Thermochemical Characteristics of a Series of Terpenoids,Alkaloids, and Flavonoids

The heats of combustion and melting of a series of natural terpenoids, alkaloids, and flavonoids were estimated by approximate thermochemical methods. From these quantities, the standard heats of formation of the compounds in the liquid (molten) and solid states were calculated.     

Thermochemistry of Sesquiterpene Lactone 3,4β-Epoxyarglabin

The enthalpies of dissolution of 3,4β-epoxyarglabin C₁₅H₁₈O₄ are measured via isothermal calorimetry at lactone: 96% ethanol molar ratios of 1: 6000, 1: 12000, 1: 24000 at 298.15 K. The standard enthalpy of dissolution of C₁₅H₁₈O₄ in 96% ethanol is calculated from the obtained data; the value is 40.1 ± 0.4 kJ/mol. The enthalpies of combustion, melting, and formation of 3,4β-epoxyarglabin C₁₅H₁₈O₄ are estimated by approximate means.     

Thermodynamic properties of sesquiterpene lactone grossheimin

The enthalpy of dissolution of sesquiterpene lactone grossheimin C₁₅H₁₈O₄ is measured using a DAK-I-IA calorimeter at a lactone/ethanol (96%) molar ratios equal to 1 : 18000, 1 : 36000, and 1 : 72000. The standard enthalpy of dissolution of grossheimin in a 96% ethanol solution is calculated based on the resulting data. The temperature dependence of the heat capacity of grossheimin C_p^° ～ f (T) is studied by means of dynamic calorimetry using a IT-C-400 device in the temperature range of 298.15–423 K. An equation describing this dependence is derived. The standard enthalpies of combustion, melting, and formation of grossheimin are calculated using approximate methods.     

La<Subscript>2</Subscript>M<Stack><Subscript>3</Subscript><Superscript>II</Superscript></Stack>Mn<Subscript>4</Subscript>O<Subscript>12</Subscript> (M = Mg,Ca, Sr,or Ba) manganites: Synthesis and X-ray diffraction study

La₂M ₃ ^II Mn₄O₁₂ (M = Mg, Ca, Sr, or Ba) manganites have been synthesized by ceramic technology from lanthanum oxide, manganese(III) oxide, and magnesium, calcium, strontium, or barium carbonate. X-ray powder diffraction shows that these compounds crystallize in cubic perovskite space group Pm3m.     

Thermochemistry of sesquiterpene lactone argolide

The enthalpies of dissolution of argolide (C₁₅H₂₀O₃) in 96% ethanol are determined by isothermal calorimetry at 298.15 K and different dilutions of 1: 18 000, 1: 36 000, and 1: 72 000 (by mole). The standard enthalpy of dissolution of argolide in 96% ethanol is calculated from the obtained data: (86 ± 17) kJ mol^?1. The temperature dependence of heat capacity of C₁₅H₂₀O₃ is studied by means of dynamic calorimetry. An equation is derived to describe the С _p ⁰ ~ f (Т) dependence, and the standard heat capacity at 298.15 K is found to be (393 ± 13) J mol^?1 K^?1. The enthalpies of combustion, fusion and formation of argolide are calculated via approximation.     

Manganites NdMg<Stack><Subscript>3</Subscript><Superscript>I</Superscript></Stack>Mg<Subscript>3</Subscript>Mn<Subscript>4</Subscript>O<Subscript>12</Subscript> (M<Superscript>I</Superscript> = Li,Na, K): X-ray diffraction data

NdLi₃Mg₃Mn₄O₁₂, NdNa₃Mg₃Mn₄O₁₂, and NdK₃Mg₃Mn₄O₁₂ manganites were synthesized for the first time by solid phase reactions of neodymium(III) and manganese(III) oxides with lithium, sodium, potassium, and magnesium carbonates. X-ray diffraction showed that the compounds crystallized in the tetragonal crystal system. Their unit cell parameters were determined.     

Thermodynamic properties of biologically active substances: 3-acetyl-9-methoxy-2-phenyl-11H-indolizino[8,7-b]indole and 8-acetylharmine

The enthalpies of solution of 3-acetyl-9-methoxy-2-phenyl-11H-indolizino[8,7-b]indole and 8-acetylharmine in dimethyl sulfoxide were measured by isothermal calorimetry at solute: solvent molar ratios of 1: 9000, 1: 18000, and 1: 36000. From the data obtained, the standard enthalpies of solution of the compounds in dimethyl sulfoxide at infinite dilution were calculated. The heat capacities of 8-acetylharmine were determined by dynamic calorimetry in the interval 298.15–673 K, and the C _p ^o = f(T) equations were obtained. The standard enthalpies of combustion of the compounds were estimated by approximate methods, and their heats of melting were calculated. From the data obtained, using Hess cycle, the standard enthalpies of formation of the compounds were calculated.     

Thermodynamic Properties of Dimethylaminoarglabin Methyl Iodide C1 8H2 8O3NI and Its Analogs

The heat of solution of dimethylaminoarglabin methyl iodide C_{1 8}H_{2 8}O₃NI at dilutions (mole of salt/mole of water) of 1 : 75000, 1 : 100000, and 1 : 150000 was determined by isothermal calorimetry. The data obtained were used to calculate the standard heat of solution of the compound in an infinitely dilute (standard) aqueous solution. The heats of combustion, melting, and formation of C_{1 8}H_{2 8}O₃NI and 33 its analogs were estimated by approximate methods of chemical thermodynamics.     

Synthesis and acute toxicity of some phosphorylated derivatives of ephedrine alkaloids

The results are given of the synthesis and a comparative study of the toxicities of some phosphorylated derivatives of the alkaloids l-ephedrine and d-pseudoephedrine. It has been shown that the introduction of phosphorus- and sulfur-containing fragments considerably lowers the toxicity of the alkaloids.Institute of Organic Synthesis and Coal Chemistry, National Academy of Sciences of the Republic of Kazakhstan, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 406–408, May–June, 1994.