Unsaturated Aliphatic Aldehydes Research Articles

A General, Highly Anti-Stereoselective Aldolization Method via Camphor-Derived Boryl Enolates

Camphor-derived chiral boryl enolates are highly reactive and highly anti-stereoselective enolate synthon systems in aldol addition reactions promoted by a TiCl4 or SnCl4 cocatalyst. More significantly, this high-yield reaction exhibits remarkable generality with respect to the aldehyde nature, as illustrated by the rapid and anti-stereoselective aldolizations with the simple saturated and unsaturated aliphatic aldehydes, and aromatic aldehydes at temperatures as low as −90 °C. The enhanced reaction generality and anti stereoselectivity of camphor-derived boryl enolates suggests the importance of the nature of chiral auxiliary architecture in determining the aldol bond construction process. Final nondestructive camphor-based auxiliary removal via hydroperoxide-mediated hydrolysis affords enantiomerically pure anti-β-hydroxy-α-methyl aldol products.

Determination of aliphatic aldehydes as their thiazolidine derivatives in foods by gas chromatography with flame photometric detection

A selective and sensitive gas chromatographic method for the determination of saturated and unsaturated aliphatic aldehydes in foods has been developed. After extraction of the sample with acetonitrile, aldehydes were converted into their thiazolidine derivatives by the reaction with cysteamine, and then measured by gas chromatography with flame photometric detection. The calibration curves for aliphatic aldehydes in the range 20–2500 ng were linear and the detection limits at a signal-to-noise ratio of 3 were ca. 4–100 pg injected. Aliphatic aldehydes in foods could be selectively determined by this method without any interference from coexisting substances. Overall recoveries of aldehydes added to food samples were 82–111%. Analytical results for the determination of aliphatic aldehydes in various food samples are presented.

The identification of odorous metabolites produced from algal monocultures

Four algal species commonly found in the River Seine were cultured for a comprehensive investigation of their odorous metabolites. Closed loop stripping analysis (CLSA), open stripping analysis (OSA) and steam distillation extraction (SDE) were used to extract and concentrate a wide range of metabolites. The odour causing compounds were identified by a combination of chemical (gas chromatography-mass spectrometry (GC-MS)) and sensory (sensory-gas chromatography (sensory-GC), flavour profile analysis (FPA)) analyses. The compounds found responsible for unpleasant odours were alkenes, saturated and unsaturated aliphatic alcohols, aldehydes, ketones, sulphides and pyrazines. Some of the odorous compounds responsible for septic and muddy/musty odours may have been of bacterial or fungal origin as the cultures were non-axenic. Sensory-GC was found to be a valuable tool in identifying compounds of very low odour thresholds, which were present at or below the detection limits of the GC-MS.

The identification of odorous metabolites produced from algal monocultures

Four algal species commonly found in the River Seine were cultured for a comprehensive investigation of their odorous metabolites. Closed loop stripping analysis (CLSA), open stripping analysis (OSA) and steam distillation extraction (SDE) were used to extract and concentrate a wide range of metabolites. The odour causing compounds were identified by a combination of chemical (gas chromatography-mass spectrometry (GC-MS)) and sensory (sensory-gas chromatography (sensory-GC), flavour profile analysis (FPA)) analyses. The compounds found responsible for unpleasant odours were alkenes, saturated and unsaturated aliphatic alcohols, aldehydes, ketones, sulphides and pyrazines. Some of the odorous compounds responsible for septic and muddy/musty odours may have been of bacterial or fungal origin as the cultures were non-axenic. Sensory-GC was found to be a valuable tool in identifying compounds of very low odour thresholds, which were present at or below the detection limits of the GC-MS.

Selectivity aspects in the multi‐phase hydrogenation of α,β‐unsaturated aldehydes over supported noble metal catalysts: Part I

AbstractThe selective hydrogenation of cinnamaldehyde and other unsaturated aliphatic aldehydes under a two‐phase liquid system using toluene and aqueous alkaline solution over supported palladium catalysts has been investigated with a view to obtaining the corresponding saturated aldehydes with sufficiently high selectivities. In the case of cinnamaldehyde, the effects of various process parameters on the reaction rate and selectivity with respect to the aldehyde have been investigated. The results obtained are likely to be useful for the rational design of the process for the production of industrially relevant products, such as hydrocinnamaldehyde and citronellal using cinnamaldehyde and citral as the starting materials.

Inhibition of microsomal glucose 6-phosphatase by unsaturated aliphatic aldehydes and ketones

Aldehydes and ketones with one double bond conjugated to the carbonyl group inhibited the enzyme glucose 6-phosphatase, which is embedded in the microsomal membrane. The Michaelis constant, K m and the maximal rate of reaction, V, were affected in a way dependent on the inhibitor's chain-length: trans-2-pentenal and 1-penten-3-one increased K m linearly with concentration and had almost no effect on V, whereas trans-2-nonenal caused a large increase in V but only a small and non-linear change in K m. The effect of the short-chain aldehydes on the kinetic parameters increased with chain-length, but pentenone increased K m more than did trans-2-heptenal and conjugated dienals did not act as inhibitors. Therefore, sterical effects apparently are of importance. Washing the microsomes after incubation with hexenal or heptenal did not substantially decrease the inhibition, but with nonenal the inhibition was reduced by washing. Inhibition by the SH-group blocking reagent p-hydroxymercuribenzoate was competitive to inhibition by the alkenals. It is concluded that the α-β unsaturated oxo-compounds inhibit glucose 6-phosphatase by binding covalently to an important mercapto group and that perturbation of the enzyme's membrane environment also plays a part in the inhibition.

Olfactory sensitivity of two sympatric species of rice leaf folders (Lepidoptera: Pyralidae) to plant volatiles

Electroantennograms (EAGs) were recorded from male and female moths of two sympatric leaf folder species,Cnaphalocrocis medinalis (Gue-née) andMarasmia patnalis Bradley (Lepidoptera: Pyralidae) to 91 volatile chemicals of plant origin. Responses of both leaf folder species were similar to all compounds except to three monoterpenes-β-myrcene, menthone, and isomenthone- and two sesquiterpenes-cis-nerolidol and isophytol. Response ofM. patnalis, an oligophagous leaf folder, to these compounds was higher compared with that of polyphagousC. medinalis. EAG responses of males to saturated and unsaturated aliphatic aldehydes were significantly higher than those of conspecific females in both species. A higher response ofC. medinalis males also was observed for 1-nonanol, 3-nonen-2-one, andtrans, trans-2,6-dimethyl-2,4,6-octatriene. In contrast, females of both species responded more to monoterpenes, borneol, isoborneol, and fenchyl alchohol. Response ofC. medinalis female was higher for terpinen-4-ol, carveol, dihydrocarveol, (-)-myrtenal, and perillaldehyde. In both species and sexes, high EAG responses were recorded for compounds of the green leaf odor complex. EAG responses to nonanal and hexanal were maximum among the aliphatic aldehydes while 1-hexanol elicited the highest response among the alcohols tested. EAG responses to terpene compounds-citronellal,α-terpineol, and (-)-myrtenal-were equal to the response to 1-hexanol. While all compounds tested elicited a negative potential, thymol and carvacrol elicited a positive EAG potential. The EAG data are discussed with regard.

Aldehydes in Poultry Chiller Water

Commercial poultry chiller water was extracted by the closed-loop-stripping technique. Extracts were analysed by gas chromatography and mass spectroscopy. Twelve saturated and unsaturated aliphatic aldehydes having 5 to 11 carbons were identified. Hexanal and nonanal were present in approximately equal quantities. Together they constitute about half of the aldehydes found. The identified aldehydes also are the primary autoxidation products of unsaturated fatty acids of chicken lipids. The presence of these aldehydes is indicative of an extensive autoxidation taking place in the chiller. Its effect on the quality and shelf-life of the poultry products is unknown.

Lethal effects of a linoleic acid hydroperoxide and its autoxidation products, unsaturated aliphatic aldehydes, on human diploid fibroblasts

The lethal effects of linoleic acid and its hydroperoxide on human diploid fibroblasts were quite similar, and that of the reaction mixture from the autoxidation of the hydroperoxide was considerable. Some unsaturated aliphatic aldehydes, the secondary products of the hydroperoxide autoxidation, were identified and their toxicity toward the cells was examined. Among them, ( E, E)-2,4-nonadienal, ( E, E)-2,4-decadienal, and ( E)-4-hydroxy-2-nonenal were the most toxic; e.g., in the presence of 25 μM nonadienal, decadienal, or hydroxynonenal, 75, 90, or almost 100% of the cells, respectively, underwent lysis within one day. Generally, alkenals were toxic and alkanals non-toxic. The toxicity was enhanced as the number of double bonds in each molecule was increased and also as the carbon chain was lengthened.

Sensory irritation response to inhaled aldehydes after formaldehyde pretreatment

Pretreatment of Fischer-344 (F-344) rats with formaldehyde (HCHO) induces significant cross tolerance to the sensory irritation properties of Cl 2. The purpose of this study was to determine if HCHO pretreatment would cause sensory irritation cross tolerance to other inhaled aldehydes. Male F-344 rats, weighing 190 to 210 g, were pretreated with 15 ppm HCHO, 6 hr/day for 9 days, and challenged on the 10th day with a saturated (acetaldehyde, propionaldehyde, and butyraldehyde), unsaturated (acrolein and crotonaldehyde), or cyclic (cyclohexanecarboxaldehyde, 3-cyclohexene-1-carboxaldehyde, and benzaldehyde) aldehyde. The sensory irritation response in these animals was quantified by measuring respiratory rate depression in a head-only inhalation chamber using plethysmographic techniques. Control animals were challenged identically without prior pretreatment. In naive (nonpretreated) animals, the concentration eliciting a 50% decrease in respiratory rate (RD50) was 23 ppm or less for unsaturated aliphatic aldehydes. For cyclic and saturated aliphatic aldehydes, the RD50 ranged from 600 to 1000 ppm and 3000 to 6800 ppm, respectively. Formaldehyde pretreatment resulted in cross tolerance only with acetaldehyde (RD50 increased 3.5-fold) and acrolein (RD50 increased 5-fold). These results indicate that the development of cross tolerance following HCHO pretreatment is not a general phenomenon. Prediction of acceptable concentrations of occupational exposure for the prevention of sensory irritation in humans has been based primarily on RD50 data for mice. Comparison of the RD50 values obtained for rats in this investigation with previously published results for mice varied by over one-half an order of magnitude, thereby disputing the usefulness of data from F-344 rats in setting threshold limit values for the prevention of sensory irritation.

Sensory irritation structure-activity study of inhaled aldehydes in B6C3F1 and Swiss-Webster mice

The sensory irritation potential of a series of saturated and unsaturated aliphatic and cyclic aldehydes was investigated in B6C3F1 and Swiss-Webster mice. With the reflex decrease in respiratory rate as the endpoint response, α,β-unsaturated aliphatic aldehydes yielded RD50 values (concentration which elicits a 50% decrease in respiratory rate) ranging from 1 to 5 ppm while saturated aliphatic aldehydes with two or more carbons produced RD50 values from 750 to 4200 ppm. Cyclic aldehydes produced intermediate RD50 values which ranged from 60 to 400 ppm. No statistically significant differences were found between concentration-response curves of B6C3F1 and Swiss-Webster mice. Saturated aliphatic aldehydes with two or more carbons were nearly 1000 times less potent than formaldehyde. Although the mechanisms responsible for stimulation of trigeminal nerve endings by airborne chemicals are poorly understood, several hypotheses may help to explain the differences seen in this study. For example, the sensory irritation potency of the saturated aliphatic aldehydes diminished with their reported dehydration constants which may determine the degree to which these aldehydes crosslink with receptor proteins. The sensory irritation potency of acrolein and crotonaldehyde was probably due to 1,2 or 1,4 addition reactions. Additionally, molecular conformation and a recently published physical mechanism may contribute to sensory irritation responses, particularly for the less reactive aldehydes. Tentative threshold limit values (TLVs), based upon prevention of sensory irritation, were extrapolated from the RD50 values of Swiss-Webster mice. With the exception of crotonaldehyde, good agreement was found with currently published TLVs.

Volatile Odorous Excretion Products of Algae and Their Occurrence in the Natural Aquatic Environment

Members of many algal groups (Chrysophyceae, Cryptophyceae, Dinophyceae, Chlorophyceae and Bacillariophyceae) have been reported to impart characteristic odours to water when blooms of these organisms occur. The volatile compounds isolated from algal cultures under controlled laboratory conditions and from surface waters during algal bloom periods are listed. The substances identified as responsible for odour problems are alkenes, saturated and unsaturated aliphatic alcohols, aldehydes, ketones, esters, thioesters and sulfides. Experimental conditions and criteria enabling one to distinguish between algal excretion products and contaminants, or pollution products are put forward.

PHOSPHORORGANISCHE VERBINDUNGEN 981CYANOPHOSPHINOYLIERUNG VON CARBONYLGRUPPEN—EIN ANALOGON ZU CYANOSILYLIERUNG

Abstract The carbonyl groups of saturated and unsaturated aliphatic and aromatic aldehydes and ketones add diphenylphosphinic acid nitrile and dimethylphosphinic acid nitrile according to (1) and (2) forming O-(phosphinoyl) cyanohydrins. O-(diphenylphosphinoyl) acrolein cyanohydrin isomerizes according to (3) to (2-diphenylphosphinoyloxy)-but-2-en-nitrile following a shift of the double bond (a) at 200°C or (b) on interaction with KOBut. Aminonitriles are formed according to (4) by a modified Strecker reaction on reacting O-(diphenylphosphinoyl) aldehyde (ketone) cyanohydrins with secondary amines. The anionic form of O-(diphenylphosphinoyl) aldehyde cyanohydrins reacts (a) with alkyl halides forming O-(diphenylphosphinoyl) ketone cyanohydrins (5) and (b) with aldehydes (6) to yield O-(diphenylphosphinoyl) acyloins after a transacylation. Phosphinic acid esters are cleaved quantitatively by fluorolysis using tetrabutylammonium fluoride at room temperature (7). Diphenylphosphinsaurecyanid und Dimethylphosp...

The chemistry of the defensive secretion of the beetle, Drusilla canaliculata

The tergal gland of the beetle, Drusilla canaliculata, contains defensive products which exhibit an extraordinary chemical diversity. This glandular exudate is fortified with alkanes, alkenes, saturated and unsaturated aliphatic aldehydes, 1,4-quinones, and hydroquinones. The aldehydes, n-dodecanal, n-tetradecanal, n-tetradec-5-enal, and n-tetradeca-5,8-dienal, constitute a major group of components. In addition, a new constituent in arthropod defensive secretions, 2-hydroxy-3-methylhydroquinone, has been identified as a minor component in this exocrine exudate.

Aroma Constituents of Plum Brandy

The aroma components of an experimental brandy produced from California French prunes were concentrated by solvent extraction and isolated by gas chromatography. Individual compounds were identified by infrared spectroscopy and retention data on SE-30 and FFAP liquid-substrate columns. Substances identified included aliphatic fatty acid esters, free fatty acids, aromatic aldehydes, esters, and alcohols, ethyl lactate, furfural, eugenol, and unsaturated aliphatic aldehydes. The constituents of the experimental brandy were compared with those of four samples of imported plum brandy. Quantitatively, the imported samples contained higher levels of benzyl alcohol, 2-phenethyl alcohol, ethyl benzoate, and eugenol, but much less of the ethyl esters of fatty acids. Ethyl lactate was 2-4 times higher in French Quetseh and Mirabelle and two brands of Yugoslavian slivovitz than in the experimental brandy.

Ellman's reagent: interference in mercapto group determination, with special reference to cigarette smoke

Cyanide, hydrogen sulphite and sulphide interfere in the determination of mercapto groups with Ellman's reagent [5,5′-dithiobis-(2-nitrobenzoic acid)] by nucleophilic substitution of the reagent. Such reactions produce significant analytical errors under certain conditions. Some saturated and unsaturated aliphatic aldehydes also interfere in the determination by formation of less reactive addition products with the mercapto compounds. When both types of compounds are present concurrently, as in cigarette smoke and related products, the aldehydes and the thionucleophilic reagents may react with each other and with other smoke components in a series of complex reactions. The degree of de-activation of mercapto groups by cigarette smoke and related products can be determined with Ellman's reagent only under carefully controlled conditions.

Mass spectrometry of long-chain aliphatic aldehydes, dimethyl acetals and alk-1-enyl ethers.

AbstractMass spectra of long‐chain saturated and unsaturated aliphatic aldehydes, dimethyl acetals and alk‐1‐enyl methyl ethers are reported and discussed. Using deuterium labeled aldehydes, knowledge about the mass spectral fragmentation is obtained. The m/e M‐44 ion is formed by a rearrangement different from the mechanism postulated previously for short‐chain aldehydes. A series of hydrocarbon fragments with even mass numbers of 68+14n (n=0,1,2...) appear in the spectra of all three series of compounds.

Organic Catalysts. V. Specific Catalytic Properties of Copper-Iron-Polyphthalocyanine in the Oxidation of Aldehydes

Abstract Copper-iron-polyphthalocyanine showed a specific catalysis for the oxidations of the substituted benzaldehydes and the saturated aldehydes with oxygen. The catalytic activity of copper-iron-polyphthalocyanine was solvent-dependent: tetrahydrofuran, ethanol, acetonitrile, ethyl acetate and anisole inhibited the oxidation of benzaldehyde by copper-iron-polyphthalocyanine and oxygen, while benzene and acetone resulted in catalytic oxidation. Benzaldehyde and the saturated aliphatic aldehydes in benzene were oxidized catalytically with copper-iron-polyphthalocyanine and oxygen to afford the corresponding peroxy acids and acids in quantitative yields. Furthermore, oxygen was absorbed with no induction period; the rate of oxygen absorption was in the range of 8–13 ml/min. On the other hand, the unsaturated aliphatic aldehydes, cinnamaldehyde and acrolein, were oxidized with a very slow rate of oxygen absorption in spite of the existence of copper-iron-polyphthalocyanine in the reaction system. p-Methylbenzaldehyde and p-chlorobenzaldehyde were oxidized by copper-iron-polyphthalocyanine and oxygen in Induction periods of about 8 and 15 min respectively, thus affording the corresponding peroxy acids and acids. However, no oxidations of p-nitrobenzaldehyde, p-hydroxycarbonylbenzaldehyde, p- and m-hydroxybenzaldehyde, p- and m-methoxybenzaldehyde and p-dimethylaminobenzaldehyde with copper-iron-polyphthalocyanine and oxygen were observed.