Search results for "aldehydes"
showing 10 items of 86 documents
A synthetic molecular pentafoil knot
2011
Knots are being discovered with increasing frequency in both biological and synthetic macromolecules and have been fundamental topological targets for chemical synthesis for the past two decades. Here, we report on the synthesis of the most complex non-DNA molecular knot prepared to date: the self-assembly of five bis-aldehyde and five bis-amine building blocks about five metal cations and one chloride anion to form a 160-atom-loop molecular pentafoil knot (five crossing points). The structure and topology of the knot is established by NMR spectroscopy, mass spectrometry and X-ray crystallography, revealing a symmetrical closed-loop double helicate with the chloride anion held at the centre…
Investigation of long-range female sex pheromone of the European tarnished plant bug, Lygus rugulipennis: chemical, electrophysiological, and field s…
2004
The European tarnished plant bug, Lygus rugulipennis, is an important pest of agricultural and horticultural crops throughout Europe. Adult male L. rugulipennis were previously shown to be attracted to traps baited with live virgin females, which suggests the females produce a sex pheromone. Volatiles produced by virgin female L. rugulipennis were shown to contain three components, hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal which elicited electroantennographic (EAG) responses from males in analyses by linked gas chromatography–electroantennography (GC-EAG). They were produced in 1.5:1:0.08 ratio, respectively, by single females. Collections from 1, 2, or 4 virgin female…
Catalytic Diastereo- and Enantioselective Synthesis of Tertiary Trifluoromethyl Carbinols through a Vinylogous Aldol Reaction of Alkylidenepyrazolone…
2022
A diastereo- and enantioselective organocatalytic aldol reaction between alkylidenepyrazolones and trifluoromethyl ketones leading to chiral tertiary alcohols bearing a trifluoromethyl group is presented. The methodology is based on the use of a bifunctional organocatalyst in order to activate the γ-hydrogen atoms of the alkylidenepyrazolone nucleophile and the carbonyl group of the trifluoromethylarylketone providing highly functionalized trifluoromethyl alcohols with moderate yields, excellent diastereoselectivity, and moderate to good enantioselectivity. Experiments monitoring the conversion by 1H NMR and the enantiomeric excess by HPLC with the reaction time showed that full conversion …
Influence of packaging on the aroma stability of strawberry syrup during shelf life
2001
Different types of packaging (glass bottle, PVC, and PET) were compared for the preservation of aroma quality of a strawberry syrup during shelf life. Esters, alcohols, and aldehydes were analyzed by solid-phase micro-extraction (SPME) and solvent extraction. During storage, hydrolysis of esters in acids and alcohols led to a modification of the aroma profile which can be explained by the replacement of “fruity” and “fresh” notes by “dairy note” in the syrup. Aroma compounds that are responsible for fruity notes, such as methyl cinnamate, methyl anthranilate, and methyl dihydrojasmonate, were strongly reduced after 90 days. This could be explained by a selective interaction of these compoun…
Supported Organocatalysts as a Powerful Tool in Organic Synthesis
2010
no abstract
Synthesis, Properties and Antimicrobial Activity of 5-Trifluoromethyl-2-formylphenylboronic Acid
2020
2-Formylphenylboronic acids display many interesting features, not only from synthetic but also from an application as well as structural points of view. 5-Trifluoromethyl-2-formyl phenylboronic acid has been synthesized and characterized in terms of its structure and properties. The presence of an electron-withdrawing substituent results in a considerable rise in the acidity in comparison with its analogues. In some solutions, the title compound isomerizes with formation of the corresponding 3-hydroxybenzoxaborole. Taking into account the probable mechanism of antifungal action of benzoxaboroles, which blocks the cytoplasmic leucyl-tRNA synthetase (LeuRS) of the microorganism, docking stud…
Rhodium catalyzed oxidative coupling of salicylaldehydes with diazabicyclic olefins: a one pot strategy involving aldehyde C–H cleavage and π-allyl c…
2013
An efficient one pot strategy for the synthesis of cyclopentene fused chromanone derivatives through the direct oxidative coupling of salicylaldehydes with bicyclic olefins in the presence of a rhodium-copper catalyst system is described. This is the first report on the ring opening-ring closing of bicyclic hydrazines via metal catalyzed oxidative coupling reaction.
Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas…
2013
Abstract A new analytical method based on simultaneous derivatization and dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography–mass spectrometry (GC–MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC–MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid–liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample …
A detailed identification study on high-temperature degradation products of oleic and linoleic acid methyl esters by GC–MS and GC–FTIR
2012
GC-MS and GC-FTIR were complementarily applied to identify oxidation compounds formed under frying conditions in methyl oleate and linoleate heated at 180ºC. The study was focused on the compounds that originated through hydroperoxide scission that remain attached to the glyceridic backbone in fats and oils and form part of non-volatile molecules. Twenty one short-chain esterified compounds, consisting of 8 aldehydes, 3 methyl ketones, 4 primary alcohols, 5 alkanes and 1 furan, were identified. In addition, twenty non-esterified volatile compounds, consisting of alcohols, aldehydes and acids, were also identified as major non-esterified components. Furanoid compounds of 18 carbon atoms form…
Does interindividual variability of saliva affect the release and metabolization of aroma compounds ex vivo? The particular case of elderly suffering…
2019
The aim of this work was to study the effects of interindividual variability of human elderly saliva on aroma release and metabolization by ex vivo approaches. Thirty individuals suffering or not from hyposalivation were selected from a panel formed by 110 elderly people (aged >65 years old) that were matched by age and sex. Then, their stimulated saliva samples were independently incubated in presence of three aroma compounds (ethyl hexanoate, octanal, 2-nonanone) to perform headspace-gas chromatography and liquid/liquid extraction-gas chromatography mass spectrometry analyses. These assays revealed that the extent of saliva effect on the release and metabolization of aroma compounds was h…