Thermodynamic properties of organic compounds in aqueous solution. II. Apparent molal heat capacities of piperidines,morpholines, and piperazines

Apparent molal heat capacities of some piperidine, morpholine, and piperazine derivatives in aqueous solution have been determined by adiabatic calorimetry in the temperature range 20–55°C and in the molality range 0.2–1m. Comparison of experimental values with those calculated through group contributions, found for monofunctional compounds, indicates strong interactions between the hydrophilic centers. An interpretation is given of the possible mechanism of this interaction. Also, values of ΔC _p for the addition reaction of proton to nitrogen centers of mono- and bifunctional organic compounds are examined.     

Determination of thermodynamic functions of sorption for cyclohexyl-, piperidyl-, morpholyl-, and thiomorpholyl-n-alkanes by capillary gas-liquid chromatography

The values of partial molar free energy (G), enthalpy (H), and entropy (S) of sorption in the homologous series ofN-alkylpiperidines,N-alkylmorpholines,N-alkyl thiomorpholines, and alkylcyclohexanes were determined. It was found that the free energy of sorption is determined to a greater extent by the enthalpy term than by the entropy one. The free energy of sorption of the first homolog decreases when then-alkyl chain is attached directly to the carbon atom of the cycle and increases in the case ofN-alkylsubstituted heterocycles. The influence of the heteroatom nature on intermolecular interactions of homologs with the nonpolar stationary phase was quantitatively estimated on the basis of thermodynamic data.Dead time necessary for calculation of the retention factor was determined by the retention of methane injected into the column simultaneously with the sample.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2030–2032, August, 1996.     

An efficient synthesis of 2-(1-methyl-1,2,5,6-tetrahydropyridin-3-yl)morpholine: a potent M1 selective muscarinic agonist

2-(1-Methyl-1,2,5,6-tetrahydropyridin-3-yl)morpholine is useful for synthesizing potent antimicrobials including the arecoline derivatives, phendimetrazine and polygonapholine and was synthesised in nine steps with an overall yield of 36%. Bromination of 3-acetylpyridine and dehydration of a diol with cyclization were pivotal to the success of the strategy.     

The influence of molecular conformation ofN-alkylsubstituted six-membered cyclic amines and alkylcyclohexanes on the thermodynamic characteristics of sorption in gas chromatography

The standard partial molar free energies, enthalpies, and entropies of sorption of the methylene units in the homologous series of alkylcyclohexanes andN-alkylsubstituted sixmembered heterocycles (piperidines, morpholines, and thiomorpholines) were determined on a capillary column with the methylsiloxane OV-101 stationary phase at 70–150°C. A characteristic feature of all series under study is an abnormally high increase in the values of thermodynamic parameters of sorption on going from the methyl to the ethyl homolog. This peculiarity is believed to be associated with the presence of thegauche butane orgauche methylethylamine fragments in the ethyl homolog. Thesegauche fragments have an increased sorption activity under conditions of gas chromatography in comparison with the correspondingtrans form. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 500–503, March, 1997.     

Synthesis of 2-substituted morpholines from dihydroxyalkylsulfamates

2-Substituted morpholines and hexahydro-1,4-oxazepines were prepared by cyclodehyration of potassium dihydroxyalkylsulfamates in concentrated sulfuric acid Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2123–2125, November, 1999.     

Iron‐Catalyzed Ring‐Closing C−O/C−O Metathesis of Aliphatic Ethers

Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring‐closing reactions. Herein, we report an iron‐catalyzed ring‐closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.     

Gas chromatographic determination of the free energy of sorption of methylene units ofN-alkylsubstituted six-membered cyclic amines

The free energy of sorption of methylene units, G(CH₂), for the homologous series ofN-alkylsubstituted morpholines, thiomorpholines, piperidines and 2-methyl-, 3-methyl-, 4-methyl- and 2,6-dimethylpiperidines was determined. It was shown that the dependence of these values on the number of CH₂ units in the carbon chain is not linear. Universal equations for calculating the values of the energy contribution depending on the number of CH₂ units in the carbon chain were obtained. Abnormally high values of free energy of sorption of the first CH₂ unit were found in all series studied and reasons for the anomaly are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 437–439, March, 1994.This work was made possible by the financial support of Russian Foundation for Basic Research, project No. 93-03-4969,