Orientational order in non-alkane chain molecules. Heats of mixing of tetralauryltin, dioctyl ether, trans- and cis-dec-5-ene with linear and branched alkanes

1975 ◽  
Vol 71 (0) ◽  
pp. 1172 ◽  
Author(s):  
Geneviève Delmas ◽  
Nguyen Thi Thanh
Keyword(s):  
Orientational Order ◽  
Chain Molecules ◽  
Heats Of Mixing ◽  
Branched Alkanes ◽  
Alkane Chain

Heats of mixing of trialkylamines: disorder and steric hindrance contributions

1978 ◽  
Vol 56 (22) ◽  
pp. 2856-2865 ◽  
Author(s):  
Robert Philippe ◽  
Geneviève Delmas ◽  
Phuong Nguyen Hong
Keyword(s):  
Steric Hindrance ◽  
Significant Contribution ◽  
Orientational Order ◽  
Class A ◽  
Heats Of Mixing ◽  
Class B ◽  
Chain Compounds ◽  
Sterically Hindered ◽  
Long Chain ◽  
Long Chains

Nine trialkylamines, triethyl- to trihexylamine trioctyl-, tridodecyl, tri(methyl-2-butyl)-, and dimethyldodecylamine have been used for heats of mixing of the following systems at 298 K: A, fourteen systems made of all the possible binary mixtures (except one) of the six shorter amines; B, twelve systems made of a long chain amine, trioctyl-, tridodecyl- or dimethyldodecylamine with the four shorter members of the series; C, two systems consisting of the mixture of two long-chain compounds, trioctylamine with tridodecyl- and dimethyldodecylamine. Heats for the class A systems are less than or equal to 40 J/mol, indicating no net effect of the small polarity of the shorter members of the series. The experimental HE of these mixtures are compared with two theories. The Monte Carlo approach gives good predictions but the heats calculated with the Snider–Herrington theory are too negative. Heats of the class B systems are suitable for the investigation of two new contributions to the heats of mixing, the positive heat of disordering of long-chains HE(dis.) and the negative heat found in systems where one of the components is sterically hindered, HE(ster.hindr.). HE(dis.) found with the long-chain amines indicates an orientational order larger than in the case of the n-alkane of the same chain-length but equivalent to that found in the tetraalkyltin compounds of the same length. Recent work has shown that the tetrapropyl and tetraethyltin derivatives when mixed with long-chain alkanes or tin derivatives give rise to a HE(ster.hindr.) contribution. From this work and the present study, the steric hindrance contributions of five sterically hindered compounds tetraethyltin and tetrapropyltin, triethyl- and tripropylamine, and 3,3-diethylpentane mixed with different second components are calculated. The steric hindrance contribution is found proportional to the volume of the second component and increasing in the following order of the sterically hindered component: triethyl- < tripropylamine < tetraethyl- < tetrapropyltin < 3,3-diethylpentane. Heats of the class C systems are small without significant contribution of HE(dis.) due to the fitting of the long-chains in solution.

Aggregation of dissolved alkane chain molecules

1974 ◽  
Vol 7 (6) ◽  
pp. 174-180 ◽  
Author(s):  
George W. Brady
Keyword(s):  
Chain Molecules ◽  
Alkane Chain

Heats of mixing. V. Systems of n-alcohols with n-hexane

1964 ◽  
Vol 17 (10) ◽  
pp. 1106 ◽  
Author(s):  
I Brown ◽  
W Fock ◽  
F Smith
Keyword(s):  
Measured Data ◽  
Alcohol Molecule ◽  
Hydroxyl Groups ◽  
Free Energies ◽  
Dilute Solutions ◽  
Chain Molecules ◽  
Heats Of Mixing ◽  
Enthalpy Difference ◽  
Higher Temperature ◽  
Generally True

Heats of mixing have been measured at 25�, 35�, and 45� for mixtures of ethanol, propan-1-ol, butan-1-ol, hexan-1-ol, and octan-1-ol with n-hexane and for methanol with n-hexane at 45�. These heats of mixing were found to increase with an increase in temperature and to decrease with an increase in the size of the alcohol molecule. They showed anomalies for the systems containing methanol and ethanol. An explanation of these anomalies has been given. The contribution of the hydroxyl groups to the enthalpy of any mixture of a n-alcohol with a n-alkane is defined as the enthalpy change on replacing the alcohol by its homomorphic alkane. The experimental results given here are consistent with the postulate that the contribution of the hydroxyl groups (per mole of alcohol) to the enthalpy depends only on the ratio of the number of hydroxyl groups to that of hydrocarbon units in the mixture. This postulate, if generally true, can be used for the prediction of the heats of mixing of any n-alcohol with a n-alkane and of the enthalpy difference between any n-alcohol and its liquid homomorphic alkane. Other data support the conclusion that the postulate holds for all concentrations of alcohol, but show that the analogous postulate applied to free energies holds only for infinitely dilute solutions of alcohols. The interaction of the hydroxyl groups with the hydrocarbon units contribute -7.8 and -4.5 kJ/mole of alcohol to the enthalpies and free energies respectively of these infinitely dilute solutions. The required values of the heats of mixing of the lower alkanes with n-hexane were estimated from the enthalpies of the alkanes using the principle of congruence; these were found to be appreciable and negative. They are in sign agreement with values extrapolated, from measured data at a higher temperature, using a principle of corresponding states for chain molecules.

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