39825-16-6

Upstream product

• 106-44-5 p-cresol 

Relevant academic research and scientific papers

RETRACTED ARTICLE: Predicting new ugi-smiles couplings: A combined experimental and theoretical study

Following our previous mechanistic studies of multicomponent Ugi-type reactions, theoretical calculations have been performed to predict the efficiency of new substrates in Ugi-Smiles couplings. First, as predicted, 2,4,6-trichlorophenol experimentally ga

Reactivity of phenolic nucleophiles towards nitroso compounds. Part 2. Reaction with alkyl nitrites (O-nitroso compounds)

Second-order rate constants, k, have been measured for the reaction of substituted phenolate ions with alkyl nitrites in aqueous solution at 25 deg C. The final products of this reaction were identified as aromatic C-nitroso compounds and/or NO2-. Nitrosation of the phenolate ion yields ca. 90 percent of the p-nitroso product. However, methylation of the activated position of the ring (as in 4-methylphenol) does not result in the decrease in the overall reaction rate that would be expected. The reactivity of all the phenolate ions studied correlates well with their basicity, with the Hammett ?- constant and with their reactivity in other reactions in which they are known to act as O-nucleophiles. All these facts suggest that the reaction of aryloxide ions with alkyl nitrites always occurs through the oxygen atom to yield an unstable O-nitroso compound. This intermediate is likely to undergo an internal rearrangement of the NO group to give the corresponding C-nitroso product, competing with homolysis of the O-NO bond to yield nitric oxide. Oxidation of NO in the presence of O2 gives N2O3, which could act as a nitrosating agent towards ArO-. Hydrolysis of N2O3 in basic media accounts for the presence of the nitrite ion as one of the products.

Nitrosation kinetics of phenolic components of foods and beverages

The kinetics of the reactions between sodium nitrite and phenol or m-, o-, or p-cresol in potassium hydrogen phthalate buffers of pH 2.5-5.7 were determined by integration of the monitored absorbance of the C-nitroso reaction products. At pH > 3, the dominant reaction was C-nitrosation through a mechanism that appears to consist of a diffusion-controlled attack on the nitrosatable substrate by NO+/NO2H2+ ions followed by a slow proton transfer step; the latter step is supported by the observation of basic catalysis by the buffer which does not form alternative nitrosating agents as nitrosyl compounds. The catalytic coefficients of both anionic forms of the buffer have been determined. The observed order of substrate reactivities (o-cresol ≈ m-cresol > phenol ? p-cresol) is explained by the hyperconjugative effect of the methyl group in o- and m-cresol, and by its blocking the para position in p-cresol. Analysis of a plot of ΔH# against ΔS# shows that the reaction with p-cresol differs from those with o- and m-cresol as regards the formation and decomposition of the transition state. The genotoxicity of nitrosatable phenols is compared with their reactivity with NO+/NO2H2+.