Marcio C. S. de Mattos

Trichloroisocyanuric acid in H2SO4: an efficient superelectrophilic reagent for chlorination of isatin and benzene derivatives

+ao anel aromatico mais eficientemente do que o TICA devido ao alivio da repulsao carga-carga. Trichloroisocyanuric acid (TICA) in H 2 SO 4 is an efficient reagent for regioselective chlorination of isatin at the 5-position and deactivated aromatic compounds, such as nitrobenzene. DFT calculations suggest formation of a superelectrophilic polyprotonated species that can transfer Cl + to the aromatic ring more efficiently than TICA due to charge-charge repulsion relief.

Trihaloisocyanuric acids/NaX: an environmentaly friendly system for vicinal dihalogenation of alkenes without using molecular halogen

The reaction of alkenes with easily handled trihaloisocyanuric acids / NaX in aqueous acetone produces the corresponding vicinal dihaloalkanes in moderate to excellent yields.

A Green Preparation of N -Chloro- and N -Bromosaccharin

Abstract The reaction of the sodium salt of saccharin, potassium chloride or bromide and oxone® in water at room temperature for 24 h produced pure N-chloro- and N-bromosaccharin in 58% and 64% yield, respectively.

Microwave-assisted free radical bulk-polyaddition reactions in a domestic microwave oven

Abstract Free radical bulk-polyaddition of diverse monomers (vinyl acetate, styrene, methyl methacrylate, and acrylonitrile) is efficiently, easily, and quickly achieved in the presence of catalytic quantities of AIBN (or benzoyl peroxide) in a domestic microwave oven. The rate of polymerization depends on the structure of the monomer, power and time of microwave irradiation; and is independent of the technique employed (periodic or continuous irradiation). The conversions of monomers to the respective polymers were mostly excellent in gram as well as multigram scale. Irradiation at low power and time produced more homogeneous polymers with higher molecular weight and low polydispersion

Characterization of natural Brazilian clays and their utilization as catalysts in the coiodination of alkenes with water and alcohols

As argilas naturais brasileiras F-101, F-117 e caulim foram caracterizadas atraves de analises quimica e textural, difracao de raios X e RMN no estado solido de 27Al e 29Si. A argila F-101 e uma esmectita, a F-117 e uma estrutura interestratificada contendo esmectita, caulinita e mica como argilominerais. O caulim e essencialmente uma caulinita. As argilas F-101 e F-117 sao catalisadores mais eficientes para a coiodacao de estireno e ciclo-hexeno com agua e alcoois para produzir iodoidrinas e b-iodo-eteres, respectivamente, comparadas ao caulim e a argila montmorilonita K-10.

N-Chloro and N-bromosaccharins: valuable reagents for halogenation of electron rich aromatics and cohalogenation of alkenes

N-Chloro- and N-bromosaccharins react with electron rich aromatic compounds (anisole, acetanilide, N,N-dimethylaniline) producing halogenated compounds. The reaction with N-bromosaccharin gives para- substituted compounds only, whereas N-chlorosaccharin produces orto and para mixtures (para isomer predominantly, ca. 4-5 : 1). The reactions of the N-halosaccharins with alkenes (cyclohexene, styrene, a-methylstyrene, and 1-hexene) give the corresponding halohydrins.

Trichloroisocyanuric Acid: An Alternate Green Route for the Transformation of Alkenes into Epoxides

The preparation of epoxides is efficiently achieved in mild conditions by reaction of alkenes with trichloroisocyanuric acid in aqueous acetone followed by treatment of the resulting chlorohydrin with aqueous KOH in ether / pentane.

Coiodação de alquenos com nucleófilos oxigenados: reações intermoleculares

A review on the electrophilic addition of iodine to alkenes in the presence of oxygen containing nucleophiles (cohalogenation reaction) is presented. The intermolecular reactions are discussed with emphasis in methods of reaction and synthetic applications of the resulting vicinal iodo-functionalized products (iodohydrins, b-iodoethers and b-iodocarboxylates).

Hydrobromination of alkenes with PBr3/SiO2: a simple and efficient regiospecific preparation of alkyl bromides

The reaction of several alkenes with 0.4 mol equiv. PBr3/SiO2 in dichloromethane at room temperature gave the alkyl bromides with Markovnikov regiospecificity in 50 - 100% yield and short reaction time. Isoprene at - 8 °C in these conditions gave 1-bromo-3-methyl-2-butene only (54%).

Cohalogenation of limonene, carvomenthene and related unsaturated monoterpenic alcohols

Cohalogenation of (R)-limonene and (R)-carvomenthene with I2/H2O/Cu(OAc)2·H 2O in aqueous dioxane followed by base treatment produced stereospecifically the corresponding trans-epoxides. Same methodology of cohalogenation applied to related monoterpenic unsaturated alcohols produced pinol derivatives [from (5R)-cis-carveol and (S)-a-terpineol] or iodohydrins [from (S)-perillyl alcohol and (5R)-trans-carveol].