Long-chain Dialkyl Research Articles

Phosphine catalyzed addition of long-chain dialkyl phosphites to electron-deficient alkenes

Conjugate addition of the long chain dialkyl phosphites to electron-deficient alkenes under PBu3 catalysis afforded the corresponding phosphonates in good yields in a short reaction time. Long chain alkyl groups in the phosphites were well tolerated in this transformation. The products of this reaction are of particular interest as components of lubrication oil composition.

Ash Catalyzed Synthesis of Long-Chain Dialkyl Carbonates Through Carbonyl Exchange Reaction

Present work is focused on development of methodology involving utilization of cost effective, highly effective heterogeneous catalyst prepared from wood ash for carbonyl exchange reaction between long chain alcohols and diethyl carbonate to produce long-chain dialkyl carbonates. Whereas long-chain dialkyl carbonates are being explored as value added compounds as they are environmentally safe and non-corrosive in nature and useful in diesel as cetane improvers, lubricants and used in cosmetics. Thermal treatment (calcination) of wood ash was carried out at 500 and 800 °C temperatures and studied the activity of resulted catalyst towards the synthesis of long-chain dialkyl carbonates through carbonyl exchange reaction. The prepared catalyst was characterized by analytical techniques for surface morphology, crystalline phases and textural characteristics. In the present study, maximum yield of long-chain dialkyl carbonates (81%) was achieved using heterogeneous wood ash catalyst at 10 wt% of reactants and at temperature of 120 °C. The synthesized products were characterized by analytical techniques like infrared (IR), nuclear magnetic resonance (NMR), gas chromatography and mass spectroscopy respectively. Applications of prepared long-chain dialkyl carbonates in ultra low sulphur diesel (ULSD) have been explored as lubricity improvers and cetane number improvers.

"Inherently Chiral" Ionic-Liquid Media: Effective Chiral Electroanalysis on Achiral Electrodes.

To achieve enantioselective electroanalysis either chiral electrodes or chiral media are needed. High enantiodiscrimination properties can be granted by the "inherent chirality" strategy of developing molecular materials in which the stereogenic element responsible for chirality coincides with the molecular portion responsible for their specific properties, an approach recently yielding outstanding performances as electrode surfaces. Inherently chiral ionic liquids (ICILs) have now been prepared starting from atropisomeric 3,3'-bicollidine, synthesized from inexpensive reagents, resolved into antipodes without need of chiral HPLC and converted into long-chain dialkyl salts with melting points below room temperature. Both the new ICILs and shorter family terms, solid at room temperature, employed as low-concentration additives in achiral ILs, afford impressive enantioselection for the enantiomers of different probes on achiral electrodes, regularly increasing with additive concentration.

Synthesis and Characterization of Long-Chain Dialkyl Carbonate

Synthesis and Characterization of Long-Chain Dialkyl Carbonate

Convenient Preparation of Long-Chain Dialkyl Phosphates: Synthesis of Dialkyl Phosphates

Reaction of phosphorus oxychloride with a primary alcohol (1.8 equiv) and triethylamine (1.8 equiv) in toluene, followed by filtration and treatment with steam, gives dialkyl phosphates in good yield and essentially free from trialkyl phosphate contamination.

Synthesis and oxidative polymerization of dialkyl fluorene-9,9-dicarboxylates

Novel long-chain dialkyl fluorene-9,9-dicarboxylates were synthesized by treating fluorene with lithium diisopropylamide followed by alkyl chloroformates. The fluorene derivatives were readily electro-oxidized to form electroactive films on the surface of a glassy carbon electrode. From the viewpoint of suitable potential window (from −2.5 to 1.5 V vs Ag/Ag +), cyclic voltammograms of the films indicated the electroactive properties of the fluorene derivatives that make them good candidates for electrochemical capacitor materials.

3-Mercaptopropionate Dioxygenase, a Cysteine Dioxygenase Homologue, Catalyzes the Initial Step of 3-Mercaptopropionate Catabolism in the 3,3-Thiodipropionic Acid-degrading Bacterium Variovorax paradoxus

The thioether 3,3-thiodipropionic acid can be used as precursor substrate for biotechnological synthesis of 3-mercaptopropionic acid-containing polythioesters. Therefore, the hitherto unknown catabolism of this compound was elucidated to engineer novel and improved polythioester biosynthesis pathways in the future. Bacteria capable of using 3,3-thiodipropionic acid as the sole source of carbon and energy for growth were enriched from the environment. From eleven isolates, TBEA3, TBEA6, and SFWT were morphologically and physiologically characterized. Their 16 S rDNAs and other features affiliated these isolates to the beta-subgroup of the proteobacteria. Tn5::mob mutagenesis of isolate Variovorax paradoxus TBEA6 yielded ten mutants fully or partially impaired in growth on 3,3-thiodipropionic acid. Genotypic characterization of two 3,3-thiodipropionic acid-negative mutants demonstrated the involvement of a bacterial cysteine dioxygenase (EC 1.13.11.22) homologue in the further catabolism of the 3,3-thiodipropionic acid cleavage product 3-mercaptopropionic acid. Detection of 3-sulfinopropionate in the supernatant of one of these mutants during cultivation on 3,3-thiodipropionic acid as well as in vivo and in vitro enzyme assays using purified protein demonstrated oxygenation of 3-mercaptopropionic acid to 3-sulfinopropionate by this enzyme; cysteine and cysteamine were not used as substrate. Beside cysteine dioxygenase and cysteamine dioxygenase, this 3-mercaptopropionic acid dioxygenase is the third example for a thiol dioxygenase and the first report about the microbial catabolism of 3-mercaptopropionic acid. Insertion of Tn5::mob in a gene putatively coding for a family III acyl-CoA-transferase resulted in the accumulation of 3-sulfinopropionate during cultivation on 3,3-thiodipropionic acid, indicating that this compound is further metabolized to 3-sulfinopropionyl-CoA and subsequently to propionyl-CoA.

Dialkyl 3,3‘-Thiodipropionate and Dialkyl 2,2‘-Thiodiacetate Antioxidants by Lipase-Catalyzed Esterification and Transesterification

Medium- and long-chain dialkyl 3,3'-thiodipropionate antioxidants such as dioctyl 3,3'-thiodipropionate, didodecyl 3,3'-thiodipropionate, dihexadecyl 3,3'-thiodipropionate, and di-(cis-9-octadecenyl) 3,3'-thiodipropionate were prepared in high yield by lipase-catalyzed esterification and transesterification of 3,3'-thiodipropionic acid and its dimethyl ester, respectively, with the corresponding medium- or long-chain 1-alkanols, i.e., 1-octanol, 1-dodecanol, 1-hexadecanol, and cis-9-octadecen-1-ol, in vacuo (80 kPa) at moderate temperatures (60-80 degrees C) without solvents. Immobilized lipase B from Candida antarctica (Novozym 435) was the most active biocatalyst for the preparation of medium- and long-chain dialkyl 3,3'-thiodipropionates showing enzyme activities up to 1489 units/g, whereas the immobilized lipases from Rhizomucor miehei (Lipozyme RM IM) and Thermomyces lanuginosus (Lipozyme TL IM) were by far less active ( approximately 10 enzyme units/g). Maximum conversions to dialkyl 3,3'-thiodipropionates were as high as 92-98% after 4 h of reaction time. Similarly, dihexadecyl 2,2'-thiodiacetate was prepared in high yield using 2,2'-thiodiacetic acid or diethyl 2,2'-thiodiacetate and 1-hexadecanol as the starting materials and Novozym 435 as the biocatalyst.

Thermal characteristics of solid–solid phase transitions in long-chain dialkyl ammonium salts

A series of symmetrical dialkyl ammonium salts, DC n X, has been prepared and characterized with respect to temperature and enthalpy of solid–solid phase transitions, temperature of melting, thermal stability as well as the reversibility of the phase transitions. The number of carbon atoms, C n , was varied between 8 and 18 and as anions X halides, nitrate, chlorate, perchlorate and hydrogen sulphate had been chosen. In dependence on chain length and anion type transition temperatures from 20 to 100 °C were observed. Mass specific solid–solid transition enthalpies reach values of 185 J g −1, which makes this class of substances attractive for heat storage applications. The influence of anion type on the transition enthalpies is explained in terms of packing requirements, hydrogen bond network formation and contributions from hindered anion rotation.

Synthese et Etude Structurale D'acides Alkylphosphoniques a Longue Chaine Hydrocarbonee

Long-chain dialkyl alkylphosphonates were synthesized by radical addition of dialkyl hydrogenphosphonates onto alkenes in presence of di(t-butyl) peroxide. This synthetic route leads to high yields between 94 and 97%. We performed chemical modifications of these phosphonates in order to obtain acidic derivatives. The structure of these compounds was characterized by NMR analyses and mass spectroscopy. We also studied their thermal behaviour and various crystalline phases were put in evidence by differential scanning calorimetry and optical microscopy. The thermal stability of these compounds was compared by thermogravimetric analyses.

Chirality-directed self-assembling of long-chain dialkyl 3,7-diazabicyclo[3.3.1]nonane-2,6-dione-1,5-dicarboxylates

Dihexyl and didodecyl 3,7-diazabicyclo[3.3.1]nonane-2,6-dione-1,5-dicarboxylates 4a,b were synthesised, and the self-assembling of the molecules of strictly alternating configurations was observed in a crystal of bis-lactam 4b , which resulted in formation of H -bonded heterochiral polymer tapes of a diagonal zigzag type combined into monomolecular layers separated by hydrophobic groups.

Liquid crystals of long-chain dialkyl phosphate salts in nonpolar solvents

The structure of a binary system of aluminum salts of dihexadecyl phosphate (C16DP Al) andn-hexadecane were studied in the high C16DP Al content region. Above the melting point of the hydrocarbon chain of C16DP Al (Tc), the experimental results of X-ray diffraction studies for the C16DP Al solution show that cylinder structures—composed of an aggregation with a center of aluminum atoms of C16DP Al molecules whose architecture consists of a trisubstituted central aluminum atom and three regional C16DP molecules—are stacked periodically to form a hexagonal liquid crystal. The Bragg spacingd between the (1010) planes in the hexagonal network increased with increasing concentration ofn-hexadecane, which should fill the C16DP Al acyl chain region and the space between the tails of C16DP Al cylinders. Below Tc this system exists as a single hard wax-like phase. The packing structure of C16DP Al in this phase is similar to the hexagonal structure of the liquid crystal phase and in the region up to 23 wt%n-hexadecane content this packing order changes with the addition ofn-hexadecane. The effects or varying amounts ofn-hexadecane on the packing states of C16DP Al are discussed.

Intermediary metabolism of Acinetobacter grown on dialkyl ethers

The microbial dissimilation of long-chain dialkyl ethers by Acinetobacter sp. H01-N involved a terminal methyl group oxidation of the dialkyl ether substrates, resulting in the formation of ether oxygen containing fatty acids of corresponding chain length. An internal carbon–carbon scission of the dialkyl ethers resulted in the formation of end-product ether fatty acids and corresponding dicarboxylic acids. Cellular carbon and energy were derived from the subsequent metabolism of the dicarboxylic acids. Dicarboxylic acid oxidation, activation, and identification of cellular dicarboxylic acids indicated dibasic acids as intermediates in the metabolism of dialkyl ethers.Key words: dialkyl ethers, dicarboxylic acids, fatty acids, Acinetobacter.

New oil‐gelling agents for cosmetics: formation mechanism of oil gels

Summary New oil-gelling agents have been developed composed of a long-chain dialkyl phosphate (DP) surfactant and aluminium ion or multinuclear aluminum ion (MAI) which provide good oil-gel systems. One such gelling agent is the aluminum salt of DP (DP-Al) prepared as a precipitate by mixing DP with aluminum chloride in aqueous solutions. Addition of small amounts of the salt to non-polar oils led to hardening of the oil solutions at temperature below the melting point of the alkyl chain (Tc) of DP-Al. Results obtained by X-ray diffraction techniques and with scanning electron microscopy (SEM) revealed that linearly-polymerized assemblies of DP-Al expand in oils three-dimensionally, which suggests that the excellent stability of the gel systems arises from the highly ordered structure. The gelling agent of DP-Al offered the ideal rheological property to waxy cosmetic products such as lipsticks. The complexes of DP with MAI particles (1 nm diameter) of aluminum chlorohydrate, Al(13)O(4)(OH)(24)(H(2)O)(12)CI(7), provided the ideal thixotropic behaviour in non-polar oils. The DP-MAI particle complexes were found to interact weakly by cohesive forces which makes a highly ordered structure of the DP-MAI particle complexes. The DP-MAI particle complexes gave excellent stability and transparency to cosmetic products such as w/o creams.

Presence of long-chain dialkyl ethers in cuticular wax of the Australian chrysomelid beetleMonolepta australis

Investigation of the lipid extract of the Australian chrysomelid beetle,Monolepta australis, has revealed a novel homologous series of long-chain, unsaturated-saturated dialkyl ethers in the cuticular wax. Gas chromatography-mass spectrometry, proton magnetic resonance, infrared spectroscopy, and chemical degradation have shown that ethers of formula CH3(CH2)9CH=CH(CH2)6O(CH2)12-16CH3 predominate.

Solution Behavior and Gel Properties of Long-chain Dialkyl Phosphates in Nonpolar Solvents

Some Aluminum salts of long-chain alkylphosphates (Al-DHP) form stiff gels in the presence of nonpolar oils such as isooctane, n-heptane, cyclohexane, p-xylene, benzene and n-hexadecane. The mechanism of gelation of the Al-DHP-hydrocarbon system and association state of Al-DHP in this system were investigated by measurement of gel hardness, differential scanning calorimetry (DSC), scanning electron microscopic observation (SEM) and polarizing technique. Above the gel/jelly transition temperature (Tc), the gel converted into a highly viscous solution, indicating the formation of linear polymeric molecules of Al-DHP. Cooling down under Tc caused this viscous solution to become a hard and staff gel. Uunder Tc, a flexible Al-DHP polymer changes to linear micro crystals. The stabilization of the gel is considerd due to formation of a well dispersed three dimensional network structure consisting of linear microcrystals. SEM observation of the gel indicated formation of a fiber network, thus supporting the above assumption. The hardness of the gel varied according to the solubility parameter (S.P.) of the solvent. The gel became hardest when the S.P. of the solvent was 8.2 to 8.75. Tc was lowest when the gel was hardest. It is thus evident that gelation is closely related to the dissolution of Al-DHP to the solvent.

Synthesis and Cation Complexing Ability of Crown Ethers with Glycerol-skeleton

Glycerol-substituted crown compounds (4) were prepared in good yields by the cyclization of monoisopropylidene diglycerol with oligoethylene glycol ditosylates or the corresponding dihalides in the presence of alkali bases, followed by hydrolysis of 1, 3-dioxolane ring. Alkylation of 4 gave long-chain dialkyl crown ethers with glycerol-skeletons (5). The cation complexing stability constants of 35 in methanol were measured.

Infrared spectra of long-chain dialkyl sulfates

Infrared spectra of long-chain dialkyl sulfates