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Here we present first Eddy Covariance (EC) measurements of fluxes of glyoxal, the smallest α-dicarbonyl product of hydrocarbon oxidation, and a precursor for secondary organic aerosol (SOA). The unique physical and chemical properties of glyoxal, i.e., high solubility in water (Henry's Law constant, KH =4.2 × 105Matm-1) and short atmospheric lifetime (∼2 h at solar noon) make it a unique indicator species for organic carbon oxidation in the marine atmosphere. Previous reports of elevated glyoxal over oceans remain unexplained by atmospheric models. Here we describe a Fast Light Emitting Diode Cavity Enhanced Differential Optical Absorption Spectroscopy (Fast LED-CE-DOAS) instrument to measure diurnal variations and EC fluxes of glyoxal, and inform about its unknown sources. The fast in situ sensor is described, and first results are presented from a cruise deployment over the Eastern tropical Pacific Ocean (20° N to 10° S; 133° W to 85° W) as part of the Tropical Ocean Troposphere Exchange of Reactive Halogens and OVOC (TORERO) field experiment (January to March 2012). The Fast LED-CE-DOAS is a multispectral sensor that selectively and simultaneously measures glyoxal (CHOCHO), nitrogen dioxide (NO2), oxygen dimers (O4) and water vapor (H2O) with ∼2 Hz time resolution, and a precision of ∼40 pptv Hz-0.5 for glyoxal. The instrument is demonstrated to be a "white-noise" sensor suitable for EC flux measurements; further, highly sensitive and inherently calibrated glyoxal measurements are obtained from temporal averaging of data (∼2 pptv detection limit over 1 h). The campaign averaged mixing ratio in the Southern Hemisphere (SH) is found to be 43 ± 9 pptv glyoxal, and is higher than in the Northern Hemisphere (NH: 32 ±6 pptv; error reflects variability over multiple days). The diurnal variation of glyoxal in the MBL is measured for the first time, and mixing ratios vary by ∼8ppt (NH) and ∼12 pptv (SH) over the course of 24h. Consistently, maxima are observed at sunrise (NH: 35 ±5 pptv; SH: 47 ±7 pptv) and minima at dusk (NH: 27 ±5 pptv; SH: 35 ±8 pptv). Ours are the first EC flux measurements of glyoxal. In both hemispheres, the daytime flux was directed from the atmosphere into the ocean, indicating that the ocean is a net sink for glyoxal during the day. After sunset the ocean was a source for glyoxal to the atmosphere (posi?tive flux) in the SH; this primary ocean source was operative throughout the night. In the NH, the nighttime flux was positive only shortly after sunset, and negative during most of the night. Positive EC fluxes of soluble glyoxal over oceans indicate the presence of an ocean surface organic microlayer (SML), and locate a glyoxal source within the SML. The origin of atmospheric glyoxal, and possibly other oxygenated hydrocarbons over tropical oceans warrants further investigation. [ABSTRACT FROM AUTHOR]

New 1-[1-(1H-indol-3-yl) alkyl]-1H-indoles, surprisingly, have been obtained from the addition of indole to a variety of aldehydes under neat conditions. CaO, present in excess, was fundamental for carrying out the reaction with paraformaldehyde. Under the same reaction conditions, aromatic and heteroaromatic aldehydes afforded only classical bis (indolyl) aryl indoles. In this paper, the role of CaO, together with the regiochemistry and the mechanism of the reaction, are discussed in detail. The effect of some selected 3,3′- and 1,3′-diindolyl methane derivatives on cell proliferation of the hepatoma cell line FaO was also evaluated. [ABSTRACT FROM AUTHOR]

Peroxisome proliferator-activated receptor γ (PPARγ) is a well-known target for thiazolidinedione antidiabetic drugs. In this paper, we present the synthesis and biological evaluation of a series of dihydropyrano[2,3-c]pyrazole derivatives as a novel family of PPARγ partial agonists. Two analogues were found to display high affinity for PPARγ with potencies in the micro molar range. Both of these hits were selective against PPARγ, since no activity was measured when tested against PPARα, PPARδ and RXRα. In addition, a novel modelling approach based on multiple individual flexible alignments was developed for the identification of ligand binding interactions in PPARγ. In combination with cell-based transactivation experiments, the flexible alignment model provides an excellent analytical tool to evaluate and visualize the effect of ligand chemical structure with respect to receptor binding mode and biological activity. [ABSTRACT FROM AUTHOR]

Our new, simple, and accurate colorimetric method is based on diarylethenes (DAEs) for the rapid detection of a wide range of primary and secondary amines. The probes consist of aldehyde- or ketone-substituted diarylethenes, which undergo an amine-induced decoloration reaction, selectively to give the ring-closed isomer. Thus, these probes can be activated at the desired moment by light irradiation, with a sensitivity that allows the detection of amines at concentrations as low as 10−6 m in solution. In addition, the practical immobilization of DAEs on paper makes it possible to detect biogenic amines, such as cadaverine, in the gas phase above a threshold of 12 ppbv within 30 seconds. [ABSTRACT FROM AUTHOR]

The transient-state kinetics of enzymic reduction of acetaldehyde and benzaldehyde by NADH, catalyzed by horse liver alcohol dehydrogenase, have been examined under single-turnover conditions, obtained by carrying out reactions either with limiting amounts of enzyme in the presence of 20 mM pyrazole or with limiting amounts of substrate. Analysis of the variation with substrate, coenzyme, and enzyme concentrations of amplitudes and time constants for the exponential transients observed at 328 nm and 300 nm shows that the kinetics of enzymic aldehyde reduction are qualitatively and quantitatively consistent with the relationships derived in the preceding paper for an ordered ternary-complex mechanism involving identical and independent catalytic sites. It is concluded that there is no evidence whatsoever for the kinetic significance of a half-of-the-sites reactivity or any other kind of subunit interaction in the liver alcohol dehydrogenase system. The biphasic transients observed at 328 nm for the reduction of aromatic aldehydes such as benzaldehyde are a normal kinetic characteristic of the ordered ternary-complex mechanism, being attributable to accumulation of the ternary enzyme · NAD · product complex when product dissociation from this complex is slow in comparison to its formation by ternary-complex interconversion. [ABSTRACT FROM AUTHOR]

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Originating in the grapes, anthocyanins and their derivatives are the crucial pigments responsible for the red wine color. During wine maturation and aging, the concentration of monomeric anthocyanins declines constantly, while numerous more complex and stable anthocyanin derived pigments are formed, mainly including pyranoanthocyanins, polymeric anthocyanins produced from condensation between anthocyanin and/or flavan-3-ols directly or mediated by aldehydes. Correspondingly, their structural modifications result in a characteristic variation of color, from purple-red color in young red wines to brick-red hue of the aged. Because of the extreme complexity of chemical compounds involved, many investigations have been made using model solutions of know composition rather than wine. Thus, there is a large amount of research still required to obtain an overall perspective of the anthocyanin composition and its change with time in red wines. Future findings may well greatly revise our current interpretation of the color in red wines. This paper summarizes the most recent advances in the studies of the anthocyanins derived pigments in red wines, as well as their color evolution. [ABSTRACT FROM AUTHOR]

Highlights • Volatile profiles for strawberries were significantly influenced by minimal processing. • Hot water treatment inhibited the synthesis of methyl and ethyl esters. • Hot water dipping for 5 min prevented the accumulation of methyl isobutyl ketone. • Sucrose declined with concomitant increase in glucose and fructose. Abstract Strawberries flavour attributes are important quality parameters that have a significant impact on consumer acceptability. Minimal processing and postharvest treatments in many cases neglect the importance of flavour attributes or sacrifice them for better appearance and/or longer shelf life. In addition, only few information is available on the impact of postharvest handling on flavour attributes. Thus, the objectives of this paper were to investigate: i) the effects of minimal processing on changes in composition and relative abundance (%) of volatile organic compounds (VOCs) emitted from strawberries; and ii) the effects of hot water treatments (45 °C) at different dipping duration (5 and 10 min) on the shift in VOC composition of 'Sonata' strawberries. Based on gas chromatography-mass spectrometry (GC–MS) analysis, the volatile profiles obtained for strawberries were significantly (p ≤ 0.05) influenced by minimal processing. Aldehydes were most abundant in strawberry puree (34.1%) compared to sliced samples (17.5%) and none were detected in the headspace of intact fruit. Esters were most abundant in the sliced samples (62.9%) compared to intact strawberries (51.2%) and fruit puree (≈ 49%) samples. Hot water treatment and dipping durations had significant impact on the synthesis of methyl and ethyl esters and acetaldehyde in comparison to the untreated (control) samples (p ≤ 0.05). At the end of storage, concentrations of methyl acetate (4.9 ± 0.86 mg mL−1), methyl butanoate (6.7 ± 0.05 mg mL−1), ethyl butanoate (0.6 ± 0.37 mg mL−1), and acetaldehyde (3.1 ± 0.99 mg mL−1) were lowest in strawberries dipped in hot water at 45 °C for 10 min. In contrast, hot water treatment with dipping duration of 5 min best maintained and enhanced the synthesis of methyl butanoate and prevented the accumulation of methyl isobutyl ketone. This study showed that minimal processing had a significant impact on the volatile profile of 'Sonata' strawberries, and that hot water treatments play a crucial role on the emission of volatile compounds. [ABSTRACT FROM AUTHOR]

Branched aldehydes, such as 2-methyl propanal and 2- and 3-methyl butanal, are important flavour compounds in many food products, both fermented and non-fermented (heat-treated) products. The production and degradation of these aldehydes from amino acids is described and reviewed extensively in literature. This paper reviews aspects influencing the formation of these aldehydes at the level of metabolic conversions, microbial and food composition. Special emphasis was on 3-methyl butanal and its presence in various food products. Knowledge gained about the generation pathways of these flavour compounds is essential for being able to control the formation of desired levels of these aldehydes. [ABSTRACT FROM AUTHOR]

Estimation of hydroxymethylfurfural (HMF) exposure of the Spanish population from heat-processed food was performed. HMF levels in Spanish foods were obtained from the data previously published in peer-reviewed papers; in addition, it was identified which food categories contributed significantly to HMF exposure. The potential HMF exposure was calculated for three different scenarios by using individual food intakes and the minimum (scenario 1), median (scenario 2) and maximum (scenario 3) values of analytical data on the HMF content in foods. A mean HMF intake of 10 mg day-1 (corresponding to scenario 2) was obtained, which is only ten-fold lower than the tolerable daily intake. Coffee and bread are the most important food items that contribute nearly 85% to the total HMF daily exposure, although biscuits, breakfast cereals, beer, UHT milk and tomato products are also important for HMF exposure. [ABSTRACT FROM AUTHOR]

The aim of the study reported herein was to characterize occupants’ simultaneous exposure to mixtures of organic compounds in homes. Statistical distributions for concentrations of 28 organic compounds (17 VOCs and 11 aldehydes) measured in 1417 homes were generated to analyze concentration distributions. Three candidate distributions were identified for fitting the measured data: log-normal, exponential and gamma distributions. It appears from the results of fitting tests that gamma distributions are capable of representing 28 compound concentrations. Probability distributions show that formaldehyde and acetaldehyde ranged from 25 to 220 μg/m3 at 90% probabilities and most VOCs ranged from 3 to 80 μg/m3 at 90% probabilities. In order to characterize the occupant's exposure to the mixtures, the joint probability distributions of organic compounds were generated from the best-fitted distributions of individual compounds under the assumption that concentrations of organic compounds are mutually independent in homes. These joint distributions provided the statistical data for characterizing the occupant's exposure to the mixtures of organic compounds in homes. Occupants often encounter not just one compound in indoor environments, but many compounds due to their concurrent emissions from several sources. This paper describes characteristics of statistical distributions for concentrations of 17 VOCs and 11 aldehydes in homes in Japan. After applying a probability model to the occupants’ simultaneous exposure to mixtures of organic compounds, the authors interpret the current state of the occupant's exposure to the mixtures within homes using joint probability distributions of 28 organic compounds. [ABSTRACT FROM AUTHOR]

A new mild and efficient process for the aqueous preparation of aldehydes, which are employed as flavour and fragrance components in food, beverage, cosmetics, as well as in pharmaceuticals, was developed using a continuous-flow approach based on an immobilised pure transaminase-packed bed reactor. HEWT, an ω-transaminase from the haloadapted bacterium Halomonas elongata, has been selected for its excellent stability and substrate scope. Sixteen different amines were rapidly (3-15 min) oxidised to the corresponding aldehydes (90 to 99 %) with only 1 to 5 equivalents of sodium pyruvate. The process was fully automated, allowing for the in-line recovery of the pure aldehydes (chemical purity >99 % and isolated yields above 80 %), without any further work-up procedure. [ABSTRACT FROM AUTHOR]

Working as a professional hairdresser involves the daily usage of many different hair treatment products containing chemicals in complex mixtures. Exposure may induce symptoms in the airways and on the skin. In this study, exposure of hairdressers to volatile organic compounds (VOCs), including aldehydes, was measured in the personal breathing zone in the spring of 2017. The study included 30 hairdressers evenly distributed over ten hair salons in the town of Örebro, Sweden. Work tasks and indoor climate were also surveilled. A hazard index (HI) based on chronic reference values for health was calculated to indicate combined exposure risk. In total, 90 VOCs, including nine aldehydes, were identified. Individual exposure expressed as a total concentration of VOCs (TVOCs) were in the range of 50–3600 µg/m3 toluene equivalent (median 460 µg/m3) and the HI was in the range 0.0046–13 (median 0.9). Exposure was more strongly influenced by variability among hairdressers than among salons. The HI indicated an increased risk of non-carcinogenic effects (HI ≥ 1) at four of the 10 hair salons. Individual working procedures, ventilation, volumetric usage of hair treatment products, certain chemicals in products (formaldehyde, isopropanol, and 2,4- and 2,6-toluene diisocyanate), and availability of reference values may have affected estimates of exposure risks. Nevertheless, the HI may be suitable as a screening tool to assess potential exposure risk posed to hairdressers since it considers the complexity of chemical mixtures and the chronic component of VOC exposure occurring in all indoor environments. [ABSTRACT FROM AUTHOR]

Aldehydes constitute a main class of organic compounds widely applied in synthesis. As such, catalyst-controlled enantioselective α-functionalization of aldehydes has attracted great interest over the years. In this context, α-branched aldehydes are especially challenging substrates because of reactivity and selectivity issues. Firstly, the transient trisubstituted enamines and enolates resulting upon treatment with an aminocatalyst or a base, respectively, would exhibit attenuated reactivity; secondly, mixtures of E- and Z-configured enamines/enolates may be formed; and third, effective face-discrimination on such trisubstituted sp2 carbon intermediates by the incoming electrophilic reagent is not trivial. Despite these issues, in the last 15 years, several catalytic approaches for the α-functionalization of prostereogenic α-branched aldehydes that proceed in useful yields and diastereo- and enantioselectivity have been uncovered. Developments include both organocatalytic and metal-catalyzed approaches as well as dual catalysis strategies for forging new carbon–carbon and carbon–heteroatom (C-O, N, S, F, Cl, Br, ...) bond formation at Cα of the starting aldehyde. In this review, some key early contributions to the field are presented, but focus is on the most recent methods, mainly covering the literature from year 2014 onward. [ABSTRACT FROM AUTHOR]

Extracts of the exuviae (cast skins) of nymphal bed bugs (Cimex lectularius) were analyzed for volatile compounds that might contribute to arrestment of adult bed bugs. Four volatile aldehydes, (E)-2-hexenal, 4-oxo-(E)-2-hexenal, (E)-2-octenal, and 4-oxo-(E)-2-octenal were consistently detected in the headspace of freshly shed exuviae regardless of the developmental stages from which the exuviae were obtained. Quantification of the aldehydes in the solvent extracts of homogenized fresh, 45- or 99-d aged 5th instar exuviae indicated that the aldehydes are present in the exuviae and dissipate over time, through evaporation or degradation. Microscopic observation of the fifth instar exuviae indicated that the dorsal abdominal glands on the exuviae maintained their pocket-like structures with gland reservoirs, within which the aldehydes might be retained. Two-choice olfactometer studies with the volatiles from exuviae or a synthetic blend mimicking the volatiles indicated that adult bed bugs tend to settle close to sources of the aldehydes. Our results imply that the presence and accumulation of bed bug exuviae and the aldehydes volatilizing from the exuviae might mediate bed bugs’ interaction with their microhabitats. [ABSTRACT FROM AUTHOR]

Terminal alkynes (RCCH) are homologated by a sequence of ruthenium-catalyzed anti-Markovnikov hydration of alkyne to aldehyde (RCH2CHO), followed by Bestmann-Ohira alkynylation of aldehyde to chain-elongated alkyne (RCH2CCH). Inverting the sequence by starting from aldehyde brings about the reciprocal homologation of aldehydes instead. The use of 13C-labeled Bestmann-Ohira reagent (dimethyl ((1-13C)-1-diazo-2-oxopropyl)phosphonate) for alkynylation provides straightforward access to singly or, through additional homologation, multiply 13C-labeled alkynes. The labeled alkynes serve as synthetic platform for accessing a multitude of specifically 13C-labeled products. Terminal alkynes with one or two 13C-labels in the alkyne unit have been submitted to alkyne-azide click reactions; the copper-catalyzed version (CuAAC) was found to display a regioselectivity of >50 000:1 for the 1,4- over the 1,5-triazine isomer, as shown analytically by 13C NMR spectroscopy. [ABSTRACT FROM AUTHOR]

A new biosensor for determination of benzaldehyde based on carbon past electrode (CPE) modified with a Fe3O4-graphen oxide/polyvinyl pyrrolidone/polyaniline (Fe3O4/GO/PVP/PANI) nanocomposite was developed. The nanocomposite was electrodeposited on the surface of CPE using cyclic voltammetry technique. The crude extract aldehyde (AOX) oxidase enzyme isolated from rat liver was immobilized on the Fe3O4/GO/PVP/PANI nanocomposite and the prepared biosensor was employed for benzaldehyde oxidation to H2O2. The benzaldhyde measured amperometrically based on reduction of produced H2O2 at −0.25 V(vs. Ag/AgCl). The cyclic voltammetry and electrochemical impedance spectroscopy studies of the modified electrode indicated that Fe3O4/GO has an excellent electrocatalytic activity and can be used as an electron mediator for H2O2 reduction. The presence of PVP in the nanocomposite could substantially improve the dispersibility of GO, leading to enhanced sensitivity of the biosensor. Under optimum conditions, the biosensor exhibited a fast response time to benzaldhyde within 10 s. The sensor showed a linear response to benzaldehyde concentration in the range of 0.5-50 µM with a limit of detection of 0.4 µM( S/ N=3) and sensitivity of 4.173 µA µM−1 cm−2. The biosensor revealed a preference for benzldehyde than studied aliphatic aldehydes. The new biosensor showed good performance to analysis of benzaldhyde in drugs injection formulations. [ABSTRACT FROM AUTHOR]

The commercially available resin Amberlyst A-31 was efficiently used to promote the propargylation of aldehydes using potassium allenyltrifluoroborate. The method is simple and fast, and the products were obtained in short reaction times in high yields and purity at room temperature in a regio- and chemoselective manner. [ABSTRACT FROM AUTHOR]

We are reporting structural characterization of two new hexanuclear cages (H3O)2[Cu3(μ3-OH)-(μ3-NH3)0.5(L)3]2·8H2O (1) and (H3O)2[Cu3(μ3-OH)(μ3-H2O)0.5(L)3]2·8H2O (1a) where L2- is the dianionic form of the Schiff base of L-alanine and salicylaldehyde. The complex 1 has two C3 symmetric hydroxo bridged trinuclear halves joined by an ammonia or water molecule at the center through H-bonding. Each of the trinuclear halves is enantiopure but of opposite chirality to the other half, making the hexanuclear unit a meso isomer. Temperature dependent magnetic measurements showed the presence of ferromagnetic interactions among trinuclear Cu(II) units, a rare occurrence among trinuclear Cu(II) complexes. Characterization of the LiHL showed it to be enantiopure. Addition of a base, monitored using optical rotation, showed that racemization occurs as a result of base addition. The racemization depends on the base as well as the temperature. Base or Cu(II) induced racemization of amino acid derivatives has been indicated in a number of cases in the past but structural characterization of the products or formation of this type of chiral hexanuclear architecture was never reported. Structures of the complex and the ligand have a number of interesting H-bonding situations. [ABSTRACT FROM AUTHOR]

Although single- and multi-step biocatalytic approaches show persuasive advantages for the synthesis of especially chiral compounds (e.g. high chemo- and stereoselectivity), their application often suffers from low substrate loads and hence low space-time-yields. We herein present a synthetic cascade approach in which lyophilised, recombinant whole cells are applied in micro-aqueous reaction systems yielding extremely high space-time-yields. As an example we investigated the two-step synthesis of 1-phenylpropane- 1,2-diol starting from cheap aldehydes and achieved high selectivities (ee/de > 99%) and high product concentrations. The new concept of running biocatalytic cascades in a mixture of high substrate loads and organic solvents under addition of small amounts of highly concentrated buffer is not only very easyto- apply, but also exhibits several economic and ecologic advantages. On the one hand the usage of whole, lyophilised cells circumvents time-consuming enzyme purification as well as addition of expensive cofactors (here ThDP and NADPH). Additionally, catalyst and product workup is facilitated by the application of organic solvents (here MTBE). On the other hand, the employment of whole cells very effectively circumvents stability problems of biocatalysts in unconventional media enabling the addition of extremely high substrate loads (up to 500 mM in our example) and is therefore an easy and effective approach for multi-step biocatalysis. After optimisation, the combination of a carboligation step followed by a second oxidoreduction step with whole cell catalysts afforded an efficient two-step cascade for the production of 1-phenylpropane-1,2-diol with space-time yields up to 327 g L-1 d-1 and an E-factor of 21.3 kgwaste kgproduct -1. [ABSTRACT FROM AUTHOR]

A simple, catalyst free, water mediated, one pot four component, green protocol was developed for title compounds 7 starting from aromatic aldehydes (1), malononitrile (2), 1,3-diones (3) and N-chlorosuccinimide (NCS) in a sequential addition reaction at ambient temperature. The approach presented herein, for the first time, is through an unusual rearrangement where NCS was reacted with 2-amino-7,7-dimethyl- 5-oxo-4-aryl-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (4), which was formed by the Knoevenagel condensation of aldehyde and malononitrile followed by the Michael addition of 3. In addition, this novel protocol is compatible with various aldehydes and active C-H functional derivatives, accomplishes high yields and follows the GAP chemistry principle. Interestingly, compound 4 when reacted with NCS in alcohol medium gave 2-cyano-6,6-dimethyl-4-oxo-3-aryl-2,3,4,5,6,7-hexahydrobenzofuran-2-carboxylate (5). [ABSTRACT FROM AUTHOR]

An efficient method has been developed for the synthesis of a novel series of N-alkyl-2-aryl-5H-imidazo[1,2-b]pyrazol-3-amines in good-to-high yields by the three-component condensation of an aromatic aldehyde, an aminopyrazole, and an isocyanide in acetonitrile with 4-toluenesulfonic acid as a catalyst at room temperature. [ABSTRACT FROM AUTHOR]

1,10-Phenanthrolinium N-ylide, reacts with malonitrile and aldehydes via a domino-Knoevenagel- cyclisation to produce a new class of (8aRS,10SR,11SR)-9,9-dicyano-10-aryl-11-benzoyl-8a,9,10,11-tetrahydropyrrolo[1,2-a][1,10] phenanthrolines in a simple and efficient protocol. Structural elucidation was done by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

The article discusses studies on the chemistry of organic compounds of silicon and its analogs by several researchers at the Grebenshchikov Institute of Silicate Chemistry of the Russian Academy of Sciences. It was established that the interaction of phenylsilane with aromatic aldehydes results only to the reduction of the carbonyl group to the hydroxyl group. Methods were developed to synthesize 1-halosilatranes and 1-halogermatranes chosen as precursors of atranyl cations.

This paper describes the phosphine-catalyzed annulation of methyl allenoate with various aromatic aldehydes to form 6-aryl-4-methoxy-5,6-dihydro-2-pyrones. In this reaction, the addition of an alcohol was necessary to induce dihydropyrone formation, with the optimal agent being methanol. Moreover, the addition of n-butyllithium suppressed the formation of the noncyclized product, leading to the exclusive isolation of the dihydropyrone. This method provides an efficient, one-step route toward disubstituted dihydropyrones from simple, stable starting materials. [ABSTRACT FROM AUTHOR]

Abstract: This paper outlines our efforts to study the influence of an oxygen atom adjacent to the stereogenic center of β-aminoalcohol derivatives used as ligands for catalysts in the asymmetric alkylation of aldehydes. Thirty-four enantiomerically pure (S)-dihydrofuran-2-yl, (S)-tetrahydrofuran-2-yl-, and furan-2-yl-β-dialkylamino alcohols have been prepared from 1,4:3,6-dianhydromannitol, 1,4:3,6-dianhydrosorbitol, and aminoacids, and then have been evaluated as ligands for the enantioselective addition of diethylzinc to benzaldehyde. Attention has been focused on the structural features governing the extent of chiral induction, the reaction rate, and the chemical yield of 1-phenyl-1-propanol which has been promoted by this wide collection of β-dialkylamino alcohols. [Copyright &y& Elsevier]

This paper describes, with examples, a critical assessment of thermochemical data for some small molecules and free radicals. The available heats of formation, ΔfH° (all 298 K values). for simple alkyl hydroperoxides and di-alkyl peroxides were compared and new data are provided. The ΔfH° values, all ±5 kJ/mol, are: CH3OOH, −135; CH3CH2OOH, −168; n-C3H7OOH, −189; s-C3H7OOH, −205; t-C4H9OOH, −240; CH3OOCH3, −132; CH3CH2OOCH3, −165; C2H5OOC2H5, −198; n-C3H7OOn-C3H7, −240; s-C3H7OOs-C3H7, −272; t-C4H9OOt-C4H9, −342. These are consistent with established O–O bond dissociation energies and with additivity considerations. ΔfH° values for the corresponding alkoxy radicals are also addressed. A similar survey was applied to the homologous n-alkyl aldehydes, C2 to C8, for which recommended ΔfH° values, all ±1.5 kJ/mol, are: −166.5, −189, −207.5, −227, −248, −268 and −289, respectively. Particular attention was given to ΔfH°(CH3CO) = −10.3 ± 1.8 kJ/mol. The current NIST WebBook datum, ΔfH°(CS) = 280.3 kJ/mol, is arguably the best value, being consistent with related thermochemical data. Finally the ΔfH° values for the allylic free radicals •CH2CHCH2, 174 ± 3 kJ/mol, CH2CHCH•(OH), 4.5 ± 4 kJ/mol, and (CH2CH)2•C(OH), 37 ± 4 kJ/mol, derived from experimental data and results of computational chemistry are described, together with some related homolytic bond strengths. [Copyright &y& Elsevier]