Aldehyde Acetate Research Articles

Preparation of acetals from aldehydes and alcohols under basic conditions.

A new, simple protocol for the synthesis of acetals under basic conditions from non-enolizable aldehydes and alcohols has been reported. Such reactivity is facilitated by a sodium alkoxide along with a corresponding trifluoroacetate ester, utilizing formation of sodium trifluoroacetate as a driving force for acetal formation. The usefulness of this protocol is demonstrated by its orthogonality with various acid-sensitive protecting groups and by good compatibility with functional groups, delivering synthetically useful acetals complementarily to the synthesis under acidic conditions from aldehydes and alcohols.

Phosphorylated Polyacrylonitrile Fiber Catalyzed Acetalization of Aldehydes

Key words flow process - acetalization - polyacrylonitrile fiber - recyclability - solid-acid catalyst

Hierarchical porous organic polymer as an efficient metal-free catalyst for acetalization of carbonyl compounds with alcohols

An efficient melamine-porous organic polymer (M-POP) as N-functionalized organic polymer catalyst was synthesized with melamine and terephthalaldehyde by a facile microwave-assisted method. The synthesized M-POP exhibited a high specific surface area with hierarchical pore structure of both mesoporosity and microporosity. The rich N-moieties namely, CN and NH from the melamine precursor were found to show hydrogen-bonding ability with various organic molecules such as carbonyl compounds. This was illustrated in the acetalization of aldehydes and ketones with methanol or ethylene glycol under mild conditions as a metal-free H-bonding catalyst with high product selectivity. The superior catalytic performance of M-POP was attributed to the availability of a large number of H-bonding sites both as H-donor and H-acceptor between the reactants and the catalyst.

Ru(II)-functionalized SBA-15 as highly chemoselective, acid free and sustainable heterogeneous catalyst for acetalization of aldehydes and ketones

Combining electron deficient Ru(II) coordination sites with organofunctionalized SBA-15, (L)Ru(II)@SBA-15, result in a mild, neutral, water scavenger free and chemo-selective acetalization catalyst for cyclic/acyclic acetals. Vacant coordination sites of ruthenium in (L)Ru(II)@SBA-15 activates protecting groups as well as reactants simultaneously and restricts the reverse acetalization reaction. Synthesized (L)Ru(II)@SBA-15 catalyst has been thoroughly characterized and act as competitive catalyst compared to conventional acid catalysts. (L)Ru(II)@SBA-15 performs high catalytic activity as well as selectivity within 20min with high TOF. The catalyst can be recycled and reaction parameters are optimized.

Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst.

A novel solid acid catalyst (PANEAP F) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PANEAP F shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro-environment in the surface layers of PANEAP F make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous-flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PANEAP F such as simple preparation, convenient regulation of acid amount, high durability, and eco-friendly process make it very attractive for fixed-bed reactors in the chemical industry.

Change of plasmalogen content of red blood cells in myocardial hypoxia and acidosis

Background: The contribution of hypoxic conditions to the chemical composition of membranes is not completely established. Plasmalogens, containing an alkenyl group with aldehydogenic ether linkage, are significant components of membrane lipids and their level can change in oxygen deficiency.Methods: Analysis of plasmalogens in red blood cells was performed in patients (n = 17) with coronary heart disease, stable angina (functional class II–III) and coronary atherosclerosis. The control group consisted of 17 healthy volunteers. In addition, isolated blood samples of seven healthy volunteers were analysed before and after 180 min incubation at 37 °C.Fatty acid ethyl esters and diethyl acetals of fatty aldehydes, obtained during sample preparation from red blood cells, were analysed by capillary gas–liquid chromatography. Quantitative assessment of the change of the plasmalogen levels was evaluated as change of the share of fatty aldehyde diethyl acetals in the total sum of fatty aldehyde diethyl acetals and fatty acid ethyl esters.Results: In comparison with the healthy volunteers, an increase in plasmalogen content of red blood cells and a reduction of the pH of the blood plasma in the group of patients with coronary heart disease were detected. In experimental hypoxia, there was an increase in the plasmalogen content of the red blood cells and a plasma pH decrease in all samples subjected to the incubation.Conclusions: The results indicate changes in the physicochemical properties of the cell membrane in hypoxia. One of the most likely reasons of the increase of plasmalogen content in the membranes may be a more significant increase in activity of calcium-dependent phospholipases in comparison with the activity of calcium-independent plasmalogen phospholipases.

Synthesis of aromatic aldehyde acetals from (dibromomethyl)arenes

Zinc chloride-catalyzed double debromoalkoxylation of (dibromomethyl)arenes on treatment with trialkyl orthoformates resulted in the corresponding aromatic aldehyde acetals. On the first step, α-brominated ether is formed, which undergoes the second debromoalkoxylation producing acetal. This method is tolerated to ester functionalized derivatives.

Production of Alcohols from Olefins via One-Pot Tandem Hydroformylation–Acetalization–Hydrogenolysis over Bifunctional Catalyst Merging RuIII–P Complex and RuIII Lewis Acid

A novel three-step tandem hydroformylation–acetalization–hydrogenolysis was first proposed to produce alcohols (derivatives) from olefins, and the developed unique Ru(III)-complex [Ru(III)-L2] ligated by the ionic diphosphine (L2) proved efficient toward this tandem reaction. In Ru(III)-L2, the strong π-acceptor nature of L2 guaranteed Ru-center remaining in +3 valence state without redox reaction. Hence, Ru(III)-L2 was able to behave as a bifunctional catalyst merging RuIII–P complex and RuIII Lewis acid, which acted not only as a transition metal catalyst responsible for hydroformylation of olefins and hydrogenolysis of (hemi)acetals but also as a Ru3+ Lewis acid in charge of acetalization of aldehydes [to form (hemi)acetals]. The easily performed acetalization served as a bridge step to get through the pathway from aldehydes to alcohols instead of the direct hydrogenation.

Upgrading of fast pyrolysis condensates via esterification with higher alcohols

The utilization of fast pyrolysis condensates is hindered by unwanted properties like corrosivity, high viscosity and tendency to polymerization. These characteristics result from the high content of organic acids and multiple functional groups and C-C double bonds. As an alternative to severe hydroprocessing, the addition of alcohol and subsequent esterification of acids and acetalization of aldehydes is investigated. Pyrolysis condensates are mixed with butanol and an acidic catalyst is added. This mixture is heated and kept under reflux in a dean-stark-apparatus to continuously boil off the water. As reference homogeneous liquid acids are used and compared to solid acid catalysts like ZnO or zeolites. The advantage of the heterogeneous, solid catalysts is the possibility to remove the solids after reaction and use them again for another batch in contrast to the homogeneous acids, which remain in the solution and need to be neutralized at the end. The most promising catalyst candidates are then used in experiments with varying process parameters. All products are analyzed for total acid number, water mass fraction, dynamic viscosity and higher heating value. The total acid number can be reduced by 90 % (from 110 to below 10 mg g−1), the water mass fraction by 90 % (from 25 % to below 2 %), the viscosity by 70 % (from 18 to 5 mm2 s−1) and the higher heating value can be increased by 45 % (from 16.6 to 31 MJ kg−1). These improvements should allow the utilization of upgraded pyrolysis liquids in standard boilers and as fuel in CHP plants.

Antimony(v) catalyzed acetalisation of aldehydes: an efficient, solvent-free, and recyclable process

A highly selective, solvent-free process for the acetalisation of aldehydes was achieved by the use of a readily accessible antimony(v) catalyst which we previously prepared in our lab as a tetraarylstibonium triflate salt ([1][OTf]).

Facile synthesis of Cu3(BTC)2/cellulose acetate mixed matrix membranes and their catalytic applications in continuous flow process

The Cu3(BTC)2/cellulose acetate mixed matrix membranes were fabricated for the acetalization of aldehydes.

Visible-Light-Induced Acetalization of Aldehydes with Alcohols.

In this work, we have achieved a simple and general method for acetalization of aldehydes by means of a photochemical reaction under low-energy visible light irradiation. A broad range of aromatic, heteroaromatic, and aliphatic aldehydes have been protected under neutral conditions in good to excellent yields using a catalytic amount of Eosin Y as the photocatalyst. Our visible light mediated acetalization strategies are successful for more challenging acid-sensitive aldehydes and sterically hindered aldehydes. Notably, this protocol is chemoselective to aldehydes, while ketones remain intact.

Solvent-Free One-Pot Synthesis of 1,8-Dioxo-Decahydroacridines by a [Et3NH][HSO4] Catalyzed Multicomponent Reaction

ABSTRACT[Et3NH][HSO4] has been used as an effective catalyst for one-pot, three-component condensation of an aromatic aldehyde, 5,5-dimethyl-1,3-cyclohexanedione and ammonium acetate for the synthesis of 1,8-dioxo-decahydroacridines under solvent-free conditions. The present methodology offers several advantages, such as high yields, short reaction times, mild condition, and a recyclable catalyst with a very easy work-up.

A Recyclable Fluorous Organocatalyst for Acid-free Acetalization of Aldehydes

A fluorous hydrazinecarbothioate organocatalyst was prepared. Together with orthoformate, the catalyst showed a good activity for acid-free acetalization of aldehydes and alcohols. The fluorous cat...

Oxa-Pictet–Spengler reaction as key step in the synthesis of novel σ receptor ligands with 2-benzopyran structure

The Oxa-Pictet–Spengler reaction of methyl 3-hydroxy-4-phenylbutanoate (8) was explored to obtain novel σ receptor ligands. 1-Acyl protected piperidone ketals 10 and 11 reacted with phenylethanol 8 to yield spirocyclic compounds. Aliphatic aldehyde acetals 19 provided 1,3-disubstituted 2-benzopyrans 20 with high cis-diastereoselectivity. The intramolecular Oxa-Pictet–Spengler reaction of 24 led to the tricyclic compound 25. The spirocyclic compounds 18 show high σ1 affinity (Ki 20–26nM) and σ1/σ2 selectivity (>9-fold), when a large substituent (n-octyl, benzyl, phenylpropyl) is attached to the piperidine N-atom. Opening of the piperidine ring to yield aminoethyl (22, 23) or aminomethyl derivatives (21) resulted in reduced σ1 affinity and σ1/σ2 selectivity.

Diverse acetals from stoichiometric amounts of aldehydes and alcohols under very mild conditions: a new twist to PPh3–CCl4 reagent combination

A very mild, stoichiometric PPh3–CCl4 method for the preparation of diverse acetals of aromatic and aliphatic aldehydes was developed.

ChemInform Abstract: The Stereoselective Formation of Highly Substituted CF3‐Dihydropyrans as Versatile Building Blocks.

AbstractThe enantioselective reaction of bromides (I) and (VI) with unsaturated aldehydes (II) followed by reduction or acetalization of intermediate aldehydes gives rise to alcohols (III) or acetals (VIII), which are readily converted into dihydropyran derivatives (V) and (X).

ChemInform Abstract: Cyclopentyl Methyl Ether—NH4X: A Novel Solvent/Catalyst System for Low Impact Acetalization Reactions.

Cyclopentyl methyl ether, a low impact ether forming a positive azeotrope with water, was successfully employed as a solvent in the synthesis of 1,3-dioxanes and 1,3-dioxolanes carried out under Dean-Stark conditions by the acetalization of aliphatic and aromatic aldehydes or ketones, employing ammonium salts as environmentally friendly acidic catalysts.

ChemInform Abstract: Polyfluoroethoxy Derivatives of Malonic Aldehyde Acetal in the Synthesis of Heterocyclic Compounds.

AbstractPolyfluoroethoxy derivatives of malonic aldehyde acetal (III) are synthesized and shown to be useful building blocks for the synthesis of nitrogen heterocycles.

High activity Fe-MIL-101 solid acid catalyst for acetalization of aldehydes with methanol and enamination of β-dicarbonyl compounds

Catalytic activity Fe-MIL-101 as a reusable solid acid catalyst for acetalization of aldehydes with methanol and enamination of β-dicarbonyl compounds was explored. The recovered Fe-MIL-101 could be reused over ten cycles without any loss of activity. The novel solid acid catalyst has great potential for green chemical application.