Naslov
What is the Nature of the Electrophilic species in the Interaction of C-nitroso Group With Formaldehyde in Acidic Acetonitrile ?

Autori
Pilepić, Viktor ; Uršić, Stanko

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

Izvornik
8TH European Symposium on Organic Reactivity (ESOR-8), Programme and abstract / - , 2001

Skup
8TH European Symposium on Organic Reactivity (ESOR-8)

Mjesto i datum
Dubrovnik, Hrvatska; Cavtat, Hrvatska, 01.09.2001. - 06.09.2001

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Sažetak
The acid catalyzed formation of N-phenylformohydroxamic acid from nitrosobenzene and formaldehyde in 99.9 % acetonitrile is 2000-fold faster than the same reaction1 in a water acidic medium. Substituted nitrosobenzenes exibit ; Hammett value of -3.18 (r=0.995, Fig. 1) for the reaction in acetonitrile, while the corresponding values for water and 92.6 % acetonitrile are -1.71 and -2.11, respectively. At constant acid concentration and the increasing excess of total formaldehyde concentration (or vice versa) levelling-off of the observed pseudo-first order rate constants for the formation of hydroxamic acid was observed1, Fig. 2. Analogously, variation of the concentration of formaldehyde keeping the concentration of acid constant and in sufficient excess over aldehyde concentration (or vice versa) gave the linear dependence of the pseudo-first order rate constants (conc. of nitrosobenzene was much smaller than that of formaldehyde or acid), with the same slope in both cases. In contrast with the reaction in water, where the primary kinetic isotope effect (PKIE) of ca. 8 was observed, the PKIE between formaldehyde and formaldehyde-d2 in acetonitrile was not observed (kH/kD ca. 1.0). These results suggest that the nucleophilic attack of nitroso group on the protonated aldehyde-chloride ion pair could be the first reaction step .

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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