Yields Of Aldehydes Research Articles

Formation of aldehyde during ozonation of taste and odour compounds in water

This study was conducted to investigate ketoaldehydes as another form of taste and odour (T&O) compound generated during the ozonation of commonly known T&O compounds, such as 2-methylisoborneol (MIB) and 2,4,6-trichloroanisole (TCA), which are typical T&O compounds. The ketoaldehydes generated during the ozonation process of T&O were studied. Results revealed that the main aldehydes produced during ozonation of MIB and TCA were formaldehyde, acetaldehyde, propionic aldehyde, n -butyl aldehyde, glyoxal and methyl glyoxal. The production of aldehydes during ozonation of T&O depended on several variables, including ozone dosage, temperature, water pH and the concentration of the matrix. According to results, ozonation is not an effective method for removal of MIB and decreasing the yield of aldehydes. Conversely, increasing ozone dosage or hydroxyl radicals resulted in a lower yield of aldehydes and higher removal efficiency of TCA.

Process of lignin oxidation in an ionic liquid coupled with separation

A novel approach has been developed in order to use lignin as a renewable resource for the production of a high added-value aromatic aldehyde. The concept is based on the use of an ionic liquid as a reversible medium coupled with the separation process, which prevents the aromatic aldehyde products from oxidizing and increases their yields. The conversion of lignin reached 100%, and the total yield of the aromatic aldehydes (vanillin, syringaldehyde and p-hydroxybenzaldehyde) was 29.7% in the coupled process. In addition, the mixture of product and IL phase was easily separated, and the IL phase demonstrated good reusability. Hence, a clean and environmentally friendly strategy for overall utilization of lignin and preparation of an aromatic aldehyde is developed.

Nutrient uptake, biomass yield and quantitative analysis of aliphatic aldehydes in cilantro plants

The objective of this study was to evaluate the nutrient uptake, biomass production and yield of the major compounds in the essential oil of five genotypes of Coriandrum sativum L. The treatments were composed for four accessions provided by the National Genetic Resources Advisory Council (NGRAC), U.S. Department of Agriculture's Agricultural Research Service (USDA/ARS) germplasm: (“AMES 18596”; “PI 171592”; “AMES 4998” and “PI 193770”) and one commercially available cultivar, (Santo). Plants were harvested 50 days after sowing and evaluated for nutrient uptake, the number of leaves, fresh and dry weight of shoot per plant and yield of major compounds in the essential oil. Accessions AMES 18596 and PI 171592 presented the following order of accumulation of macronutrients: K>N>Ca>Mg>P>S. For the accessions AMES 4998, PI 193770 and the cultivar Santo, the order K>N>Ca>P>Mg>S was observed. Micronutrients accumulation in cilantro shoot in descending order for all genotypes was: Fe>Zn>B>Mn>Cu. The highest number of leaves per plant was found in the accession AMES 18596 (9.94), while the others produced on average 7.24. Accessions AMES 18596 and PI 193770 produced 7.34gplant−1 of fresh weight of shoots. Accession PI 171592 produced slightly higher yields (6.23gplant−1) than the cultivar Santo and AMES 4998 (4.75gplant−1). For dry weight of shoots, accessions AMES 18596 and PI 193770 produced the highest yields (0.58gplant−1), followed by PI 171592 (0.47gplant−1) and the accession AMES 4998 and the cultivar Santo that had on average 0.35gplant−1. The yield of the major compounds in the essential oil was higher for accessions AMES 18596 and PI 193770 (88.84μgplant−1) following by AMES 4998 and Santo (38.95μgplant−1) and PI 171592 (23.31μgplant−1). On average the yield of aliphatic aldehydes in fresh weight followed the order: trans-2-dodecenal>decanal>trans-2-decenal>tetradecenal>dodecanal>tetradecanal.

Hydroformylation of 1-Dodecene in the Thermomorphic Solvent System Dimethylformamide/Decane. Phase Behavior–Reaction Performance–Catalyst Recycling

An economically meaningful hydroformylation of long-chain olefins requires an efficient combination of both a high-yield reaction step and efficient catalyst recycling. The application of thermomorphic multicomponent solvent (TMS) systems allows for optimal reaction as well as catalyst-recycling conditions. In this work, the TMS concept was applied to the homogeneously rhodium-catalyzed hydroformylation of 1-dodecene in the TMS system dimethylformamide (DMF)/decane using Rh(acac)(CO)2/Biphephos as the catalyst system. Thermodynamic investigations focused on the influence of the olefin (hydroformulation educt) and the aldehyde (hydroformylation product) on the phase behavior of the TMS system. Temperature dependent liquid–liquid equilibrium (LLE) data were measured for the binary systems DMF/decane and DMF/1-dodecene and for the ternary systems DMF/decane/1-dodecene and DMF/decane/dodecanal. Additionally, the corresponding LLE data were modeled applying the Perturbed Chain Polar Statistical Associating Fluid Theory (PCP-SAFT) using a heterosegmented approach for modeling the long-chain aldehyde. On the basis of the LLE data, adequate working points for hydroformylation experiments in the TMS system were selected. In these experiments, aldehyde yields of up to 87% with an n/iso ratio of up to 99:1 were achieved. Moreover, the TMS system was successfully applied to catalyst recycling in eight recycling runs with a catalyst leaching of 7 ppm rhodium at lowest.

Catalyzed Ozonation Decomposition of Taste and Odor-Causing Substances in Water and Simultaneous Control of Aldehyde Generation

Ozone oxidation is commonly used to remove taste and odor (T&O) from drinking water. However, this technique is only moderately effective, and is complicated by the formation of aldehyde by-products. In this study, we investigated the efficiency of ozonation with which aluminum oxide catalysts (γ-AlOOH [HAO], γ-Al2O3 [RAO], and α-Al2O3 [AAO]) removed three representative odorous substances (2-methylisoborneol [MIB], 2,4,6-trichloroanisole [TCA], and 2-isopropyl-3-methoxypyrazine [IPMP]) from water and reduced the yields of aldehydes. Application of ozonation alone led to incomplete mineralization of odorous substances and generation of large amounts of aldehydes. In comparison, catalyzed ozonation by the three aluminum oxides substantially increased the removal efficiencies of T&O and reduced the production of aldehydes, albeit to different degrees. In all forms of ozonation, the main aldehyde products were formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and methylglyoxal. HAO satisfactorily catalyzed the ozone oxidation of TCA and IPMP and effectively reduced the total aldehyde production during their oxidation. Catalyzed ozonation by AAO could not effectively reduce total aldehyde production during the oxidation of TCA and IPMP, which resulted in incomplete removal of T&O from water. Catalyzed ozonation by RAO provided the best results in removing MIB, TCA, and IPMP and reducing total aldehyde production.

Efficient and Highly Aldehyde Selective Wacker Oxidation

A method for efficient and aldehyde-selective Wacker oxidation of aryl-substituted olefins using PdCl(2)(MeCN)(2), 1,4-benzoquinone, and t-BuOH in air is described. Up to a 96% yield of aldehyde can be obtained, and up to 99% selectivity can be achieved with styrene-related substrates.

Rice husk supported FeCl3 nanoparticles as an efficient and reusable catalyst for the chemoselective 1,1-diacetate protection and deprotection of aldehydes

1,1-Diacetates were produced from a variety of aromatic aldehydes using rice husk supported FeCl3 nanoparticles as a catalyst. The procedure generally resulted in good yields (98%) of aromatic aldehydes including those carrying electron donating- or withdrawing-substituents. Deprotection of the resulting 1,1-diacetates was also achieved using the same catalyst in ethanol. This new method consistently has the advantages of excellent yields and relatively short reaction times. Further, the catalyst can be reused and recovered for several times.

ChemInform Abstract: Reimer—Tiemann Reaction of Coumarins.

AbstractImproved yields of aldehydes (III) are achieved when the Reimer—Tiemann reaction is carried out as a 2‐step process.

Rhodium nanoparticles as catalysts in the hydroformylation of 1-dodecene and their recycling in thermomorphic solvent systems

Rhodium nanoparticles of about 3nm in size were provided in stabilizing polar solvents. These nanoparticles were used in hydroformylation reactions of higher alkenes; 1-dodecene was used as a model substance. With a metal/substrate ratio of 1:1000, a 97% yield of aldehydes was achieved and an n/iso ratio of 72:28 was obtained. The addition of the ligand biphephos decelerated the reaction, but high n/iso ratios of up to 96:4 were achieved.For the first time, an effective catalyst recycling of these long-term stable nanoparticles in a thermomorphic multicomponent solvent (TMS) system was performed. The catalyst phase was recycled for three runs without any evident loss in activity. TEM images proved that after the recycling runs rhodium nanoparticles were still the active catalyst.

Does switching to a tobacco-free waterpipe product reduce toxicant intake? A crossover study comparing CO, NO, PAH, volatile aldehydes, “tar” and nicotine yields

Waterpipe (hookah, narghile, shisha) use has become a global phenomenon, with numerous product variations. One variation is a class of products marketed as “tobacco-free” alternatives for the “health conscious user”. In this study toxicant yields from waterpipes smoked using conventional tobacco-based and tobacco-free preparations were compared. A human-mimic waterpipe smoking machine was used to replicate the puffing sequences of 31 human participants who completed two double-blind ad libitum smoking sessions in a controlled clinical setting: once with a tobacco-based product of their choosing and once with a flavor-matched tobacco-free product. Outcome measures included yields of carbon monoxide, nitric oxide, volatile aldehydes, nicotine, tar, and polycyclic aromatic hydrocarbons. Smoke from both waterpipe preparations contained substantial quantities of toxicants. Nicotine yield was the only outcome that differed significantly between preparations. These findings contradict advertising messages that “herbal” waterpipe products are a healthy alternative to tobacco products.

Rh Nanoparticles Catalyzed Hydroformylation of Olefins in a Thermoregulated Ionic Liquid/Organic Biphasic System

Rh nanoparticles were investigated as a catalyst for hydroformylation of olefins in thermoregulated ionic liquid/organic biphasic systems composed of an ionic liquid, namely [CH 3 (OCH 2 CH 2 ) 16 N + Et 3 ][CH 3 SO 3 − ] (IL PEG750 ), and an organic solvent. This enables not only a homogeneous reaction but also easy biphasic separation. Under the optimized reaction conditions, the conversion of 1-octene and yield of aldehyde were 99% and 91%, respectively. The catalyst was easily separated from the product by phase separation and used eight times without evident loss of activity. 将具有“高温混溶、室温分相”功能的离子液体[CH 3 (OCH 2 CH 2 ) 16 N + Et 3 ][CH 3 SO 3 – ] (IL PEG750 ) 与甲苯-正庚烷组成的两相体系用于纳米 Rh 催化的烯烃氢甲酰化反应中, 在优化的反应条件下, 1-辛烯转化率和醛收率分别为 99% 和 91%. 催化剂经简单分相即可与产物分离, 且可连续使用 8 次, 其活性基本保持不变. Rh nanoparticles were used as a catalyst for hydroformylation of olefins in thermoregulated ionic liquid/organic biphasic system, giving a homogeneous reaction and biphasic separation.

Alkoxy‐1,3,5‐triazapentadien(e/ato) Copper(II) Complexes: Template Formation and Applications for the Preparation of Pyrimidines and as Catalysts for Oxidation of Alcohols to Carbonyl Products

Template combination of copper acetate (Cu(AcO)(2)⋅H(2)O) with sodium dicyanamide (NaN(C≡N)(2), 2 equiv) or cyanoguanidine (N≡CNHC(=NH)NH(2), 2 equiv) and an alcohol ROH (used also as solvent) leads to the neutral copper(II)-(2,4-alkoxy-1,3,5-triazapentadienato) complexes [Cu{NH=C(OR)NC(OR)=NH}(2)] (R = Me (1), Et (2), nPr (3), iPr (4), CH(2)CH(2)OCH(3) (5)) or cationic copper(II)-(2-alkoxy-4-amino-1,3,5-triazapentadiene) complexes [Cu{NH=C(OR)NHC(NH(2))=NH}(2)](AcO)(2) (R = Me (6), Et (7), nPr (8), nBu (9), CH(2)CH(2)OCH(3) (10)), respectively. Several intermediates of this reaction were isolated and a pathway was proposed. The deprotonation of 6-10 with NaOH allows their transformation to the corresponding neutral triazapentadienates [Cu{NH=C(OR)NC(NH(2))=NH}(2)] 11-15. Reaction of 11, 12 or 15 with acetyl acetone (MeC(=O)CH(2)C(=O)Me) leads to liberation of the corresponding pyrimidines NC(Me)CHC(Me)NCNHC(=NH)OR, whereas the same treatment of the cationic complexes 6, 7 or 10 allows the corresponding metal-free triazapentadiene salts {NH(2)C(OR)=NC(NH(2))=NH(2)}(OAc) to be isolated. The alkoxy-1,3,5-triazapentadiene/ato copper(II) complexes have been applied as efficient catalysts for the TEMPO radical-mediated mild aerobic oxidation of alcohols to the corresponding aldehydes (molar yields of aldehydes of up to 100 % with >99 % selectivity) and for the solvent-free microwave-assisted synthesis of ketones from secondary alcohols with tert-butylhydroperoxide as oxidant (yields of up to 97 %, turnover numbers of up to 485 and turnover frequencies of up to 1170 h(-1)).

Gaseous Nitrogen Dioxide for Sustainable Oxidative Deprotection of Trimethylsilyl Ethers

In this study, trialkylsilyl ethers of indispensable protected alcohols are oxidatively deprotected in neat form with gaseous nitrogen dioxide (NO2). Quantitative yields of aldehydes or ketones are obtained without the necessity of chromatography. The byproducts, nitrogen monoxide, anhydrous nitric acid, and hexamethyldisiloxane, can be quantitatively separated by evaporation and distillation in closed systems for recycling or further use. The direct new method supersedes the previous techniques that produce dangerous wastes and require chromatographic workup, while the atmospheric gas NO2 and its gaseous reduction products are easily kept in closed systems until further use.

Significance of Smoking Machine Toxicant Yields to Blood-Level Exposure in Water Pipe Tobacco Smokers

The global increase in tobacco smoking with a water pipe (hookah, narghile, or shisha) has made understanding its health consequences imperative. One key to developing this understanding is identifying and quantifying carcinogens and other toxicants present in water pipe smoke. To do so, the toxicant yield of machine-generated water pipe smoke has been measured. However, the relevance of toxicant yields of machine-generated smoke to actual human exposure has not been established. In this study, we examined whether carbon monoxide (CO) and nicotine yields measured with a smoking machine programmed to replicate the puffing behavior of 31 human participants who smoked a water pipe could reliably predict these participants' blood-level exposure. In addition to CO and nicotine, yields of polyaromatic hydrocarbons, volatile aldehydes, nitric oxide (NO), and "tar" were measured. We found that when used in this puff-replicating manner, smoking machine yields are highly correlated with blood-level exposure (nicotine: r > 0.76, P < 0.001; CO: r > 0.78, P < 0.001). Total drawn smoke volume was the best predictor of toxicant yield and exposure, accounting for approximately 75% to 100% of the variability across participants in yields of NO, CO, volatile aldehydes, and tar, as well as blood-level CO and normalized nicotine. Machine-based methods can be devised in which smoke toxicant yields reliably track human exposure. This finding indicates the basic feasibility of valid analytic laboratory evaluation of tobacco products for regulatory purposes.

Highly Regioselective Isomerization–Hydroformylation of Internal Olefins Catalyzed by Rhodium/Tetraphosphine Complexes

AbstractA new class of substituted tetraphosphine ligands has been applied in the rhodium‐catalyzed regioselective isomerization–hydroformylation of internal olefins. The rhodium/tetraphosphine ligand system is highly effective for the isomerization and hydroformylation of 2‐alkenes to form linear aldehydes. Greater than 95% linear selectivity and up to 94% yield of the total aldehydes were obtained for 2‐pentene, 2‐hexene and 2‐octene. The catalyst system also showed high to moderate linear selectivity for the isomerization and hydroformylation of 3‐hexene, 3‐octene and 4‐octene but with slow reaction rates.

Reimer–Tiemann Reaction of Coumarins

Improved yields of aldehydes from the Reimer–Tiemann reaction of coumarin and two of its derivatives, namely 7-methylcoumarin and 3,4-benzocoumarin, are obtained by carrying the reaction in a two-step procedure. Using crown ether as phase transfer catalyst, a further improvement in the yield of products is achieved. Additionally, coumarin and 7-methylcoumarin are shown to give dialdehydes under this condition. Dialdehydes are reported for the first time from the Reimer–Tiemann reaction.

Concomitant degradation in periodate oxidation of carboxymethyl cellulose

Conversion of carboxymethyl cellulose (CMC) to its dialdehyde derivatives by periodate oxidization in acid solutions has been investigated as a function of pH, temperature, reaction time and periodate dosage. Our results show that the stoichiometric ratio of NaIO 4 to CMC and the pH of aqueous medium are substantially responsible for the aldehyde content and yield of the product. Laser light scattering (LLS) and wide angle X-ray diffraction (WAXD) measurements demonstrate that physical and chemical degradations concomitant with the oxidization process occur, leading to the decrease in 〈 R h〉 and crystallinity, respectively. The degradation mechanism for acid-catalyzed cleavage of β-1-4-glycosidic bond is proposed. Atomic force microscopy (AFM) images reveal the morphological changes of CMC with the degree of oxidization. The present study quantitatively indicates the substantial degradation in derivatization of cellulose by periodate oxidization method, and is helpful for exploring novel carboxymethyl polysaccharide derivatives.

Kinetics of Eucalypt Lignosulfonate Oxidation to Aromatic Aldehydes by Oxygen in Alkaline Medium

The oxidation kinetics of lignosulfonates (LS) from acidic magnesium-based sulfite pulping of Eucalyptus globulus wood with oxygen under alkaline conditions was studied. The analysis of oxidation products in the reaction system O2/NaOH revealed a predominance of aromatic aldehydes (vanillin and syringic aldehyde) though small amounts of vanillic and syringic acids and acetophenone/phenylacetaldehyde derivatives have also been detected. The rate constant of syringic aldehyde formation was roughly twice of that for vanillin. The effective activation energies for the oxidation of LS to aromatic aldehydes (ca. 60−70 kJ/mol) were rather different to those found for the formation of aromatic acids (ca. 110 kJ/mol) indicating different mechanisms involved in the rate-determining reaction step. The addition of catalyst (copper salt, 20% w/w) promoted the LS oxidation with increments of aromatic aldehyde yields by 25−50%. The maximum yields of syringic aldehyde and vanillin upon LS oxidation were 16.1 and 4.5%, respectively (150 °C, 20 min, PO2 = 10 bar, 0.9 M NaOH solution). The highly negative effect of concomitant sugars in sulfite liquor to the yield of aromatic aldehydes was highlighted.

Acid-assisted catalytic oxidation of benzyl alcohol by NO with dioxygen

Efficient transformation of alcohols to the corresponding aldehydes is an important process in organic synthesis and industry. In the absence of transition metal ion, an acid-activated NO x has been explored for the catalytic oxidation of benzyl alcohol. Under the optimal conditions, 95% yield of benzyl aldehyde could be achieved at room temperature with dioxygen as the terminal oxidant. The reaction mechanism was investigated through UV–visible spectrometry and cyclic voltammetry, and the key active species for oxidation have been assigned to the nitrosonium cation. ► NO x /acid catalyzes the oxidation of benzyl alcohol using oxygen. ► NO + is the key active species in the catalytic cycle. ► Acid promotes the generation of NO + .

A novel thermoregulated phosphine ligand used for the Rh-catalyzed hydroformylation of mixed C 11–12 olefins in aqueous/organic biphasic system

A novel thermoregulated phosphine ligand Ph 2P(CH 2CH 2O) n CH 3 ( n = 22) was synthesized and used for the Rh-catalyzed hydroformylation of mixed C 11–12 olefins in aqueous/organic biphasic system. Under the optimized conditions, pressure = 5 MPa (H 2:CO = 1:1), phosphine/Rh = 13 (molar ratio), reaction time = 6 h and temperature = 130 °C, the conversion of C 11–12 olefins and the yield of aldehyde are 99% and 94%, respectively. The catalyst retained in aqueous phase can be easily separated from the product-containing organic phase by simple phase separation and the catalytic activity remains almost constant after four consecutive cycles.