Ludwik Syper

Lithium diselenide in aprotic medium - a convenient reagent for synthesis of organic diselenides

Abstract The reduction of selenium with lithium in THF in the presence of diphenylacetylene as a catalyst afforded lithium diselenide, which reacted with electrophiles giving alkyl or aryl diselenides 1 - 3 and selenides 4 , as by-products. The useful method for preparation of diselenides based on this reaction was elaborated.

Benzeneperoxyseleninic acids-synthesis and properties

Abstract Benzeneperoxyseleninic acid ( 3 ) and its analogs, 2-nitro and 2,4-dinitrobenzeneperoxyseleninic acids ( 10 , 11 ), were obtained by oxidation of corresponding arylseleninic acids or diaryldiselenides with hydrogen peroxide. Their chemical properties were studied and rearrangement of 3 to benzeneselenic acid 7 was found as an useful method for preparation of this compound. In was also shown that peroxyseleninic acid 10 can be used as an efficient oxidant in the Baeyer-Villiger transformation of the formyl group into formyloxy one.

Synthesis of oxiranylquinones as new potential bioreductive alkylating agents

Abstract 1,4-Benzoquinones and 1,4-naphthoquinones carrying oxiranyl substituents have been synthesized as potential bioreduetive alkylating agents. The method presented here involves the syntheses of 1,4-dimethoxybenzalkehydes or 1,4-dimethoxynaphthaldehydes, and conversion of the carbonyl groups into the oxiranyl function using trimethylsulfonium chloride in the presence of powdered sodium hydroxide 1,4-Dimethoxy-2-oxiranyl-benzenes and 1,4-dimethoxy-2-oxiranylnaphthalenes have been oxidized to quinones with silver(II) dipicolinate.

Reaction of α, β-unsaturated aldehydes with hydrogen peroxide catalysed by benzeneseleninic acids and their precursors

Abstract Oxidation of α,β-unsaturated aldehydes with hydrogen peroxide catalysed by benzeneseleninic acids and their precursors has been investigated. Bis 2-nitrophenyl diselenide has proved to be the most effective catalyst. The major products resulting from the oxidation are vinyl formates ( a ) which on hydrolysis give saturated aldehydes or ketones ( g ) having the carbon chain shortened by one carbon atom, compared with the starting alde-hydes. The minor products are formyloxyoxiranes ( b ), α-hydroxy-carbonyl ( e ) and α-formyloxycarbonyl ( f ) compounds with the carbon chain shortened by one carbon atom. Carbonyl compounds d , formally derived from an oxidative fission of the carbon-carbon double bond, have been also isolated. Diformyloxy ( 4c ) and formy-loxyacetoxy phenylmethane ( 5c ) have been isolated when cinnamaldehyde ( 4 ) or 1-phenyl-2-formyloxypropane ( 5a ) were oxidized, respectively. Possible mechanisms of formation of these products are discussed. Similar products resulted when α, β -unsaturated aldehydes were oxidized with organic peroxy acids.

Reactions of normal alcohols in the presence of a dehydrogenating iron catalyst

A oxidizing condensation of normal alcohols C4 to C12 in the gas phase over Fe3O4 catalyst containing Cr, Si and K oxides was studied. The reactions were carried out in a continuous process at atmospheric pressure. Initially the alcohols undergo dehydrogenation to aldehydes and esters, and at higher temperatures symmetric ketones containing 2n - 1 atoms of carbon in a molecule are formed. A mechanism for the reaction is proposed.

ONE-POT OXIDATION OF AZOMETHINE COMPOUNDS INTO ARENECARBOXYLIC ACIDS

Aromatic azomethine compounds, such as aldazines 1, aldoximes 7 and tosylhydrazones 8 oxidized with 30% hydrogen peroxide in the presence of poly(bis-1,2-phenylene) diselenide (6) as catalyst produce arenecarboxylic acids 2 mostly in high to excellent yields. The presented one-pot procedure has a synthetic value.

A new efficient catalytic method of naphthols ring alkylation

Abstract The attempts carried out so far concerning catalytic ring alkylation of naphthols with alcohols have, as a rule, brought about a complex mixture of products from which the separation of individual compounds with the aim of their practical utilization has been proved to be impossible. We have found that naphthols and some of their derivatives could be easily alkylated with methanol or higher alcohols in the presence of iron oxide catalyst by a gas-phase continuous process. As a result of alkylation the alkyl group enters into the ortho -position to the hydroxyl group. The yields of alkylnaphthols are approximately about 90%, which simplifies their separation and purification considerably. The advantage of the newly developed method of alkylation is that it leads to high degree of raw materials utilization: it is practically wasteless, thus it is well suited to the requirements of modern process technologies. Its application may contribute to the increase of the demand for naphthol derivatives as potential raw materials for many new syntheses of pharmaceuticals, plant protection agents, dyes, etc.

t‐Butyl Hydroperoxide Oxidative Dealkylation of Hydroquinone Ethers to 1,4‐Quinones

Abstract Various organoselenium compounds (diselenides, benzisoselenazol‐3(2H)‐ones, and 1,3,2‐thiaselenazolones) are effective catalysts for oxidative dealkylation of hydroquinone ethers with t‐butyl hydroperoxide to 1,4‐quinones. The reactions is most efficient when t‐butyl hydroperoxide in the presence of poly(bis‐1,2‐phenyl) diselenide is used as an oxidizing agent. In this way 1,4‐benzo and 1,4‐naphthoquinones are produced in good to high yields.

Ketonization of long chain esters from transesterification of technical waste fats

The methyl ester mixture obtained from rape oil, and the mixture of butyl esters produced from animal fatty acids, were converted into mixtures of ketones with a total yield above 65%. The experiments were performed at atmospheric pressure in a temperature range of 300-400°C using a standard flow system, with an iron catalyst modified with silicon, chromium, and potassium oxides, in the molar ratio of 100:2:1:0.1. The described method may extend the prospects of using waste technical fats.

Catalytic reactions of oxidized n-C10 derivatives over an iron oxide

Abstract The susceptibility to ketonization of oxidized derivatives of n -decane ( n -decanol, n -decanal, their equimolar mixtures, n -decyl n -decylate, and 3-hydroxy-2-octyl-dodecanal) in the gas phase at atmospheric pressure over Fe 3 O 4 catalyst was studied. Using those reactants, 10-nonyldecanone was the main product. Condensing n -decanal, n -decyl n -decylate, and 3-hydroxy-2-octyl-dodecanal, ketone is obtained with higher yields than from n -decanol.