The standard molar enthalpies of combustion and formation of 2-methylbenzothiazole, 2-methylbenzoxazole, and 2-methyl-2-thiazoline

A static-bomb combustion calorimeter and a rotating-bomb combustion calorimeter were used to determine the energies of combustion of 2-methylbenzothiazole, 2-methylbenzoxazole, and 2-methyl-2-thiazoline. The static- and rotating-bomb calorimeters were recently calibrated by the standard benzoic acid combustion runs and they were tested with adequate secondary combustion standards. The rotating-bomb calorimeter was tested using thianthrene and, in the present work, 1,2,4-triazole was used to test the static-bomb calorimeter. From the energies of combustion of the compounds under study, the liquid-phase standard molar enthalpies of formation were derived, at T = 298.15 K, as: (72.5 ± 1.5), (?50.7 ± 2.1), and (?88.5 ± 2.8) kJ mol^?1, respectively.     

Determinations of combustion and formation enthalpies of C60 and C70

By using a micro-bomb calorimeter, the standard enthalpies of combustion of C₆₀ and C₇₀ have been determined to be - (25 947.1±8.5) and - (29 956.1 ± 8.9) kJ/mol respectively. A g. 1. c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion ofC60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C₆₀ and C₇₀ were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close. Project supported by the National Natural Science Foundation of China (Grant No. 29473143)     

Determination of the energies of combustion and enthalpies of formation of nitrobenzenesulfonamides by rotating-bomb combustion calorimetry

The energies of combustion for 2-nitrobenzenesulfonamide (cr), 3-nitrobenzenesulfonamide (cr), and 4-nitrobenzenesulfonamide (cr) were determined using a recently described rotating-bomb combustion calorimeter. The condensed phase molar energies of combustion obtained were ?(3479.2 ± 1.0) kJ · mol^?1 for 2-nitrobenzenesulfonamide (cr), ?(3454.2 ± 1.1) kJ · mol^-1 for 3-nitrobenzenesulfonamide (cr), and ?(3450.1 ± 1.9) kJ · mol^-1 for 4-nitrobenzenesulfonamide (cr). From these combustion energy values, the standard molar enthalpies of formation in the condensed phase were obtained as: ?(341.3 ± 1.3) kJ · mol^?1, ?(366.3 ± 1.3) kJ · mol^?1, and ?(370.4 ± 2.1) kJ · mol^?1, respectively. Polyethene bags were used as an auxiliary material in the combustion experiments. The heat capacities and purities of the compounds were determined using a differential scanning calorimeter.     

Measurement of mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) and its demethylated metabolite by selective ion monitoring

Mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) and its demethylated metabolite Nirvanol (5-ethyl-5-phenylhydantoin) were measured by a selective ion monitoring technique. This method was used in the analysis of both compounds in plasma from a patient receiving 50 mg and 400 mg of mephenytoin in single oral doses. Both compounds were extracted from plasma and ethylated prior to analysis by electron-impact mass spectrometry. Alkylation, using ethyl iodide in 2-butanone, occurred in the N-1 and N-3 positions of the hydantoin ring when concentrated KOH was added to the reaction mixture. The lower limits of quantitation for mephenytoin and Nirvanol were 10 ng/ml and 50 ng/ml, respectively, and were found to be reproducible within 8% upon repeated quantification.     

Standard enthalpies of combustion and formation for fatty acid esters in the condensed state

The energies of combustion are determined for methyl heptadecanoate (crys.), methyl stearate (crys.), ethyl stearate (crys.), methyl behenate (crys.), methyl oleate (liq.), and methyl erucate (liq.) by bomb calorimetry method. The standard enthalpies of combustion and formation are calculated for these compounds in the condensed state.     

Standard molar enthalpies of formation of 5- and 6-nitroindazole

The present work reports the experimental determination of the standard (p ^o = 0.1 MPa) molar enthalpies of formation in the condensed and gaseous phases, at T = 298.15 K, of 5- and 6-nitroindazole. These results were derived from the measurements of the standard molar energies of combustion, using a static bomb calorimeter and from the standard molar enthalpies of sublimation derived by the application of Clausius–Clapeyron to the temperature dependence of the vapour pressures measured by the Knudsen effusion technique. The results are interpreted in terms of the energetic contributions of the nitro groups in the different positions of the aromatic ring.     

Determinations of combustion and formation enthalpies of C_(60)and C_(70)

Ｆｕｌｌｅｒｅｎｅｓａｒｅａｋｉｎｄｏｆｃａｒｂｏｎａｌｌｏｔｒｏｐｅｓｆｏｕｎｄｒｅｃｅｎｔｌｙ,ａｎｄｈａｖｅｄｉｓｔｉｎｃｔｉｖｅｓｔｒｕｃｔｕｒｅｓａｎｄｐｒｏｐｅｒｔｉｅｓ.Ｆｏｒｅｘａｍｐｌｅ,Ｃ60ｈａｓａｆｏｏｔｂａｌｌｌｉｋｅｃａｒｂｏｎｓｋｅｌｅｔｏｎｗｉｔｈ20ｓｉｘｍｅｍｂｅｒｅｄｒｉｎｇｓ,12ｆｉｖｅｍｅｍｂｅｒｅｄｒｉｎｇｓａｎｄａｌａｒｇｅｂａｌｌｓｈｅｌｌｌｉｋｅπｂｏｎｄｓｙｓｔｅｍ.Ａｌｔｅｒｎａｔｉｖｅｌｙ,Ｃ70ｈａｓａｎｅｌｌｉｐｓｏｉｄｌｉｋｅｃａｒｂｏｎｓｋｅｌ…     

三氯苯的标准生成焓和异构化焓

报导了用精密转动弹量热计测定诸三氯苯燃烧热的实验结果,并计算出这些化合物在液态(或固态)和气态下的标准生成焓.同时还计算出它们的异构化焓和原子化热,并与一般公认为比较精确的热化学键能模式的计算值进行比较和讨论.     

Kinetics and mechanism of formation of isomeric 1-methyl- and 2-methyl-5-vinyltetrazoles

The alkylation of 5-(β-dimethylaminoethyl)tetrazole (1) with dimethyl sulfate afforded 5-(β-dimethylaminoethyl)-1-methyltetrazole (2) and 5-(β-dimethylaminoethyl)-2-methyltetrazole (3). The exhaustive alkylation of compounds 2 and 3 at the terminal dimethylamino group gave 1-methyl-(4) and 2-methyl-5-(β-trimethylammonioethyl)tetrazole (5) methyl sulfates. The proton elimination from the α-methylene (with respect to the tetrazole cycle) groups of the quaternary ammonium cations of salts 4 and 5 by the action of a base leads to the corresponding zwitterions 4 ^± and 5 ^±, which in the rate-determining step undergo the cleavage of the nitrogen—carbon bond with the formation of 1-methyl-5-vinyl- (6) and 2-methyl-5-vinyltetrazole (7). The true constant of the transformation of zwitterion 4 ^± into tetrazole 6 is 21 times higher than that for the transformation of zwitterion 5 ^± into tetrazole 7.     

Crystal Structure of 1-Methyl-5-phenylhydantoin

1　INTRODUCTIONInourinvestigationofhemithioacetals,wediscoveredthatα-benzoylhemithioac-etalisquitestableandhastwoelectrophilicsitesthatcanreactwithalkylureastoformahydantoinring[1].Althoughthehydantoinringitselfdoesnotpresentanymedicinalactivity,somedisubstitutedhydantoinshavebeenwidelyusedasmedicineforitsregulareffectonthebioelectricactivityofthenervoussystem.Inordertoim-proveandexpandtheactivityaswellastopreventsideeffects,variouskindsofhy-dantoinderivativeshavebeenpreparedandtested[2].…     

Standard enthalpies of formation of 2-aminobenzothiazoles in the crystalline phase by rotating-bomb combustion calorimetry

The standard molar enthalpies of combustion of 2-aminobenzothiazole (2AB), 2-amino-4-methyl-benzothiazole (2A4MB), and 2-amino-6-methyl-benzothiazole (2A6MB) were determined in the crystalline phase at T = 298.15 K using a rotating-bomb combustion calorimeter. The molar energies of combustion of these compounds were found to be: (−4273.6 ± 0.9), (−4896.9 ± 1.1), and (−4906.9 ± 1.2) kJ · mol⁻¹, respectively. From these values, the corresponding standard molar enthalpies of formation in the solid phase were obtained as: (59.55 ± 1.28), (2.71 ± 1.50), and (13.53 ± 1.53) kJ · mol⁻¹, respectively. The enthalpies of formation in the gas phase were determined using the experimental enthalpies of formation in the solid phase and predicted values of the enthalpies of sublimation. Additionally, the enthalpies of formation in the gas phase were calculated by means of the Gausian-4 theory, using several gas-phase working reactions, and were compared with those found using the predicted enthalpies of sublimation.