Synthesis of methyl 3-amino-4-aryl(or methyl)sulfonyl-2-thiophenecarboxylates from 3-alkoxy-2-aryl(or methyl)-sulfonylacrylonitriles

The synthesis of a series of methyl 3-amino-4-aryl(or methyl)sulfonylthiophene-2-carboxylates by reaction of 3-alkoxy-2-aryI(or methyl)sulfonylacrylonitriles with methyl thioglycolate in the presence of triethylamine is described. Hydrolysis/decarboxylation of the ester at the 2-position and acylation of the resulting amine represents a convenient route to 4-arylsulfonyl-3-carboxamidothiophenes. Attempted acylation of a title aminothiophene under standard conditions was unsuccessful.     

An effective new access to ethyl 2-[(alkylamino)(cyano)methyl] acrylates: first synthesis of ethyl 3-cyano-2-(hydroxymethyl) acrylate

A regioselective coupling of ethyl 2-(bromomethyl)-3-cyanoacrylate and primary amines is described to give ethyl 2-[(alkylamino)(cyano)methyl] acrylates in good yields. Whereas the conversion of allyl bromide in the presence of TEAF leads to the first synthesis of ethyl 3-cyano-2-(hydroxymethyl) acrylate.     

Experimental and computational thermochemical study of 2- and 3-thiopheneacetic acid methyl esters

Thiophene-based compounds have widespread use in modern drug design, biodiagnostics, electronic and optoelectronic devices, and conductive polymers. The present study reports an experimental and computational thermochemical study on the relative stabilities of 2- and 3-thiopheneacetic acid methyl esters. The enthalpies of combustion and vaporization were measured by a rotating-bomb combustion calorimeter, Calvet microcalorimetry, and correlation gas chromatography, and the gas-phase enthalpies of formation at T=298.15 K were determined. Standard ab initio molecular orbital calculations at the G3 level were performed, and a theoretical study of the molecular and electronic structure of the compounds studied was carried out. Calculated enthalpies of formation, using atomization and isodesmic reactions are in very good agreement with the experimental results.     

Synthesis of ethyl 3-(3-hydroxy-2-thienyl)-3-oxopropanoates

An approach to the synthesis of substituted ethyl 3-(3-hydroxy-2-thienyl)-3-oxopropanoates was developed based on the reaction of ethyl cyanoacetate, carbon disulfide, and ethyl 4-chloroacetoacetate. The reaction regioselectively involved the ester group, rather than the nitrile one like in the case when malononitrile or cyanacetamide were used.     

Psilocin analogs II. Synthesis of 3-[2-(dialkylamino)ethyl]-, 3-[2-(N-methyl-N-alkylamino)ethyl]-, and 3-[2-(cycloalkylamino)ethyl]indol-4-ols

Structural alteration of the N^b-substituents of psilocin (3-[2-dimethylamino)ethyl]indol-4-ol) ( 12a ) has led to a number of compounds containing known pharmacophoric groups. Further, it is hoped that the subtle changes in the nature of these substituents may lead to a clearer understanding of the structure-activity relationships of the 4-hydroxytryptamine hallucinogens.     

Calorimetric study of the kinetics of the bulk polymerization of ethyl acrylate

The bulk polymerization of ethyl acrylate using 1-1′-azobisisobutyronitrile as initiator at several temperatures has been studied by DTA. The order with respect to the monomer and the apparent activation energy of the polymerization process have been determined.     

Synthesis of poly(dimethyl){methyl[2-(2,2,3-trifluoro-3-trifluoromethylcyclobutyl)ethyl]}siloxane

The possibility of preparing a new fluorosiloxane elastomer by hydrolytic copolycondensation of the hydrosilylated derivative of 1-vinyl-2,2,3-trifluoro-3-trifluoromethylcyclobutane with dimethyldichlorosilane was examined.     

Experimental and modeling study of C5H10O2 ethyl and methyl esters

Due to the world's over-reliance on fossil fuels there has been a developing interest in the production of renewable biofuels such as methyl and ethyl esters derived from vegetable oils and animal fats. To increase our understanding of the combustion chemistry of esters, the oxidation of methyl butanoate and ethyl propanoate, both with a molecular formula of C5H10O2, have been studied in a series of high-temperature shock tube experiments. Ignition delay times for a series of mixtures, of varying fuel/oxygen equivalence ratios (phi = 0.25-1.5), were measured behind reflected shock waves over the temperature range 1100-1670 K, and at pressures of 1.0, and 4.0 atm. It was found that ethyl propanoate was consistently faster to ignite than methyl butanoate, particularly at lower temperatures. Detailed chemical kinetic mechanisms have been assembled and used to simulate these experiments with good agreement observed. Rate of production analyses using the detailed mechanisms shows that the faster reactivity of ethyl propanoate can be explained by a six-centered unimolecular decomposition reaction with a relatively low activation energy barrier producing propanoic acid and ethylene. The elimination reaction itself is not responsible for the increased reactivity; it is the faster reactivity of the two products, propanoic acid and ethylene that leads to this behavior.     

A kinetic study of the solvolyses of methyl and ethyl chloroglyoxalates

[reaction: see text] Solvolyses of methyl and ethyl chloroglyoxylates proceed about 10(6) times faster than the identical solvolyses of the corresponding chloroformates. The correlation parameters obtained from application of the extended Grunwald-Winstein equation are consistent with an addition-elimination (association-dissociation) mechanism over the full range of solvents, with the addition step being rate determining.     

Calorimetric study of melts in the system KF - K2TaF7

Enthalpy increment measurements on melts in the system KF-K₂TaF₇ were carried out by drop calorimetry at temperatures between 298 K and 1063, 1103 and 1143 K for selected compositions. Heat capacities of the melted mixtures and enthalpies of mixing have been determined. Careful calorimetric experiments showed small but distinct non-ideality of the melt. The molar heat capacity of melt exhibits small positive divergence from additivity. The molar enthalpy of mixing shows negative deviation from ideality which decreases with increasing temperature. The thermal effect at mixing was assigned predominantly to association reactions producing more complex fluorotantalate anions. The formation of complex anions with lower coordination number of Ta may not be excluded.      

First synthesis of 2-[alkylamino(diethoxyphosphoryl)methyl]acrylic ethyl esters

The ethyl α-bromomethyl-β-(diethoxyphosphoryl)acrylic acid ester 9 has been prepared by addition of bromine to allylphosphonate 7 then dehydrobromination with DBU in acetonitrile. Reaction of allylic bromide 9 with primary amines in a bimolecular S_N2′-type mecanism in methanol at low temperature, gives rise to the 2-[alkylamino(diethoxyphosphoryl)methyl]acrylic acid ethyl esters 6.     

On the geometric isomers of ethyl 2-nitro-3-ethoxyacrylate,ethyl 2-nitro-3-phenylaminoacrylate and ethyl 2-cyano-3-phenylaminoacrylate

The title compounds exist as mixtures of Z,E-isomers. The assignment of the proton signals of PNMR spectra is performed empirically and by application of lanthanide shift reagents.     

Oxidation of methyl and ethyl butanoates

This paper describes an experimental and modeling study of the oxidation of methyl and ethyl butanoates in a shock tube. The ignition delays of these two esters mixed with oxygen and argon for equivalence ratios from 0.25 to 2 and ester concentrations of 0.5% and 1% were measured behind a reflected shock wave for temperatures from 1250 to 2000 K and pressures around 8 atm. To extend the range of studied temperatures in the case of methyl butanoate, two sets of measurements were also made in a jet‐stirred reactor at 800 and 850 K, at atmospheric pressure, at residence times varying between 1.5 and 9 s and for equivalence ratios of 0.5 and 1. Detailed mechanisms for the combustion of methyl and ethyl butanoates have been automatically generated using a version of EXGAS software improved to take into account these oxygenated reactants. These mechanisms have been validated through comparison of simulated and experimental results in both types of reactor. The main reaction pathways have been derived from reaction flux and sensitivity analyses performed at different temperatures. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 226–252, 2010     

Calorimetric and computational study of 1,3- and 1,4-oxathiane sulfones

The enthalpies of formation in the condensed and gas states, DeltafH degrees m(cd) and DeltafH degrees m(g), of 1,3- and 1,4-oxathiane sulfones were derived from their respective enthalpies of combustion in oxygen, measured by a rotating bomb calorimeter and the variation of vapor pressures with temperatures determined by the Knudsen effusion technique. Standard ab initio molecular orbital calculations at the G2(MP2) and G3 levels were performed, and a theoretical study on molecular and electronic structure of the compounds has been carried out. Calculated DeltafH degrees m(g) values at the G3 level using atomization reactions agree well with the experimental ones. These experimental and theoretical studies support that the destabilization found in 1,3-oxathiane sulfone, 11.2 kJ mol-1 respecting to 1,4-oxathiane sulfone, is due to the electrostatic repulsion between the negative charges of the axial oxygen of the sulfone and the oxygen of the ring and apparently masks any stabilization originating from the hyperconjugative nO --> sigma*C-SO2 stereoelectronic interaction.