Search results for "Dicarboxylic Acid"
showing 10 items of 75 documents
High efficiency joint CZE determination of sugars and acids in vegetables and fruits
2012
In this work, an improved CE method for the medium-throughput determination of main organic acids (oxalate, malate, citrate), the amino acid glutamate and the sugars fructose, glucose and sucrose in several food matrices is described. These compounds have been identified as key components in the taste intensity of fruit and vegetable crops. Using a running buffer with 20 mM 2,6-pyridine dicarboxylic acid pH 12.1 and 0.1% hexadimethrine bromide, replacing it every 5 h to avoid pH decrease, and optimizing capillary conditioning between runs with 58 mM SDS during 2 min at 20 psi, it is possible to effectively quantify these compounds while increasing medium throughput repeatability. This proce…
Isoniazid cocrystallisation with dicarboxylic acids: vapochemical, mechanochemical and thermal methods
2016
Cocrystallisation with a series of related compounds allows for the exploration of trends and limitations set by structural differences between these compounds. In this work, we investigate how the length of a dicarboxylic acid influences the outcome of cocrystallisation with isoniazid. We have performed a systematic study on the mechanochemical, thermal and solvent vapour-assisted cocrystallisation of aliphatic dicarboxylic acids (C3–C10) with isoniazid. Our results demonstrate that the rate of mechanochemical and vapour-assisted cocrystallisation depends on the acid chain length and shows alternation between odd- and even-chain acids. The results of thermal cocrystallisation showed that t…
A series of lanthanide(iii) metal-organic frameworks derived from a pyridyl-dicarboxylate ligand: single-molecule magnet behaviour and luminescence p…
2020
The reactions of LnIII ions with a versatile pyridyl-decorated dicarboxylic acid ligand lead to the formation of a series of novel three-dimensional (3D) Ln-MOFs, [Ln3(pta)4(Hpta)(H2O)]·xH2O (Ln = Dy (1), Eu (2), Gd (3), Tb (4), H2pta = 2-(4-pyridyl)-terephthalic acid, x = 6 for 1, 2.5 for 2, 1.5 for 3 and 2 for 4). The Ln3+ ions act as nine-coordinated muffin spheres, linking to each other to generate trinuclear {Ln3(OOC)6N2} SBUs, which are further extended to be interesting 3D topological architectures. To the best of our knowledge, the Dy-MOF exhibits zero-field single-molecule magnet (SMM) behaviour with the largest effective energy barrier among the previously reported 3D MOF-based Dy…
Bicyclo[2.2.2]octane-1,4-dicarboxylic acid: towards transparent metal–organic frameworks
2017
The preparation of transparent porous materials can offer a different access towards the study of molecules under solid confined space. Metal-organic frameworks represent a unique opportunity due to their tunable pore size, however aromatic linkers present strong absorption and reduce the transparency. Herein, we report the first example of a MOF with bicyclic organic dicarboxylic linkers and its use as a solid solvent.
Production of Dicarboxylic Acids and Flagrances by Yarrowia lipolytica
2013
Yeasts are excellent biocatalysts in the field of alkane and fatty acids transformation into dicarboxylic acids and lactones. Their ability to produce some diacids through simple, less expensive and more environment friendly routes than chemical pathways and to produce particular diacids (e.g. unsaturated ones) but also to transform natural substrates into lactones with a natural label has made them the subject of many researches. Although Candida species were often first studied, the development of genetic tools, the knowledge of the genome and some genomic and biotechnological particularities of Yarrowia lipolytica resulted to interesting developments with this species. This chapter aims …
Cyclodextrins in Polymer Synthesis: Synthesis and Influence of Methylatedβ-Cyclodextrin on the Radical Polymerization Behavior of 1,1-Disubstituted 2…
2001
The chemical and enzymatic hydrolyses of 1,1-diethoxycarbonyl-2-vinylcyclopropane (1) were investigated. The product of the pig liver esterase (PLE)-catalyzed hydrolysis of 1 is a chiral trans monoester of 2-vinylcyclopropane dicarboxylic acid. New 1,1-disubstituted 2-vinylcyclopropane monomers (2a, b) were synthesized by the esterification of this ester. Methylated β-cyclodextrin was used to complex monomers 2a, b, yielding water-soluble 1 : 1 host/guest complexes. These complexes were polymerized in aqueous media by a free-radical ring-opening mechanism.
Molecular self-assembly on an insulating surface: interplay between substrate templating and intermolecular interactions
2012
We report on molecular self-assembly of biphenyl-4,4'-dicarboxylic acid (BPDCA) on CaCO3(10 (1) over bar4) under ultra-high vacuum conditions. Two-dimensional, ordered islands are obtained upon deposition at room temperature, coexisting with a streaky structure that is ascribed to individual, mobile molecules forming a two-dimensional gas-like phase. High-resolution non-contact atomic force microscopy (NC-AFM) images of the molecular islands reveal an ordered inner structure that is dominated by rows of molecules aligned side by side running along the [(42) over bar 61] crystallographic direction. A detailed analysis of these rows exhibits inter-row distances that are multiples of the calci…
Salt effects on the protonation of l-histidine and l-aspartic acid: a complex formation model
1991
Abstract Protonation constants of l -histidine (histidinate: his − ) and l -aspartic acid (aspartate: asp 2− ) were determined potentiometrically, using the (H + ) glass electrode, in aqueous tetraethylammonium iodide (Et 4 NI), calcium chloride and sodium chloride solutions, at 0 −3 and 10 ⩽, T ⩽, 45 ° C. Differences in protonation constants determined in different salt media were explained by a complex formation model and, according to this model, the presence of the following species was hypothesized: Ca(his) + , CaH(his) 2+ , CaH 2 (his) 3+ Na(his) 0 , H 3 (his)X + , H 2 (his)X 0 , Et 4 N(his) 0 , Et 4 NH(his) + , Ca(asp) 0 , CaH(asp) + , CaH 2 (asp) 2+ , Na(asp) − , NaH(asp) 0 , H 3 (a…
Reaction of lithium enediolates with perfluoroketene dithioacetals. Synthesis of α-trifluoromethyl γ-dicarboxylic acid derivatives
2004
The reaction of perfluoroketene dithioacetals with dianions of carboxylic acids proceeds through the substitution of the vinylic fluoride. The preparative value of this reaction depends strongly on the reaction and work-up conditions, the optimisation of which led to use LDA as a base and multiple extraction techniques. The overall process may be considered as a formal synthesis of α-trifluoromethyl γ-dicarboxylic acid derivatives.
- conformational preference of , -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid
1985
Abstract The 1 H and 13 C nmr spectra of exo , exo -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d 6 or alkaline D 2 O, clearly show that it exists in a boat - chair -conformation with equatorial carboxyl groups, thus being the first case of boat - chair preference of a bicyclo[3.3.1] nonan-9-one due to the presence of exo , exo -2,4- substituents.