Investigation on molar heat capacity, standard molar enthalpy of combustion for guaiacol and acetyl guaiacol ester

The molar heat capacities(C_p) of guaiacol(CAS 90-50-1) and acetyl guaiacol ester(AGE, CAS 613-70-7) were determinated from 290 K to 350 K by differential scanning calorimetry(DSC), and expressed as a function of temperature. Two kinds of group contribution models were used to estimate the molar heat capacities of both guaiacol and AGE, the average relative deviation is less than 10%. The standard molar enthalpies of combustion of guaiacol and AGE were- 3590.0 k J·mol^(-1)and- 4522.1 k J·mol^(-1) by a precise thermal isolation Oxygen Bomb Calorimeter. The standard molar enthalpies of formation of guaiacol and AGE in a liquid state at298.15 K were calculated to be- 307.95 k J·mol^(-1) and- 448.72 k J·mol^(-1), respectively, based on the standard molar enthalpies of combustion. The thermodynamic properties are useful for exploiting the new synthesis method, engineering design and industry production of AGE using guaiacol as a raw material.

Enthalpy and Heat Capacity Data for 1,2-Cyclohexanediol

The thermodynamic properties of different geometric structures of 1,2-cyclohexanediol which were rarely reported in literature, such as combustion enthalpy, formation enthalpy, melting enthalpy and heat ca-pacities, were determined by NETZSCH DSC 204 Scanning Calorimeter. The relationship between the melting point and the composition for the mixture system of cis-1,2-cyclohexanediol and trans-1,2-cyclohexanediol was investigated and corresponding phase diagram was obtained. 'The melting enthalpies of both cis-1,2-cyclohexanediol and trans-1,2-cyclohexanediol are 20.265kJ·mol-1 and 16.368kJ·mol-1 respectively. The standard combustion enthalpies of cia- and trans-1,2-cyclohexaneddiol were determined by calorimeter. They are respec-tively -3507.043 kJ·mol-1 and - 3497.8 kJ·mol-1 at 298.15 K.The standard formation enthalpies are respectively 568.997 kJ·mol-1 and 578.240 kJ·mol-1 for cia- and trans -1,2-cyclohexaneddiol.

Preparation and Standard Formation Enthalpy of 2-Amino-4,6-dimethylpyrimidine and Its Related Complexes of Copper

The complexes of hydrous copper chloride and copper nitrate with 2-amino-4,6-dimethylpyrimidine(ADMP) were prepared via reflux in alcohol. The compositions of the complexes were identified as Cu(ADMP) 2Cl 2·2H 2O(b) and Cu(ADMP)(NO 3) 2·H 2O(c) by chemical and elemental analyses. The complexes were characterized by IR, XPS, 1H NMR and TG-DTG techniques. The constant-volume combustion energies of ADMP and the complexes, Δ c E , were determined by a precise rotating-bomb calorimeter at 298 15 K. They were (-3664 53±1 18), (-4978 47±2 72) and (-1696 70±1 36) kJ/mol, respectively. Their standard enthalpies of combustion, Δ c H 0 m, and standard enthalpies of formation, Δ f H 0 m, were calculated to be (-3666 39±1 18), (-4977 23±2 72), (-1691 12±1 36) kJ/mol and (19 09±1 43), (-2041 80±3 29), (-2397 24±1 65) kJ/mol, respectively.

Thermochemical Properties of Ternary Complexes of RE Perchlorate with Glycine and Imidazole

The combustion energy has been determined for the nine solid complexes of rare earth perchlorate with glycine and imidazole using a rotatingbomb calorimeter.The standard enthalpy of combustion,H0 -c,coor(s), and standard enthalpy of formation,H0 -f,coor(s), for these complexes have been calculated. From the plot of standard enthalpy of formation versus atomic number of the elements in lanthanide series the tripartite effect regularity was observed and the unknown standard enthalpy of formation for similar complexes,Ce(Gly)4(Im)(ClO4)32H2O and Pm(Gly)4(Im)(ClO4)32H2O,can be estimated according to the figure.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Gramine （C11H14N2）

Low-temperature heat capacities of gramine （C11H14N2） were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 401 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 5 K intervals. The constant-volume energy of combustion of the compound at T=298.15 K was measured by a precision oxygen-bomb combustion calorimeter as △cU=-（35336.7±13.9） j·g^-1. The standard molar enthalpy of combustion of the compound was determined to be △cHm=-（6163.2±2.4） kJ·mol^-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be △cHm=-（166.2±2.8） kJ·mol-1 in accordance with Hess law.

Synthesis, Crystal Structure and Thermochemical Properties of a One-Dimensional Chain Complex [Cd（succ）PIP]n

A new complex, [Cd（succ）PIP], （PIP=2-phenyl-imidazo[4,5-J]l,10-phenanthroline, H2-succ=succinate）, was synthesized and characterized by X-ray crystallography, elemental analysis, and TG-DTG. The results show that the complex crystallizes in an orthorhombic space group Pcca; a=14.065（2） A, b=9.901（8） A, c=28.933（2） A and Z=8. The structure of the complex is one-dimensional chain [Cd（succ）PIP],, and each Cd2＋ is five-coordinated by two chelating nitrogen atoms from one PIP ligand, three oxygen atoms from three different succ dianionic ligands to form a distorted trigonal-bipyramida geometry. The constant-volume combustion energy of the complex, AoU, was determined by an intelligent micro-rotating-bomb calorimeter （IMRBC-type I） at 298.15 K. Then the standard mo- lar enthalpy of combustion, AcHm, and the standard molar enthalpy of formation, △fHm have been calculated.