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Milan M, Salamone M, Bietti M. Hydrogen atom transfer from 1,n-alkanediamines to the cumyloxyl radical. Modulating C-H deactivation through acid-base interactions and solvent effects. J Org Chem. 2014;79(12):5710-6doi: 10.1021/jo5008493.
Milan, M., Salamone, M., & Bietti, M. (2014). Hydrogen atom transfer from 1,n-alkanediamines to the cumyloxyl radical. Modulating C-H deactivation through acid-base interactions and solvent effects. The Journal of organic chemistry, 79(12), 5710-6. https://doi.org/10.1021/jo5008493
Milan, Michela, et al. "Hydrogen atom transfer from 1,n-alkanediamines to the cumyloxyl radical. Modulating C-H deactivation through acid-base interactions and solvent effects." The Journal of organic chemistry vol. 79,12 (2014): 5710-6. doi: https://doi.org/10.1021/jo5008493
Milan M, Salamone M, Bietti M. Hydrogen atom transfer from 1,n-alkanediamines to the cumyloxyl radical. Modulating C-H deactivation through acid-base interactions and solvent effects. J Org Chem. 2014 Jun 20;79(12):5710-6. doi: 10.1021/jo5008493. Epub 2014 Jun 04. PMID: 24869917.
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J Org Chem. 2014 Jun 20;79(12):5710-6. doi: 10.1021/jo5008493. Epub 2014 Jun 04.

Hydrogen atom transfer from 1,n-alkanediamines to the cumyloxyl radical. Modulating C-H deactivation through acid-base interactions and solvent effects.

The Journal of organic chemistry

Michela Milan, Michela Salamone, Massimo Bietti

Affiliations

  1. Dipartimento di Scienze e Tecnologie Chimiche, Università "Tor Vergata? , Via della Ricerca Scientifica, 1 I-00133 Rome, Italy.

PMID: 24869917 DOI: 10.1021/jo5008493

Abstract

A time-resolved kinetic study on the effect of trifluoroacetic acid (TFA) on the hydrogen atom transfer (HAT) reactions from 1,n-alkanediamines (R2N(CH2)nNR2, R = H, CH3; n = 1-4), piperazine, and 1,4-dimethylpiperazine to the cumyloxyl radical (CumO(•)), has been carried out in MeCN and DMSO. Very strong deactivation of the α-C-H bonds has been observed following nitrogen protonation and the results obtained have been explained in terms of substrate basicity, of the distance between the two basic centers and of the solvent hydrogen bond acceptor ability. At [substrate] ≤ 1/2 [TFA] the substrates exist in the doubly protonated form HR2N(+)(CH2)nN(+)R2H, and no reaction with CumO(•) is observed. At 1/2 [TFA] < [substrate] ≤ [TFA], HAT occurs from the C-H bonds that are α to the nonprotonated nitrogen in R2N(CH2)nN(+)R2H. At [substrate] > [TFA], HAT occurs from the α-C-H bonds of R2N(CH2)nNR2, and the mesured kH values are very close to those obtained in the absence of TFA. Comparison between MeCN and DMSO clearly shows that in the monoprotonated diamines R2N(CH2)nN(+)R2H remote C-H deactivation can be modulated through solvent hydrogen bonding.

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