Christo Chanev

Methylation of 2-naphthol over molecular sieves

The mesoporous molecular sieves of the type MCM-41 with different pore openings (40, 64 and 80 Å) were used as catalysts in the gas-phase methylation of 2-naphthol by methanol at 473 K. Their catalytic activity was compared with that of BEA, SAPO-5 and SAPO-11. The molar ratio of 2-naphthol : methanol was varied from 1 : 4 to 1 : 6. The alkylation of the hydroxyl group (O-alkylation) as well as of the aromatic ring (C-alkylation) proceeded. The best yield of 2-methoxynaphthalene was achieved using MCM-41 40 Å and molar ratio 2-naphthol : methanol = 1 : 6.

Heterocyclic compounds from allyl alcohol over molecular sieves

The conversion of allyl alcohol on SAPO molecular sieves (37, 34, 11 and 5) and H ZSM-5 zeolite at 523–623 K and WHSV=5.1 h−1 results in the formation of diallyl ether, propanal, 2-methyl-2-pentenal and also tetrahydropyran-2-carbaldehyde and 2-oxepanone probably obtained from intermediate acrolein. The catalytic action of the molecular sieves used corresponds to the presence of Bronsted acid sites and basic sites activating the dehydration, dehydrogenation, aldol condensation, Diels–Alder reaction and ring expansion.

Aerial oxidation of alcohols over CuAl-, CoAl-, NiAl-, ZnAl- layered double hydroxides and their mixed oxides

This paper reports the oxidative conversion of benzyl alcohol, cyclohexanol and allyl alcohol in the presence of CuAl-, CoAl-, NiAl-, ZnAl-layered double hydroxides (LDH) and their corresponding mixed oxides (MAlO) as catalysts. The mixed oxides were obtained by thermal decomposition at different temperatures. The catalysts were characterized by elemental analysis, BET method and X-ray diffraction (XRD). The partial oxidation was carried out with air oxygen and under solvent-free mild conditions. The reaction temperatures were the boiling temperatures of the alcohols. The catalytic activity and selectivity of the used LDHs and of their mixed oxides were evaluated using the air oxidation of mentioned alcohols to benzaldehyde, adipic acid and glycidol as major products. Benzyl benzoate, cyclohexyl ester of 6-hydroxyhexanoic acid and 2-2′-[oxybis(methylene)]dioxirane were determined as by-products. The interactions between catalytically active acid and basic sites and reactants are discussed. Some reaction routes and mechanisms are suggested.

6-[1-Acetyl-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole-3-yl]-2(3H)-benzoxazolone

The title compound, 6-[1-acetyl-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-3-yl]-2(3H)-benzoxazolone, was synthesized by condensation of 6-[3-(4-methoxyphenyl)-2-propenoyl]-2(3H)-benzoxazolone (1) and hydrazine hydrate in acetic acid in 84% yield. The structure of the target compound was confirmed using 1H-NMR, 13C-NMR, IR, MS, and elemental analysis.

(E)-3-Methyl-6-(3-oxo-3-(thiophen-2-yl)-1-propenyl)-2 (3H)-benzothiazolone

The title compound, (E)-3-methyl-6-(3-oxo-3-(thiophen-2-yl)-1-propenyl)-2(3H)-benzothiazolone, was synthesized by Claisen-Schmidt condensation of 3-methyl-2(3H)-benzothiazolone-6-carbaldehyde with 2-acetylthiophene in 94% yield. The structure of the target compound was confirmed using 1H-NMR, 13C-NMR, IR, MS, and elemental analysis.

(E)-3-Methyl-6-(3-oxo-3-(3,4,5-trimethoxyphenyl)prop-1-en-1-yl)-2(3H)-benzothiazolone

The title compound, (E)-3-methyl-6-(3-oxo-3-(3,4,5-trimethoxyphenyl)prop-1-en-1-yl)-2(3H)-benzothiazolone, was synthesized by both an acid- and base-catalyzed aldol condensation of 3-methyl-6-acetyl-2(3H)-benzothiazolone and 3,4,5-trimethoxyacetophenone. The structure of the target compound was confirmed using 1H-NMR, 13C-NMR, IR, MS, and elemental analysis.

6-[(4-Chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-3-methyl-2(3H)-benzoxazolone

A new hybrid molecule containing a triazole and a benzoxazolone ring was synthesized. The structure of 6-[(4-chlorophenyl)(1H-1,2,4-triazol-1-yl) methyl]-3-methyl-2(3H)-benzoxazolone was confirmed by IR, 1H-, 13C-NMR, MS and elemental analysis.