Ester Functional Groups Research Articles

Design and synthesis of guaianolide-germacranolide heterodimers as novel anticancer agents against hepatocellular carcinoma.

Inspired by our previous finding that disesquiterpenoids showed more potent antihepatoma cytotoxicity than their corresponding parent monomers, natural product-like guaianolide-germacranolide heterodimers were designed and synthesized from guaianolide diene and germacranolides via a biomimetic Diels-Alder reaction to provide three antihepatoma active dimers with novel scaffolds. To explore the structure-activity relationship, 31 derivatives containing ester, carbamate, ether, urea, amide, and triazole functional groups at C-14' were synthesized and evaluated for their cytotoxic activities against HepG2, Huh7, and SK-Hep-1 cell lines. Among them, 25 compounds were more potent than sorafenib against HepG2 cells, 15 compounds were stronger than sorafenib against Huh7 cells, and 17 compounds were stronger than sorafenib against SK-Hep-1 cells. Compound 23 showed the most potent cytotoxicity against three hepatoma cell lines with IC50 values of 4.4 µM (HepG2), 3.7 µM (Huh7), and 3.1 µM (SK-Hep-1), which were 2.7-, 2.2-, and 2.8-fold more potent than sorafenib, respectively. The underlying mechanism study demonstrated that compound 23 could induce cell apoptosis, prevent cell migration and invasion, cause G2/M phase arrest in SK-Hep-1 cells. Network pharmacology analyses predicted PDGFRA was one of the potential targets of compound 23, and surface plasmon resonance (SPR) assay verified that 23 had strong affinity with PDGFRA with a dissociatin constant (KD) value of 90.2 nM. These promising findings revealed that structurally novel guaianolide-germacranolide heterodimers might provide a new inspiration for the discovery of antihepatoma agents.

SYNTHESIS AND APPLICATION OF EFFECTİVE PLASTICIZERS, ANTIOXIDANTS

The article presents a one-stage method for the synthesis of effective plasticizers and antioxidants with a heterogeneous catalyst under mild conditions with a high yield. In order to obtain plasticizers and antioxidants, a number of studies were carried out to determine the optimal temperature, amount of catalyst and molar ratio of reacting components based on natural petroleum and aliphatic fatty acids (C6-C8) using a heterogeneous catalyst. Based on the studies carried out under optimal conditions (temperature -110-120°C, the amount of catalyst – 1,5 wt.%, acid, the molar ratio of components - acid: alcohol - 2:1,4), mixed diesters were synthesized with a yield of 88-90%. To confirm the structures of the synthesized diesters on the "Alpha" IR Fourier spectrometer, the corresponding IR-spectra were obtained, where the absorption bands characteristic of the carbonyl and ester functional groups appear with greater intensity. The good compatibility of the synthesized plasticizers with the polymer matrix and the effect of these compounds on the reduction of sludge in diesel fuel are shown. Keywords: 1,4-butanediol, natural petroleum acids, mixed diesters, diesel fuel, polyvinyl chloride, plasticizer, antioxidant.

Modifying Poly(caprolactone) Degradation through C-H Functionalization.

There is a growing need for degradable polymers for applications in sustainable plastics and medical implants. To enhance the utility of degradable polymers, both better understanding of the factors that influence their degradation and new tools to modulate degradation are needed. We report the C-H xanthylation of poly(caprolactone), a biodegradable polyester, which results in changes in materials properties even at small incorporations. Despite the functionalized materials exhibiting a decrease in crystallinity and hydrophobicity, xanthylated poly(caprolactone) degrades more slowly than its unfunctionalized counterpart. To understand this rate difference, kinetic studies with a small-molecule surrogate were performed and demonstrated that functionalization adjacent to the hydrolyzable ester functional group led to slower degradation. This study illustrates how the interplay between molecular and materials characteristics can impact degradation.

Immobilization of Phosphamide on the TiO2 Surface for Heterogeneous Phase Catalytic Appel Reaction

Global consumption of triphenylphosphine (Ph3P) for phosphorus-mediated organic synthesis and production of the dead-end triphenylphosphine oxide (Ph3PO) waste is exceptionally high. Recycling Ph3PO and/or use of it as a reaction mediator gained significant attention. On the other end, phosphamides, traditionally used as a flame redundant, are stable analogues to Ph3PO. Herein, via a low temperature condensation reaction of methyl 4-(aminomethyl)benzoate (AMB) and diphenyl phosphinic chloride (DPPC), methyl 4-((N,N-diphenylphosphinamido)methyl)benzoate (1) has been synthesized and hydrolysis of the ester functional group of 1 leads to a phosphamide with a carboxylate terminal, 4-((N,N-diphenylphosphinamido)methyl)benzoic acid (2). The presence of phosphamide functionality (NH─P═O) in 2 can be confirmed by its characteristic Raman vibration at 999 cm-1 with expected P-N and P═O bonds distances from the single-crystal X-ray structure. In-situ hydrolysis of [Ti(OiPr)4] in the presence of 2 followed by hydrothermal heating results in immobilization of 2 on a ca. 5 nm TiO2 surface (2@TiO2). The covalent attachment of 2 via coordination through the carboxylate terminal to the TiO2 nanocrystal's surface has been established via multiple spectroscopic and microscopic studies. 2@TiO2 is further used as the heterogeneous mediator for the catalytic Appel reaction, halogenation of alcohol (typically mediated by phosphine), with a fair catalytic conversion and a recorded TON up to 31. The major advantage of the heterogeneous approach studied herein is the recovery of used 2@TiO2 from the reaction mixture via centrifugation only leaving the organic product in the supernatant, which is limiting in Ph3P-mediated homogeneous catalysis. Time-resolved Raman spectroscopy confirms amino phosphine as the active species formed in-situ during the catalytic Appel reaction. Post-catalytic characterization of the material recovered after catalysis from the reaction mixture confirms the chemical integrity and that can further be utilized for another two catalytic runs. The developed reaction scheme showcases the use of a phosphamide as a reactive analogue to Ph3PO for an organic reaction in a heterogeneous approach, and the same strategy can be explored further as a general scheme for other phosphorus-mediated reactions.

PHAs production by facultative anaerobic bacteria Bacillus cereus FM5 through submerged and solid-state fermentation under anoxic condition.

PHAs (polyhydroxyalkanoates) are the bio-polyester synthesized by different aerobic and anaerobic bacteria as energy storage granule. However, its synthesis by anaerobes or facultative anaerobes is an imperative part of their physiology via assimilating broad range of substrates than aerobes. Thus, three Gram positive facultative anaerobic PHAs producers viz., Enterococcus sp. FM3, Actinomyces sp. CM4 and Bacillus sp. FM5 were selected. Among them, Bacillus sp. FM5 showed higher cell biomass production in MSM (mineral salt medium) comprised of glucose & peptone as carbon & nitrogen source at pH 9, temperature 37°C, inoculum 10% and incubation period 72h. Under optimized condition, Bacillus sp. FM5 produced 0.89 and 1.5gl-1 of PHAs through submerged and solid-state fermentation in anoxic condition. In-silico analysis confirmed the facultative anaerobic PHAs producing bacteria as Bacillus cereus FM5. IR spectra of PHAs illustrated a strong absorption peak at 1718.50cm-1 representing carbonyl ester (C=O) functional group of PHB (polyhydroxybutyrate), belonging to the family PHAs. It is the first report demonstrating PHAs production by Bacillus cereus FM5 in anoxic condition through different bioprocess technology, which may pave the way in the arena of further biopolymer research.

Formal Synthesis of Dictyodendrin B

A formal synthesis of dictyodendrin B is described. Regiocontrolled functionalization of the α,β-dibromopyrrole derivative provided the fully substituted pyrrole bearing an indole moiety. Subsequent reductive cyclization using a combination of sodium dispersion and triethylsilyl chloride enabled the formation of the benzene ring in the characteristic tetracyclic pyrrolo[2,3-c]carbazole skeleton, while the ethyl ester remained untouched. Further chemical transformation of the ester moiety and functional group manipulation completed the formal synthesis of dictyodendrin B.

Synthesis and identification of aromatic poly (Ester-Amide) containing chalcone groups in backbone chain

The purpose of this research is to synthesize a new monomer (E)-5-(3-(4-aminophenyl)-3-oxoprop-1-en-1-yl)-2-hydroxybenzoic acid and poly (ester-amide) polymer. Chalcone compound, α, β- unsaturated ketone is a new monomer that includes both the functional group (-CO-CH=CH-) and α, β - unsaturated carbonyl group of the present system. It is prepared via the condensation of aryl ketone with an aromatic aldehyde in the presence of suitable condensation agents which is known as condensation of aldol. The monomer was reacted with (phthalic anhydride and maleic anhydride) by solution polycondensation reactions to yield polymer. The synthesized monomer and polymer were characterized via FT.IR-spectra, Nuclear magnetic resonance13 C.NMR-spectra, 1H.NMR-spectra] and DSC (Differential scanning calorimetry)]. The polymer demonstrated excellent thermal stability. The findings revealed that poly (ester-amide) was successfully synthesized by providing a good spectrum that improved the existing amide functional group (-CONH-) and ester functional group (-COO-) in the spectrum of prepared polymer, as well as the presence of chalcone functional groups(CO-CH=CH-) improved in the spectrum of monomer.

THIOSULFINATE-DERIVED THIOALDEHYDES AS ENOPHILES FOR MODIFICATION AND VULCANIZATION OF CIS-1,4-POLYISOPRENE VIA ALDER-ENE REACTIONS

ABSTRACT Thioaldehydes are explored as enophiles in Alder-ene reactions for modification and crosslinking of cis-1,4-polyisoprene. The highly reactive thioaldehydes were generated from thiosulfinates in conventional rubber processing equipment. Monofunctional thiosulfinates were used to graft ester and amide functional groups to cis-1,4-polyisoprene. Oligomeric thiosulfinates were used to crosslink cis-1,4-polyisoprene under mild conditions. The networks formed using these new crosslinking agents are characterized. Good mechanical properties were obtained under optimized crosslinking conditions.

Design, synthesis, in vitro evaluation, and molecular modeling studies of N-substituted benzomorphans, analogs of LP2, as novel MOR ligands.

6,7-Benzomorphans have been investigated in medicinal chemistry for developing new drugs. This nucleus could be considered a versatile scaffold. The physicochemical properties of benzomorphan N-substituent are crucial in achieving a definite pharmacological profile at opioid receptors. Thus, the dual-target MOR/DOR ligands LP1 and LP2 were obtained through N-substituent modifications. Specifically, LP2, bearing as N-substituent the (2R/S)-2-methoxy-2- phenylethyl group, is a dual-target MOR/DOR agonist and is successful in animal models of inflammatory and neuropathic pain. To obtain new opioid ligands, we focused on the design and synthesis of LP2 analogs. First, the 2-methoxyl group of LP2 was replaced by an ester or acid functional group. Then, spacers of different lengths were introduced at N-substituent. In-vitro, their affinity profile versus opioid receptors has been performed through competition binding assays. Molecular modeling studies were conducted to deeply analyze the binding mode and the interactions between the new ligands and all opioid receptors.

Nanosizing Approach-A Case Study on the Thermal Decomposition of Hydrazine Borane.

Hydrazine borane (HB) is a chemical hydrogen storage material with high gravimetric hydrogen density of 15.4 wt%, containing both protic and hydridic hydrogen. However, its limitation is the formation of unfavorable gaseous by-products, such as hydrazine (N2H4) and ammonia (NH3), which are poisons to fuel cell catalyst, upon pyrolysis. Previous studies proved that confinement of ammonia borane (AB) greatly improved the dehydrogenation kinetics and thermodynamics. They function by reducing the particle size of AB and establishing bonds between silica functional groups and AB molecules. In current study, we employed the same strategy using MCM-41 and silica aerogel to investigate the effect of nanosizing towards the hydrogen storage properties of HB. Different loading of HB to the porous supports were investigated and optimized. The optimized loading of HB in MCM-41 and silica aerogel was 1:1 and 0.25:1, respectively. Both confined samples demonstrated great suppression of melting induced sample foaming. However, by-products formation was enhanced over dehydrogenation in an open system decomposition owing to the presence of extensive Si-O···BH3(HB) coordination that further promote the B-N bond cleavage to release N2H4. The Si-OH···N(N2H4) hydrogen bonding may further promote N-N bond cleavage in the resulting N2H4, facilitating the formation of NH3. As temperature increases, the remaining N-N-B oligomeric chains in the porous silica, which are lacking the long-range structure may further undergo intramolecular B-N or N-N cleavage to release substantial amount of N2H4 or NH3. Besides open system decomposition, we also reported a closed system decomposition where complete utilization of the N-H from the released N2H4 and NH3 in the secondary reaction can be achieved, releasing mainly hydrogen upon being heated up to high temperatures. Nanosizing of HB particles via PMMA encapsulation was also attempted. Despite the ester functional group that may favor multiple coordination with HB molecules, these interactions did not impart significant change towards the decomposition of HB selectively towards dehydrogenation.

Halogenated PETN derivatives: interplay between physical and chemical factors in explosive sensitivity.

Determining the factors that influence and can help predict energetic material sensitivity has long been a challenge in the explosives community. Decades of literature reports identify a multitude of factors both chemical and physical that influence explosive sensitivity; however no unifying theory has been observed. Recent work by our team has demonstrated that the kinetics of "trigger linkages" (i.e., the weakest bonds in the energetic material) showed strong correlations with experimental drop hammer impact sensitivity. These correlations suggest that the simple kinetics of the first bonds to break are good indicators for the reactivity observed in simple handling sensitivity tests. Herein we report the synthesis of derivatives of the explosive pentaerythritol tetranitrate (PETN) in which one, two or three of the nitrate ester functional groups are substituted with an inert group. Experimental and computational studies show that explosive sensitivity correlates well with Q (heat of explosion), due to the change in the number of trigger linkages removed from the starting material. In addition, this correlation appears more significant than other observed chemical or physical effects imparted on the material by different inert functional groups, such as heat of formation, heat of explosion, heat capacity, oxygen balance, and the crystal structure of the material.

Synthesis of oxetane and azetidine ethers as ester isosteres by Brønsted acid catalysed alkylation of alcohols with 3-aryl-oxetanols and 3-aryl-azetidinols.

Oxetanes and azetidines continue to draw significant interest in medicinal chemistry, as small, polar and non-planar motifs. Oxetanes also represent interesting surrogates for carbonyl-containing functional groups. Here we report a synthesis of 3,3-disubstituted oxetane- and azetidine-ethers, with comparisons made to the ester functional group. The tertiary benzylic alcohols of the 4-membered rings are selectively activated using Brønsted acid catalysis and reacted with simple alcohols to form the ethers and maintain the oxetane ring intact. This approach avoids the use of strong bases and halide alkylating agents and allows alcohol libraries to be leveraged. Oxetane ethers demonstrate excellent chemical stability across a range of conditions and an improved stability vis-à-vis analogous esters under basic and reducing conditions.

Atomistic approach for predicting mechanical properties and creep behavior of graphene reinforced natural rubber composites

Graphene has proven to be one of the finest nanomaterials for rubber. In the present study the effect of volume fraction and functionalization of graphene sheets on the mechanical properties and creep behavior of natural rubber (NR) composites has been predicted using the molecular dynamics approach. The properties of NR nanocomposite with the graphene sheet volume fractions of 2.5%, 4.72%, and 11.35% have been compared with the properties of pristine NR. It was observed that the values of Young’s modulus, bulk modulus, and shear modulus were increased up to 104%, 68.40%, and 17.5% respectively for the NR nanocomposite with the reinforcement of 11.35% of graphene compared to pristine NR. The ultimate tensile strength was also increased up to 46% with a higher volume fraction of the graphene sheet. The carboxyl and ester functional groups were used for the functionalization of the graphene sheet. Among the two groups, it was observed that the carboxyl group functionalized graphene sheet provided a better result than the ester group functionalized graphene sheet reinforced NR nanocomposite. The results showed that the introduction of graphene sheets improved the creep resistance of NR nanocomposites significantly. The pristine NR reached the failure stage in just 600 ps for the stress level of 140 MPa, whereas the NR nanocomposite with an 11.35% volume fraction sustained a higher stress level of 160 MPa and has not shown any sign of failure, even after the simulation time of 1000 ps.

Carbon-based metal-free catalysts for selective oxidation of glycerol to glycolic acid

Exploring efficient and cheap catalyst for the selective oxidation of glycerol to valuable carboxylic acids is a critical and complicated challenge. Herein, we innovatively realized the efficient oxidation of glycerol to glycolic acid over metal-free catalyst under mild conditions via carbon material defect engineering. Multiple characterizations revealed that the stepwise functionalization of active carbon caused by simple high temperature control is adopted to fine-tune the composition and electronic structure of oxygen-containing functional groups. Specifically, the abundant ester and carboxyl functional groups exhibit stronger electronegativity than the hydroxyl group, and this enhanced electronic coupling effect strengthens the adsorption of glycerol, thus improving the catalytic activity. Kinetic analysis and density functional theory calculations demonstrated that the oxygen-containing functional groups (mainly ester and carboxyl) could promote the C–H bond activation of RCH2O* intermediate and once C–C bond cleavage of glyceric acid, ensuring the high selectivity of glycolic acid (53.2% over AC-400 catalyst). We anticipate that this work could sheds some light on the application and design of more new type of carbon-based metal-free catalysts in the aqueous phase oxidation of various polyols.

Synthesis of Alkyd Resin Through Alcoholysis – Polyesterification Process from Used Cooking Oil Pretreatment Using Alkaline Activated Natural Bayah Zeolite

Waste cooking oil can be treated by an adsorption process using Bayah natural zeolite as raw material for alkyd resin synthesis. This study aimed to determine the optimum conditions for the equivalent ratio of OH:COOH and the temperature of the alkyd resin synthesis. The research was carried out by preparing used cooking oil and Bayah natural zeolite (BNZ), adsorption process, and alkyd resin synthesis through the alcoholysis-polyesterification process. The optimum addition of Bayah natural zeolite-activated NaOH 0.75 N in pretreatment waste cooking oil is 30% weight in terms of color, density, viscosity, and functional group characteristics of the resulting alkyd resin. The characteristics of the alkyd resin product at optimum conditions obtained light brown color with an OH: COOH equivalent ratio of 1.4, and the alcoholysis and esterification temperature at 190 oC with a density value is 1.112 g/cm3, FFA value is 0.1528%, viscosity value is 4808 cP. The ester functional group at wavelengths 1267 cm-1 and 1722 cm-1, the 1H NMR spectrum of the ester group at the peak of 3.5 ppm, and a functional group of 7.6 ppm.

Enhanced mobility preservation of polythiophenes in stretched states utilizing thienyl-ester conjugated side chain

Recently, diverse approaches to synthesizing intrinsically stretchable conjugated polymers have been presented, such as incorporating the conjugation break spacers or intermolecular interactions in conjugated backbones, resulting in a compromise in the charge carrier mobility. In this study, polythiophenes with flexible [2,2':5′,2'':5″,2‴]-quaterthiophene (QT) or rigid 2-([2,2′-bithiophen]-5-yl)thieno[3,2-b]thiophene (BTTT) backbones were engineered with ester- (E−), thienyl- (T-), and thienyl-ester-substituted (TE) side chains for an enriched amorphous content and an improved mechanical tolerance. Polythiophene with QT backbone and TE side chain (PQT-TE) represents the best mobility−stretchability properties evidenced by the polarized UV–vis absorption, grazing incidence X-ray diffraction, and surface morphological analyses. Accordingly, PQT-TE presents a higher chain conformability and crack-onset strain than QT-based polythiophene with T (PQT-T) or E (PDCBT) side chains. This improvement originated from enriched amorphous domains and enhanced backbone planarity using a biaxially extended conjugation design. PQT-TE exhibits high orthogonal mobility preservations of (64, 90)% under 60% strain parallel/perpendicular to the channel direction. Notably, PQT-TE achieves high orthogonal mobility preservations of (48, 65)% after 800 cyclic stretch−release tests under 60% strain, and these improvements are similarly observed in that of BTTT-based polythiophene (PBTTT-TE). This study demonstrates that the jointed design of the biaxial extension and ester functional groups is efficacious in improving the mobility−stretchability properties of polythiophenes.

Corn oil based cinnamate amide/Fe2O3 nanocomposite anticorrosive coating material

ObjectivesThe efforts are being focused to utilise sustainable resources such as vegetable oils, which are amenable to chemical transformations producing monomers and polymers yielding protective coatings. The present manuscript describes the preparation of nanocomposite coatings from corn oil (CO). MethodsCO was subjected to amidation followed by esterification by cinnamic acid producing CO cinnamate-amide (COCA). COCA was next enriched with Fe2O3 nanoparticles (COCA/ Fe2O3) and crosslinked with phenol formaldehyde to produce polymeric coatings on mild steel panels. ResultsCOCA obtained was rich in functional groups: benzene ring, conjugated with an acrylic group, ester and amide functional group with pendant alkyl chain, and terminal hydroxyl group. The multiple functional groups and nanoparticles offered good adhesion, scratch resistance and flexibility to the resulting nanocomposite coatings. COCA/Fe2O3 coatings showed good physico-mechanical properties and corrosion resistance performance in 3.5 wt% NaCl medium and can be safely used upto 225 °C.

Identifying the Molecular Properties that Drive Explosive Sensitivity in a Series of Nitrate Esters.

Energetic materials undergo hundreds of chemical reactions during exothermic runaway, generally beginning with the breaking of the weakest chemical bond, the “trigger linkage.” Herein we report the syntheses of a series of pentaerythritol tetranitrate (PETN) derivatives in which the energetic nitrate ester groups are systematically substituted by hydroxyl groups. Because all the PETN derivatives have the same nitrate ester-based trigger linkages, quantum molecular dynamics (QMD) simulations show very similar Arrhenius kinetics for the first reactions. However, handling sensitivity testing conducted using drop weight impact indicates that sensitivity decreases precipitously as nitrate esters are replaced by hydroxyl groups. These experimental results are supported by QMD simulations that show systematic decreases in the final temperatures of the products and the energy release as the nitrate ester functional groups are removed. To better interpret these results, we derive a simple model based only on the specific enthalpy of explosion and the kinetics of trigger linkage rupture that accounts qualitatively for the decrease in sensitivity as nitrate ester groups are removed.

Infrared Spectroscopy of Polymers, VIII: Polyesters and the Rule of Three

In the last column, we reviewed the spectroscopy of the carbonyl group and that of ketones. We then analyzed our first C=O containing polymer. In this column, we continue to study C=O containing polymers by first reviewing the spectroscopy of the ester functional group and then analyzing the spectra of several important polyesters. Among the spectra we study is that of polyethylene terephthalate (PET), one of the most economically important polymers in the world.

Preliminary design for establishing compost maturity by using the spectral characteristics of five organic fertilizers

The maturity of compost is involved in the availability of nutrients to crops and improvement of soil properties after fertilization. In the past, the determination of composts maturity mostly required analysis in the laboratory previously and it must consume a lot of time and cost. This study was conducted to use Fourier Transform Infrared (FTIR) spectroscopy and solid 13C Nuclear Magnetic Resonance (13C NMR) spectroscopy to understand the mature characteristics of five type of common composts. The FTIR analysis showed that all composts contained aromatic groups. In addition, the surface of five composts contained the functional groups including hydroxyl group, carboxyl group, amino group etc. However, these functional groups changed along with maturity degree. It is recognized that the aliphatic group located at 2930 cm−1 and 2850 cm−1 showed a decreasing peak, and amino acid at 1385 cm−1 was disappearing gradually due to the decomposition of organic matter by bacteria. There may be used to identify the maturity degree of composts. Increase of aromatic group at 1650 cm−1, carboxy (–COOH) and phenolic OH group at 1385 cm−1 may prove the full maturity of composts. 13C NMR analysis showed that five type of matured composts are mainly consisted with aliphatic groups and aromatic groups. The surfaces of the composts contained C–O bonds (ester, ethers, carbohydrate and other functional groups), COO− (carboxyl and ester carbons) and C=O bond (aldehydes and ketones). The strength of different absorptive characteristics of FTIR and 13C NMR may be a clue to identify the maturity of composts for the design of detective instruments in the future.