Some Nuclearly Substituted Catechols and their Acid Dissociation Constants

Development of a liquid chromatographic method based on ultraviolet–visible and electrospray ionization mass spectrometric detection for the identification of nitrocatechols and related tracers in biomass burning atmospheric organic aerosol

“…In a first series of experiments hydrophilic interaction liquid chromatography (HILIC) was evaluated for their separation. 4NC and methyl nitrocatechols are weak acids in aqueous solution with the first pKa values between 6 and 8, while 2NP, 4NP and 2,4DNP have pKa values of 7.23, 7.15 and 4.07, respectively . All these compounds are polar and can be transformed into a more polar state by dissociation to monoanions, i.e.…”

“…All standards had purity higher than 95% and were used without further purification. 3‐Methyl‐5‐nitrocatechol (3M5NC) and 3‐methyl‐6‐nitrocatechol (3M6NC) were synthesized from 3‐methylcatechol by procedures described in the literature (details about the synthesis are provided in the Supporting information) . Individual standard stock solutions of the studied nitro compounds were prepared at concentrations of 500 mg L –1 in methanol.…”

“…3-Methyl-5-nitrocatechol (3M5NC) and 3-methyl-6-nitrocatechol (3M6NC) were synthesized from 3-methylcatechol by procedures described in the literature (details about the synthesis are provided in the Supporting information). [9,19,20] Individual standard stock solutions of the studied nitro compounds were prepared at concentrations of 500 mg L -1 in methanol. A composite standard solution with a concentration of 2 mg L -1 of each nitro compound in methanol/water (3/7; v/v) mixture containing 10 mM ammonium formate buffer pH 3 was initially used for the optimization of the chromatography of the nitro-aromatic compounds.…”

Studies on soil humic acids II: Observations on the estimation of free amino groups. Reactions of humic acid and lignin preparations with nitrous acid

“…It appears likely that nitroso compounds are formed, but the possibility that nitro compounds are produced cannot be excluded, as several workers have found that phenolic compounds yield nitro derivatives when treated with nitrous acid (e.g. Rosenblatt, Epstein & Levitch, 1953). The reaction of lignin with nitrous acid does not appear to have been investigated in any detail, but the reaction with nitric acid has received considerable attention (see Brauna, 1952) and several workers have reported that nitration of lignin does not occur in the presence of urea, which destroys nitrous acid.…”

Effect of Metal Ions on the Formation of Trichloronitromethane during Chlorination of Catechol and Nitrite

“…6a). However, because the rate-limiting step of TCNM formation (nitration of catechol) is an exothermal reaction (Rosenblatt et al, 1953), the increase was weak (Fig. 6b).…”