Naslov
Behaviour of some ferrocenylphenylmethyl-4- methoxypyridinium cations in various solvents

Autori
Sandra Jurić

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Skup
Veli Lošinj, Hrvatska

Mjesto i datum
Veli Lošinj, Hrvatska, 05.10.2021. - 08.10.2021

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
nucleofugality, 4-methoxypyridine, pyridinium salts, solvolysis

Sažetak
The nucleofugalities of 4-methoxypyridine (4- OMePy) in pure and aqueous solvents have been derived from the SN1 solvolysis rate constants of the corresponding ferrocenylphenylmethyl-4- methoxypyridinium salts by aplying the linear free energy relationship (LFER) equation, log k (25 °C) = sf (Nf + Ef).[1] In this equation k is a first order rate constant for SN1 reaction, sf (slope of the log k/Ef correlation line) and Nf (nucleofugality, negative intercept on the abscissa of the log k/Ef correlation line) are nucleofuge specific parameters, while Ef is the electofugality parameter of the corresponding ferrocenylphenylmethyl cations determined earlier. In more polar solvents, pyridinium ions are more stabilized by solvation in the reactant ground state than in the corresponding transition state[3] and the reactivity (nucleofugality, Nf) of 4-OMePy decrease with increasing solvent polarity. Due to strong electron-donor effect of the ferrocenyl group, it seems that 4-OMePy is somewhat better leaving group if the substrate is benzhydryl-4-methoxypyridinium salts than if it is ferrocenylphenylmethyl-4-methoxypyridinium salts. The electron-withdrawing substituents on the 4 position of pyridine ring increase the rate of heterolysis step of pyridinium salts and Nf value of substituted pyridine decreasing in order Nf (4- ClPy) > Nf (Py) > Nf (4-MePy) > Nf (4-OMePy) in all examined solvents.

Izvorni jezik
Engleski

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