Long-chain Synthesis Research Articles

A Closed-Loop Recyclable Low-Density Polyethylene.

Low-density polyethylene (LDPE) is one of the most important plastics, which is produced unfortunately under extreme conditions. In addition, it consists of robust aliphatic C─C bonds which are challenging to cleave for plastic recycling. A low-pressure and -temperature (pethylene=2bara, T=70°C) macromonomer-based synthesis of long chain branched polyethylene is reported. The introduction of recycle points permits the polymerization (grafting to) of the macromonomers to form the long chain branched polyethylene and its depolymerization (branch cleavage). Coordinative chain transfer polymerization employing ethylene and co-monomers is used for the synthesis of the macromonomers, permitting a high flexibility of their precise structure and efficient synthesis. The long chain branched polyethylene material matches key properties of low-density polyethylene.

Synthesis of Long Chain Oxygenates via Aldol Condensation of Furfural and Acetone over Metal-Organic Frameworks.

Enormous efforts have been made to convert biomass to liquid fuels and products catalytically. Long molecules with a suitable structure are ideal precursors for fuels and value-added products. Here, a C21 oxygenate was synthesized for the first time in one step through aldol condensation of furfural and acetone over the amine-functionalized zirconium-based metal-organic framework (MOF), UiO-66-NH2. Structural changes of UiO-66-NH2 were investigated to improve the yield and evaluate the role of the ligand, cluster node, defectiveness, modulator, surface area, and textural properties on the product distribution. We demonstrate the possibility of making long-chain oxygenates without using vegetable oil-derived fatty acids toward 100% waste biomass-derived renewable fuels, lubricants, and surfactants.

Early biochemical observations point to nutritional strategies to manage non-alcoholic fatty liver disease

Abstract Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disease globally. The first stage of NAFLD is steatosis, the accumulation of triacylglycerols within hepatocytes. Inflammation and oxidative stress both contribute to progression to more severe disease. In 2004 Clinical Science published two papers reporting on fatty acids and oxidative stress markers in the livers of patients with NAFLD; both these papers are highly cited. One paper reported an altered pattern of fatty acids within the livers of patients with NAFLD; there was a lower contribution of polyunsaturated fatty acids (PUFAs) including both n - 6 and n - 3 PUFAs and an altered balance between n - 6 and n - 3 PUFAs in favour of the former. Ratios of precursor PUFAs to their long chain more unsaturated derivatives were altered in NAFLD and were interpreted to indicate a reduced activity of the pathway of synthesis of long chain highly unsaturated PUFAs. The authors interpreted their findings to indicate that a low hepatic content of n - 3 PUFAs has a causal role in NAFLD. The second paper reported lower hepatic antioxidant defences and increased markers of oxidative stress in NAFLD, consistent with a role for oxidative stress in the disease. Many studies have now explored the effect of supplemental n - 3 PUFAs or antioxidants, including vitamin E, in patients with NAFLD with some benefits being reported. There remains much interest in n - 3 PUFAs and antioxidants as preventive and therapeutic strategies in NAFLD and therefore it seems likely that citation of the two papers from 2004 will be sustained.

Synergistic Catalysis Induced Reaction Pathway for Facile Synthesis of Long Chain 1,2-Diol from Xylose in Acid-Metal Dual Catalyst System

Synergistic Catalysis Induced Reaction Pathway for Facile Synthesis of Long Chain 1,2-Diol from Xylose in Acid-Metal Dual Catalyst System

Synergistic Catalysis Induced Reaction Pathway for Facile Synthesis of Long Chain 1,2-Diol from Xylose in Acid-Metal Dual Catalyst System

Synergistic Catalysis Induced Reaction Pathway for Facile Synthesis of Long Chain 1,2-Diol from Xylose in Acid-Metal Dual Catalyst System

The influence of maternal and child FADS genotype on cord blood polyunsaturated fatty acid (PUFA) concentrations

AbstractOptimal maternal polyunsaturated fatty acid (PUFA) status is essential for foetal development. The desaturase enzymes, encoded by the fatty acid desaturase (FADS) genes, are involved in the endogenous synthesis of long chain (LC)PUFA and influence maternal LCPUFA concentrations. The minor allele of various FADS SNPs has been associated with increased maternal concentrations of the precursors linoleic acid (LA) and α-linolenic acid (ALA), and lower concentrations of the LCPUFA arachidonic acid (AA) and docosahexaenoic acid (DHA); however, there is limited research to date on the influence of FADS genotype on cord PUFA status. The aim of the current study was to investigate the influence of maternal and child genetic variation on cord blood PUFA status in a high fish-eating cohort.Cord blood samples collected from mother-child pairs (n = 1088) taking part in the Seychelles Child Development Study (SCDS) Nutrition Cohort 2 (NC2) were analysed for total serum PUFA. Maternal (n = 1088) and child genotype (n = 592) were determined for the FADS SNPs rs174537, rs174561, rs174575, and rs3834458. Regression analysis determined associations between maternal and child FADS genotype and cord PUFA status. In all regression models, the major allele homozygote genotype for each SNP was used as the reference group.Directions of significant associations were as predicted. In mothers, the minor allele homozygote genotype for SNPs rs174537, rs174561 and rs3834458 was associated with lower cord DHA and lower total n-3 PUFA when compared to the major allele homozygous genotype (p < 0.05 for all). The heterozygous genotype was associated with increased concentrations of LA compared to the reference genotype for rs174561 (p = 0.021) and rs383448 (p = 0.023). In children, the heterozygous genotype was associated with lower AA concentrations and lower cord n-6:n-3 ratio for all SNPs (p < 0.05 for all) compared to those with the major allele homozygous genotype. A lower cord AA:LA ratio was also observed for children heterozygous for rs174547, rs174561 and rs174575 (p < 0.05 for all). Contrary to expected, there were no associations between cord PUFA concentrations and child minor allele homozygous genotype.The current study indicates that variation in maternal and child FADS genotype influences cord PUFA concentrations, despite the high intake of preformed dietary LCPUFA from fish in this population. The sample size for minor allele homozygous children was likely too small to observe any statistically significant associations in the current analysis. Further research is needed to determine whether increased dietary intake can compensate for lower PUFA status as a result of FADS genotype.

Construction and Verification of CRISPR/Cas9 Gene Editing Vector for Cassava <i>MeSSIII</i> Gene

Starch glucan chain structure of cassava root is the key factor to determine starch quality. Soluble starch synthase III (SSIII) is the key enzyme to regulate the synthesis of long chain in plant amylopectin glucan. Cassava has two MeSSIII homologous genes MeSSIII-1 and MeSSIII-2 . To study the effect of cassava MeSSIII on the quality formation of cassava root starch, a double gene editing vector for MeSSIII-1 and MeSSIII-2 was constructed. The sgRNA target for MeSSIII-1 and MeSSIII-2 was designed simultaneously by online software CRISPR-Pv2.0 based on the conserved segments, and the recombinant pCAMBIAP1301-Cas9-MeSSIII-gRNA plasmid was constructed by digestion and ligation. The gene editing vector was transformed into LBA4404 Agrobacterium competent cells and used to infect the friable embryogenic callus of cassava, and the their DNA was extracted. The target segments of MeSSIII-1 and MeSSIII-2 were amplified by PCR for Sanger sequencing, and analyzed the editing of target position. The results showed that the target sites of MeSSIII-1 and MeSSIII-2 were successfully edited. This study helps to further obtain mutants of the MeSSIII gene to analyze the role of this gene in the cassava starch synthesis pathway.

Efficient Protocol for the Synthesis of "N-Coded" Oligo- and Poly(N-Substituted Urethanes).

Sequence-defined poly(N-substituted urethanes) were synthesized via a solid-phase iterative protocol including two successive orthogonal coupling steps: the formation of an activated carbonate and its chemoselective reaction with the secondary amine group of amino alcohol building blocks. This simple method was used to write binary information on the formed polymers using four-coded molecules, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(propylamino)ethanol, and 2-(butylamino)ethanol, symbolizing binary dyads 00, 01, 10, and 11, respectively. The method is fast and allows synthesis of uniform oligomers and polymers with controlled lengths (4-mer to 28-mer) and digital information sequences. Furthermore, the coded poly(N-substituted urethanes) were easily characterized by electrospray mass spectrometry and decoded by tandem mass spectrometry. Overall, these digital macromolecules offer interesting advantages over conventional sequence-coded polyurethanes, i.e., synthesis of longer chains, reduced synthesis times, and better solubility and processing in common organic solvents.

Synthesis of Long Chain Bonding Agent of CSRP and its Effect on Propellant Mechanical Properties

AbstractMechanical properties of composite solid rocket propellant are one of the most important propellant specifications and also improvement of the interfacial interactions between bonding agents and solid particles is a demand for composite solid propellants in order to withstand stresses produced due to various loading conditions, changes in environmental condition, transportation and handling. In this work, long chain bonding agent prepared from the reaction of fatty monocarboxylic acid and dicarboxylic acid with methyl aziridinyl phosphine oxide (MAPO) to form (MSA) bonding agent which is improved the mechanical properties especially strain value corresponding to stress value which gives the highest value in formulation B1 but with low yield properties. Also using an percentage of MAPO as a mixed bonding agent in order to increase the yield properties of the propellant has a significant effect on mechanical properties as giving high value of Young′s modulus and good strain value with the percentage of 0.1 % of MAPO and 0.2 % of MSA then by changing the curing agent using IPDI instead of HMDI also gives a remarkable mechanical properties as high strain corresponding stress with a good value with modulus in formulation CI2.

Effects of Wx and Its Interaction With SSIII-2 on Rice Eating and Cooking Qualities.

The Wx gene encodes a granule-bound starch synthase (GBSS) and plays a key role in determining rice eating and cooking qualities (ECQs). SSIII-2 (SSIIIa), a member of the soluble starch synthases, is responsible for the synthesis of long chains of amylopectin. To investigate the effects of Wx and its interaction with SSIII-2 on grain ECQs, a population from a hybrid combination was established as a research material. The genotypes of SSIII-2 and the single nucleotide polymorphisms (SNPs) on intron1, exon6, and exon10 of Wx, and the physicochemical indicators and rapid visco analyzer (RVA) profile characteristics were analyzed. The results revealed various effects of SSIII-2 on rice quality under different backgrounds of Wx alleles. There was no obvious difference between different SSIII-2 alleles under the same background of Wxa, whereas there was a significant diversity under the same background of Wxb. Wxa had a dominant epistasis to SSIII-2 because the effect of SSIII-2 was masked by the massive synthesis of GBSS under Wxa. The apparent amylose content (AAC) was mainly controlled by the In1G/T SNP, and rice gel consistency (GC) was regulated by the Ex10C/T SNP. The combined effects of three SNPs had a significant influence on all ECQs and RVA profile parameters, except for gelatinization temperature. In1T-Ex6A-Ex10C and In1T-Ex6A-Ex10T were classified as being low AAC type. TT-AA-CC and TT-AA-TT had a low AAC and a soft GC. The combined effects of different SNPs of Wx are very important for rice quality breeding.

Distribution of (n‐9) and (n‐7) Isomers of Monounsaturated Fatty Acids in Indian Mustard (Brassica juncea)

AbstractThe seed oils of 19 Indian mustard varieties were analyzed for fatty acid composition using GC–MS, reporting the presence of n‐7 isomers of C18:1, C20:1 and C22:1 fatty acids. n‐7 isomers namely cis‐vaccenic (C18:1), 11, eicosenoic(C20:1) and 13‐cis‐docosenoic (C22:1) acids ranged from 0.61 to 1.73, 1.04 to 1.69 and 0.58 to 1.17 %, respectively. The average values of C20:1(n‐7) was highest (1.36) amongst the three acids. Nervonic acid was also reported in the range of 0.69 to 2.52 %. The ratios of (n‐7)/(n‐9) ranged from 6.22 to 14.62, 12.38 to 27.35 and 2.01 to 3.24 % for C18:1, C20:1 and C22:1 fatty acids, respectively. The variety RLM‐619 had the lowest elongation ratio (ER) as 0.44 and the highest desaturation ratio (DR) as 0.41 indicating higher efficiency of the desaturation pathway than for other varieties. The oleic desaturation ratio (ODR) values varied from 0.68 (Basanti) to 0.75 (GM‐2) with a mean value of 0.72 and linoleic desaturation ratio from 0.40 (Basanti) to 0.49 (Pusa Bold) with a mean value of 0.45. Palmitoleic acid showed positive correlation with C18:1(n‐7), C20:1(n‐7), C20:2, C22:0, C22:1(n‐7), C24:1, (n‐7)/(n‐9) ratio of C18:1 and C22:1 and a positive trend with ER but a significant negative correlation with C18:3, DR and ODR. The results indicated that palmitoleic acid is an important intermediate component in the synthesis of long chain (n‐7) fatty acids.

Synthesis of Long Chain Brønsted Acidic Ionic Liquids

With the depletion of petroleum, a new source of feedstock chemicals for polymers is needed. The new source should be a renewable source to avoid future depletion and environmental impact. A potential source of new feedstock chemicals is chitin. The use of ionic liquids for the dissolution of chitin has enabled new processing methods for this biopolymer. Recent results demonstrate that chitin can be depolymerizes in ionic liquid. The products of this depolymerization are N-acetylglucosamine and a furfural derivative. This research investigates the use of ionic liquids and various acid catalysts for the depolymerization of chitin into its monomer units. This research evaluates the effects of temperature, the nature of the catalyst, and solvent effects on the depolymerization of chitin.

An efficient microwave-assisted enzyme-catalyzed regioselective synthesis of long chain acylated derivatives of flavonoid glycosides

This work describes a method of microwave-assisted regioselective enzymatic acylation, using Novozyme 435®, of quercetin-3-O-glucoside (isoquercitrin) and phloretin-2′-glucoside (phloridzin) with different long chain saturated, mono-, and poly-unsaturated fatty acids. The synthesized esters were analyzed by 1H NMR, and 13C NMR spectroscopy. In this investigation, microwave irradiation under solvent free condition has been found to be more efficient and economical than conventional conditions both, in terms of time and energy.

Synthesis of Long Chain Unsaturated‐α,ω‐Dicarboxylic Acids from Renewable Materials via Olefin Metathesis

AbstractThe self‐metathesis reaction of soy, rapeseed, tall, and linseed oil fatty acids was investigated for the synthesis of symmetrical long‐chain unsaturated‐α,ω‐dicarboxylic acids. The metathesis reactions were carried out in the presence of a Grubbs catalyst under solvent‐free condition at a catalyst loading of 0.01 mol% to fatty acid substrate at 50 °C. Under these conditions, the conversions of starting unsaturated acids to metathesis products were >80% and the isolated yields of unsaturated dicarboxylic acid products were >70% of theoretical. This approach represents an effective and efficient route for the synthesis of these potentially useful dicarboxylic acids since they can serve as important intermediates in the production of several materials such as biodegradable polymers.

Asymmetric synthesis of long chain α-methyl-β-thiotrifluoromethyl ketones employing the SAMP-/RAMP-hydrazone alkylation methodology

The enantioselective synthesis of both enantiomers of ( Z)-1,1,1-trifluoro-3-methyl-4-thia-13-octadecen-2-one and ( Z)-1,1,1-trifluoro-3-methyl-4-thia-13-hexadecen-2-one (ee ⩾90%), potential inhibitors of the pheromone action of two major maize pests Sesamia nonagrioides and Ostrinia nubilalis, is described. The key step is based upon a stereoselective alkylation with methyl iodide using the SAMP-/RAMP-chiral auxiliary methodology, followed by deprotection under non-racemization conditions.

Cuticular hydrocarbons of triatomines

Triatomine insects (Hemiptera) are the vectors of Chagas disease. Their cuticular surface is covered by a thin layer of lipids, mainly hydrocarbons, wax esters, fatty alcohols, and free or esterified fatty acids. These lipids play a major role in preventing a lethal desiccation, altering the absorption of chemicals and microorganism penetration, they also participate in chemical communication events. Lipid components are biosynthetically related, the synthesis of long chain and very long chain fatty acids was first shown in the integument of Triatoma infestans through the concerted action of fatty acid synthases (FAS's) and fatty acyl-CoA elongases. A final decarboxylation step produces the corresponding hydrocarbon. Capillary gas chromatography coupled to mass spectrometry analyses showed that cuticular hydrocarbons of Triatominae comprise saturated straight and methyl-branched chains, from 18 to more than 43 carbon atoms. Odd-chain hydrocarbons, mostly from 27 to 33 carbons, are the major straight chains. Different isomers of mono, di, tri, and tetramethylcomponents, mostly from 29 to 39 atoms in the carbon skeleton, account for the major methyl-branched hydrocarbons. The presence, absence, and relative quantities of these hydrocarbons represent characters for their chemical phenotype, and are useful for differentiating genera, species and populations. In this review, we will discuss the metabolic pathways involved in hydrocarbon formation, and their structure, together with their role in insect survival. We will also review the utility of cuticular hydrocarbon fingerprints in chemotaxonomy.

Synthesis of long chain n-3 and n-6 fatty acids having a photoactive conjugated tetraene group

Fatty acids of the n-3 and n-6 families containing a photoactive conjugated tetraene group near the carboxylate were prepared from several naturally occurring fatty acids by sequential iodolactonization and treatment with excess 1,8-diazabicyclo[5.4.0]undec-7-ene. The new conjugated fatty acids include 5 E,7 E,9 E,11 Z,14 Z- and 5 E,7 E,9 E,11 E,14 Z-eicosapentaenoic acids derived from arachidonic acid; 5 E,7 E,9 E,11 Z,14 Z,17 Z- and 5 E,7 E,9 E,11 E,14 Z,17 Z-eicosahexaenoic acids from eicosapentaenoic acid; and 4 E,6 E,8 E,10 Z,13 Z,16 Z,19 Z- and 4 E,6 E,8 E,10 E,13 Z,16 Z,19 Z-docosaheptaenoic acids from docosahexaenoic acid. All of the newly synthesized fatty acids were characterized by UV, 1 H NMR and mass spectroscopy. These new products represent the first examples of directed conjugation of methylene interrupted double bond systems. The products can be synthesized in gram quantities and in high yields (>50%). Interestingly, it did not prove possible to synthesize fatty acids having a triene group near the carboxyl group even using mild conditions and different synthetic approaches. Once initiated, the isomerization always continued until a tetraene group was formed. Because of the sensitivity of the tetraene group to light, these fatty acids have the potential for being used in tracking fatty acid movements in cells employing fluorescence techniques and in UV light-induced cross linking to membrane proteins.

Synthesis of Long Chain 2‐Alkyl‐1‐(2‐hydroxyethyl)‐2‐imidazolines under Microwave in Solvent‐Free Conditions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Long Chain 2-Alkyl-1-(2-hydroxyethyl)-2-imidazolines under Microwave in Solvent-Free Conditions

An efficient method for the synthesis of long chain 2-alkyl-1-(2-hydroxyethyl)-2-imidazolines, and their amide precursors, by condensing aminoethylethanolamine and several fatty acids under non-solvent microwave irradiation using CaO as support, is described. Products were obtained in good yields and high purity in a few minutes, in both multimode microwave and monomode microwave oven. Evidences of non-thermal microwave effects are given.

Synthesis of Long Chain Branched Polypropylene with Relatively Well-Defined Molecular Structure

Synthesis of Long Chain Branched Polypropylene with Relatively Well-Defined Molecular Structure