Determination of the Heat of Formation of Hexafluorobenzene

1972 ◽  
Vol 50 (18) ◽  
pp. 2935-2938 ◽  
Author(s):  
M. Krech ◽  
S. J. W. Price ◽  
W. F. Yared
Keyword(s):  
Aromatic Compounds ◽  
Visual Inspection ◽  
Material Balance ◽  
Heat Of Formation ◽  
Heat Of Combustion ◽  
New Method ◽  
Complete Combustion ◽  
Auxiliary Substance ◽  
Hydrocarbon Oil

A new method has been developed for determining the heat of combustion of perfluoro aromatic compounds. The basic differences from previous methods are that no auxiliary substance is used and no water is present in the bomb. The combustion of hexafluorobenzene in a platinum lined bomb yields CO2, CF4, and F2. Visual inspection and the material balance indicate that complete combustion is obtained. The value of [Formula: see text] obtained by this method is −224.0 ± 2.0 kcal/mol. Recalculation of the result of Cox etal. (1, 2) obtained from combustion of C6F6 in mylar bags in the presence of hydrocarbon oil and water leads to[Formula: see text]

Determination of the Heat of Formation of Octafluorotoluene and Calculation of D[C6F5—F] – D[C6F5—CF3]

1973 ◽  
Vol 51 (22) ◽  
pp. 3662-3664 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Wayne F. Yared
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Enthalpies Of Formation ◽  
Direct Combustion ◽  
Fold Excess

The heat of formation of octafluorotoluene has been determined using the direct combustion method previously developed for hexafluorobenzene. As in the hexafluorobenzene case the combustion of octafluorotoluene in oxygen yields CO2, CF4, and F2. With a ten-fold excess of oxygen the CO2 to CF4 ratio is 3.85 ± 0.06. A full material balance was obtained. The value of ΔHf2980(C6F5CF3,g) = −303.2 ± 1.8 kcal mol−1 may be combined with the enthalpies of formation of C6F6, CF3, and F to give D[C6F5—F] – D[C6F5—CF3] = 55.7 ± 4.0 kcal mol−1.

scholarly journals Determination of ΔHf2980(C12F10,g) from studies of the combustion of decafluorobiphenyl in oxygen and calculation of D(C6F5—C6F5)

1979 ◽  
Vol 57 (12) ◽  
pp. 1468-1470 ◽  
Author(s):  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Direct Combustion ◽  
Related Compounds ◽  
Fold Excess

The heat of formation of decafluorobiphenyl has been determined by the direct combustion method previously developed and used for hexafluorobenzene and related compounds. As in the hexafluorobenzene case the combustion of decafluorobiphenyl in oxygen yields CO2, CF4, and F2. With a ten-fold excess of oxygen the CO2 to CF4 ratio is 5.85 ± 0.08. A full material balance was obtained. The value of ΔHf2980(C12F10,g) = −1263.2 ± 5.1 kJ mol−1 may be combined with ΔHf2980(C6F5,g) = −387.4 ± 12.0 kJ mol−1 to give D(C6F5—C6F5) = 488.4 ± 24.5 kJ mol−1. Also with ΔHf2980(C6F6,g) = −945.6 ± 8.0 kJ mol−1 ΔH2980 for reaction [3][Formula: see text]is calculated to be −628.0 ± 16.8 kJ mol−1.

Determination of ΔHf2980(C6F5Br, g) from studies of the combustion of bromopentafluorobenzene in oxygen and calculation of D[C6F5 — Br]

1977 ◽  
Vol 55 (24) ◽  
pp. 4222-4226 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Molar Ratio ◽  
Direct Combustion ◽  
A Value ◽  
Fold Excess

The heat of formation of bromopentafluorobenzene has been determined through the use of the direct combustion method which has been applied to hexafluorobenzene, octafluorotoluene, and iodopentafluorobenzene. While a platinum lined bomb is normally used for these types of compounds a steel bomb had to be adopted in this work. The combustion of bromopentafluorobenzene in the steel bomb yields CO2, CF4, F2, Br2, and BrF3. With a ten-fold excess of oxygen, the average CO2 to CF4 molar ratio is 7.29 ± 0.07. A material balance was obtained for carbon, fluorine, and bromine. The value of ΔHf2980(C6F5Br, g) = −711.6 ± 16.7 kJ mol−1 (−170.1 ± 4.0 kcal mol−1) has been combined with ΔHf2980(C6F5, g) = −387.4 kJ mol−1 (−92.6 kcal mol−1) and ΔHf2980(Br, g) = 111.7 kJ mol−1 (26.7 kcal mol−1) to obtain a value for D[C6F5—Br] of 435.9 kJ mol−1 (104.2 kcal mol−1).

Determination of ΔHf2980(C6F5I,g) from Studies of the Combustion of Iodopentafluorobenzene in Oxygen and Calculation of D(C6F5—X) Bond Dissociation Energies

1974 ◽  
Vol 52 (15) ◽  
pp. 2673-2678 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Wayne F. Yared
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Molar Ratio ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Direct Combustion ◽  
Tenfold Excess

The heat of formation of iodopentafluorobenzene has been determined using the direct combustion method previously developed and used for hexafluorobenzene and octafluorotoluene. The combustion with oxygen yields CO2, CF4, F2, I2, and IF5. With a tenfold excess of oxygen the average CO2 to CF4 molar ratio is 11.08 ± 0.028. A material balance was obtained for carbon and fluorine. An apparent shortfall of about 30% in iodine has been related to the formation of IO2(OH) during analysis. The value of ΔHf2980 (C6F5I,g) = −133.2 ± 3.0 kcal mol−1 has been combined with D(C6F5—I) and ΔHf2980(I, g) to obtain ΔHf2980(C6F5,g) = −92.6 kcal mol−1 Using this value and the appropriate values of ΔHf2980 (C6F5X,g) and ΔHf2980(X, g), values of D(C6F5—X) have been calculated for X = OH, H, F, Cl, I, CH3, and CF3.

New method for determination of vaporization and sublimation enthalpy of aromatic compounds at 298.15K using solution calorimetry technique and group-additivity scheme

2015 ◽  
Vol 622 ◽  
pp. 88-96 ◽  
Author(s):  
Boris N. Solomonov ◽  
Mikhail A. Varfolomeev ◽  
Ruslan N. Nagrimanov ◽  
Vladimir B. Novikov ◽  
Aleksey V. Buzyurov ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Solution Calorimetry ◽  
New Method ◽  
Sublimation Enthalpy ◽  
Group Additivity

A new method for the determination of nitrates

1960 ◽  
Vol 23 ◽  
pp. 227-232 ◽  
Author(s):  
P WEST ◽  
G LYLES
Keyword(s):  
New Method

A New Method for the Determination of Plasma Activators of Fibrinolysis

1977 ◽  
Vol 37 (02) ◽  
pp. 210-215 ◽  
Author(s):  
R Margalit ◽  
E Gidron ◽  
Y Shalitin
Keyword(s):  
New Method ◽  
Effective Activator

SummaryThe term “effective activator” of plasminogen is proposed, to denote the resultant of activator-antiactivator interaction, and a method for the determination of the level of these activators is described. By adding axcess plasminogen to the euglobulin fraction of plasma the influence of the level of endogenous plasminogen and of the antiplasmin is eliminated. It is shown that the level of fibrinogen has very little bearing on the results. An effective activator unit is defined as equal to 1 CTA unit of urokinase activity on a fibrinogen-plasminogen substrate.

The Plasmin Inhibitors of Plasma

1964 ◽  
Vol 12 (01) ◽  
pp. 119-125 ◽  
Author(s):  
Y Shamash ◽  
A Rimon
Keyword(s):  
Human Plasma ◽  
New Method ◽  
Normal Amount ◽  
Caseinolytic Activity ◽  
Before And After ◽  
Plasmin Inhibitors

SummaryA new method for the assay of plasmin inhibitors in human plasma is described. The method consists of determination of the caseinolytic activity of a standard plasmin solution before and after incubation with the inhibitor, with lysine added to the mixture as a stabilizer of plasmin. Using this method, it was found that plasma contains enough inhibitors to inactivate 30 caseinolytic units of plasmin, or 10 times the normal amount of plasminogen in human plasma.

Sign in / Sign up

Export Citation Format

Share Document