Synthesis of long chain alkanes via aldol condensation over modified chitosan catalyst and subsequent hydrodeoxygenation

Distillation of sugar-cane cuticle wax under reduced pressure gives a high yield of long-chain aldehydes, which are considered to occur in the wax in polymeric form. The products obtained from the wax under normal saponification conditions are apparently produced from the aldehydes by a Cannizzaro reaction, and by aldol condensation with subsequent dehydration. The cuticle wax also contains hydrocarbons and free alcohols and acids, but there is no conclusive evidence for the presence of esters.

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Rh-Catalyzed Reductive Amination of Undecanal in an Aqueous Microemulsion System Using a Non-Ionic Surfactant

Catalysts ◽

10.3390/catal11101223 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1223

Author(s):

Ariane Weber ◽

Linus Porthun ◽

Reinhard Schomäcker

Keyword(s):

Reductive Amination ◽

Aldol Condensation ◽

Catalyst System ◽

Water Soluble ◽

Ionic Surfactant ◽

Microemulsion System ◽

Strong Impact ◽

Equilibrium Reactions ◽

Reaction Performance ◽

Long Chain

The homogeneously catalyzed reductive amination of the long-chain aldehyde undecanal with diethylamine was performed in an aqueous microemulsion system using the non-ionic surfactant Marlophen NP8. The experiments showed that the used water-soluble rhodium/SulfoXantphos catalyst system is suitable for this reaction. The Rh-catalyzed formation of the alcohol by-product can be completely suppressed by the use of carbon monoxide with its stabilizing effect of the catalyst system. In addition to pressure and temperature, the most important parameters for the reaction performance of the reductive amination are the concentrations of reactants. Especially, the initial concentration of the aldehyde has a strong impact on the chemoselectivity, and the formation of aldol by-product due to the fact that both, the enamine condensation and the aldol condensation are equilibrium reactions.

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Polymer Morphology Revealed by Staining Techniques

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098204 ◽

1981 ◽

Vol 39 ◽

pp. 340-341

Author(s):

A. C. Reimschuessel ◽

V. Kramer

Keyword(s):

Polymer Melt ◽

Nylon 6 ◽

Morphological Features ◽

Negative Staining ◽

Polymer Morphology ◽

Crystallizable Polymer ◽

Staining Techniques ◽

Long Chain

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.

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A theory of contamination in electron microscopes by surface diffusion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107721 ◽

1978 ◽

Vol 36 (1) ◽

pp. 116-117

Author(s):

J.T. Fourie

Keyword(s):

Electron Beam ◽

Surface Diffusion ◽

High Vacuum ◽

Ultra High Vacuum ◽

Physical Parameters ◽

Carbon Compounds ◽

Hydrocarbon Molecules ◽

Electron Microscopes ◽

Primary Electrons ◽

Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

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Characterization of Chemical Impurities in Glutaraldehyde

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100116723 ◽

1975 ◽

Vol 33 ◽

pp. 620-621

Author(s):

B. J. Grenon ◽

A. J. Tousimis

Keyword(s):

Glutaric Acid ◽

Spectroscopic Analysis ◽

Aldol Condensation ◽

Condensation Product ◽

Amorphous Solid ◽

Water Soluble ◽

Impurity Component ◽

Chemical Impurities ◽

Soluble Liquid

Ever since the introduction of glutaraldehyde as a fixative in electron microscopy of biological specimens, the identification of impurities and consequently their effects on biologic ultrastructure have been under investigation. Several reports postulate that the impurities of glutaraldehyde, used as a fixative, are glutaric acid, glutaraldehyde polymer, acrolein and glutaraldoxime.Analysis of commercially available biological or technical grade glutaraldehyde revealed two major impurity components, none of which has been reported. The first compound is a colorless, water-soluble liquid with a boiling point of 42°C at 16 mm. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopic analysis, this compound has been identified to be — dihydro-2-ethoxy 2H-pyran. This impurity component of the glutaraldehyde biological or technical grades has an UV absorption peak at 235nm. The second compound is a white amorphous solid which is insoluble in water and has a melting point of 80-82°C. Initial chemical analysis indicates that this compound is an aldol condensation product(s) of glutaraldehyde.

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The effects of low-ratio n-6/n-3 PUFA on biomarkers of inflammation: a systematic review and meta-analysis

Food & Function ◽

10.1039/d0fo01976c ◽

2021 ◽

Author(s):

Yali Wei ◽

Yan Meng ◽

Na Li ◽

Qian Wang ◽

Liyong Chen

Keyword(s):

Systematic Review ◽

Fatty Acid ◽

Polyunsaturated Fatty Acid ◽

Meta Analysis ◽

Chain Polyunsaturated Fatty Acid ◽

Inflammation Markers ◽

Pufa Supplementation ◽

Long Chain

The purpose of the systematic review and meta-analysis was to determine if low-ratio n-6/n-3 long-chain polyunsaturated fatty acid (PUFA) supplementation affects serum inflammation markers based on current studies.

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Biophysics (and sociology) of ceramides.

Biochemical Society Symposium ◽

10.1042/bss0720177 ◽

2005 ◽

Vol 72 ◽

pp. 177-188 ◽

Cited By ~ 28

Author(s):

Félix M. Goñi ◽

F-Xabier Contreras ◽

L-Ruth Montes ◽

Jesús Sot ◽

Alicia Alonso

Keyword(s):

Cell Biology ◽

Positive Curvature ◽

Acyl Chain ◽

Cell Signalling ◽

Hexagonal Structure ◽

Lipid Monolayer ◽

Flip Flop ◽

Long Chain ◽

Bilayer Permeability

In the past decade, the long-neglected ceramides (N-acylsphingosines) have become one of the most attractive lipid molecules in molecular cell biology, because of their involvement in essential structures (stratum corneum) and processes (cell signalling). Most natural ceramides have a long (16-24 C atoms) N-acyl chain, but short N-acyl chain ceramides (two to six C atoms) also exist in Nature, apart from being extensively used in experimentation, because they can be dispersed easily in water. Long-chain ceramides are among the most hydrophobic molecules in Nature, they are totally insoluble in water and they hardly mix with phospholipids in membranes, giving rise to ceramide-enriched domains. In situ enzymic generation, or external addition, of long-chain ceramides in membranes has at least three important effects: (i) the lipid monolayer tendency to adopt a negative curvature, e.g. through a transition to an inverted hexagonal structure, is increased, (ii) bilayer permeability to aqueous solutes is notoriously enhanced, and (iii) transbilayer (flip-flop) lipid motion is promoted. Short-chain ceramides mix much better with phospholipids, promote a positive curvature in lipid monolayers, and their capacities to increase bilayer permeability or transbilayer motion are very low or non-existent.

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