Tautomeric and conformational properties of dipivaloylmethane

The tautomeric and structural properties of 5-hydroxy-2,2,6,6-tetramethyl-3-heptanone, (dipivaloylmethane, C(CH3)3C(O)CH2C(O)C(CH3)3) have been studied by means of gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 approximation with different basis sets up to aug-cc-pVTZ). Both, quantum chemistry and GED analyses resulted in the presence of 100(5)% enol tautomer at 296(3)K. Quantum chemical calculations predict the existence of two enol conformers in about equal amounts. In both conformers the enol ring possesses Cs symmetry and they possess different torsional orientations of the two tert-butyl groups. The experimental data refinement results in an enol tautomer, in which the tert-butyl group adjacent to the carbonyl group possesses an intermediate orientation between those in “enol1” and “enol 2” forms (torsional angle is about 30 ), and the tert-butyl group adjacent to the hydroxyl group slightly deviates from orientation in the theoretical conformers (by about 10 ). The enol ring possesses CS symmetry with a strongly asymmetric hydrogen bond. The experimental geometric parameters are reproduced very closely by the B3LYP/aug-cc-pVTZ method.

Title: Tautomeric and conformational properties of dipivaloylmethane
Authors: Belova, Natalya V.
Nguyen, Hoang Trang
Oberhammer, Heinz
Keywords: Dipivaloylmethane
Gas phase structure
Tautomeric and conformational properties
Gas electron diffraction
Quantum chemical calculations
Issue Date: 2017
Publisher: ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Citation: ISIKNOWLEDGE
Abstract: The tautomeric and structural properties of 5-hydroxy-2,2,6,6-tetramethyl-3-heptanone, (dipivaloylmethane, C(CH3)3C(O)CH2C(O)C(CH3)3) have been studied by means of gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 approximation with different basis sets up to aug-cc-pVTZ). Both, quantum chemistry and GED analyses resulted in the presence of 100(5)% enol tautomer at 296(3)K. Quantum chemical calculations predict the existence of two enol conformers in about equal amounts. In both conformers the enol ring possesses Cs symmetry and they possess different torsional orientations of the two tert-butyl groups. The experimental data refinement results in an enol tautomer, in which the tert-butyl group adjacent to the carbonyl group possesses an intermediate orientation between those in “enol1” and “enol 2” forms (torsional angle is about 30 ), and the tert-butyl group adjacent to the hydroxyl group slightly deviates from orientation in the theoretical conformers (by about 10 ). The enol ring possesses CS symmetry with a strongly asymmetric hydrogen bond. The experimental geometric parameters are reproduced very closely by the B3LYP/aug-cc-pVTZ method.
Description: TNS06972 ; JOURNAL OF MOLECULAR STRUCTURE Volume: 1132 Special Issue: SI Pages: 63-69 Published: MAR 15 2017
URI: http://repository.vnu.edu.vn/handle/VNU_123/28155
http://www.sciencedirect.com/science/article/pii/S002228601630919X
ISSN: 0022-2860
1872-8014
Appears in Collections:Bài báo của ĐHQGHN trong Web of Science

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