Diol Units Research Articles

New Synthetic Route to (3-Glycidoxypropyl)trimethoxysilane-Based Hybrid Organic−Inorganic Materials

Hybrid organic−inorganic materials have been obtained by cohydrolysis of (3-glycidoxypropyl)trimethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) in acidic conditions. Boron trifluoride diethyl etherate (BF3OEt2) has been used to catalyze the epoxide polymerization. The effect of BF3OEt2 has been studied by multinuclear magnetic resonance (NMR) in the precursor sol and by Fourier transform infrared spectroscopy in the final material. The addition of BF3OEt2 to a prereacted sol of GPTMS and TEOS has allowed the epoxide ring opening at room temperature, without formation of diol units or boric acid precipitation in the final material. The prereaction time of GPTMS with TEOS has been found to be an important parameter. The catalytic effect of BF3OEt2 with respect to other commonly used catalysts in sol−gel processing of GPTMS-based hybrid organic−inorganic materials, such as zirconium butoxide and 1-methylimidazole, has been studied.

An NMR study of chain transfer to diols containing both primary and secondary hydroxy groups in the polymerization of ɛ-caprolactone

A. Kavros, T. N. Huckerby and S. Rimmer, J. Mater. Chem., 1999, 9, 1071 DOI: 10.1039/A810010A

The effect of structural variations on the properties of polycarbonates susceptible to thermolytic or acidolytic degradation

Abstraet-Copolycarbonates containing thermosensitive cycloallylic, benzylic, or tertiary diols were synthesized in solution from bis(imidazolecarboxylate)s or bis(4-nitrophenylcarbonate)s under phase-transfer conditions. By variation of the diol component, fully amorphous as well as crystalline materials were obtained. The molar masses Mn varied from 1500 to 9000 g/mol. Depending on the structure, the polymers decomposed between 194°C (with tertiary diol units) and 243 °C (without tertiary diol units) in a clean and fast process liberating volatile products which could be identified by GC/MS. We found carbon dioxide, the original diols, and dienes formed by elimination reactions to be the main decomposition products. The thermal stability is drastically reduced in the presence of acids. This fact renders these polymers in the presence of a photochemical acid generator (PAG) suitable for applications in imaging systems, which was shown in lithographic experiments.

Wholly aromatic thermotropic liquid crystalline polyesters of 2‐(α‐phenylisopropyl)hydroquinone; copolymers with 1,1′‐biphenyl‐4,4′‐diol and 2,6‐dihydroxynaphthalene

Two series of new aromatic copolyesters have been synthesized and their properties including liquid crystallinity have been studied. The first series was synthesized by polymerizing mixtures of diacetates of 2-(α-phenylisopropyl)hydroquinone and 1,1′-biphenyl-4,4′-diol with terephthalic acid, and the second by polymerizing mixtures of diacetates of 2-(α-phenylisopropyl)hydroquinone and 2,6-dihydroxynaphthalene with terephthalic acid. These polyesters were characterized by differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffractomerty, and optical microscopy. The glass transition temperatures of the first series decrease from 167 to 138°C as one increases the content of the 1,1′-biphenyl-4,4′-diol unit to 50 mol %. The Tg values of the second series are slightly higher than those of the first series, and appear to be less dependent on their composition. The degree of crystallinity of the first series decreases rapidly by copolymerization, much faster than that of the second series. The melting points of the first series copolymers are significantly lower than those of the second series. All of the copolyesters reported in this investigation form nematic melts. The initial decomposition temperatures of the copolymers were higher than 450°C. It was confirmed that thermal stability of the homopolyester, PIBPL-1.00, containing the isopropylidene units is significantly improved when compared with that carrying benzylic hydrogens. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2777–2786, 1997

Wholly aromatic thermotropic liquid crystalline polyesters of 2-(?-phenylisopropyl)hydroquinone; copolymers with 1,1?-biphenyl-4,4?-diol and 2,6-dihydroxynaphthalene

Two series of new aromatic copolyesters have been synthesized and their properties including liquid crystallinity have been studied. The first series was synthesized by polymerizing mixtures of diacetates of 2-(α-phenylisopropyl)hydroquinone and 1,1'-biphenyl-4,4 '-diol with terephthalic acid, and the second by polymerizing mixtures of diacetates of 2-(α-phenylisopropyl)hydroquinone and 2,6-dihydroxynaphthalene with terephthalic acid. These polyesters were characterized by differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffractomerty, and optical microscopy. The glass transition temperatures of the first series decrease from 167 to 138°C as one increases the content of the 1,1'-biphenyl-4,4'-diol unit to 50 mol %. The T g values of the second series are slightly higher than those of the first series, and appear to be less dependent on their composition. The degree of crystallinity of the first series decreases rapidly by copolymerization, much faster than that of the second series. The melting points of the first series copolymers are significantly lower than those of the second series. All of the copolyesters reported in this investigation form nematic melts. The initial decomposition temperatures of the copolymers were higher than 450°C. It was confirmed that thermal stability of the homopolyester, PIBPL-1.00, containing the isopropylidene units is significantly improved when compared with that carrying benzylic hydrogens.

New chemical hydrogels based on poly(vinyl alcohol)

The syntheses of two new types of chemical hydrogels based on poly(vinyl alcohol), PVA, are reported. Common to both synthetic routes is the preparation of a telechelic PVA (tel-PVA) obtained by periodate splitting of the vicinal diol units present in few percent along the chain. tel-PVA was then used as crosslinking agent with chitosan and PVA in two simple reactions in aqueous phase such as reductive alkylation of chitosan and acetalyzation of PVA. Both reactions yielded firm wall-to-wall networks showing marked differences in their swelling capability. © 1996 John Wiley & Sons, Inc.

Molecular design of artificial sugar sensing systems

For the development of new receptor molecules that can precisely recognize sugar molecules, we synthesized a number of diboronic acids. Since one boronic acid can react with two OH groups (one diol group) to form a boronate ester, one diboronic acid can immobilize two diol units to form a sugarcontaining macrocycle. The selectivity can be tuned by the relative spatial position of the two boronic acids and the complexation event can be read out by circular dichroism spectroscopy. When a boronic acid group is combined intramolecularly with an amino-methylfluorophore, the complexation event can be conveniently read out by fluorescence spectroscopy. This is a novel application of a PET (photoinduced electron transfer) sensor: the sugar-binding changes the strength of the B … N interaction, which eventually changes the fluorescence quenching efficiency of the amine. We have demonstrated using a chiral 1,1′-binaphthyl group as a fluorophore that even chiral recognition of sugars is possible. These abundant examples support the superiority of boronic-acidbased covalent bond recognition over hydrogen-bond-based non-covalent bond recognition for sugars in water.

Compositional sequence distribution in unsaturated polyesters as revealed by 13C n.m.r. spectroscopy

A series of model unsaturated polyesters derived from maleic anhydride and various diols were synthesized and a study of their structures was carried out by means of 13C n.m.r. spectroscopy. The n.m.r. spectra of polyesters produced by different procedures are reported and interpreted in terms of variety in the arrangement of diol components. Both fumarate and ester carbon atoms were found to be sensitive to compositional differences in the polyester chains. Diversity of the diol—fumarate—diol sequences was evidenced to account for the observed splitting of the resonances. Assignment of the peaks to different compositional sequences was accomplished through systematic alterations in polyester composition. The contributions of individual sequences were calculated assuming random and block distribution of diol units and compared with the experimental results. The comparison confirmed the validity of the assignment as well as the efficiency of the approach in the description of diol unit distribution in unsaturated polyesters.

Synthesis and characterization of liquid crystalline polysiloxanes with “two‐chain” diol units in the side chain

AbstractThe synthesis and the thermal behaviour of different polysiloxanes containing cis,cis‐(3,5‐dihydroxycyclohexyl) 3,4‐bis(alkoxy)benzoate mesogens (“two‐chain” diol unit) in the side chain are described. Aggregation via intermolecular hydrogen bonding between different “two‐chain” diol units leads to the formation of mesomorphic supramolecular structures. The phase behaviour changes drastically by variation of the dimethylsiloxane content of the backbone. Thus, the homopolysiloxane is the first example of a polymer with a thermotropic cubic mesophase, being observed below a hexagonal columnar one. However, the copolymers exclusively form the hexagonal columnar mesophase. The thermal transitions of all polymers, investigated by means of differential scanning calorimetry (DSC) as well as by polarizing microscopy, are discussed. The mesophase structures have been determined by X‐ray measurements in combination with miscibility studies.

N.m.r. study of maleate ( cis)—fumarate ( trans) isomerism in unsaturated polyesters and related compounds

Unsaturated polyesters and dicarboxy diesters from maleic anhydride and various diols were investigated by means of 1H and 13C nuclear magnetic resonance spectroscopy. The carbons of diol units were found to be sensitive to maleate/fumarate transformation, enabling the process to be followed in detail. The cis—trans isomerism of dicarboxy diesters was described and related to the structure of the corresponding diols. The effects induced by the isomerism were examined separately for various carbons and, in the case of 1,2- propylene glycol, direct evidence was provided of the preference of CH over CH 2 groups in promoting the trans isomer. The results of the study on dicarboxy diesters along with data concerning the distribution of diol units along the chain were utilized to interpret the isomerism of unsaturated mixed polyesters.

The synthesis of a catechol-based bis(ether anhydride) and poly(ether imide)s derived therefrom

This work reports the development of nitrodisplacement reactions between catechol and nitrophthalodinitriles, thus providing a bis(ether anhydride) and high-molecular-weight, thermally stable poly(ether imide)s with ortho-linked units. These polymers are far more soluble and more readily processable than corresponding polymers with para- and meta-linked diol units.

A novel drug delivery system utilizing a glucose responsive polymer complex between poly (vinyl alcohol) and poly ( N-vinyl-2-pyrrolidone) with a phenylboronic acid moiety

A novel polymer complex system sensitive to glucose was studied as a candidate material for formulating a chemically regulated insulin delivery system. A phenylboronic acid (PBA) moiety was incorporated in poly( N-vinyl-2-pyrrolidone) [poly(NVP-co-PBA) ] as a glucose sensor molecule by the radical copolymerization of N-vinyl-2-pyrrolidone with m-acrylamidophenylboronic acid. Complex formation as well as dissociation was estimated by viscosity changes in the complex solution. A positive viscosity change was observed for the poly (vinyl alcohol) (PVA)/poly(NVP-co-PBA) complex system due to complex formation between PVA diol units and poly(NVP-co-PBA) boronate units; minimal or no change in viscosity was observed for either PVA/boric acid or PVA/poly(NVP). The viscosity of the PVA/poly(NVP-co-PBA) system is able to be controlled through changes in polymer molecular weight and/or polymer concentration. The maximum point in viscosity was observed at a molar ratio of PVA to poly (NVP-co-PBA) of 4:1 in this system. The diol-boronate complex interaction was further investigated by following decreased complex viscosity with the addition of a competitive polyol: glucose, tris(hydroxymethyl)aminomethane (TRIS) or (±)-3-amino-1,2-propanediol (APD). The viscosity decreased steeply when glucose was added while minimal change in viscosity was observed when either TRIS or APD was added. This suggested that the chemical structure of the diol compound had an important role in exchange with the diol-boronate complex. These results point to the promising use of PVA/poly(NVP-co-PBA) complex systems in the development of a novel glucose responsive insulin release system.

キラルなビスアリリックジオールを用いる鎖状立体化学制御の新手法

A method for differentiating allylic diastereofaces of carbon-carbon double bonds has been developed based on the ground state molecular design of allylic compounds in which a protected vicinal (S, S) - or (R, R) -diol unit is incorporated as a controller. The protected vicinal diol groups, if they are the most bulky substituents, should arrange anti to each other and the remaining medium-sized groups involving the allylic carbon-carbon double bonds, for instance, stay gauche accordingly. This situation allows only a pair of diastereofaces exposed outside to be attacked by external reagents because a remaining pair of diastereofaces is mutually shielded from intermolecular processes. Such diastereo-bias has been successfully and diversely employed in diastereoselective processes such as double Michael reaction, osmium tetraoxide-catalyzed vicinal hydroxylation, halo-etherification, and Diels-Alder reaction, giving rise to exceptionally high diastereomeric excess for every case examined, appealing prospect for wide applicability in selective organic syntheses.

Preparation and reactivity of polyepoxides and polyketones: catalytic oxidation of polybutadienes

The epoxidation of polybutadienes containing varying proportions of pendant (1,2-polymerized) and backbone (1,4-polymerized) double bonds with ButOOH catalysed by [MoO2Cl2(3-diethoxyphosphoryl)camphor]{systematic name: dichloro [(IR)-endo-(+)-3-(diethoxyphosphoryl)camphor] dioxomolybdenum(VI)}, gives very high selectivity to epoxidation of the backbone double bonds. In the absence of molecular sieves some diol units are produced, but addition of molecular sieves (4A) prevents the formation of diols and greatly increases the rate of the reaction. With [Pt(Ph2PCHCHPPh2)CF3(CH2Cl2)]BF4 as catalyst and ButOOH as oxidant, polyketones are formed with pendant: trans : cis reactivities in the ratio 6 : 5 : 3. The introduction of ketonic functions on the pendant double bonds allows functionalisation on the carbon atom next to the main chain, a position that is otherwise difficult to functionalise. The polyepoxides are found to be unreactive towards ring-opening reactions with water, alcohols, amines etc., although ring-opening is observed in reactions with alcohols or carboxylic acids under forcing conditions in the presence of H2SO4 as a catalyst. Ring-opening is also observed with aryllithium reagents although BunLi gives allyl alcohol units in the backbone of the polymer. The polyketones are more susceptible to reaction, e.g. with 6-lithio-2,2′-bipyridyl and soluble polymer-bound bipyridyl is readily synthesised. The polymers are characterised by 1H and 13C NMR studies.

Effect of the incorporation of amino groups in a glucose‐responsive polymer complex having phenylboronic acid moieties

AbstractA novel polymer complex system sensitive to glucose was studied as a candidate material for formulating a chemically regulated insulin release system. A ternary copolymer of N‐vinyl‐2‐pyrrolidone (NVP), 3‐acrylamidophenylboronic acid (AAm‐PBA) and N,N‐dimethylaminopropylacrylamide (DMAPAA) (poly(NVP‐co‐PBA‐co‐DMAPAA)) was synthesized by radical copolymerization. The phenylboronic acid group in this copolymer serves as a glucose sensor moiety. Poly(NVP‐co‐PBA‐co‐DMAPAA) was soluble in water in the pH range of 3–12, in sharp contrast to a binary copolymer of NVP and AAm‐PBA (poly(NVP‐co‐PBA)) which showed solubility only under alkaline aqueous conditions, where the boronic acid group is in a tetrahedral ionized form. The protonated amino group in poly(NVP‐co‐PBA‐DMAPAA) contributed to increase the solubility of the polymer under physiological and acidic aqueous conditions. Furthermore, poly(NVP‐co‐PBA‐co‐DMAPAA) formed a stable polymer complex gel with poly(vinyl alcohol) (PVA) in pH 7.4 phosphate buffered solution due to the formation of a covalent linkage between the boronic acid groups in ternary copolymer and diol units in PVA. The release of myoglobin as model protein from the complex gel was increased immediately after the addition of glucose, due to the transition of gel into sol state, indicating the feasibility of this complex gel as a candidate material for a glucose‐responsive delivery system for insulin.

Structural elucidation and antigenicity of a novel phenolic glycolipid antigen from Mycobacterium haemophilum

The structure of a novel antigenic glycolipid that distinguishes the opportunistic pathogen Mycobacterium haemophilum from all other mycobacteria was established by a series of degradation reactions leading to products that were analyzed by gas/liquid chromatography-mass spectrometry. The complete structure of the oligosaccharide unit was determined as 2,3-di-O-CH3-alpha-L-Rhap(1----2)3-O-CH3-alpha-L-Rhap(1----4 )-2,3-di-O-CH3-alpha-L-Rhap(1----. The lipid portion of the phenolic glycolipid was composed of two component phenolphthiocerols differing by two methylene groups, as determined by analysis of their per-O-trideuteriomethylated derivatives. The diol unit of the phenolphthiocerols has a threo relative configuration. The absolute stereochemistry of the asymmetric centers of the phenolphthiocerols is uncertain, but the centers are probably 3R, 4S, 9R, and 11R as found for phthiocerol A from Mycobacterium tuberculosis. The hydroxyl functions of the branched glycolic chain are esterified to a complex mixture of multi-methyl branched mycocerosic acids, C27, C30, C32, C34, and C37 with molecular weights (as methyl esters) of 424, 466, 494, 522, and 564, respectively. The stereochemistry of the methyl branches of the mycocerosates have R absolute configuration. The glycolipid is highly antigenic and appears to be specific for M. haemophilum. There are intriguing similarities between the product from M. haemophilum and the well-known phenolic glycolipid I of Mycobacterium leprae, a matter that is discussed.

Amphiphilic propane-l,2-diol derivatives incorporating calamitic structural units

Abstract Novel amphiphilic propane-1,2-diol derivatives incorporating a wide variety of calamitic structural units, like biphenyl, dicyclohexyl. phenylbemzoate, phenyl pyrimidine and phenylthiadiazole, were synthesized and their mesomorphic behaviour studied. Most of these compounds exhibit broad smectic A and C mesophases in the water-free state. These mesophases could be stabilized further by addition of water. The transition temperatures depend mainly on the hydrophilic properties of the rigid core and on the length of the spacer by which the core is connected to the diol unit.

The liquid-crystalline behaviour of amphiphilic ethane-1,2-diol derivatives incorporating a six membered ring in their principal structure

Abstract Novel 3-phenyloxy substituted propane-1,2-diol derivatives, 4-(4-n-hexyloxyphenyl)-butane-1,2-diol and 4-(trans-4-n-pyropylcyclohexyl)-butane-1,2-diol have been synthesized and their thermal behaviour has been studied. These compounds exhibit thermotropic and, after addition of water, also lyotropic liquid-crystalline behaviour. The clearing temperatures of the smectic mesophases were found to be strongly dependent on the alkyl chain length and on the structural units that link the aromatic ring to the alkyl chain and to the diol unit. The behaviour of the aromatic compounds is compared with that of the cyclohexane derivative. Thereby it has been realized that the mesophase stability of the amphiphilic diols incorporating a rigid unit is largely determined by both, the molecular geometry (molecular shape and intramolecular flexibility) and the amphiphilic structural pattern.

Alcoholysis of esterlinkages in solution

AbstractPoly(alkylene adipate)diols having molar masses of 1500, 2000 and 3000 were stored at temperatures of 25 and 60°C in the presence of low amounts of different alcohols and some polyurethane (PUR) catalysts, such as dibutyltindilaurate (DBTL), dibutyltindiethoxide (DBTEO), dibutyltinoxide (DBTO), and 1,4‐diazabicyclo[2.2.2]octane (DABCO). Alcoholysis was studied using either ethyl acetate (EA) or toluene as solvent. The results were compared with those obtained by examining the behaviour of several dialkyl adipates and ethyl acetate under identical conditions. The alcoholysis in the presence of the tin catalysts proceeds at the same reaction rate without significant decomposition of the catalyst, whereas DABCO is practically inactive. The nucleophilic activity of the alcohols depends on their bulk size rather than their basicity. The resistance of polyalkylene adipates to transesterification increases with the increasing alkyl chain length of diol units in polyester. A partial transesterification of dialkyl adipates takes place too, in spite of ethyl acetate being present in excess.

Characteristic new members of the phthiocerol and phenolphtiocerol families from Mycarbacterium ulcerans

Mycobacterum ulcerans: Lipids, Phthiocerol family; Phenolphthiocerol family