1 / 7

Correlation between Functionalized Hydrocarbons Enthalpies

Explore if the values of heat of vaporization at 298.15K correlate with melting entropy change. The heat of vaporization equation is provided, considering the contributions of carbon atoms and a constant. The analysis leads to correlations specific to compounds with the same functional groups or varied functional groups but constant carbon numbers. Relevant studies on crown ethers, pyridine isomers, ketones, and esters are referenced for further insights.

louisa
Download Presentation

Correlation between Functionalized Hydrocarbons Enthalpies

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What about functionalized hydrocarbons? Do values of lgHm(298.15 K) correlate with slngHm(Tm)? Hv(298)/kJmol-1=4.69(nC -nQ)+1.3nQ+3.0+nMM +b +C For the present let’s ignore metals and lump the quaternary carbons contribution with the constant. Hv(298)/kJmol-1  4.69nC + b + C if we allow C to be a variable, then this relationship is an equality such that 4.69nC + b >> C

  2. The b term can be expressed as 4.69*a such that b = 4.69*a Then Hv(298)/kJmol-1  4.69(nC + a) + C Hv(298)/kJmol-1  4.69nC’ + C where nC’ = (nC + a) Since 298.15 is an arbitrary temperature, the following relationship should hold for any temperature. Hv(Tm)/kJmol-1  AnC’ + B + C’ It should be possible to express B (contribution of the functional group as B = 4.69*a + c as long as we are referring to the same functional group Hv(Tm)/kJmol-1 = A(nC + a) + C’’ if we allow C’’ to be a variable

  3. Hv(Tm)/kJmol-1 = A(nC + a) + C’’ Hv(Tm)/kJmol-1 = AnC’ + C’’ slnHm(Tm)/kJmol-1 is generally small andits contribution can be expressed in similar form. slnHm(Tm) = A’nC’ + C’’’ where C’’’ is a variable. slope = lgHm (298.15 K) / slngHm(Tm) slope = (4.69nC’ + C)/(AnC’ + C’’+ A’nC’ + C’’’ ) slope = (4.69nC’ + C’)/[(A+A’) nC’ +C’’+C’’’] slope = [MnC’ + X]/[M’nC’ + X’]

  4. Consequences of this analysis: 1. Only compounds with the same functional group can be correlated. 2. Only compounds with the same number of functional groups can be correlated unless: a) group values of the functional group are the same as for C; b) the number of carbon atoms is kept constant and the number of identical functional groups varied.

  5. Ethers tertiary amines and hydrocarbons correlate. "The vaporization enthalpies of some crown ethers by correlation gas-chromatography", Nichols, G. Orf, J.; Reiter, S.; Chickos, J. S.; Gokel, G. W. Thermochimica Acta2000, 346, 15-28. "A thermochemical and theoretical study of the phenylpyridine isomers," Ribeiro da Silva, M. A. V.; Matos, M. A. R.; Rio, C. A.; Morais, V. M. F.; Wang, J.; Nichols G.; Chickos, J. S. J. Phys. Chem.2000, 104, 1774-1778. ketones and esters correlate “The Enthalpies of Formation of Two Dibenzocyclooctadienones,” St. Perisanu, St. Contineanu, J.; Banciu, M. D.; Liebman, J. F.; Farivar, B. S.; . Mullan, M. A.; Chickos, J. S.; Rath, N.; Hillesheim, D. M. Thermochim. Acta2003, 400, 109-120.

More Related