Linear Dicarboxylic Acids Research Articles

Thin sensitive organic membranes on selective iron-ion sensors

The organic supramolecular compound synthesized from pyrochatechol units bound in the α-position of a linear dicarboxylic acid (AE6) previously used as a stable chelate iron(III) in solution is applied in this work as an ionophoric reagent on ion-sensitive field-effect transistor (ISFET) and electrolyte—insulator—semiconductor (EIS) structures for iron detection. The surface gate oxide (SiO 2) sensitization of sensors was performed, using three deposition methods: chemical grafting to obtain an AE6 monolayer, deposition by vacuum sublimation of an AE6 thin film and incorporation in a polysiloxane gel membrane. Classical electrochemical measurements were made to test the sensitivity towards iron of the AE6 membranes, in EIS and ISFET structures. A Nernstian sensitivity, a good selectivity and a long lifetime were obtained for the evaporated layer and the gel membranes.

ChemInform Abstract: Regio‐ and Stereoselective Functionalization of Linear Dicarboxylic Acid Derivatives. A Sequential Aldol‐Lactonization Strategy for the Synthesis of (‐)‐Roccellaric Acid, (‐)‐Protolichesterinic Acid, and (‐) ‐Methylenolactocin.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Regio- and Stereoselective Functionalization of Linear Dicarboxylic Acid Derivatives. A Sequential Aldol-Lactonization Strategy for the Synthesis of (-)-Roccellaric Acid, (-)-Protolichesterinic Acid, and (-)-Methylenolactocin

Regio- and Stereoselective Functionalization of Linear Dicarboxylic Acid Derivatives. A Sequential Aldol-Lactonization Strategy for the Synthesis of (-)-Roccellaric Acid, (-)-Protolichesterinic Acid, and (-)-Methylenolactocin

Polarization and Internal Electric Field in Aromatic Polyamides Based on m-Xylylenediamine with Linear Aliphatic Dicarboxylic Acids

Polarization reversal and internal electric field were studied for the aromatic polyamides of m-xylylenediamine (MXD) with linear aliphatic dicarboxylic acids in which the number of methylene groups is in the range of 4−10. Polarization reversal was measured for all MXD polyamides at room temperature and at a temperature just above the glass transition temperature (Tg). Large polarization was measured for the polyamides with odd numbers of methylene groups in a dicarboxylic acid unit poled at temperatures above Tg. Internal electric field was measured from the electrochromic spectrum shift and broadening of the probe molecule of 4-(dimethylamino)-4‘-nitrostilbene in the polyamides with even numbers of methylene groups in a dicarboxylic acid unit. Large internal electric field was measured for the samples in which the remanent polarization measured from the polarization reversal is small. The large internal electric field is mainly ascribed to the space charges created by the injected charges. Upon thermal...

Escherichia coli fumarase A catalyzes the isomerization of enol and keto oxalacetic acid.

Fumarase A, a product of the fumA gene of Escherichia coli, has been found to catalyze the isomerization of enol to keto oxalacetic acid (OAA) in addition to catalyzing the fumarase reaction. The kcat/Km for the isomerization is almost identical to that for the fumarase reaction. The isomerization reaction apparently takes place at the same active site as the fumarase reaction since both reactions show a similar sensitivity to inactivation by O2, both reactions are strongly inhibited by 2-hydroxy-3-nitropropionate, and the isomerization reaction is inhibited by fumarate and malate. The isomerization requires the presence of a [4Fe-4S] or [3Fe-4S] cluster, perhaps for structural rather than catalytic reasons. Hydration of enol OAA to the gem diol has been ruled out as a possible mechanism of isomerization on the basis of the preservation of the oxygen on carbon 2 and the position of protonation on carbon 3. The isomerization is not stereospecific in the position of protonation at carbon 3 but appears to be stereoselective, with protonation preferentially occurring in the 3-pro-S position. Porcine fumarase, isopropyl malate isomerase, and dihydroxyacid dehydratase do not catalyze this isomerization. Fumarase A and aconitase, two enzymes with 4Fe-4S clusters that bind a linear 4-carbon dicarboxylic acid moiety in the trans conformation during their normal hydro-lyase reaction, do catalyze this isomerization.

Occurrence of tightly bound isoprenoid acids in an algal, resistant biomacromolecule: possible geochemical implications

The tightly bound acids, i.e. only released on pyrolysis, of the resistant biomacromolecule PRB L isolated from the outer walls of the microalga Botryococcus braunii L race were analyzed. They are dominated by linear fatty monocarboxylic acids but also comprise a linear dicarboxylic acid and a “pseudo” isoprenoid acid and exhibit a substantial contribution of isoprenoid acids. Such tightly bound acids in a resistant biomacromolecule will be selectively preserved on fossilization and their occurrence suggests that isoprenoid acids tightly bound to kerogens, or occurring in the bitumen of mature rock samples, can be directly inherited. Accordingly, such acids do not necessarily derive from the degradation of isoprenoid biolipids like the phytyl chain of chlorophyll.

New crosslinking agents for vinyl polymers

The synthesis of diallyl esters of linear dicarboxylic acids, and their use as multifunctional crosslinking agents for vinyl polymers, was studied. The number of carbon atoms in the chains of the diacids used varied from 2 to 10 in order to define the effect of the chemical structure on the reactivity of the crosslinkers prepared. Measurements of swelling in chloroform were performed to determine the average molecular weight between crosslinks, thus making an overall evaluation of the crosslinking efficiency. Sorption experiments were also carried out, using aqueous ethanol.

Cross-linking of myosin subfragment 1 and heavy meromyosin by use of vanadate and a bis(adenosine 5'-triphosphate) analogue.

The synthesis of a divalent ATP analogue [3,3'-dithiobis[3'(2')-O-[6-(propionylamino)hexanoyl]adenosine 5'-triphosphate] (bis22ATP)] is described in which two molecules of ATP are linked via esterification of their 3'(2')-hydroxyls to the linear dicarboxylic acid 3,3'-dithiobis[N-(5-carboxypentyl)-propionamide] [[HO2C(CH2)5NHC(O)(CH2)2S-]2]. This linkage introduces 22 atoms (a maximum of approximately 2.8 nm) between the ribose oxygens of two ATP molecules. Myosin subfragment 1 (SF1) or heavy meromyosin (HMM) readily cleave bis22ATP to bis22ADP. Upon subsequent addition of excess vanadate ion, both enzymes are rapidly inactivated by formation of a stable vanadate-bis22ADP complex at the active site. By adjustment of the reaction conditions, dimers of SF1 or HMM, both cross-linked with bis22ADP-vanadate, could be prepared. Dimers of SF1 could be separated from monomers by sucrose gradient centrifugation but not by gel filtration. These observations imply that the average Stokes radius of the dimer approximates that of the monomer, a result predicted only for monomers linked approximately side by side. Conversely, dimers of HMM were separated from HMM monomers by gel filtration, reflecting an increase in their Stokes radii. This increase, however, prevented resolution of HMM dimers from monomers by sucrose gradient centrifugation. These results and the molecular dimensions of bis22ATP suggest that the 3'-(2')-hydroxyl of ATP is no more than 1.3 nm from the surface of myosin and suggest further in the simplest interpretation that the active site is most likely located near the middle of the heads of myosin. Analytical sedimentation velocity experiments were performed in order to compare the sedimentation coefficient (s0(20),w) of the SF1 dimer formed by cross-linking to values predicted from ellipsoidal models of the dimer. The observed s0(20),w of the dimer was much closer to the range predicted for a side-to-side arrangement of SF1 monomers than the range predicted for two monomers linked end to end, a result consistent with the active site location suggested above. During the course of these experiments, unmodified SF1 was used as a control, and its sedimentation behavior was reexamined. We have corroborated the finding that the s0(20),w displayed by SF1 can be affected to a limited extent by the particular experimental parameters employed during centrifugation [Morel, J. E., & Garrigos, M. (1982) Biochemistry 21, 2679-2686].(ABSTRACT TRUNCATED AT 400 WORDS)

The stepwise aqueous alkaline permanganate oxidation of Irati formation shale kerogen and of its reaction product with N-bromosuccinimide

The stepwise aqueous alkaline permanganate oxidation of Irati shale kerogen gave a mixture of carboxylic acids identified (as their methyl esters) as series of linear monocarboxylic (C 8–C 28), dicarboxylic (C 6–C 22), isoprenoidal monocarboxylic (C 10, C 11, C 14, C 15, C 17), aromatic di-(1 isomer), tri-(1 isomer), tetra-(3 isomers), and pentacarboxylic acids (in lower yields) as well as one hopanoic acid (C 31-17αH, 21βH). Under the same oxidation conditions, kerogen preliminarily treated with N-bromosuccinimide (NBS) gave a larger range of compounds. In addition to the monocarboxylic, dicarboxylic and isoprenoidal compounds mentioned above, three aromatic dicarboxylic (phthalic, isophthalic and terephthalic), three isomers of aromatic tricarboxylic, one methylbenzene dicarboxylic, three methylbenzene tricarboxylic, 3,3-dimethyl-pentanedioic, 4,4-dimethyl-hexanedioic, δ-methyl-heptanedioic and brominated aromatic di-, tri- and tetracarboxylic acids were identified. Treatment with NBS caused a relative increase in the oxidation yields of aromatic and linear dicarboxylic acids, indicating that bromination directed cleavage to certain sites, producing structures which could not be obtained by direct oxidation with potassium permanganate. The method may prove useful in the study, by oxidation, of the structure of kerogens.

ChemInform Abstract: SULFENYLATED CYCLIC β‐KETO ESTERS AND CYCLIC β‐DIKETONES; SYNTHESIS AND REACTIONS WITH NUCLEOPHILES

AbstractDie 2‐Oxocycloalkancarbonsäureester (I) reagieren mit Phenylsulfenylchlorid unter Bildung der α‐sulfenylierten Produkte (II), die regiospezifisch in die Dicarbonsäuren (IIIa) (Methode A), Monocarbonsäureester (IIIb) und (IIIc) (Methode B) bzw. Diester (IIId) und (IIIe) (Methode C) umgewandelt werden.

Copolyamides derived from brassylic acid

AbstractPolyamides were prepared from C6 to C12 diamines with brassylic acid, a linear C13 dicarboxylic acid, derived from Crambe seed oil. One distinct characteristic of these polymers is their low moisture adsorption as compared to nylon 66 and nylon 6. To modify the properties of these nylons, multi‐component copolyamides were prepared from hexamethylene diamine and mixtures of brassylic acid with adipic, terephthalic, or isophthalic acids. It was found that the melting points of the co‐polyamides were changed by the choice and the levels of the diacids used. The melting point‐composition curves all show a eutectic minimum. The glass transition temperature of nylon 6,13 is also changed by the incorporation of other diacids. Water adsorption of nylon 6,13 increases with increased substitution of brassylic acid by other diacids in the order of adipic > isophthalic ≥ terephthalic. Mechanical properties of some copolyamides are in the same range as the commercial nylon 11 and nylon 12. The low moisture absorption, reduced fabrication temperature, and the wide range of properties obtainable through copolymerization make copolyamides derived from brassylic acid potentially suitable as specialty tubing, powder coatings, and molded machine parts. They will be commercially viable when brassylic acid becomes available on a large scale and is competitively priced.

Sulfenylated cyclic β‐keto esters and cyclic β‐diketones; synthesis and reactions with nucleophiles

AbstractQuenching the enolates of cyclic β‐diketones or 2‐oxocycloalkanecarboxylates with phenylsulfenyl chloride or methylsulfenyl chloride produces the corresponding x‐sulfenylated products. Nucleophilic attack on these x‐sulfenylated 1,3‐dicarbonyl compounds produces regiospecific sulfenylated linear dicarboxylic acids, acid esters, diesters or oxo esters suitable for further chemical transformation, this has been demonstrated in the synthesis of the queen substance of the honoy bee. In some cases recyclization of the intermediate enolates was observed to regiospecific sulfenylated cyclohexenones.

Dilute Solution Viscoelasticity of Simple Ionic Polymers—A Theory for Charged Bead-Spring Models

As part of a comprehensive study of the viscoelastic properties of ionic polymers, a theoretical investigation of the dilute solution viscoelasticity of simple ionic polymers was undertaken. The bead-spring model of Rouse was modified to include electrostatic charges in the beads. For the two simplest cases of this model (the elastic dumbbell and the three bead-two spring assembly), the diffusion equation for the distribution function of bead separation in shearing flow was formulated. Numerical solutions were obtained for a range of values of the charge and spring parameters. The values were chosen to correspond to real polymers for which the charged bead-spring model would be appropriate, such as linear dicarboxylic acids and polymeric zwitterions for the dumbbell, and linear triacids for the three bead model. It was found that the effect of ions can be described by simple multiplicative shifts in the relaxation times of the uncharged material. For like-charged dumbbells, both the relaxation time and the intrinsic viscosity increase; for oppositely-charged dumbbells, both of these functions decrease in value. For the three bead model, the intrinsic viscosity and both of the relaxation times increase. In addition, the ratio of the two relaxation times increases, indicating a broadening in the distribution of relaxation times.

Synthesis of nylon-like oligoamides

We report syntheses of oligoamides that consist of oligomers of 6-aminohexanoic acid condensed with a central linear dicarboxylic acid or diamine.