Diols.

Glycidyl ethers are prepared from a series of furan-based diols and cured with a diamine to form thermosets. The furan diols demonstrate lower toxicity than bisphenol-A in a prior study. The diglycidyl ethers show improved thermal stability compared to the parent diols. Cured thermosets are prepared at elevated temperature using isophorone diamine (IPDA). Glass transition temperatures are in the range of 30-54 °C and depend on the structure of the furan diol. Coatings are prepared on steel substrates and show very high hardness, good adhesion, and a range of flexibility. Properties compare favorably with a control based on a bisphenol-A epoxy resin. The study demonstrates that epoxy resins based on furan diols, which have been shown to have lower toxicity than bisphenol-A, can form thermosets having properties comparable to a standard epoxy resin system; and thus, are viable as replacements for bisphenol-A epoxy resins.

Synthesis and properties of polyurethane acrylate oligomer based on polycaprolactone diol

Abstract The polycaprolactone diol (PCL diol) was prepared by ring-opening polymerization method, with hydroquinone bis(2-hydroxyethyl) ether as the reactive initiator and ε-caprolactone as the monomer. The polyurethane acrylate (PUA) was prepared with the self-made PCL diol. Then, PUA was used to prepare the ultraviolet curable coatings. The structure and molecular weight of PCL diol was characterized by Fourier transform infrared spectroscopy, gel-permeation chromatography, and hydroxyl value titration. The performance of the cured coating film was characterized by thermogravimetric analysis and scanning electron microscope. The flexibility and hardness of the cured coating film were tested. The results showed that the narrow molecular weight PCL diol was successfully synthesized. The UV curing coating film had the optimal performance with a hardness of 3H, flexibility of 1.5 mm, abrasion resistance of 0.028 g−1, and adhesion of grade 1, all coating films showed good thermal properties.

Heat-Resistant Polyurethane Coatings

Polyurethane varnishes synthesized using complex aromatic oligoester diols. The coatings obtained from the varnishes are temperature resistant. The influence of the molecular mass and the structure of aromatic oligoester diol, as well as the origin of isocyanate, are studied from the standpoint of influencing coating properties. A composition of polyurethane varnish is found that makes heat-resistant coatings featuring a wide range of physical, mechanical, and protective properties.

Synthetic scheme to increase the abrasion resistance of waterborne polyurethane–urea by controlling micro‐phase separation

AbstractAs an environmental‐friendly coating material in industry, waterborne polyurethane–urea (WPU) is still not comparable with solvent‐based polyurethane (SPU) in mechanical properties, due to the hydrophilic chain‐extender. Herein, a synthetic scheme to increase the abrasion resistance of WPU with ether diol, and conventional hydrophilic chain‐extender (DMBA, 2,2‐bis[hydroxymethyl]butanoic acid) is revealed. This study discuss the degree of micro‐phase separation (DPS) with toughness, elongation, abrasion resistance, and compared with the WPU contain various types of diol, such as esters, ether and carbonates, and the ether‐based SPU. From the results, the major factor that affect to the abrasion properties of WPU is DPS, which is highly depend on the chemical structure of diol, and hard segment content. WPU film achieve higher toughness with ether‐based diol with higher DPS, and better abrasion resistance than SPU. This study demonstrate a strategy for the composition designing, and the synthesis of high‐abrasion resistance WPU by controlling the micro‐phase separation, and content of DMBA without any inorganic fillers.

Eco-friendly waterborne coating from bio-based polyester amide resin

The vegetable oil-based waterborne polyurethane coatings have gained significant interest due to low volatile organic compounds, and hence, this has been considered as a proper substitute to the commonly used solvent-borne coating systems. In the present work, we have developed the polyurethane coatings from diethanolamide of fatty acid and dicarboxylic acid (sebacic acid and succinic anhydride)-based poly(esteramide) resin as a diol along with 2,2′-dimethylol propionic acid and isophorone diisocyanate. The chemical structure of bio-based diol and PU coatings was elucidated by FTIR and 1H NMR spectroscopy. The polyurethane dispersions (PUDs) prepared were analysed by particle size analysis and stability. The mahua oil-based PUDs were coated on the metal panels and the cured material obtained was characterized by the physico-mechanical, chemical resistance and the thermal properties which were compared with the petroleum resource-based PUDs. The PUD coatings showed good physico-mechanical properties, chemical resistance and thermal stability. Hence, the dispersion prepared from bio-based diols may find application as eco-friendly coatings.

Thermally Stable Bio-Based Aliphatic Polycarbonates with Quadra-Cyclic Diol from Renewable Sources

CM diol (i.e., 2,4:3,5-di-O-camphor-D-mannitol) is bio-based monomer derived from D-mannitol and camphor. CM diol consists of complex hexagonal rings that are linked as the form of spiro, fused and bridged ring and the structure of CM diol influence the rigidity and thermal properties. Primary alcohol at the ends of CM diol is more reactive than secondary alcohol in isosorbide which is applied for the field of polycarbonate. A series of copolycarbonates based on CM diol was synthesized and a homo-polycarbonate except bisphenol A (BPA) diol had a high Tg value of 164 °C, which is higher than T g (138 °C) of polycarbonates based on BPA (BPA-PC). In addition, the polycarbonates containing CM diol showed enhanced susceptibility to hydrolysis at acidic solution and decomposed better than BPA-PC.

Grafting polycaprolactone diol onto cellulose nanocrystals via click chemistry: Enhancing thermal stability and hydrophobic property

Hydrophobic and thermally-stable cellulose nanocrystals (CNCs) were synthesized by polycarpolactone diol (PCL diol) grafting via click chemistry strategy. The synthesis was designed as a three-step procedure containing azide-modification of CNCs, alkyne-modification of PCL diol and sequent copper(I)-catalyzed azide–alkyne cycloaddition reaction. The structure of azide-modified CNCs and alkyne-modified PCL diol, the structure, hydrophobic ability and thermal stability of click products CNC-PCL were characterized. FTIR, XPS and H1 NMR results indicated a successful grafting of the N3 groups onto the CNCs, synthesis of PCL diol-CCH, and formation of the CNC-PCL material. CNC-PCL had enhanced dispersion in the non-polar solvent chloroform owing to the well-maintained microscale size and PCL-induced hydrophobic surface. The thermal stability of CNC-PCL was largely increased due to the grafting of thermally-stable PCL. This work demonstrates that click chemistry is an attractive modification strategy to graft CNCs with polyester chains for further potential application in polymer composites.

Synthesis and Characterization of Novel Polyurethanes Based on N,N'-1,2-Ethanediylbis-(4-Hydroxy-Pentanamide) and 4-Hydroxy-N-(2-Hydroxyethyl)-Pentanamide

As diols, N,N'-1,2-ethanediylbis-(4-hydroxy-pentanamide) (1) and 4-hydroxy-N-(2-hydroxyethyl)-pentanamide (2)) are versatile precursors for the manufacture of bio-polymers. Polymer design, by exploiting the variation in structure of both diol and di-isocyanate monomers, such as backbone structure and presence of functional groups, appears to be a promising biopolymer engineering pathway to synthesize polyurethanes. Both diols (1) and (2) were then polymerized by reaction with aliphatic and aromatic di-isocyanates at 140 °C in (N,N-dimethylacetamide (DMA) solvents using triethylamine (TEA) catalysts, to obtain novel polyurethanes. The products were characterized by FTIR, 1H-NMR, 13C-NMR, and Elemental Analysis. This working has created a new chance to synthesis bio-polyurethanes based on levulinic acid, as one of biomass compounds

A green approach toward oleic‐ and undecylenic acid‐derived polyurethanes

AbstractNaturally occurring oleic and undecylenic acids were used as raw materials for the synthesis of novel polyurethanes (PUs). The application of environmentally friendly thiol‐ene additions to 10‐undecenoate and oleate derivatives was studied with the goal of obtaining renewable diols. The resulting monomers were then polymerized with 4,4′‐methylenebis (phenylisocyanate), in N,N‐dimethylformamide solution using tin (II) 2‐ethylhexanoate as catalyst, to produce the corresponding thermoplastic PUs (TPUs). Also, ultrasound irradiation has been tested to improve the synthesis of PU. Under these conditions, TPUs were obtained in high yields (80–99%) with weight‐average molecular weights in the 36–83 kDa range. The chemical structures of PUs were assessed by FTIR and NMR spectroscopy. The thermal and mechanical properties of the synthesized TPUs have been studied and they showed a clear dependence on the structure of the parent diol. MTT test was carried out to asses the potential cytotoxicity of the prepared PUs, indicating no cytotoxic response. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Helical Tubuland Diols: A Synthetic and Crystal Engineering Quest

Despite many advances in recent years, crystal engineering remains a risky venture. A successful outcome requires manipulation of the noncovalent bonding and properties such as size, shape, repulsion, attraction, polarity, and chirality. In this Account, we describe the interplay of crystal engineering and synthetic organic chemistry required to develop the family of helical tubuland diol hosts, the members of which exhibit a wide range of tube dimensions and inclusion properties. Certain alicyclic dialcohols crystallize with a hydrogen-bonded network structure, termed the helical tubuland lattice, in space group P3(1)21 (or its enantiomorph P3(2)21). Double helices of diol molecules surround parallel tubes that contain guest molecules, which are included on the basis of size and shape rather than functional group. The crystal structure of (diol)(3).(chloroacetic acid)(1.2) is illustrative. These chiral helical tubulate lattice inclusion compounds are formed when the racemic host diol is allowed to crystallize from solution. Complete enantiomer separation occurs during this process, producing a 1:1 mixture of pure (+)- and pure (-)-crystals (a conglomerate). The challenge of creating this family of compounds required the development of much synthetic chemistry, in particular new pathways to alicyclic ring systems with specific substitution patterns. It was also necessary to understand and control the supramolecular properties of the diol molecules. What makes the original compound tick, and why did it behave in this remarkable manner, when most of its structural neighbors crystallize totally differently? The synthesis of new helical tubuland diols requires not just preparation of a new molecular structure but also a transplant of the original unchanged hydrogen-bonding supramolecular synthon. Synthesis of the specific crystal space group is necessary. This was achieved by defining structural characteristics, termed molecular determinants, which are essential for the helical tubuland structure to occur. If these requirements were met, then the target molecule had a high probability of success. This investigation has close conceptual parallels with the search for pharmacophore properties of bioactive molecules. In both situations, parts of a molecule with little or no chemical reactivity may actually play vital supramolecular roles. The review illustrates how crystal engineering is based on specific supramolecular properties that can be uncovered and then exploited by synthetic chemists.

Catalytic Enantioselective Allyl- and Crotylboration of Aldehydes Using Chiral Diol•SnCl4 Complexes. Optimization, Substrate Scope and Mechanistic Investigations

We report a novel class of C2-symmetric chiral diols derived from the hydrobenzoin skeleton. The combination of these diols with SnCl4 under Yamamoto's concept of Lewis acid assisted Brønsted acidity (LBA catalysis) leads to high levels of asymmetric induction in the allylboration of aldehydes by commercially available allylboronic acid pinacol ester 1a. The corresponding homoallylic alcohol products of synthetically useful aliphatic aldehydes are obtained in excellent yields with up to 98:2 er. This combined acid manifold is also efficient in catalyzing the diastereo- and enantioselective crotylboration of aldehydes, thus providing the propionate units in >95:5 dr and up to 98:2 er. The X-ray crystal structure of the optimal diol x SnCl4 complex, Vivol (4m) x SnCl4, unambiguously shows the Brønsted acidic character of this LBA catalyst and its highly dissymmetrical environment. Further controls have ruled out a possible boron trans-esterification mechanism with the chiral diol and point to LBA catalyst-derived activation of the pinacol allylic boronates 1. Due to slow dissociation of the diol x SnCl4 complex, a small excess of diol is required in order to suppress a competing racemic cycle catalyzed by free SnCl4.

Moisture‐cured polyurethane/polysiloxane copolymers: Effects of the structure of polyester diol and NCO/OH ratio

AbstractMoisture‐cured polyurethane is one of the commercially important polymers, which is widely used in sealants, coatings, and reactive hot‐melt adhesives. A series of moisture‐cured polyurethane/polysiloxane (PUSR) copolymers were successfully prepared using a two‐step solution polymerization procedure. Both amine‐terminated polysiloxane (PDMS) and polyester diol were together used as mixed soft segments to react with 4,4′‐diphenlymethane diisocyanate (MDI), and the alkoxysilane was used as end‐capping agents. The effects of structure variation of building blocks such as the polyester diol structure and NCO/OH ratio on the properties and morphology of PUSR copolymers were studied. The tensile properties, dielectric behavior, thermal stability, surface, and water‐repellency properties were investigated. The results showed that the properties and morphology of PUSR copolymers were greatly affected by the variations in molecular architecture. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Synthesis, characterization of novel dihydrazide containing polyurethanes based on N1,N2‐bis[(4‐hydroxyphenyl)methylene]ethanedihydrazide and various diisocyanates

AbstractFour novel types of polyurethanes (PUs) were prepared from N1,N2‐bis[(4‐hydroxyphenyl)methylene]ethanedihydrazide with two aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate and tolylene 2,4‐diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate). The chemical structure of both diol and PUs was confirmed by UV–vis, fluoroscence, FTIR, 1H NMR, and 13C NMR spectral data. DSC data show that PUs have multiple endotherm peak. X‐ray diffraction revealed that the PUs contained semicrystalline and amorphous regions that varied with the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Stereoselective Transacetalization of 1,1,3,3-Tetramethoxypropane andN-Benzoylaminodiols

The transacetalization of 1,1,3,3-tetramethoxypropane and an N-benzoylaminodiol provided stereoselectively the corresponding 2,5-disubstituted-1,3-dioxanes. The stereochemistry of the rings formed in the transacetalization depended on the structure of the amino diol, and the ratio of the products depended on the reaction conditions, as expected. This kind of stereoselective transacetalization not only gives a series of useful building blocks but also generates interesting 1,3-dioxanes which target protein kinase C.

Stereoselective Transacetalization of 1,1,3,3-Tetramethoxypropane andN-Benzoylaminodiols

The transacetalization of 1,1,3,3-tetramethoxypropane and an N-benzoylaminodiol provided stereoselectively the corresponding 2,5-disubstituted-1,3-dioxanes. The stereochemistry of the rings formed in the transacetalization depended on the structure of the amino diol, and the ratio of the products depended on the reaction conditions, as expected. This kind of stereoselective transacetalization not only gives a series of useful building blocks but also generates interesting 1,3-dioxanes which target protein kinase C.

Radical catalysis of B12 enzymes: structure, mechanism, inactivation, and reactivation of diol and glycerol dehydratases.

Enzymatic radical catalysis is defined as a mechanism of catalysis by which enzymes catalyze chemically difficult reactions by utilizing the high reactivity of free radicals. Adenosylcobalamin (coenzyme B12) serves as a cofactor for enzymatic radical reactions. The recent structural analysis of adenosylcobalamin-dependent diol dehydratase revealed that the substrate 1,2-propanediol and an essential potassium ion are located inside a (beta/alpha)8 barrel. Two hydroxyl groups of the substrate coordinate directly to the potassium ion which binds to the negatively charged inner part of the cavity. Cobalamin bound in the base-on mode covers the cavity to isolate the active site from solvent. Based on the three-dimensional structure and theoretical calculations, a new mechanism for diol dehydratase is proposed in which the potassium ion plays a direct role in the catalysis. The mechanisms for generation of a catalytic radical by homolysis of the coenzyme Co-C bond and for protection of radical intermediates from undesired side reactions during catalysis are discussed based on the structure. The reactivating factors for diol and glycerol dehydratases have been identified. These factors are a new type of molecular chaperone which participate in reactivation of the inactivated holoenzymes by mediating ATP-dependent exchange of the modified coenzyme for free intact coenzyme.

Structure of an unusual cage dimer diol

The title compound arises from an unexpected rearrangement and oxidation. The molecules contain a center of symmetry and are held together by hydrogen bonds. The relatively strain-free molecules are closely packed with a density of 1.441 g cm−3. The compound crystallizes in space group P-1 with cell dimensions a = 8.999(3), b = 9.142(2), c = 8.625(3) A, α = 95.47(3), β = 105.06(3), and γ = 83.08(2)° There are two independent molecules per cell with each sitting on a center of symmetry.

Synthesis and proof of stereostructure of a new (+)-isomenthone-derived homochiral 1,3-diol

Diastereopure (+)-isomenthone-derived ketoalcohol 2 was converted to the homochiral 1,3-diol 6 either by direct reduction or reduction of silyl protected derivatives. The diastereomeric preference of the reduction was the same in all cases. Reduction of 2 with NaBH4 gave essentially a single diastereomer, while reduction with LiAlH4 gave ∼6:1 selectivity in favour of the same diastereomer. Reduction of the silyl protected substrates 7 and 8 gave, after column chromatography, 98% yield of a single diastereomer, desilylation of which established this to be the same diastereomer as obtained through hydride reductions of unprotected 2. The structure of diol 6 was proven through coupling data and NOE experiments at 600 MHz. Overall, two stereochemistry introducing steps have elaborated the two stereogenic centres of (+)-isomenthone to the five contiguous stereogenic centres of 6.

The X-ray crystal structure, conformation and preparation of anti-3,3,6,6-tetramethylthiepane-4,5-diol: stereochemistry of reduction of a heterocyclic α-hydroxy ketone

The X-ray crystal structure and conformation of the anti title diol is described together with stereoselective syntheses of syn- and anti-diols from a readily available acyloin. Some control of the stereoselective reduction of α-hydroxy ketones by chelating and non-chelating reducing agents is possible.

Cerium(III) chloride mediated addition of mono- and dilithium ferrocene to (+)-camphor and (−)-fenchone: synthesis and structure of new chiral ferrocenyl alcohols and diols

Cerium(III) chloride activated (+)-camphor ( 1) and (−)-fenchone ( 2) react with lithiated ferrocene (reagent 3, (Li-Cp) 2Fe/LiCp-FeCp = 50:1) to give the corresponding optically active ferrocenyl diols 4 and 6 and monosubstituted ferrocenyl alcohols 5 and 7. The preparation of the diols 4 and 6, as well as of the alcohols 5 and 7 respectively, in high yields is optimized depending on the composition of the lithiated ferrocenes (reagent 3 contains mainly 1,1′-dilithium ferrocene; reagent 8 contains mainly monolithium ferrocene) and on the amounts (stoichiometric, diminished or catalytic) of the CeCl 3 used for activation of the ketones 1 and 2. The catalytic CeCl 3 promotion (5 mol%) of the addition reactions of reagents 3 and 8 to 1 and 2 respectively is observed only in the case of fenchone ( 2). The new optically active ferrocenyl alcohols 4, 5, 6 and 7 have been studied in detail by NMR, MS and IR spectroscopy. The crystal structure of diol 4 has been determined, and shows an unusual eclipsed conformation of the ferrocenyl moiety, possibly a result of the observed strong intramolecular hydrogen bond formation.