Alkyl Acetates Research Articles

Volumetric and FT-IR Studies of the Binary Liquid Mixtures of Tributylamine and Alkyl Ester (C1–C5)

Herein, physicochemical functions were obtained using the density (ρ) and speed of sound (u) data of tributylamine (TBA) + alkyl acetate (C1–C5) mixtures at a pressure of 101.325 kPa and at five di...

Transesterification instead of N‐Alkylation: An Intriguing Reaction

AbstractAn intriguing transesterification reaction is reported here for the first time. Different carbocyclic N‐1 alkoxycarbonyl methyl substituted hydantoins were treated with alkyl halides and sodium hydride as a base, in the presence of N,N‐dimethylformamide. Under these typical N‐alkylation reaction conditions, hydantoin alkyl acetates were also isolated, along with the expected N‐alkylated products. Additional experiments were also performed to investigate the role of N,N‐dimethylformamide in the transesterification reaction and a possible mechanism is also proposed.

Synthesis and Structure of Disodium 1,2-Bis(2-oxocycloalkylidene)ethane-1,2-diolates and Disodium 4-Alkoxy-4-oxo-1-(2-oxocycloalkylidene)but-2-ene-1,2-diolates

Two-stage condensation of cycloalkyl ketones with dimethyl oxalate or alkyl acetates with dialkyl oxalates and cycloalkyl ketones produced disodium 1,2-bis(2-oxocycloalkylidene)ethane-1,2-diolates and disodium 4-alkoxy-4-oxo-1-(2-oxocycloalkylidene)but-2-ene-1,2-diolates, respectively. The structural features of the obtained compounds were discussed on the basis of their IR, 1H NMR spectroscopy, and mass spectrometry data.

Determination of Abraham model solute descriptors for xanthone based on experimental solubility measurements at 298.2 K

ABSTRACTExperimental solubilities have been determined for xanthone dissolved in 15 different alcohol solvents (ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-methyl-1-propanol, 3-methyl-1-butanol, 2-ethyl-1-hexanol, 2-propanol, 2-butanol, 4-methyl-2-pentanol, 2-methyl-2-propanol and 2-methyl-2-butanol), in five alkyl acetate solvents (methyl acetate, ethyl acetate, propyl acetate, butyl acetate and pentyl acetate), in diisopropyl ether and in 2-ethoxyethanol at 298.2 K. In total, solubility measurements were performed in 22 organic solvents of varying polarity and hydrogen-bonding character. Results of the experimental measurements were used to calculate the Abraham model solute descriptors for xanthone. The calculated solute descriptors describe the experimental solubility data to within 0.096 log units.

Palladium-Catalyzed C(sp3 )-H Arylation of Primary Amines Using a Catalytic Alkyl Acetal to Form a Transient Directing Group.

C−H Functionalization of amines is a prominent challenge due to the strong complexation of amines to transition metal catalysts, and therefore typically requires derivatization at nitrogen with a directing group. Transient directing groups (TDGs) permit C−H functionalization in a single operation, without needing these additional steps for directing group installation and removal. Here we report a palladium catalyzed γ‐C−H arylation of amines using catalytic amounts of alkyl acetals as transient activators (e.g. commercially available (2,2‐dimethoxyethoxy)benzene). This simple additive enables arylation of amines with a wide range of aryl iodides. Key structural features of the novel TDG are examined, demonstrating an important role for the masked carbonyl and ether functionalities. Detailed kinetic (RPKA) and mechanistic investigations determine the order in all reagents, and identify cyclopalladation as the turnover limiting step. Finally, the discovery of an unprecedented off‐cycle free‐amine directed ϵ‐cyclopalladation of the arylation product is reported.

Chalcone and cinnamate synthesis via one-pot enol silane formation-Mukaiyama aldol reactions of ketones and acetate esters

Aryl alkyl ketones, acetate esters, and acetamides undergo facile one-pot enol silane formation, Mukaiyama aldol addition, and dehydrosilyloxylation in the presence of an amine base and excess trimethylsilyl trifluoromethanesulfonate. The chalcone and cinnamate products are generally recovered in high yield. The relative stoichiometry of the trimethylsilyl trifluoromethanesulfonate and amine base reagents determines whether the reaction yields the β-silyloxy carbonyl product or the α,β-unsaturated carbonyl.

Physicochemical Properties of Mixtures of Morama Seed Oil With Alkanols and Alkyl Acetates at 298.15 K Atmospheric Pressure

AbstractDensities, ρ, ultrasonic speed, u, and dynamic viscosities, η, of mixtures of morama, Tylosema esculentum, seed oil with 1‐propanol, 1‐butanol, methyl acetate, and ethyl acetate were determined over the entire composition range at 298.15 K and atmospheric pressure. Excess molar volumes, , excess molar‐free volumes , deviations in isentropic compressibility, Δκs, deviations in ultrasonic speed, Δu, deviations in dynamic viscosity, Δη, and the excess free energy of activation of viscous flow, ΔG*E, were calculated and correlated using the Redlich–Kister equation for each of the (morama seed oil + 1‐propanol or 1‐butanol or methyl acetate or ethyl acetate) mixtures. The results obtained were discussed in terms of possible dipole–dipole intermolecular interactions and structural effects.

CO2-Expanded Alkyl Acetates: Physicochemical and Molecular Modeling Study and Applications in Chemical Processes

Different physicochemical properties of CO2-expanded alkyl acetates (methyl, ethyl, propyl, and isoamyl acetates) have been studied by experimental and molecular modeling methods. Changes in the π* Kamlet–Taft parameter with CO2 pressure were determined by UV–vis spectroscopy by following the hypsochromic shift of Nile Red. Modeling of the systems by molecular dynamics (MD) and equation of state (EoS) methods to assess physical equilibrium, density, and viscosity were performed in order to fully characterize these media with the aim to control the physicochemical properties of these phases by pressure and temperature. The studied expanded phases were used in the fabrication of TiO2 microparticles and the morphological properties measured. It is clear from this study that density, viscosity, and polarity of the expanded phase plays a key role in the morphological properties of the particles obtained. On the basis of these results, we propose these green media and CO2 pressure as a way to control the proper...

Chromonic self-assemblies in a series of dialkyl-thiacarbocyanine dyes and generalization of a facile route for the synthesis of fluorescent nanostructured silica fibers

Abstract In the search for new chromonic liquid crystals, we have explored the self-assembly behavior in water of a series of high-purity dialkylthiacarbocyanine dyes with different alkyl chain lengths and acetate as counterion. The dimer model was used to fit the UV–vis spectra and estimate the dissociation energy between molecules, which increases with the alkyl chain length suggesting that not only aromatic π–π interactions but also entropic/steric effects contribute to the aggregation process. NMR spectra suggest the existence of aromatic stacking interactions within the aggregates. At high concentrations, the dyes form nematic and hexagonal chromonic liquid crystals (CLC) in water within a limited range of alkyl chain lengths (ethyl to butyl); for longer lengths (pentyl) no liquid crystals were observed because of insufficient dye solubility. From small angle X-ray scattering patterns, it can be inferred that dye aggregates have cylindrical morphology with a multimolecular cross-section. The dye aggregates template the formation of silica nanofibers synthetized via sol–gel method in alkaline media. After removing excess dye, the silica/dye nanofibers showed high fluorescence emission with superb photochemical stability. The present report demonstrates a generalized route for the wet synthesis of nanostructured silica nanofibers with tunable optical properties.

High-Temperature Batch and Continuous-Flow Transesterification of Alkyl and Enol Esters with Glycerol and Its Acetal Derivatives

A new procedure for the transesterification of alkyl acetates and formates with model glycerol acetals (GAs: Solketal and glycerol formal) was explored in the absence of any catalysts at 180–275 °C. Highly selective transformations occurred in both batch and continuous-flow (CF) modes; particularly, the enol derivative isopropenyl acetate (iPAc) was the best performing reactant by which quantitative acetylation reactions were achieved with yields on GAs acetates >95%. An excess acylating agent was necessary (2–20 molar equivs), but the unconverted ester was fully recovered and could be reused. The reaction plausibly involved multiple mechanisms where either the electrophilic and the nucleophilic activation of reagents took place through both traces of acetic acid (formed in situ by the hydrolysis of esters) and the autoprotolysis of GAs. iPAc confirmed a superior performance than other esters also for the high-temperature conversion of glycerol; in this case, although acylation and acetalization processes...

Synthesis of 2-sulfanylidene-1,3-thiazolidin-4-one derivatives

Three-component condensation of primary amines with carbon disulfide and dialkyl maleates afforded the corresponding alkyl (3-R-4-oxo-2-sulfanylidene-1,3-thiazolidin-5-yl)acetates whose structure was confirmed by independent synthesis and IR and 1H NMR spectroscopy.

Proton affinities and ion enthalpies

Proton affinities of a number of alkyl acetates (CH3–C(=O)–OR) and of methyl alkanoates (R–C(=O)–OCH3, R=H, alkyl) have been assembled from the literature or measured using the kinetic method. It was observed that the proton affinities for the isomeric species CH3–C(=O)–OR and R–C(=O)–OCH3 are almost identical, an unexpected result as the charge in these protonated ester molecules is largely at the keto carbon atom and so this site should be more sensitive to alkyl substitution. Analysis of the data, including those from lone pair ionisation and core-electron ionisation experiments available from the literature, indicate that after protonation, extensive charge relaxation (or polarisation) takes place (as is also the case, according to the literature, after core-electron ionisation). By contrast, after lone pair ionisation, which results in radical cations, such relaxation processes are relatively less extensive. As a consequence, changes in ion enthalpies of these protonated molecules follow more closely the changes in neutral enthalpies, compared with changes in enthalpies of the corresponding radical cations, formed by electron detachment. Preliminary analyses of published energetic data indicate that the above finding for organic esters may well be another example of a more general phenomenon.

Photochemical rearrangement of 5,6-epoxy derivatives of the Diels–Alder adduct of levoglucosenone and piperylene

Photolysis of 5,6-epoxy 4-keto derivatives of the Diels–Alder adduct of levoglucosenone and piperylene in C6H6–MeOH causes cleavage of the C4–C5 bond giving product containing vicinal acetone and alkyl acetate moieties, the latter would further transform into 1-alkoxycarbonyl-2-hydroxy-2-methylcyclopentane derivative annulated to 5,8-dioxabicyclo[3.2.1]octane cage.

Determination of Abraham model solute descriptors for 2-methyl-3-nitrobenzoic acid from measured solubility data in alcohol, alkyl ether, alkyl acetate and 2-alkoxyalcohol mono-solvents

ABSTRACTSpectroscopic methods are employed to measure the solubility of 2-methyl-3-nitrobenzoic acid dissolved in 10 alcohol, 3 alkyl ether, 5 alkyl acetate and 3 alkoxyalcohol solvents at 298.2 K. 2-Methyl-3-nitrobenzoic acid is believed to exist in monomeric form in each of the organic solvents studied. The measured solubilities are used to calculate the Abraham model solute descriptors for the monomeric form of 2-methyl-3-nitrobenzoic acid, which will enable one to predict the solubility of 2-methyl-3-nitrobenzoic acid in additional organic solvents. The derived solute descriptors back-calculated the observed solubility data to within 0.06 log units.

Metal ion hydrocarbon bidentate bonding in alkyl acetates, methyl alkanoates, alcohols and 1-alkenes: a comparative study.

The relative affinity of the monovalent metal ions Li+, Na+, Cu+ and Ag+ towards a series of aliphatic alkyl acetates and some selected 1-alkenes (P) was examined using the kinetic method. A detailed analysis of the dissociation characteristics of a series of mixed metal-bound dimer ions of the type P1-M+-P2 and the evaluated proton affinities (PAs) of the monomers shows that the affinity of the cation towards long-chain alkyl acetates and alkenes (having a chain length ≤ C4) is markedly enhanced. In line with recent studies of nitriles, alcohols and methyl alkanoates, this is attributed to a bidentate interaction of the metal ion with the functional group or double bond and the aliphatic chain. In particular, the longer chain alkyl acetates, methyl alkanoates and alcohols show a remarkably similar behaviour with respect to silver ion hydrocarbon bonding. The Ag+ adducts of the alkyl acetates dissociate by loss of CH3COOH. This reaction becomes more pronounced at longer chain lengths, which points to metal ion bidentate formation in [Ag+···1-alkene] product ions having a long hydrocarbon chain. In the same vein, the heterodimers [1- hexene···Ag+···1-heptene] and [1- heptene···Ag+···1-octene] dissociate primarily into [Ag+···1-heptene] and [Ag+···1-octene] ions, respectively. Hydrocarbon bidentate formation in [Ag+···1-octene] also reveals itself by the reluctance of this ion to react with water in an ion trap, as opposed to [Ag+···1-hexene] which readily undergoes hydration.

Defining the extreme substrate specificity of Euonymus alatus diacylglycerol acetyltransferase, an unusual membrane-bound O-acyltransferase.

Euonymus alatus diacylglycerol acetyltransferase (EaDAcT) synthesizes the unusually structured 3-acetyl-1,2-diacylglycerols (acetyl-TAG) found in the seeds of a few plant species. A member of the membrane-bound O-acyltransferase (MBOAT) family, EaDAcT transfers the acetyl group from acetyl-CoA to sn-1,2-diacylglycerol (DAG) to produce acetyl-TAG. Invitro assays demonstrated that the enzyme is also able to utilize butyryl-CoA and hexanoyl-CoA as acyl donors, though with much less efficiency compared with acetyl-CoA. Acyl-CoAs longer than eight carbons were not used by EaDAcT. This extreme substrate specificity of EaDAcT distinguishes it from all other MBOATs which typically catalyze the transfer of much longer acyl groups. Invitro selectivity experiments revealed that EaDAcT preferentially acetylated DAG molecules containing more double bonds over those with less. However, the enzyme was also able to acetylate saturated DAG containing medium chain fatty acids, albeit with less efficiency. Interestingly, EaDAcT could only acetylate the free hydroxyl group of sn-1,2-DAG but not the available hydroxyl groups in sn-1,3-DAG or in monoacylglycerols (MAG). Consistent with its similarity to the jojoba wax synthase, EaDAcT could acetylate fatty alcohols invitro to produce alkyl acetates. Likewise, when coexpressed in yeast with a fatty acyl-CoA reductase capable of producing fatty alcohols, EaDAcT synthesized alkyl acetates although the efficiency of production was low. This improved understanding of EaDAcT specificity confirms that the enzyme preferentially utilizes acetyl-CoA to acetylate sn-1,2-DAGs and will be helpful in engineering the production of acetyl-TAG with improved functionality in transgenic plants.

Computation of Abraham model solute descriptors for 3-methyl-4-nitrobenzoic acid from measured solubility data

ABSTRACTSpectroscopic methods have been used to determine the solubility of 3-methyl-4-nitrobenzoic acid dissolved in 17 different alcohols, five alkyl acetates, tetrahydrofuran, 1,4-dioxane, and diisopropyl ether at 298.2 K. Abraham model solute descriptors for 3-methyl-4-nitrobenzoic acid are calculated by combining the solubility measured in this study with recently published solubility data for the carboxylic acid solute dissolved in acetone, acetonitrile, and N,N-dimethylformamide. The calculated solute descriptors were found to describe the experimental solubility data to within an overall average standard error of 0.081 log units.

β-Alkyloxazolochlorins: Revisiting the Ozonation of Octaalkylporphyrins, and Beyond.

The reaction of β-octaalkylporphyrins (octaethylporphyrin and etioporphyrin I) with ozone generated the corresponding heptaalkyloxazolochlorinhemiacetals in which a pyrrolic subunit of the porphyrins was replaced by an oxazoline moiety. Thus, a pyrrolic β-carbon with its alkyl substituent was excised and replaced by an oxygen atom, and the neighboring β-carbon was hydroxylated. This work clarifies the nature of the products first described by Fischer and Deželić, in 1933, and verifies the work by Shulg'a and coworkers, from 1977. Furthermore, the chemistry of the oxazolochlorin hemiacetals was studied: They could be dehydroxylated or converted to alkyl acetals and gem-dialkyl derivatives, all possessing chlorin-type optical spectra. Their oxidative conversions generated a unique tetrahydrofuran-linked oxazolochlorin dimer and a hexaethylporpholactone. The work expands on the knowledge of converting porphyrins to porphyrinoids of potential utility containing nonpyrrolic building heterocycles.

Chemical interesterification of rapeseed oil with methyl, ethyl, propyl and isopropyl acetates and fuel properties of obtained mixtures

An alternative method for the synthesis of biodiesel fuel from rapeseed oil that prevents formation of glycerol and produces the fuel in mass exceeding the mass of oil has been proposed. Upon the interesterification reaction with different alkyl acetates triacetin is formed (instead of glycerol) which can be considered as a valuable additive and do not have to be removed from the reaction mixture. In this study the influence of the alcohol moiety of alkyl acetate on the interesterification process was studied using sodium methoxide solution in methanol as catalyst. The reactivity of the acetates in the interesterification reactions decrease in the following order: methyl-;ethyl-;propyl-≫isopropyl acetate. However, performing reactions with these alkyl acetates at its boiling points for 1h using optimal amount of catalyst with alkyl acetate to oil molar ratio of 36:1, reaction mixtures with high content of fatty acid alkyl esters can be obtained. Fuel properties of the obtained mixtures were investigated. Obtained renewable fuels do not meet the requirements of standard EN 14214 for biodiesel, although the main characteristics of the biodiesel obtained in the reaction with methyl acetate are marginally close to the standard requirements.

Design, synthesis and antiproliferative activity of novel 5-nitropyrimidine-2,4-diamine derivatives bearing alkyl acetate moiety

In order to discover new anticancer drug leads, a series of novel alkylamino pyrimidine derivatives were designed and synthesized based on our previous work via a ring-opening strategy. Biological evaluation with four human cancer cell lines (MDA-MB-231, A549, HepG2, and MCF-7) showed that most of these compounds possessed moderate to potent antiproliferative activities. The most promising compound 7w displayed a three-fold improvement compared with commercial anticancer drug fluorouracil in inhibiting HepG2 cell proliferation with IC50 value of 10.37 μM. Moreover, flow-activated cell sorting analysis suggested that compound 7w mainly arrested HepG2 cells in G2/M stage. Hence, it could serve as a promising lead for the design of novel anticancer small-molecule drugs.