Julio Casado

Learn More
The kinetics of nitrosation of dimethylamine (DMA) in aqueous perchloric acid solution haves been studied using a differential spectrophotometric technique. The rate law is Initial rate=e[DMA]0 [nitrite] 0 2 [H+]/(f+[H+])2 where [DMA]0 and [nitrite]0 represent initial stoichiometric concentrations. At 310.0 K and μ=2.0 M, e=(2.2±0.2)×10−5 M−1 s−1 and(More)
The neutral and base-catalyzed hydrolysis of nine carboxylic acid esters was studied using a hybrid supermolecule-PCM approach including six explicit water molecules. The molecules studied included two linear esters, four β-lactones, two γ-lactones, and one δ-lactone: ethyl acetate and methyl formate, β-propiolactone, β-butyrolactone, β-isovalerolactone,(More)
Nitrosation reactions of amino acids with an -NH(2) group [namely, six alpha-amino acids (glycine, alanine, alpha-aminobutyric acid, alpha-aminoisobutyric acid, valine, and norvaline); two beta-amino acids (beta-alanine and beta-aminobutyric acid), and one gamma-amino acid (gamma-aminobutyric acid)] were studied. Nitrosation was carried out in aqueous acid(More)
A kinetic study of the alkylating potential of potassium sorbate (S)-a food preservative used worldwide-in 7:3 water/dioxane medium was performed. The following conclusions were drawn: (i) Potassium sorbate shows alkylating activity on the nucleophile 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to(More)
Nitrosation reactions of alpha-, beta-, and gamma-amino acids whose reaction products can act as alkylating agents of DNA were investigated. To approach in vivo conditions for the two-step mechanism (nitrosation and alkylation), nitrosation reactions were carried out in aqueous acid conditions (mimicking the conditions of the stomach lumen) while the(More)
The alkylating potential of beta-propiolactone (BPL), beta-butyrolactone (BBL), gamma-butyrolactone, and delta-valerolactone, which can be formed by the in vivo nitrosation of primary amino acids, was investigated kinetically. The nucleophile NBP, 4-(p-nitrobenzyl)pyridine, a trap for alkylating agents, was used as an alkylation substrate. The alkylation(More)
The behavior of lactones in their hydrolysis reactions is a good indicator of their reactivity as electrophilic molecules. The hydrolysis of four- to six-membered lactones was investigated in neutral (water) and slightly acid media and in water/dioxane media. The following conclusions were drawn: (i) The reactivity of beta-propiolactone in neutral water is(More)
Hydration reactions are relevant for understanding many organic mechanisms. Since the experimental determination of hydration and hemiacetalization equilibrium constants is fairly complex, computational calculations now offer a useful alternative to experimental measurements. In this work, carbonyl hydration and hemiacetalization constants were calculated(More)
The alkylating potential of diketene (4-methylene-2-oxetanone), the basic unit of many derivatives of pesticides, chemicals, pharmaceuticals, and dyestuffs, was investigated kinetically. The nucleophile 4-( p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to DNA bases, was used as an alkylation substrate.(More)
Sorbic acid reacts with nitrite to yield mutagenic products such as 1,4-dinitro-2-methylpyrrole (NMP) and ethylnitrolic acid (ENA). In order to know the stability of these compounds, a kinetic study of their decomposition reactions was performed in the 6.0-9.5 pH range. The conclusions drawn are as follows: (i) The decomposition of NMP occurs through a(More)