Thermochemistry and bond energies of acetohydrazide, amides and cyclic alkyl ethers

Author

Sumit Charaya, New Jersey Institute of Technology

Document Type

Thesis

Date of Award

Spring 5-31-2011

Degree Name

Master of Science in Pharmaceutical Chemistry - (M.S.)

Department

Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Tamara M. Gund

Third Advisor

Rubik Asatryan

Abstract

Structure, thermochemical properties, bond energies and internal rotation potentials of Acetic Acid Hydrazide (CH₃CONHNH₂), Acetamide (CH₃CONH₂) and N-methyl Acetamide (CH3CONHCH3) and their radicals corresponding to loss of hydrogen atom have been studied. Gas phase standard enthalpies of formation and bond energies were calculated using the DFT methods B3LYP/6-31G(d,p), B3LYP/6-31G(2d,2p) and the composite CBS-QB3 methods employing a series of work reactions to further improve accuracy of the ΔH_f°(298K). Molecular structures, vibration frequencies and internal rotor potentials were calculated at DFT level. The enthalpies of the parent molecules CH₃-C=ONHNH₂, CH₃-C=ONH₂ and CH₃-C=ONHCH₃ are evaluated as -28.6, -58.1 and -56.5 kcalmol^-1 respectively at B3LYP/6-31G(D,P), B3LYP/6-31G(2d,2p) and CBS-QB₃ levels. Bond dissociation energies for H--CH₂C=ONHNH₂, CH₃-C=ON(--H)NH₂, CH₃- C=ONHNH--H, H--CH₂C=ONH₂, CH₃-C=ONH--H, H--CH₂-C=ONHCH₃, CH₃-C=ON(- -H)CH₃ and CH₃-C=ONHCH₂ - H are 99.9, 78.2, 81.9, 100.1, 111.5, 99.9, 104.2 and 93.7 kcal mol-1 respectively. The computed DFT and the Complete Basis Set enthalpy values are in close agreement with each other; and this accord is attributed to use of isodesmic work reactions for the analysis. The agreement also suggests this combination of B3LYP / work reaction approach is acceptable for larger molecules.

Cyclic ethers are a major initial product from the reactions or hydrocarbon radicals with triplet dioxygen (³O₂) in low to moderate temperature oxidation and combustion reaction systems and atmospheric chemistry of small hydrocarbons. Thermochemical properties, ΔH°_f(298), S°₂₉₈ and Cp° (T) (10K

Recommended Citation

Charaya, Sumit, "Thermochemistry and bond energies of acetohydrazide, amides and cyclic alkyl ethers" (2011). Theses. 88.
https://digitalcommons.njit.edu/theses/88