402932-81-4

Upstream product

• 327-97-9 chlorogenic acid 
• 880074-30-6 3,4-dimethoxy-6-nitrocinnamic acid 
• 331-39-5 caffeic acid 
• 347163-34-2 2-nitrochlorogenic acid 
• 20567-38-8 6-nitro-3,4-dimethoxycinnamic acid 

Relevant academic research and scientific papers

Antioxidant properties of nitrocaffeic acids

A series of nitrodihydroxybenzenes and nitrocaffeic acids were prepared and their hydroxyl radical (OH°) and superoxide anion (O2-) scavenging activities and xanthine oxidase inhibition activities were evaluated. 2-Nitrocaffeic acid

Reaction of caffeic acid derivatives with acidic nitrite

Caffeic derivatives were reacted with acidic nitrite at controlled pH in order to mimic the gastric juice conditions. At pH 2, whereas caffeic acid reacts exclusively on the side chain, its esters are readily nitrated. Under more acidic conditions (pH 1),

New insights into the acid-promoted reaction of caffeic acid and its esters with nitrite: Decarboxylation drives chain nitrosation pathways toward novel oxime derivatives and oxidation/fragmentation products thereof

In 0.05 M acetate buffer, pH 4, containing 1% methanol, caffeic acid (1a) (2 × 10-3 M) reacted smoothly with nitrite (NO2-) (4 × 10-3 M) to afford as main products the novel 2-hydroxy- and 2-methoxyaldoximes 7a,b, the 2-oxoaldoxime 9a, 3,4-dihydroxybenzoic acid, 3,4-dihydroxybenzaldehyde, and the known furoxan 3c and benzoxazinone 4b in smaller amounts. At lower 1a concentration (e.g., 1 × 10-4 M), 7a was the main product, whereas with 0.1 M 1a and 0.5 M NO2- 3c and 9a were prevailing. At pH 2, 7a was still the most abundant product, together with 3,4-dihydroxybenzaldehyde and some 9a, whereas at pH 1 9a and 3,4-dihydroxybenzaldehyde were formed in higher yields. No evidence for ring nitration products, including the previously reported 4,5-dihydroxy-2-nitrobenzaldehyde, was obtained. At 2 × 10-3 M concentration and at pH 4, caffeic acid methyl ester (1b) reacted with NO2- chiefly via ring nitration and/or dimerization to give 5a, the novel nitrated neolignan derivative 10, and the parent 6. Chlorogenic acid (1c) afforded only the ring nitrated derivative 5b. A unifying mechanism for the reaction of 1a and its esters with NO2- is proposed involving reversible formation of nitroso intermediates via chain nitrosation at the 2-position of the (E)-3-(3,4-dihydroxyphenyl)propenoic system. In the case of 1a, decarboxylation would drive the nitroso intermediates toward the formation of oximes 7a,b and 3c, reflecting nucleophilic addition of water, methanol, and NO2-, and their oxidation or breakdown products, viz. 9a, 3,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzoic acid, and the benzoxazinone 4b. In the case of esters 1b,c, to which decarboxylation is precluded, ring nitration or dimerization become the favored routes, triggered by preliminary oxidation at the catechol moiety.

Synthesis and physico-chemical properties of nitrocaffeic acids

The synthesis and spectroscopic properties of the three isomers of nitrocaffeic acid are described. The three pKa s of each isomer were measured by UV-visible spectroscopy. The comparison of the UV-visible spectra of nitrocaffeic acids and those obtained from the reaction of caffeic acid with reactive nitrogen species led to the conclusion that the nitration of caffeic acid with acidic nitrite does not significantly occur and confirmed trie absence of nitration when caffeic acid reacts with peroxynitrite. Attempts to obtain free radical species from nitrocaffeic acids by classical methods showed a different reactivity to that of nitroaromatics and catechols. Nitrocaffeic acids do not autoxidize under aqueous basic conditions and are insensitive to t-BuOK or O2-. (two reactants known for their capabilities to oxidize catechols and reduce nitroaromatics). Nitroaromatic anion radicals may be obtained using sodium borohydride as reductant and are particularly stable under an uncontrolled atmosphere. Copyright