Search results for "Benzyl"

Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide

2008

Abstract Oxygenated aqueous suspensions of home-prepared (HP) and commercial TiO2 catalysts were used in a batch photoreactor for carrying out the oxidation of benzyl alcohol (BA) and 4-methoxybenzyl alcohol (MBA) under different operative conditions. HP catalysts were synthesized from TiCl4 and underwent a hydrolysis treatment of different times under mild conditions. The textural characterization of catalysts was carried out with XRD, SEM observations, BET surface area and porosity measurements. For both alcohols the main oxidation products were the corresponding aromatic aldehydes and CO2. The HP catalysts exhibited selectivity values towards the aldehyde production up to 28% (BA convers…

Oxidation of N,N-Benzylalkylamines to Nitrones by Mo(VI) and W(VI) Polyperoxo Complexes

1996

Abstract Oxidation of N,N-benzylalkylamines in chloroform by Mo(VI) and W(VI) polyperoxo complexes (PPC) of general formula Q+3{PO4[MO(O2)2]4}3− (Q+ = onium ion) yield the corresponding nitrones as oxidized products quantitatively. Only in the case of N,N-benzylmethylamine the formation of nitrone is accompanied by 25% of benzaldoxime. Oxidation of N,N-benzyltertbutylamine and N,N-benzylisopropylamine follows second order kinetics. This finding does not disqualify the hypothesis that the reaction might occur by a rate determining nucleophilic attack of the amine onto the peroxide oxygens leading, through a Bartlett-type transition state, to the probable formation of the corresponding hydrox…

Unexpectedly ambivalent O-2 role in the autocatalytic photooxidation of 2-methoxybenzyl alcohol in water

2015

An unusual autocatalytic photooxidation of 2-methoxybenzyl alcohol has been observed under UV irradiation in aqueous medium. The homogeneous oxidation is catalyzed by the corresponding aldehyde that is also the main oxidation product. The trend of alcohol disappearance rate matches the typical shape of an autocatalytic process, where a crucial and ambivalent role is played by the presence of molecular oxygen. Low oxygen concentrations give rise to a zero-order reaction since the beginning of irradiation, while higher amounts of oxygen reduce the alcohol oxidation rate until the aldehyde reaches a concentration high enough to speed up the alcohol's conversion. Experiments performed by varyin…

Kinetics of 4-Methoxybenzyl Alcohol Oxidation in Aqueous Solution in a Fixed Bed Photocatalytic Reactor

2010

WOS: 000280384800004

Glycosidsynthese mit 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyrancsylbromid

1982

Die Glycosylierung von Benzylalkohol und Cholesterin gelingt mit 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosylbromid (2) in Gegenwart von Silbersalzen in hoher Ausbeute. Die bei Koenigs-Knorr-Synthesen mit 2,3,4,6-Tetra-O-acetyl-α-D-glucopyranosylbromid (5) storende Orthoesterbildung wird beim Einsatz von 2 weitgehend unterdruckt. Die Lenkung der Reaktion zugunsten der Glycosidbildung wird dadurch erklart, das der tert-Butyl-Substituent im zwischenzeitlich gebildeten Acyloxoniumion A den nucleophilen Angriff am Acyloxoniumkohlenstoff sterisch behindert. Glycoside Synthesis Using 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosyl Bromide In the presence of silver salts the glycosylation of benzyl alc…

ChemInform Abstract: (S)-Proline Benzyl Ester as Chiral Auxiliary in Lewis Acid-Catalyzed Asymmetric Diels-Alder Reactions.

1989

Asymmetric Diels-Alder reaction of cyclopentadiene (I) with (S)-proline benzyl ester (II) yields a mixture of the diastereomeric cycloadducts (R)-(III) and (S)-(IV).

ChemInform Abstract: Multi-Arm 1,2,3-Thiadiazole Systems.

2010

Benzene derivatives 2a–c with 6, 4, and 3 side chains bearing terminal 1,2,3-thiadiazole rings, respectively, have been prepared. Alkaline cleavage of 2a–c led to the corresponding alkynethiolates 6a–c, which were trapped by electrophiles such as benzyl bromide or iodomethane. The method provides an alternative to the thermal or photochemical cleavage of 1,2,3-thiadiazoles to thioketenes, which react further with nucleophiles.

Heterotope Wirtmoleküle zur Einlagerung von zwei verschiedenen Gästen

1991

Polymere ester von Säuren des phosphors, 5. Ringöffnende polymerisation des 2-phenoxy-1,3,2-dioxaphospholan durch Michaelis-Arbuzov-reaktion

1977

2-Phenoxy-1,3,2-dioxaphospholane (14) was polymerized by benzyl halogenides at temperatures between 120 and 200°C. It was found that the main chain consists predominantly of unexpected ethylene 1,2-ethanediphosphonate units 7; only about 10% of the monomer was incorporated as the expected 2-hydroxyethanephosphonate structure. An insertion mechanism, proposed by Harwood and Patel for the analogous polymerization of 2-phenyl-1,3,2-dioxaphospholane, does not agree with our experimental results. A hypothesis is developed involving a two step addition process, which exclusively occurs at the chain end. Alternating, one monomer molecule is added by a normal Michaelis-Arbuzov-reaction, and then a …

Multi-Arm 1,2,3-Thiadiazole Systems

1997

Benzene derivatives 2a–c with 6, 4, and 3 side chains bearing terminal 1,2,3-thiadiazole rings, respectively, have been prepared. Alkaline cleavage of 2a–c led to the corresponding alkynethiolates 6a–c, which were trapped by electrophiles such as benzyl bromide or iodomethane. The method provides an alternative to the thermal or photochemical cleavage of 1,2,3-thiadiazoles to thioketenes, which react further with nucleophiles.