Alkenoic Acid Research Articles

ChemInform Abstract: Synthesis of Activated Alkenes Bearing the Difluoromethylenephosphonate Group: A Range of Building Blocks for the Synthesis of Secondary Difluorophosphonates.

Active methylene compounds reacted readily with stable hydrate 2-diethoxyphosphoryl-2,2-difluoroethane-1,1-diol to afford a range of activated alkenes bearing the difluoromethylenephosphonate group, a useful motif in the synthesis of phosphate ester mimics of biological interest. Wadsworth–Horner–Emmons reactions were employed using modified Rathke conditions for the syntheses of alkenoates, an alkenoic acid and a vinyl sulfone, while a Henry reaction followed by E1cB dehydration afforded an enedioate and a nitroalkene. A vinyl sulfoxide was less straightforward to synthesise and dephosphorylation to a difluoromethyl congener accompanied attempts to force the reaction to completion.

The ecosystem evolution of penguin colonies in the past 8,500 years on Vestfold Hills, East Antarctica

Penguin colony is one of the Earth’s simplest ecosystems. As the seabird with the largest population in Antarctica, penguin is a unique indicator of Antarctic environment and climate changes. In this study, we collected an ornithogenic sediment core from Gardner Island in Vestfold Hills, East Antarctica, reconstructed an 8,500 years variation history of penguin population and vegetation abundance on this island, and examined the evolution of the penguin colony. We used the levels of two molecular markers cholesterol and cholestanol as the proxy indicators of penguin population size. Other molecular markers, including C24:0 alkenoic acid, C18n-alkanol and phytol were used as the proxy indicators of aquatic moss, algae, and general vegetation, respectively. It is shown that the growth of algae was mainly affected by the nutritional supply from penguin droppings, so their abundance was positively linked with penguin population. The growth of aquatic moss, however, was controlled more by the degree of water body transparency than by nutrient availability. Because the pollution of water body increased as penguin population grew, aquatic moss abundance showed a seesaw-like relationship with penguin population. These results suggested that penguins played a dominant role in this simple ecosystem in the Antarctic environment. The reconstructed relationship between penguin population and vegetation abundance may offer new insights to understand ancient Antarctic environment and ecology.

Synthesis, characterization, and in vitro antimicrobial activities of 5-alkenyl/hydroxyalkenyl-2-phenylamine-1,3,4-oxadiazoles and thiadiazoles

The long-chain alkenoic acid hydrazides ( 1a– d) on reaction with phenylisocyanate and phenylthiocyanate gave their corresponding semicarbazides ( 2a– d) and thiosemicarbazides ( 4a– d), which on further refluxing with POCl 3 and Ac 2O yielded corresponding 1,3,4-oxadiazoles ( 3a– d) and thiadiazoles ( 5a– d), respectively. The structure elucidation of synthesized compounds is based on the elemental analysis and spectral data (IR, 1H NMR, 13C NMR and MS). The synthesized oxadiazoles and thiadiazoles have been screened for antibacterial and antifungal activities. The investigation of antimicrobial screening revealed that compounds 3c, 3d, 5c, 5d and compounds 3b, 5b, showed good antibacterial and antifungal activities, respectively.

A New Reaction for Organoselenium Compounds: Alkyl Transfer from Diorganoselenium(IV) Dibromides to Alkenoic Acids To Give γ- and δ-Lactones

Various 1-[[bis(1-methylethyl)amino]carbonyl]-2-(dibromo-n-alkylseleno)ferrocene derivatives reacted with 2 equiv of 4-pentenoic acid or 5-hexenoic acid to give the corresponding γ- or δ-lactones, respectively, from transfer of the alkyl group bound to selenium to the terminal alkene carbon. In the lactone cyclization, 1-[[bis(1-methylethyl)amino]carbonyl]-2-(bromoselenenyl)ferrocene (25) is formed and reacts with a second equivalent of the alkenoic acid to give either 5-[1-[[bis(1-methylethyl)amino]carbonyl]ferrocene-2-selenenylmethyl]tetrahydro-2-furanone (23) or 6-[1-[[bis(1-methylethyl)amino]carbonyl]ferrocene-2-selenenylmethyl]tetrahydro-2H-pyran-2-one (26) as a mixture of diastereomers in yields comparable to the corresponding γ- or δ-lactone. The addition of 1-[[bis(1-methylethyl)amino]carbonyl]-2-(dibromo-n-butylseleno)ferrocene to 3-butenoic acid gave alkyl transfer to the internal alkene carbon and formation of the γ-lactone. Density functional theory (DFT) geometry optimizations were performed on several idealized n-alkyldibromselenoferrocene structures to examine the role of iron in the alkyl transfer and the role of various structural features on the alkyl carbon−selenium bond length. The results of the computations suggested that the ferrocenyl iron was not involved in the alkyl transfer reactions.

Reactive uptake studies of NO3 and N2O5 on alkenoic acid, alkanoate, and polyalcohol substrates to probe nighttime aerosol chemistry

Heterogeneous reactions between NO3 and N2O5 and diethyl sebacate (DES), glycerol, oleic acid (OA), linoleic acid (LA), and conjugated linoleic acid (CLA) were studied to understand better nighttime aerosol chemistry. The reactive uptake coefficient of NO3 on the liquid alkenoic acids (OA, LA, and CLA) was found to be >0.07, which is higher than previous results for unsaturated organics, including alkenoic acids. This reaction could potentially be an important loss process of particle-phase unsaturated organic compounds in the atmosphere and in laboratory secondary organic aerosol studies. The reactive uptake coefficient of N2O5 on liquid glycerol was also found to be relatively large with a value of (3.2-8.5)x10(-4), suggesting that N2O5 heterogeneous reactions with alcohols may also be atmospherically relevant. For all measurements with OA, CLA, and DES, the reactive uptake coefficients decreased significantly upon freezing. One possible explanation is that the liquid reaction is due to both a surface reaction and a bulk reaction and that the freezing process significantly decreases the importance of any bulk reactions. NO3 reactive uptake coefficients for liquid-phase compounds decreased in magnitude in the order: alkenoic acids>DES>glycerol. This is different compared to previous gas-phase studies and the difference may be due to the large viscosity of glycerol compared to the other organic compounds studied. N2O5 reactive uptake coefficients for liquid-phase compounds decreased in magnitude in the order: glycerol>LA>DES congruent with OA congruent with CLA.

Evaporation Rates and Vapor Pressures of the Even-Numbered C8−C18 Monocarboxylic Acids

Temperature-dependent vapor pressures of the even-numbered alkanoic monoacids from C8-C18 were measured using temperature-programmed desorption (TPD). In TPD, the evaporation rates from the samples are directly measured and the vapor pressures are subsequently determined from the Hertz-Knudsen equation. Our measurements indicate that the vapor pressures of the solid even-numbered alkanoic acids decrease monotonically with increasing carbon number by more than 6 orders of magnitude going from C8 to C18. The enthalpies of sublimation increase monotonically with carbon number, from approximately 110 to 205 kJ/mol. The liquid-phase vapor pressure was measured for oleic acid, a C18 alkenoic acid. Comparison to the estimated liquid-phase vapor pressure for the corresponding C18 alkanoic acid indicates that the liquid-phase vapor pressures of these two compounds are identical. Our measured solid-phase vapor pressures for the C14 and larger alkanoic acids are lower than in previous studies. We attribute these differences to the influence of residual solvent molecules on the previous measurements, which cause the measured vapor pressures to be too large.

A novel alkenoic acid ester and a new benzophenone from Ranunculus ternatus

A novel alkenoic acid ester, ( E)-4-hydroxy-dodec-2-enedioic acid-12- O-methyl ester and a new benzophenone, ethyl ( S)-3-[2-(3,4-dihydroxybenzoyl)-4,5-dihydroxyphenyl]-2-hydroxypropanoate, together with a known compound, ( E)-4-hydroxy-dodec-2-enedioic acids were isolated from the roots of Ranunculus ternatus. Their structures were elucidated by spectroscopic methods.

Water-Induced Coacervation of Alkyl Carboxylic Acid Reverse Micelles: Phenomenon Description and Potential for the Extraction of Organic Compounds

Coacervates made up of alkanoic (C8-C16) and alkenoic (C18) acid reverse micelles were described for the first time, and their potential for the extraction of organic compounds prior to liquid chromatography was examined. The coacervation process occurred in miscible binary mixtures of water and a variety of protic and aprotic solvents. The phase behavior of alkyl carboxylic acids was found to be a function of both the Hildebrand solubility parameter, delta, and the hydrogen-bonding capability of the solvent. The best solvents for analytical extractions were those featuring the lowest delta values. The phase behavior of alkyl carboxylic acid/water/tetrahydrofuran (THF) ternary systems as a function of component concentration, pH, ionic strength, and temperature was investigated. The efficiency and the time required for phase separation depended on the experimental procedure used (i.e., standing, centrifugation, stirring, and sonication). The formation of alkyl carboxylic acid reverse micelles in THF was proven using both hydrophilic fluorescent probes and scattered light measurements. The structure of the coacervates consisted of spherical droplets dispersed in a continuous phase. Phase volume ratios were a function of both alkyl carboxylic acid and THF concentration. The low volume obtained (e.g., 1.5 microL per mg of decanoic) compared to that obtained by other coacervates (e.g., 5.1 microL per mg of dodecane sulfonic acid and 11.3 microL per mg of Triton X-114) greatly improved the concentration factors reached by coacervation-based extractions. Parameters affecting the extraction efficiency were assessed. Analytes in a wide range of polarity were efficiently extracted on the basis of the hydrophobic (e.g., PAHs) and hydrogen bond (e.g., chlorophenols, bisphenols, pesticides, phthalates, nonionic surfactants, dyes, and photographic developers) interactions that reverse micelles can establish. The coacervates were compatible with the chromatographic determination of analytes following UV or MS detection. They were successfully applied to the extraction of alkylphenol ethoxylates (octyl and nonyl) and alcohol ethoxylates (C12-C16) from influent and effluent wastewater and river water samples. Nonionic surfactants in the coacervate were directly separated and quantified by liquid chromatography-ion trap mass spectrometry. Concentration factors were around 160. The recovery of nonionics in the environmental water samples ranged from 90 to 104%.

Synthesis and evaluation of novel light‐curable amino acid‐constructed glass–ionomer cements

AbstractPoly(alkenoic acid)s constructed with β‐alanine and glutamic acid were synthesized and grafted with glycidyl methacrylate (GM). The purified polymers were further formulated with water, acrylic acid (AA), and Fuji II LC glass filler to form photocurable dental cements. Compressive strength (CS) and flexural strength (FS) of the cement, and viscosity of the resin liquid were used as screening tools to find the optimal formulation. The specimens were conditioned in distilled water at 37°C for 24 h, prior to testing. The results show that the effects of grafting ratio, polymer content, powder liquid (P/L) ratio, initiator concentration, and light exposure time were significant, but the effect of molecular weight was not. Aging study shows that the experimental cement showed a constant increase in mechanical strength for up to 1 week and then kept constant over 1 month. The formulation with 50/25/25 (liquid composition of polymer/AA/water), 70% (grafting ratio of GM), 3.2/1 (P/L ratio) as well as 0.9% (camphorquinone) and 1‐min light exposure time were found to be the optimal. The experimental cement was 19% higher in CS, 47% higher in diametral tensile strength and 176% higher in FS, compared to Fuji II LC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1587–1595, 2007

DABCO‐Catalyzed Reaction of Phenols or 1,2‐Diphenols with Activated Alkynes Leading to the Formation of Alkenoic Acid Esters (III)/(IV) or 1,3‐Dioxole Derivatives (VI).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

DABCO Catalyzed Reaction of Various Nucleophiles with Activated Alkynes (I) Leading to the Formation of Alkenoic Acid Esters, e.g. (III)/(IV), 1,4‐Dioxane (XI), Morpholine (XIII), and Piperazinone Derivatives (XVII).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

DABCO-Catalyzed Reaction of Phenols or 1,2-Diphenols with Activated Alkynes Leading to the Formation of Alkenoic Acid Esters or 1,3-Dioxole Derivatives

The reaction of phenols or 1,2-diphenols with activated alkynes took place smoothly and rapidly in the presence of a catalytic amount of 1,4-diazabicyclo[2.2.2]octane (DABCO) at room temperature and resulted in the formation of various alkenoic acid esters or 1,3-dioxole derivatives in excellent yields. The scope and limitations, together with a plausible mechanism of the reaction are disclosed in this paper.

Iodolactonization of 4-Pentenoic Acid

An experiment in which 4-pentenoic acid is converted into a lactone via iodolactonization is described. In this lab activity, the alkenoic acid is treated with I2 prepared in situ, forming an iodonium ion that undergoes intramolecular nucleophilic attack to produce 5-iodo-γ-valerolactone. Students use the infrared spectrum to determine which functional groups are present in the product and their understanding of the nature of the reactants to determine that product formation occurs through attack of the carboxylic acid's oxygen on the iodonium ion intermediate. The NMR spectrum of the product establishes that nucleophilic attack occurs in accordance with Markovnikov's rule.

DABCO catalyzed reaction of various nucleophiles with activated alkynes leading to the formation of alkenoic acid esters, 1,4-dioxane, morpholine, and piperazinone derivatives

Abstract The reaction of acids, alcohols, acylamides, 1,2-diols, 1,2-diamines or amino alcohols with activated alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) was systematically investigated. A series of unsaturated alkenoic acid esters or heterocycles were formed in the reaction of monobasic or dibasic nucleophiles in excellent yields, respectively.

Reactive Uptake of O3 by Multicomponent and Multiphase Mixtures Containing Oleic Acid

The heterogeneous reaction of O3 with lauric acid/oleic acid (LA/OA) mixtures and myristic acid/oleic acid (MA/OA) mixtures were studied as a function of composition, physical state, and microstructure at 298 K. Lauric acid and myristic acid are both alkanoic acids, whereas oleic acid is an alkenoic acid. Additionally, we investigated the uptake of O3 by multicomponent mixtures that closely represent the composition of meat-cooking aerosols. These measurements were performed with a rotating-wall flow-tube reactor coupled to a chemical ionization mass spectrometer. The reactive uptake coefficients (gamma) of O3 on liquid LA/OA and MA/OA solutions range from 4 x 10(-4) to 7.2 x 10(-4). The gamma values measured for solid-liquid LA/OA and MA/OA mixtures (which consist of solid LA or solid MA in equilibrium with a liquid) range from 2 x 10(-5) to 1.7 x 10(-4). These experiments show that only 7% solid by mass in the solid-liquid mixture can decrease gamma by an order of magnitude compared to the liquid mixtures. The gamma values for solid-liquid mixtures that closely represent the composition of meat-cooking aerosols range from 1.6 x 10(-5) to 6.9 x 10(-5). We found that gamma of solid-liquid mixtures depends on the microstructure of the mixtures, which in turn depends on the method of preparing the films. Furthermore, experiments employing solid-liquid mixtures show an increase in gamma with increasing film age. This can be explained either by the formation of a nonequilibrium phase followed by its relaxation to the stable phase or by Ostwald's ripening, which refers to a change in the solid microstructure due to a tendency to minimize the total surface free energy of the solid. We used the obtained gamma values to estimate OA lifetimes for polluted atmospheric conditions. For liquid solutions, the lifetimes were on the order of a few minutes. The lifetimes derived for solid-liquid mixtures are up to 75 min, significantly longer than for liquid solutions. Our study emphasizes the effect of the physical state and microstructure of multicomponent mixtures on the heterogeneous chemistry.

Measuring rates of reaction in supercooled organic particles with implications for atmospheric aerosol

The kinetics of heterogeneous reactions involving supercooled organic droplets is reported for the first time. Reactions between ozone and internally-mixed sub-micrometre particles containing an unsaturated alkenoic acid, oleic acid, and an n-alkanoic acid, myristic acid, were studied as a simple model for the oxidation of meat-cooking aerosol. The reactions were followed by monitoring the rate of oleic acid loss using an Aerosol CIMS (chemical ionization mass spectrometry) instrument for real-time particle analysis. Evidence of as much as 32 degrees C supercooling at room temperature was observed depending on particle composition. FTIR spectra of the aerosol also demonstrate features indicative of supercooling. Particles in which crystallization was induced by cooling below room temperature demonstrated decreased reactivity by a factor of 12 compared to supercooled particles of the same composition. This drastic difference in reactivity could have significant implications for the lifetimes of reactive species in ambient aerosol as well as for the accurate source apportionment of particulate matter.

Investigation into the ultrasonic setting of glass ionomer cements Part II Setting times and compressive strengths

Glass ionomer cements (GICs) are formed by the reaction of an ion leachable alumino-silicate glass with an aqueous solution of poly (alkenoic acid), PAA. Water is used as the reaction medium [1]. A two-stage setting reaction occurs, resulting in a cement consisting of residual glass particles embedded in a hydrogel polysalt matrix [2]. During the first stage the material is susceptible to water uptake and during the second it is susceptible to dehydration. For example, when GICs are stored in water after an initial set of 15 min, a surface softening occurs, which may be caused by an inhibition of the setting reaction in a superficial layer of the cement [3]. This short-term relationship with water restricts the potential of GICs for healthcare applications. It is for this reason that resin modified GICs (RMGICs) were developed. These materials, conventional GICs into which an organic, photo-polymerisable monomer has been incorporated [4], can be command set by the application of an intense light source. However, RMGICs have drawbacks related to the presence of both non-polymerised monomer and the resin itself [5, 6]. Rapid setting is important both for providing resistance to attack from moisture in the mouth and improving wear resistance, but an alternative method to light-curing which does not require the incorporation of additional chemicals would be beneficial. The application of ultrasonic waves has long been used for setting cement in the building industry, and so studies were performed to utilise the same method for setting dental cements [7]. Most dental clinics have ultrasonic capability as it is used for de-scaling teeth. The effects of applying ultrasonic waves to the surface of the cement include a reduction in both porosity and mean glass particle size (due to breaking up of agglomerates), an improvement in the packing of the glass particles and a decrease in the mean molecular weight of the PAA [8]. Whilst it is not possible to further explain the curing mechanism at this stage, this work will determine the extent to which ultrasound affects the setting times and mechanical properties of a series of hand mixed and mechanically triturated GICs.

Alkenone and alkenoic acid compositions of the membrane fractions of Emiliania huxleyi

The lipid classes and unsaturation ratios of long-chain alkenones ( nC 37–C 39), related alkyl alkenoate compounds ( nC 37–C 38) and alkenoic acids ( nC 14–C 22) were determined in isolated membrane and organelle fractions of Emiliania huxleyi. The percentage distribution of these compounds was predominantly high in the endoplasmic reticulum (ER) and coccolith-producing compartment (CPC)-rich membrane fraction, although alkenones and alkenoates could be detected in all membrane fractions. In particular, the alkenones were mainly located in CPC, since their distribution was closely correlated with that of uronic acids which are markers of CPC. In contrast, the alkenoic acids seemed to be mainly located in chloroplast (thylakoid)-rich fractions. The alkenone unsaturation ratio and the ratio of alkenoates to alkenones were similar in all fractions, while the unsaturation ratio of alkenoic acids in the thylakoid-rich and plasma membrane (PM)/Golgi body-rich fractions was overwhelmingly higher than that in the ER/CPC-rich fractions. Thus, alkenoic acids seemed to be typical membrane-bound lipids, and could be closely related to photosynthesis and involved in regulating membrane fluidity and rigidity in E. huxleyi. It is presumed from these results that the alkenones and alkenoates were membrane-unbound lipids that might be associated with the function of CPC.

A novel acrylic copolymer for a poly(alkenoate) glass-ionomer cement.

The interest in the clinical use of polyalkenoate cements stems mainly from their behavior as bioactive adhesive materials with therapeutic action. Glass-ionomer cements set by an acid-base reaction between a degradable glass and a poly(alkenoic acid) and the therapeutic action is related to the release of fluoride ions which are present in the hardened cement that show a sustained release over years, responsible for caries inhibition in teeth. Conventional glass-ionomers, however, suffer from some disadvantages such as short working time, initial moisture sensitivity and prone to desiccation after setting and are generally brittle. In the present study, a poly(alkenoic acid) copolymer was synthesized based on acrylic acid and 2-hydroxyethylmethacrylate (HEMA) using azobisisobutyronitrile as the initiator and characterized. The acid-base reaction was carried out by reacting aqueous solutions of the new copolymer (40 and 60%) with a commercial aluminofluorosilicate glasses as used in conventional glass-ionomer cements. The results showed that the copolymer of HEMA and acrylic acid was a viable poly(alkenoic) acid for formation of glass-ionomer cements.

Investigation into the ultrasonic setting of glass ionomer cements Part I Postulated modalities

Glass ionomer cements (GICs) are formed by the reaction of an ion leachable alumino-silicate glass with an aqueous solution of poly (alkenoic acid). Water is used as the reaction medium [1]. An acid-base reaction occurs, whereby the acid attacks and degrades the glass structure, releasing metal cations which are then chelated by the carboxylate groups and serve to crosslink the polyacid chains. The cement consists of residual glass particles embedded in a hydrogel polysalt matrix [2]. The setting reaction in GICs is a continuous process evident by the increase in compressive strength of the cement with ageing time [3–5]. GICs undergo a two-step setting reaction. During the first step the material is susceptible to water uptake and during the second it is susceptible to dehydration. For example, when GICs are stored in water after an initial set of 15 min, a surface softening occurs, which may be caused by an inhibition of the setting reaction in a superficial layer of the cement [6]. This short-term relationship with water restricts the full potential of GICs for healthcare applications. It is for this reason that resin modified GICs (RMGICs) were developed. These materials, which are conventional GICs to which an organic, photo-polymerizable monomer has been incorporated [7], can be command set by the application of an intense light source. However, RMGICs have recognized drawbacks, related to the presence of both non-polymerized monomer and the resin itself [8, 9]. The authors have already shown that conventional GICs can be command set by ultrasonic excitation [10]. Ultrasound not only imparts an instant set to a GIC, but also imparts superior mechanical properties when compared to its chemically cured counterpart, particularly within the first 24 h after setting. The ultrasonically cured GIC does not require the incorporation of additional chemicals and therefore avoids the drawbacks associated with RMGICs. In the previous study [10], nano-indentation testing was used to show that ultrasonically cured Fuji IX had hardness an order of magnitude greater than its chemically cured counterpart (Table I), while also