- Self- and cross-aldol condensation of propanal catalyzed by anion-exchange resins in aqueous media
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Carbon-carbon bond formation using strong and weak anion-exchange resins as green catalysts for self- and cross-aldol condensation of propanal in aqueous media was investigated. The reaction pathway followed the route of aldol condensation to a β-hydroxy aldehyde and dehydration to an α,β-unsaturated aldehyde. The resulting products were further converted to hemi-acetal, and/or acetal moieties, which were confirmed by FT-IR and NMR. In self-condensation using strong anion-exchange resin, 97% conversion of propanal was achieved with 95% selectivity to 2-methyl-2-pentenal within 1 h using 0.4 g/mL resin at 35 °C. The conversion and selectivity using weak anion exchanger was lower. During cross-aldol condensation of propanal with formaldehyde, 3-hydroxy-2-methyl-2-hydroxymethylpropanal was obtained as the main product through first and second cross-condensation followed by hydration reaction in acidic aqueous conditions. The strong anion-exchange resin provided maximal propanal conversion of 80.4% to the product with 72.4% selectivity after 7 h reaction at 35 °C and resin concentration of 1.2 g/mL. Using weak anion-exchange resin, the optimal conversion of propanal was 89.9% after 24 h at 0.8 g/mL resin and 35 °C, and the main product was 3-hydroxy-2- methylpropanal by first cross-aldol condensation along with relatively minor amounts of methacrolein and 3-hydroxy-2-methyl-2-hydroxymethylpropanal.
- Pyo, Sang-Hyun,Hedstroem, Martin,Hatti-Kaul, Rajni,Lundmark, Stefan,Rehnberg, Nicola
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supporting information; experimental part
p. 631 - 637
(2011/12/02)
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- Quantitative RP-HPLC determination of some aldehydes and hydroxyaldehydes as their 2,4-dinitrophenylhydrazone derivatives
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A high-performance liquid chromatographic (HPLC) method is described for the quantitative determination of some aliphatic aldehydes and β- hydroxyaldehydes as their 2,4-dinitrophenylhydrazone derivatives. A method is described for the preparation of deriv
- Koivusalmi,Haatainen,Root
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- Synthesis of Allylazo Compounds by Reactions of Aryldiazonium Salts with Allylsilanes
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Aryldiazonium tetrafluoroborates react with allylsilanes to yield allylazo compounds.If the allylic carbon attached to the azo group carries hydrogen, tautomerization with formation of hydrazones takes place.
- Mayr, Herbert,Grimm, Klaus
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p. 1057 - 1059
(2007/10/02)
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- Synthesis of Analogues of 1,3-Dihydroxyacetone Phosphate and Glyceraldehyde 3-Phosphate for Use in Studies of Fructose-1,6-diphosphate Aldolase
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This paper describes the synthesis of five analogues of dihydroxyacetone phosphate (3-azidohydroxyacetone 1-phosphate (5), 3-(acetylamino)hydroxyacetone 1-phosphate (12), (R)-1,3-dihydroxy-2-butanone 1-phosphate (18), (+/-)-1,3-dihydroxy-2-butanone 3-phosphate (26), and phosphonomethyl glycolate (31)).The syntheses of 18 and 26 are based on a new reaction: that is, the introduction of the phosphate group by the reaction of a diazo ketone with dibenzyl phosphate.These methods provide easy access to a number of compounds that are potential substrates for the synthetically useful enzyme aldolase (fructose-1,6-diphosphate aldolase from rabbit muscle, EC 4.1.2.13, RAMA) and perhaps for other enzymes of glycolysis.This paper also describes syntheses of 14 aldehydes for examination as substrates for aldolase.When the precursor was available, ozonolysis of vinyl groups proved to be the best route to the corresponding aldehydes.
- Bischofberger, Norbert,Waldmann, Herbert,Saito, Tohru,Simon, Ethan S.,Lees, Watson,et al.
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p. 3457 - 3465
(2007/10/02)
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- SYNTHESIS AND REACTIONS OF SUBSTITUTED ACROLEINS.
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In this work we examined methods for obtaining 2-alkylacroleins and their derivatives that would render these compounds as cheap and readily available products of organic synthesis. Using aldehydes we show that ethylene glycol, glycerin, and pentaerythritol in the presence of acid catalysts react primarily at the carbonyl group. Maximal yields (50-80%) were obtained when using the cation exchanger KU-2 as the acid catalyst, which also simplified the isolation of the desired products. The 2-alkyl-1,3-dioxacyclanes obtained are of particular interest as monomers, comonomers, and intermediate products of organic synthesis.
- Saprygina,Zlot-skii,Rakhmankulov
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p. 862 - 866
(2007/10/02)
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