Pendant Hydroxyl Research Articles

Syntheses, structures, and properties of two dinuclear palladium (II) complexes of a single macrocyclic hexaaza ligand with two hydroxyethyl pendants

Two dinuclear palladium (II) complexes, trans-[Pd 2LCl 2](ClO 4) 2 · 2H 2O and cis-[Pd 2LCl 2]Cl 2 · 2H 2O, of a single macrocyclic ligand with two hydroxyethyl pendants, L (L = 3,6,9,16,19,22-hexaaza-6,19-bis(2-hydroxyethyl)tricyclo[22,2,2,2 11,14]triaconta-1,11,13,24,27,29-hexaene), have been synthesized as “inorganic proteases” and analyzed by X-ray diffraction method. The two complexes-mediated hydrolytic cleavage of amide bond in acetyl methionyl alanine has been monitored by 1H NMR, showing a moderate hydrolytic rate at 50 °C and pH ca. 1.0. The pendent hydroxyl group is responsible for the hydrolytic reaction.

Biodegradable polymers based on renewable resources. IX. Synthesis and degradation behavior of polycarbonates based on 1,4:3,6‐dianhydrohexitols and tartaric acid derivatives with pendant functional groups

AbstractNovel polycarbonates, with pendant functional groups, based on 1,4:3,6‐dianhydrohexitols and L‐tartaric acid derivatives were synthesized. Solution polycondensations of 1,4:3,6‐dianhydro‐bis‐O‐(p‐nitrophenoxycarbonyl)hexitols and 2,3‐di‐O‐methyl‐L‐threitol or 2,3‐O‐isopropylidene‐L‐threitol afforded polycarbonates having pendant methoxy or isopropylidene groups, respectively, with number average molecular weight (Mn) values up to 3.61 × 104. Subsequent acid‐catalyzed deprotection of isopropylidene groups gave well‐defined polycarbonates having pendant hydroxyl groups regularly distributed along the polymer chain. Differential scanning calorimetry (DSC) demonstrated that all the polycarbonates were amorphous with glass transition temperatures ranging from 57 to 98 °C. Degradability of the polycarbonates was assessed by hydrolysis test in phosphate buffer solution at 37 °C and by biochemical oxygen demand (BOD) measurements in an activated sludge at 25 °C. In both tests, the polycarbonates with pendant hydroxyl groups were degraded much faster than the polycarbonates with pendant methoxy and isopropylidene groups. It is noteworthy that degradation of the polycarbonates with pendant hydroxyl groups was remarkably fast. They were completely degraded within only 150 min in a phosphate buffer solution and their BOD‐biodegradability reached nearly 70% in an activated sludge after 28 days. The degradation behavior of the polycarbonates is discussed in terms of their chemical and physical properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3909–3919, 2005

Functionalization of poly(ε-caprolactone) by pendant hydroxyl, carboxylic acid and epoxide groups by atom transfer radical addition

A straightforward strategy is proposed for grafting hydroxyl, carboxylic acid and epoxide groups along poly(ε-caprolactone) chains. Statistical copolymerization of ε-caprolactone (εCL) with α-chloro-ε-caprolactone (αClεCL) has been initiated by 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP), followed by the atom transfer radical addition (ATRA) of but-3-en-1-ol, vinylacetic acid and 1,2-epoxyhex-5-ene, respectively, onto the α-chloro units of a poly(αClεCL-co-εCL) copolymer. αClεCL is easily prepared by the Baeyer–Villiger oxidation of 2-chlorocyclohexanone. The influence of the experimental conditions, i.e. temperature, solvent, catalyst, on the grafting yield has been discussed. Because ATRA is tolerant of the investigated functional groups, no protection/deprotection reaction is required, which is a major advantage of the method.

Novel Functionalized Biodegradable Polymers for Nanoparticle Drug Delivery Systems

We have prepared and screened a library of novel functionalized polymers for development of nanoparticle drug delivery systems. The polymer backbone consisting of two ester-linked, nontoxic, biological monomers, glycerol and adipic acid, was prepared using a hydrolytic enzyme. The specificity of the chosen enzyme yields a linear polymer with one free pendant hydroxyl group per repeat unit, which can be further functionalized. This protocol gives control over the backbone polymer molecular weight, together with the ability to incorporate various amounts of different fatty acyl substituents. These functionalized polymers are able to self-assemble into well-defined small particles of high homogeneity with a very low toxicity. They are able to incorporate a water soluble drug, dexamethasone phosphate, with a high efficiency and drug loading which varies with the polymer specification. The above characteristics strongly suggest that these polymers could be developed into useful nanoparticulate drug delivery systems.

One-Pot Regio- and Stereoselective Cyclization of 1,2,n-Triols

A simple and efficient process to cyclize triols containing a 1,2-diol functionality with a pendant hydroxyl group is presented. The one-pot procedure converts the 1,2-diol into an ortho ester in situ, which upon treatment with a Lewis acid generates a cyclic acetoxonium intermediate. This intermediate is subsequently trapped by the pendant hydroxyl group to generate a cyclic ether. The stereochemistry of the 1,2-diol is transferred to the product with complete fidelity (inversion at the site of cyclization), and the reaction proceeds with high regioselectivity. The process is akin to the Lewis acid-catalyzed intramolecular ring-opening of epoxides with hydroxyl groups yielding cyclic ethers of various sizes with regio- and stereochemical control.

Combining Two‐Directional Synthesis and Tandem Reactions: Synthesis of Trioxadispiroketals.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Amphiphilic Poly((R,S)-β-malic acid)-graft-poly(ε-caprolactone): “Grafting From” and “Grafting Through” Approaches

The synthesis of novel amphiphilic graft copolyesters based on hydrophobic poly(ε-caprolactone) (PCL) segments grafted all along a hydrophilic poly((R,S)-β-malic acid) (PMLA) backbone is proposed. These PMLA-g-PCL graft copolymers have been prepared in a controlled way using either the “grafting through” or the “grafting from” technique. Both approaches involve two different well-controlled ring-opening polymerization (ROP) mechanisms: anionic ROP of β-lactones, i.e., benzyl or allyl β-malolactonate (MLABz or MLAAllyl), and living ROP of ε-caprolactone (CL) through a so-called coordination−insertion mechanism. The grafting through approach relies upon the anionic copolymerization of MLABz and ω-malolactonate−PCL macromonomer as initiated by potassium carboxylic acid salt in the presence of 1 equiv of 18-crown-6 ether. The second route follows a four-step synthesis involving the anionic ROP of MLABz and MLAAllyl, the conversion of allylic groups into pendant hydroxyl functions owing to a free-radical reaction with thioethanol in the presence of 2,2‘-azobis(2-methylpropionitrile), and then the CL polymerization as initiated from these pendant −OH groups after adequate activation into aluminum alkoxide active species. Whatever the synthetic approach, the final step consists of the deprotection of the MLABz repeating units along the backbone via a soft catalytic hydrogenation reaction. The amphiphilic character of the so-prepared graft copolyesters has been evidenced by some preliminary interfacial tension experiments using the pendant drop method.

Synthesis and Characterization of Functional Methacrylate Copolymers and Their Application in Molecular Imprinting

Novel molecularly imprinted polymer systems have been designed that incorporate in a preformed polymer both specific recognition functions and cross-linkable groups. Copolymers of 2-methacryloylethyl methacrylate and methacrylic acid P(MAEMA-co-MAA) with different compositions have been synthesized and characterized. The living free radical polymerization of 2-(trimethylsilyloxy)ethyl methacrylate (HEMA-TMS) and tert-butyl methacrylate (tBMA) with different monomer feed ratios gives a series of random copolymers. These materials can then be further functionalized by methacryloylation of the pendant hydroxyl group and acid hydrolysis of tert-butyl groups. The resultant copolymers were characterized by 1H NMR, FT-IR, DSC, and TGA. These copolymers can then be imprinted with a variety of chemical templates possessing complementary functionalities, forming strong noncovalent and specific binding interactions. These polymer−template matrices can then be readily cross-linked by appropriate posttreatment, such a...

Preparation of a Novel Artificial Bacterial Polyester Modified with Pendant Hydroxyl Groups

The Poly(hydroxyalkanoate) (PHA) chemical modifications represent an alternative route to introduce functional groups, which cannot be introduced by bioconversion. PHAs containing unsaturated chains were readily converted into polyesters containing a terminal hydroxyl group on the side chains. With the use of the borane-tetrahydrofuran complex, the pendant side chain alkenes were quantitatively transformed into hydroxyl functions. The conversion proceeded to completion without a significant decrease in molecular weight. The introduction of hydroxyl groups in the products was confirmed from Fourier transform infrared and 1H NMR analysis. The presence of repeating units containing pendant hydroxyl groups in the proportion 25 mol % caused an increase in hydrophilicity of these new PHAs because they were soluble in polar solvents such as ethanol. Besides, these reactive PHAs can be used to bind bio-active molecules or to prepare novel graft copolymers with desired properties.

Ultra-thin composite films from polyimide and electroactive polymer through covalent molecular assembly

Soluble polyimide with hydroxyl pendant groups (HPI) and poly(thiophene-3-acetic acid) (PTAA) were synthesized and used to fabricate a composite film through layer-by-layer (LBL) molecular assembly. The interlayer linkage is established through esters formed between the hydroxyls from HPI and carboxylate groups from PTAA. The LBL assembly was carried out on a quartz slide or silicon wafer surface-modified with 3-aminopropyltrimethoxysilane. Fourier-transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses both confirmed the occurrence of interlayer covalent bonding. Linear increase in UV–vis absorption confirmed LBL growth of the film. After 6-bilayer construction, the composite film showed a reduced surface resistivity compared with that of the bare quartz slide and HPI cast film. Exposure to iodine vapor resulted in a further reduction in surface resistivity of the composite film. The film also showed good thermal stability.

Hyperbranched aliphatic polyethers obtained from environmentally benign monomer: glycerol carbonate

A hyperbranched aliphatic polyether with hydroxyl end groups was produced from glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one)—the benign monomer obtained from renewable starting materials: glycerol and dimethyl carbonate. Anionic polymerization of glycerol carbonate, which proceeds with simultaneous decarboxylation, was performed using partially deprotonated trimethylolpropane (TMP) as an initiator. Pendant hydroxyl groups facilitate the ring-opening multibranching polymerization leading to a hyperbranched polyether. 13C NMR analysis of the polymerization products confirmed the presence of linear, dendritic, and terminal repeating units. MALDI-TOF mass spectrum analysis confirmed the presence of TMP and glycerol core containing branched structures as well as a relatively small amount of macromolecules with cyclic groups. The polymers were soluble in water, THF, methanol and DMSO.

Combining Two-Directional Synthesis and Tandem Reactions: Synthesis of Trioxadispiroketals

A tandem bromonium ion-promoted cyclization of two pendant hydroxyl groups onto a central furan core provides a highly direct route to both the [5,5,5]- and the [6,5,6]-trioxadispiroketal ring systems.

Platinum‐Catalyzed Intramolecular Hydroalkoxylation of γ‐ and δ‐Hydroxy Olefins to Form Cyclic Ethers.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Surface anchoring stabilized high strength disclinations in smectic C phase of a schiff‐base liquid crystal

AbstractThe observation of disclination cores of high strength S= −2, −3, −4, −5, −6, −7, −8 in a smectic C phase of Schiff‐base type liquid crystal (LC) is reported. The results of polarizing optical microscope (POM), differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) prove that the sample exhibits smectic C phase. It is suggested that the formation of the high strength disclination is mainly ascribed to the stronger anchoring of LC molecules on the substrate due to the formation of hydrogen bonds between the pendent hydroxyl of the LC molecule and the substrate.

Platinum-catalyzed intramolecular hydroalkoxylation of gamma- and delta-hydroxy olefins to form cyclic ethers.

Reaction of 2,2-diphenyl-4-penten-1-ol with a catalytic mixture of [PtCl2(H2C=CH2)]2 (1 mol %) and P(4-C6H4CF3)3 (2 mol %) at 70 degrees C for 24 h led to the isolation of 2-methyl-4,4-diphenyltetrahydrofuran in 78% yield. The platinum-catalyzed hydroalkoxylation of gamma-hydroxy olefins tolerated substitution at the alpha, beta, and gamma-carbon atoms and at the internal and cis and trans terminal olefinic positions. Platinum-catalyzed hydroalkoxylation tolerated a number of functional groups including pivaloate and acetate esters, amides, silyl and benzyl ethers, and pendant hydroxyl and olefinic groups. Pt-catalyzed olefin hydroalkylation was also applicable to the formation of fused- and spirobicyclic ethers and was effective for the hydroalkoxylation of delta-hydroxy olefins to form tetrahydropyran derivatives.

Synthesis and properties of fluorine‐containing polyethers with pendant hydroxyl groups by the polyaddition of bis(epoxide)s with diols

AbstractFluorine‐containing polyethers with pendant hydroxyl groups were synthesized by the polyaddition of fluorine‐containing bis(epoxide)s with certain fluorine‐containing diols with quaternary onium salts as catalysts. When the polyaddition was performed with 2,2′,6,6′‐tetrafluoro‐4,4′‐biphenol diglycidiyl ether and 2,2′,6,6′‐tetrafluoro‐4,4′‐biphenol, the corresponding polyether with pendant hydroxyl groups was successfully obtained in good yield. The polyaddition of certain fluorine‐containing bis(epoxide)s with diols also proceeded in bulk to provide the corresponding fluorine‐containing polyethers with high molecular weights. These polyethers were highly transparent at 157 nm for 0.1 μm thickness, with their transmittance of 14–75% at 157 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2543–2550, 2004

A novel nanocomposite from multiwalled carbon nanotubes functionalized with aconducting polymer

A nanocomposite of a multiwalled carbon nanotube and polythiophene wasprepared by functionalizing the nanotube surface with a polythiophene,poly[3-(2-hydroxyethyl)-2,5-thienylene], containing pendant hydroxyl groups. Thecomposite was characterized by IR, high resolution TEM and conductivitymeasurements. The poly[3-(2-hydroxyethyl)-2,5-thienylene] (PHET) wassynthesized by the oxidation polymerization of 2-(3-thienylethanol) usingFeCl3 and CHCl3. Multiwalled carbon nanotubes were synthesized by a microwave CVD method andoxidized with potassium permanganate using a phase transfer catalyst in mild conditions.The COOH groups formed on the nanotube surface were converted to COCl using thionylchloride and it was then condensed with the polythiophene at high temperature inanhydrous DMF. High resolution TEM images showed that the functionalization provideda firm coating of the conducting polymer on nanotube walls. This nanocomposite withPHET grafted to CNT showed higher conductivity than a nanocomposite of PHET andCNT in the same percentage weight composition prepared by ultrasonic mixing of the two.Such a material was designed and synthesized with a view to electronic and sensorapplications.

Polyurethanes with Pendant Hydroxyl Groups: Synthesis and Characterization

AbstractCommunication: Phenoxycarbonyloxymethyl ethylene carbonate 4 was synthesized from glycerol carbonate and phenyl chloroformate. Polyurethanes with pendant hydroxyl groups were obtained from polycondensation reactions of this AA* monomer with diamines. These polymers contain primary as well as secondary hydroxyl groups. The obtained polyurethanes are amorphous materials. The glass transition temperature decreases with increasing number of methylene groups between the urethane groups.As the number of methylene groups increases between the urethane groups, the glass transition temperature of the polymer decreases.magnified imageAs the number of methylene groups increases between the urethane groups, the glass transition temperature of the polymer decreases.

Synthesis and Properties of Fluorine-containing Poly(ether)s with Pendant Hydroxyl Groups by the Polyaddition of Bis(oxetane)s and Bisphenol AF

Fluorine-containing poly(ether)s with pendant primary hydroxyl groups were synthesized by the polyaddition of bisphenol AF di(3-ethyl-3-oxetanylmethyl ether) (BPAFEO) with bisphenol AF (BPAF) using quaternary onium salts, crown ether complexes or organic bases as catalysts. When the polyaddition was performed with co-catalysts such as tetraphenylphosphonium chloride (TPPC) and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) without solvent at 190 °C for 120 h, the corresponding poly(ether)s pendant primary hydroxyl groups were successfully obtained in good yield. The polyaddition of various bis(oxetane)s with BPAF also proceeded in bulk to provide the corresponding poly(ether)s. It was found that these poly(ether)s are highly transparent at 157 nm, and transmittance of poly(ether)s were determined to be 34–55 % at 157 nm for 0.1 μm thickness.

Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s with functional carbonate building blocks. 1. Chemical synthesis and their structural and physical characterization.

This study presents chemical synthesis, structural, and physical characterization of novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s P(BS-co-CC) bearing functional carbonate building blocks. First, five kinds of six-membered cyclic carbonate monomers, namely, trimethylene carbonate (TMC), 1-methyl-1,3-trimethylene carbonate (MTMC), 2,2-dimethyl-1,3-trimethylene carbonate (DMTMC), 5-benzyloxytrimethylene carbonate (BTMC), and 5-ethyl-5-benzyloxymethyl trimethylene carbonate (EBTMC), were well prepared from ethyl chloroformate and corresponding diols at 0 degrees C in THF solution with our modified synthetic strategies. Then, a series of new P(BS-co-CC)s were synthesized at 210 degrees C through a simple combination of poly-condensation and ring-opening-polymerization (ROP) of hydroxyl capped PBS macromers and the prepared carbonate monomers, and titanium tetra-isopropoxide Ti(i-OPr)4 was used as a more suitable catalyst of 5 candidate catalysts which could concurrently catalyze poly-condensation and ROP. By means of NMR, GPC, FTIR, and thermal analytical instruments, macromolecular structures and physical properties have been characterized for these aliphatic poly(ester carbonate)s. The experimental results indicated that novel biodegradable P(BS-co-CC)s were successfully synthesized with number average molecular weight Mn ranging from 24.3 to 99.6 KDa and various CC molar contents without any detectable decarboxylation and that the more bulky side group was attached to a cyclic carbonate monomer, the lower reactivity for its copolymerization would be observed. The occurrences of 13C NMR signal splitting of succinyl carbonyl attributed to the BS building blocks could be proposed due to the randomized sequences of BS and CC building blocks. FTIR characterization indicated two distinct absorption bands at 1716 and 1733 approximately 1735 cm(-1), respectively, stemming from carbonyl stretching modes for corresponding BS and CC units. With regard to their thermal properties, it is seen that the synthesized P(BS-co-CC)s exhibited thermal degradation temperatures 10 approximately 20 degrees C higher than that of PBS. On the basis of the synthesized P(BS-co-BTMC)s, new aliphatic poly(butylene succinate-co-5-hydroxy trimethylene carbonate)s were further synthesized, bearing hydrophilic hydroxyl pendant functional groups through an optimized Pd/C catalyzed hydrogenation. These semi-crystalline new biodegradable aliphatic copolymers with tunable physical properties and functional carbonate building blocks might be expected as potential new biomaterials.