scholarly journals Crystalline Structures and Structural Transitions of Copolyamides Derived from 1,4-Diaminobutane and Different Ratios of Glutaric and Azelaic Acids

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 572
Author(s):  
Cristian Olmo ◽  
María Casas ◽  
Juan Martínez ◽  
Lourdes Franco ◽  
Jordi Puiggalí
Keyword(s):  
Dicarboxylic Acids ◽  
Intermediate Structure ◽  
Dilute Solution ◽  
Structure Form ◽  
Polymorphic Transitions ◽  
Melting Temperatures ◽  
Methylene Groups ◽  
Lamellar Crystals ◽  
Multiple Melting ◽  
Defective Crystals

Copolyamides derived from even 1,4-butanediamine and different mixtures of odd dicarboxylic acids with a great difference in the number of methylene groups (i.e., glutaric and azelaic acids with 3 and 7 groups, respectively) have been synthesized, characterized and structurally studied. Calorimetric analyses revealed a complex behavior with multiple melting peaks associated to lamellar reordering and the presence of defective crystals. Equilibrium melting temperatures were evaluated and showed a eutectic behavior with composition. Copolymers were able to crystallize even for samples with comonomer percentages close to 50%. Negative and ringed spherulites from the melt state and small lath-like lamellar crystals from dilute solution crystallizations were attained. Furthermore, calorimetric data pointed out the exclusion of the less abundant monomer from the lattice of the predominant structure. All samples at room temperature showed a similar crystalline structure (form I) defined by two predominant reflections at spacings close to 0.430 and 0.380 nm, which has been related for even-odd nylons with a two-hydrogen bonded structure. Real time synchrotron experiments showed that melt crystallized samples have two polymorphic transitions on heating, which were practically reversible and consequently were also detected during cooling from the melt state. Interestingly, a different behavior was detected among solution crystallized samples and specifically the transition to the intermediate structure (form II) was not detected during heating for samples enriched on the azelate component or more precisely when they were exclusively crystallized in the form I.

Regioselective Chlorination of Centered Methylene Groups in Dicarboxylic Acids

1976 ◽  
Vol 15 (5) ◽  
pp. 306-307 ◽  
Author(s):  
Friedhelm Kämper ◽  
Hans J. Schäfer ◽  
Heinrich Luftmann
Keyword(s):  
Dicarboxylic Acids ◽  
Methylene Groups

Conductimetric titrations of symmetrical aliphatic dicarboxylic acids in solvents pyridine and pyridine–benzene mixtures

1990 ◽  
Vol 68 (3) ◽  
pp. 431-434 ◽  
Author(s):  
Turgut Gündüz ◽  
Esma Kiliç ◽  
Mustafa Tastekin ◽  
Güleren Ozkan
Keyword(s):  
Dielectric Constant ◽  
Hydrogen Bonds ◽  
Titration Curve ◽  
Dicarboxylic Acids ◽  
Dielectric Constants ◽  
Tetrabutylammonium Hydroxide ◽  
End Points ◽  
Titration Curves ◽  
Methylene Groups ◽  
Aliphatic Dicarboxylic Acids

Nine symmetrical aliphatic dicarboxylic acids, namely oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, were titrated conductimetrically with tetrabutylammonium hydroxide in pyridine and pyridine–benzene mixtures ((2 + 1), (1 + 1), (1 + 2), (1 + 3), and (1 + 4)). Titration curves of the acids exhibited two distinct and stoichiometric end-points in media of dielectric constants 13.5, 10.0, 8.2, 6.3, 5.3, and 4.7, respectively. The closer investigations of the titration curves revealed that three factors mainly influence the shapes of the titration curves: dielectric constant of the medium, number of the methylene groups in the acid, and formation of hydrogen bonds between several species. As dielectric constant of the medium decreases, conductivity of the medium also decreases at any point in the titration curve. Increase in the number of methylene groups from one to five decreases conductivity of the medium linearly at the first end-points of the acids, from then the conductivity becomes practically constant in acids having five to eight methylene groups in pyridine and pyridine–benzene mixtures of 2 + 1 and 1 + 1 ratios. Keywords: conductimetric titration in pyridine, conductimetric titration in pyridine–benzene mixtures, symmetrical aliphatic dicarboxilic acids.

scholarly journals Approaches to the Synthesis of Dicarboxylic Derivatives of Bis(pyrazol-1-yl)alkanes

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 413
Author(s):  
Nikita P. Burlutskiy ◽  
Andrei S. Potapov
Keyword(s):  
Potassium Hydroxide ◽  
Oxalyl Chloride ◽  
Dicarboxylic Acids ◽  
Building Blocks ◽  
Acid Chlorides ◽  
Alternative Approach ◽  
Methylene Groups ◽  
Metal Organic ◽  
Superbasic Medium ◽  
Derivatives Of

Carboxylation of bis(pyrazol-1-yl)alkanes by oxalyl chloride was studied. It was found that 4,4′-dicarboxylic derivatives of substrates with electron-donating methyl groups and short linkers (from one to three methylene groups) can be prepared using this method. Longer linkers lead to significantly lower product yields, which is probably due to instability of the intermediate acid chlorides that are initially formed in the reaction with oxalyl chloride. Thus, bis(pyrazol-1-yl)methane gave only monocarboxylic derivative even with a large excess of oxalyl chloride and prolonged reaction duration. An alternative approach involves the reaction of ethyl 4-pyrazolecarboxylates with dibromoalkanes in a superbasic medium (potassium hydroxide–dimethyl sulfoxide) and is suitable for the preparation of bis(4-carboxypyrazol-1-yl)alkanes with both short and long linkers independent of substitution in positions 3 and 5 of pyrazole rings. The obtained dicarboxylic acids are interesting as potential building blocks for metal-organic frameworks.

ChemInform Abstract: REGIOSELECTIVE CHLORINATION OF MIDDLE METHYLENE GROUPS IN DICARBOXYLIC ACIDS

1976 ◽  
Vol 7 (36) ◽  
pp. no-no
Author(s):  
FRIEDHELM KAEMPER ◽  
HANS J. SCHAEFER ◽  
HEINRICH LUFTMANN
Keyword(s):  
Dicarboxylic Acids ◽  
Methylene Groups

scholarly journals Synthesis, Properties, and Biodegradation of Sequential Poly(Ester Amide)s Containing γ-Aminobutyric Acid

2020 ◽  
Vol 21 (10) ◽  
pp. 3674 ◽  
Author(s):  
Yuushou Nakayama ◽  
Kazumasa Watanabe ◽  
Ryo Tanaka ◽  
Takeshi Shiono ◽  
Norioki Kawasaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Decomposition ◽  
Monomer Unit ◽  
Dicarboxylic Acids ◽  
Aminobutyric Acid ◽  
High Melting ◽  
Thermal And Mechanical Properties ◽  
Melting Temperatures ◽  
Synthesis Properties ◽  
Derivatives Of

Poly(ester amide)s are attracting attention because they potentially have excellent thermal and mechanical properties as well as biodegradability. In this study, we synthesized a series of novel poly(ester amide)s by introducing γ-aminobutyric acid (GABA) regularly into polyesters, and investigated their properties and biodegradabilities. GABA is the monomer unit of biodegradable polyamide 4 (PA4). The new poly(ester amide)s were synthesized from the reaction of ammonium tosylate derivatives of alkylene bis(γ-aminobutylate) and p-nitrophenyl esters of dicarboxylic acids. All the obtained polymers showed relatively high melting temperatures (Tm). Their thermal decomposition temperatures were improved in comparison with that of PA4 and higher enough than their Tm. The poly(ester amide)s exhibited higher biodegradability in seawater than the corresponding homopolyesters. Their biodegradabilities in activated sludge were also studied.

Application of Modified Bloch Waves to Image Analysis of Extended Linear Defects

1974 ◽  
Vol 32 ◽  
pp. 402-403
Author(s):  
S. Nakahara ◽  
D. M. Maher
Keyword(s):  
Image Analysis ◽  
Computational Approach ◽  
Dislocation Loops ◽  
Plane Wave Expansion ◽  
Dynamical Equations ◽  
Bloch Waves ◽  
Linear Defects ◽  
Imperfect Crystal ◽  
Localized Defects ◽  
Defective Crystals

Since Head first demonstrated the advantages of computer displayed theoretical intensities from defective crystals, computer display techniques have become important in image analysis. However the computational methods employed resort largely to numerical integration of the dynamical equations of electron diffraction. As a consequence, the interpretation of the results in terms of the defect displacement field and diffracting variables is difficult to follow in detail. In contrast to this type of computational approach which is based on a plane-wave expansion of the excited waves within the crystal (i.e. Darwin representation ), Wilkens assumed scattering of modified Bloch waves by an imperfect crystal. For localized defects, the wave amplitudes can be described analytically and this formulation has been used successfully to predict the black-white symmetry of images arising from small dislocation loops.

Computer averaging of lattice images of poly-4-methyl-pentene-1 (P4mp1): Noise created artifacts

1987 ◽  
Vol 45 ◽  
pp. 388-389
Author(s):  
P. Pradère ◽  
J.F. Revol ◽  
R. St. John Manley
Keyword(s):  
Low Dose ◽  
Polymer Concentration ◽  
Processing System ◽  
Limiting Factor ◽  
Dilute Solution ◽  
New Techniques ◽  
Dose Unit ◽  
Lattice Images ◽  
Dose Imaging ◽  
Imaging Conditions

Although radiation damage is the limiting factor in HREM of polymers, new techniques based on low dose imaging at low magnification have permitted lattice images to be obtained from very radiation sensitive polymers such as polyethylene (PE). This paper describes the computer averaging of P4MP1 lattice images. P4MP1 is even more sensitive than PE (total end point dose of 27 C m-2 as compared to 100 C m-2 for PE at 120 kV). It does, however, have the advantage of forming flat crystals from dilute solution and no change in d-spacings is observed during irradiation.Crystals of P4MP1 were grown at 60°C in xylene (polymer concentration 0.05%). Electron microscopy was performed with a Philips EM 400 T microscope equipped with a Low Dose Unit and operated at 120 kV. Imaging conditions were the same as already described elsewhere. Enlarged micrographs were digitized and processed with the Spider image processing system.

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