EFEITOS DAS MÚLTIPLAS ESTRUTURAS E DA ANARMONICIDADE TORCIONAL PARA AS REAÇÕES DE ABSTRAÇÃO DE HIDROGÊNIO NO BUTANOATO DE METILA PELO RADICAL H

Nascimento, Joel Leitão; Alves, Tiago Vinicius

doi:10.21577/0100-4042.20230040

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Artigo • Quím. Nova 46 (7) • 2023 • https://doi.org/10.21577/0100-4042.20230040 copiar

EFEITOS DAS MÚLTIPLAS ESTRUTURAS E DA ANARMONICIDADE TORCIONAL PARA AS REAÇÕES DE ABSTRAÇÃO DE HIDROGÊNIO NO BUTANOATO DE METILA PELO RADICAL H

EFFECTS OF MULTIPLE STRUCTURES AND TORSIONAL ANHARMONICITY FOR THE HYDROGEN ABSTRACTION REACTIONS OF THE THMETHYL BUTANOATE BY H RADICAL

Autoria SCIMAGO INSTITUTIONS RANKINGS

EFFECTS OF MULTIPLE STRUCTURES AND TORSIONAL ANHARMONICITY FOR THE HYDROGEN ABSTRACTION REACTIONS OF THE THMETHYL BUTANOATE BY H RADICAL. Thermal rate constants for the hydrogen abstraction reactions of the methyl butanoate (MB) by H radical were estimated by applying the multistructural canonical variational theory with small-curvature tunneling (CVT/SCT). The conformational search was performed at MPWB1K/6-31+G(d,p) level of theory and 68 distinguishable conformers for MB and transition state located. The multistructural and torsional anharmonicity effects were corrected through the rovibrational partition functions calculated with the multistructural method based on a coupled torsional potential, MS-T(C). The MS-CVT/SCT thermal rate constants are shown in good concordance with previous combustion models. After fitting the rate constants in a four-parameters equation, the activation energy showed a temperature dependence. The product branching ratios indicate a preference for (Rα) until 500 K. Above this temperature, the contribution of other reactions becomes relevant, especially for (Rβ).

Keywords:
methyl butanoate; transition state; torsional anharmonicity

Reações	MPWB1K	DLPNO-CCSD(T)-F12
Reações	6-31+G(d,p)	cc-pVDZ-F12	cc-pVTZ-F12	cc-pVQZ-F12	CBS
(Rα’)	11,41	11,80	12,09	12,04	12,00
(Rα)	8,33	8,75	8,93	8,89	8,86
(Rβ)	9,37	9,82	10,05	9,94	9,85
(Rγ)	11,31	11,53	11,68	11,64	11,61

T/K	(Rα’)	(Rα)	(Rβ)	(Rγ)
200	300,6	75,44	50,68	114,9
300	10,60	6,808	5,413	6,480
500	2,189	2,002	1,781	1,827
1000	1,191	1,176	1,118	1,132
1500	1,067	1,056	1,031	1,040
2000	1,025	1,010	1,005	1,010
2500	1,003	0,979	0,994	0,995

T/K	(Rα’)	(Rα)	(Rβ)	(Rγ)	Total
200	1,34 × 10⁻¹⁹	3,33 × 10⁻¹⁷	4,60 × 10⁻¹⁸	6,40 × 10⁻²⁰	3,81 × 10⁻¹⁷
300	1,81 × 10⁻¹⁷	9,88 × 10⁻¹⁶	3,90 × 10⁻¹⁶	1,57 × 10⁻¹⁷	1,42 × 10⁻¹⁵
500	3,70 × 10⁻¹⁵	3,98 × 10⁻¹⁴	3,47 × 10⁻¹⁴	4,69 × 10⁻¹⁵	8,29 × 10⁻¹⁴
1000	7,10 × 10⁻¹³	1,80 × 10⁻¹²	2,40 × 10⁻¹²	9,58 × 10⁻¹³	5,86 × 10⁻¹²
1500	6,60 × 10⁻¹²	1,00 × 10⁻¹¹	1,44 × 10⁻¹¹	8,56 × 10⁻¹²	3,95 × 10⁻¹¹
2000	2,41 × 10⁻¹¹	2,81 × 10⁻¹¹	4,12 × 10⁻¹¹	3,03 × 10⁻¹¹	1,24 × 10⁻¹⁰
2500	5,75 × 10⁻¹¹	5,71 × 10⁻¹¹	8,46 × 10⁻¹¹	7,05 × 10⁻¹¹	2,70 × 10⁻¹⁰

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